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1. Critical behavior of the Anderson model on the Bethe lattice via a large-deviation approach

Author

Giulio Biroli, Alexander K. Hartmann, Marco Tarzia, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Théorique de la Matière Condensée (LPTMC), and Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Statistical Mechanics (cond-mat.stat-mech), FOS: Physical sciences, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Condensed Matter - Statistical Mechanics
Abstract

We present a new large-deviation approach to investigate the critical properties of the Anderson model on the Bethe lattice close to the localization transition in the thermodynamic limit. Our method allows us to study accurately the distribution of the local density of states (LDoS) down to very small probability tails as small as $10^{-50}$ which are completely out of reach for standard numerical techniques. We perform a thorough analysis of the functional form and of the tails of the probability distribution of the LDoS which yields for the first time a direct, transparent, and precise estimation of the correlation volume close to the Anderson transition. Such correlation volume is found to diverge exponentially when the localization is approached from the delocalized regime, in a singular way that is in agreement with the analytic predictions of the supersymmetric treatment., Comment: 11 pages, 6 figures. arXiv admin note: substantial text overlap with arXiv:1810.07545

Published
2022

2. Duality in quantum transport models

Author

Cristian Giardinà, Jorge Kurchan, Rouven Frassek, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
QC1-999, [PHYS.MPHY]Physics [physics]/Mathematical Physics [math-ph], General Physics and Astronomy, Duality (optimization), FOS: Physical sciences, 01 natural sciences, Quantum transport, Theoretical physics, 0103 physical sciences, Thermal, FOS: Mathematics, 0101 mathematics, 010306 general physics, Quantum, Condensed Matter - Statistical Mechanics, Mathematical Physics, Physics, Quantum Physics, Statistical Mechanics (cond-mat.stat-mech), 010102 general mathematics, Probability (math.PR), Mathematical Physics (math-ph), [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Homogeneous space, Quantum Physics (quant-ph), Mathematics - Probability
Abstract

We develop the `duality approach', that has been extensively studied for classical models of transport, for quantum systems in contact with a thermal `Lindbladian' bath. The method provides (a) a mapping of the original model to a simpler one, containing only a few particles and (b) shows that any dynamic process of this kind with generic baths may be mapped onto one with equilibrium baths. We exemplify this through the study of a particular model: the quantum symmetric exclusion process introduced in [D. Bernard, T. Jin, Phys. Rev. Lett. 123, 080601 (2019)]. As in the classical case, the whole construction becomes intelligible by considering the dynamical symmetries of the problem., 8 pages; v2: presentation improved, references added

Published
2021

3. Contact angle dynamics on pseudo-brushes: Effects of polymer chain length and wetting liquid

Author

Kristina Davitt, Romain Lhermerout, Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Mécanique, Matière Molle, Morphogénèse, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
polymer brush, viscoelastic dissipation, Materials science, contact angle hysteresis, 02 engineering and technology, 010402 general chemistry, 01 natural sciences, Viscoelasticity, Physics::Fluid Dynamics, Contact angle, chemistry.chemical_compound, Colloid and Surface Chemistry, Wetting dynamics, Composite material, chemistry.chemical_classification, Polydimethylsiloxane, Polymer, Dissipation, 021001 nanoscience & nanotechnology, 0104 chemical sciences, Condensed Matter::Soft Condensed Matter, Hysteresis, [CHIM.POLY]Chemical Sciences/Polymers, chemistry, Polymerization, [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Wetting, 0210 nano-technology
Abstract

International audience; In this study we investigate the exceptional wetting properties of thin polymer layers. Here the polymer is deposited in the form of a polydimethylsiloxane (PDMS) pseudo-brush and contact line dynamics are measured for both varying polymerization index and nature of the partially-wetting liquid. We use a custom-built experimental apparatus to explore wetting dynamics over 7 decades of velocity, with a precision of 0.01 • in variations of the contact angle. We show that the presence of a pseudo-brush can result in a remarkably small contact angle hysteresis as well as the appearance of an additional source of dissipation and that these two phenomena depend on the chain length and the wetting liquid. Qualitatively, we interpret these findings as the ability of the layer to behave as a liquid-like interface, and quantitatively by using a simple model of viscoelastic dissipation in soft thin films.

Published
2019

4. Quasipatterns versus superlattices resulting from the superposition of two hexagonal patterns

Author

Stéphan Fauve, Gérard Iooss, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Physique Non-Linéaire, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Institut Universitaire de France (IUF), and Ministère de l'Education nationale, de l’Enseignement supérieur et de la Recherche (M.E.N.E.S.R.)

Subjects
Strategy and Management, Superlattice, [MATH.MATH-DS]Mathematics [math]/Dynamical Systems [math.DS], Asymptotic expansion, 02 engineering and technology, Instability, law.invention, Bifurcations, Superposition principle, [NLIN.NLIN-PS]Nonlinear Sciences [physics]/Pattern Formation and Solitons [nlin.PS], 0203 mechanical engineering, law, Quantum mechanics, Media Technology, [MATH.MATH-AP]Mathematics [math]/Analysis of PDEs [math.AP], General Materials Science, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Faraday cage, Nonlinear Sciences::Pattern Formation and Solitons, Marketing, Physics, Forcing (recursion theory), Hexagonal crystal system, Quasicrystal, 35B32, 35C20, 52C23, 37S40, Nonlinear effects, 020303 mechanical engineering & transports, quasicrystals
Abstract

International audience; We present a short review of the experimental observations and mechanisms related to the generation of quasipatterns and superlattices by the Faraday instability with two-frequency forcing. We show how two frequency forcing makes possible triad interactions that generate hexagonal patterns, twelvefold quasipatterns or superlattices that consists of two hexagonal patterns rotated by an angle α relative to each other. We then consider which patterns could be observed when α does not belong to the set of prescribed values that give rise to periodic superlattices. Using the Swift-Hohenberg equation as a model, we find that quasipattern solutions exist for nearly all values of α . However, these quasipatterns have not been observed in experiments with the Faraday instability for α 6 = π/ 6. We discuss possible reasons and mention a simpler framework that could give some hint about this problem.; Nous présentons une courte revue des observations expérimentales et des mécanismes qui ont permis d'engendrer des structures quasi-cristallines à l'aide de l'instabilité de Faraday sous l'effet d'une excitation périodique comportant deux fréquences. Nous montrons comment l'excitation à excitation`excitation à deux fréquences permet d'obtenir des triades de vecteurs d'onde résonantes qui induisent la formation de structures hexagonales, de structures quasi-cristallines dodécagonales ou de super-réseaux résultant de la superposition de deux réseaux d'hexagones tournés l'un par rapport à rapport`rapport à l'autre d'un angle α. Nous considérons ensuite quelles sont les structures obtenues lorsque α ne prend pas la série de valeurs discrètes conduisant à conduisant`conduisant à un super-réseau périodique. Nous montrons sur l'´ équation de Swift-Hohenberg qu'il existe dans ce cas des solutions à solutions`solutions à symétrie quasi-cristalline pour presque toutes les valeurs de α. Nous discutons les raisons possibles pour lesquelles ces solutions n'ont pas été observées expérimentalement pour α = π/6 et nous mentionnons un cadre plus simple qui permettrait d'éclaircir cette question.

Published
2019

5. Perceptual decision making: Biases in post-error reaction times explained by attractor network dynamics: Reaction time Accuracy PES PEQ PES PEQ C B D

Author

Kevin Berlemont, Jean-Pierre Nadal, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Biophysique et Neuroscience Théoriques, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Centre d'Analyse et de Mathématique sociales (CAMS), and École des hautes études en sciences sociales (EHESS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Correctness, Computer science, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Decision Making, Models, Neurological, FOS: Physical sciences, post-error slowing, 03 medical and health sciences, Discrimination, Psychological, 0302 clinical medicine, Memory, Attractor, Reaction Time, Computer Simulation, [PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn], Physics - Biological Physics, Research Articles, Attractor network, 030304 developmental biology, 0303 health sciences, Sequence, Repetition (rhetorical device), business.industry, [SCCO.NEUR]Cognitive science/Neuroscience, General Neuroscience, post- error slowing, Disordered Systems and Neural Networks (cond-mat.dis-nn), Extension (predicate logic), Condensed Matter - Disordered Systems and Neural Networks, Perceptual decision, Nonlinear Dynamics, Biological Physics (physics.bio-ph), Dynamics (music), FOS: Biological sciences, Quantitative Biology - Neurons and Cognition, Synapses, reaction times, [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], Neurons and Cognition (q-bio.NC), Perception, Neural Networks, Computer, Artificial intelligence, attractor networks, business, perceptual decision making, Algorithms, Psychomotor Performance, 030217 neurology & neurosurgery
Abstract

Perceptual decision-making is the subject of many experimental and theoretical studies. Most modeling analyses are based on statistical processes of accumulation of evidence. In contrast, very few works confront attractor network models' predictions with empirical data from continuous sequences of trials. Recently however, numerical simulations of a biophysical competitive attractor network model have shown that such a network can describe sequences of decision trials and reproduce repetition biases observed in perceptual decision experiments. Here we get more insights into such effects by considering an extension of the reduced attractor network model of Wong and Wang (2006), taking into account an inhibitory current delivered to the network once a decision has been made. We make explicit the conditions on this inhibitory input for which the network can perform a succession of trials, without being either trapped in the first reached attractor, or losing all memory of the past dynamics. We study in detail how, during a sequence of decision trials, reaction times and performance depend on nonlinear dynamics of the network, and we confront the model behavior with empirical findings on sequential effects. Here we show that, quite remarkably, the network exhibits, qualitatively and with the correct order of magnitude, post-error slowing and post-error improvement in accuracy, two subtle effects reported in behavioral experiments in the absence of any feedback about the correctness of the decision. Our work thus provides evidence that such effects result from intrinsic properties of the nonlinear neural dynamics.SIGNIFICANCE STATEMENTMuch experimental and theoretical work is being devoted to the understanding of the neural correlates of perceptual decision-making. In a typical behavioral experiment, animals or humans perform a continuous series of binary discrimination tasks. To model such experiments, we consider a biophysical decision-making attractor neural network, taking into account an inhibitory current delivered to the network once a decision is made. Here we provide evidence that the same intrinsic properties of the nonlinear network dynamics underpins various sequential effects reported in experiments. Quite remarkably, in the absence of feedback on the correctness of the decisions, the network exhibits post-error slowing (longer reaction times after error trials) and post-error improvement in accuracy (smaller error rates after error trials).

Published
2018

6. Ultralow Threshold Polariton Condensate in a Monolayer Semiconductor Microcavity at Room Temperature

Author

Timothy Chi Hin Liew, Xue Liu, Weijie Zhao, Jiaxin Zhao, Carole Diederichs, Antonio Fieramosca, Daniele Sanvitto, Qihua Xiong, Rui Su, Wei Du, MajuLab (UMI 3654), National University of Singapore (NUS)-Sorbonne Université (SU), Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and School of Physical and Mathematical Sciences

Subjects
Materials science, Exciton, [SDV]Life Sciences [q-bio], Nanophotonics, Physics::Optics, FOS: Physical sciences, Bioengineering, 02 engineering and technology, Physics [Science], Polariton, General Materials Science, ComputingMilieux_MISCELLANEOUS, Condensed Matter::Quantum Gases, Transition-metal Dichalcogenides, Condensed Matter - Materials Science, business.industry, Condensed Matter::Other, Strong Coupling, Mechanical Engineering, Materials Science (cond-mat.mtrl-sci), General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, Semiconductor, Quasiparticle, Optoelectronics, 0210 nano-technology, Ground state, business, Lasing threshold, Physics - Optics, Coherence (physics), Optics (physics.optics)
Abstract

Atomically thin transition metal dichalcogenides possess valley dependent functionalities that are usually available only at crogenic temperatures, constrained by various valley depolarization scatterings. The formation of exciton polaritons by coherently superimposing excitons and microcavity photons potentially harnesses the valley polarized polariton polariton interactions for novel valleytronics devices. Robust EPs have been demonstrated at room temperature in TMDs microcavity, however, the coherent polariton lasing and condensation remain elusive. Herein, we demonstrate for the first time the realization of EP condensation in a TMD microcavity at room temperature. The continuous wave pumped EP condensation and lasing with ultralow thresholdsis evidenced by the macroscopic occupation of the ground state, that undergoes a nonlinear increase of the emission and a continuous blueshift, a build up of spatial coherence, and a detuning-controlled threshold. Our work presents a critically important step towards exploiting nonlinear polariton polariton interactions and polaritonic devices with valley functionality at room temperature., Comment: 21 pages, 5 figures

Published
2021

7. Surface waves along liquid cylinders. Part 2. Varicose, sinuous, sloshing and nonlinear waves

Author

Stéphane Perrard, Chi-Tuong Pham, Gabriel Le Doudic, Matière et Systèmes Complexes (MSC), Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris-Saclay, Laboratoire Interdisciplinaire des Sciences du Numérique (LISN), Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), COuplages Multiphysiques Et Transferts (COMET), Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Mécanique-Energétique (M.-E.), and Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut National de Recherche en Informatique et en Automatique (Inria)-CentraleSupélec-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)

Subjects
dispersive regime, Slosh dynamics, Context (language use), 01 natural sciences, Leidenfrost effect, 010305 fluids & plasmas, experimental set up, Physics::Fluid Dynamics, rectangular channel, dispersion relations, [SPI]Engineering Sciences [physics], Inviscid flow, Dispersion relation, 0103 physical sciences, 010306 general physics, drops, Physics, [PHYS]Physics [physics], saint venant equation, Mechanical Engineering, plateau borders, Mechanics, Condensed Matter Physics, gravity capillary waves, Nonlinear system, Mechanics of Materials, Surface wave, solitary waves, liquid cylinders, Soap film
Abstract

No comment; International audience; © 2021 The Author(s). Published by Cambridge University Press.Gravity-capillary waves propagating along extended liquid cylinders in the inviscid limit are studied in the context of experiments on sessile cylinders deposited upon superhydrophobic substrates, with tunable geometries. In Part 1 of this work (Pham et al., J. Fluid Mech., vol. 891, 2020, A5), we characterised the non-dispersive regime of the varicose waves. In this second part, we characterise the varicose waves in the dispersive regime, as well as the sinuous and the sloshing modes. We numerically study the shape function of the system (the counterpart of the standard function of the dispersion relation of a gravity-capillary wave in a rectangular channel) and the cutoff frequencies of the sloshing modes, and show how they depend on the geometry of the substrate. A reduced-gravity effect is evidenced and the transition between a capillary- and a gravity-dominated regime is expressed in terms of an effective Bond number and an effective surface tension. Semiquantitative agreement is found between the theoretical computations and the experiments. As a consequence of these results, resorting to the inviscid section-averaged Saint-Venant equations, we propose a Korteweg-de Vries equation with adapted coefficients that governs the propagation of localised nonlinear waves. We relate these results to the propagation of depression solitons observed in our experimental set-up and along Leidenfrost cylinders levitating above a hot substrate (Perrard et al., Phys. Rev. E, vol. 92, 2015, 011002(R)). We extend our derivation of the Korteweg-de Vries equation to solitary-like waves propagating along Plateau borders in soap films, evidenced by Argentina et al. (J. Fluid. Mech., vol. 765, 2015, pp. 1-16).

Published
2021

8. Marvels and pitfalls of the Langevin algorithm in noisy high-dimensional inference

Author

Lenka Zdeborová, Florent Krzakala, Chiara Cammarota, Pierfrancesco Urbani, Giulio Biroli, Stefano Sarao Mannelli, Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Mathematics, King's College London, Strand, London WC2R 2LS, United Kingdom, affiliation inconnue, The Simons Foundation (#454935 GB), ANR-10-LABX-0039,PALM,Physics: Atoms, Light, Matter(2010), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
FOS: Computer and information sciences, Computer Science - Machine Learning, Computer science, QC1-999, Posterior probability, General Physics and Astronomy, Inference, FOS: Physical sciences, Context (language use), Machine Learning (stat.ML), Mathematics - Statistics Theory, Statistics Theory (math.ST), Residual, algorithms, 01 natural sciences, Measure (mathematics), 010305 fluids & plasmas, Machine Learning (cs.LG), Statistics - Machine Learning, 0103 physical sciences, Statistical inference, FOS: Mathematics, risk landscape, 010306 general physics, [PHYS]Physics [physics], inference, Conjecture, Physics, Message passing, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, 16. Peace & justice, inference, algorithms, risk landscape, Algorithm
Abstract

Gradient-descent-based algorithms and their stochastic versions have widespread applications in machine learning and statistical inference. In this work we perform an analytic study of the performances of one of them, the Langevin algorithm, in the context of noisy high-dimensional inference. We employ the Langevin algorithm to sample the posterior probability measure for the spiked matrix-tensor model. The typical behaviour of this algorithm is described by a system of integro-differential equations that we call the Langevin state evolution, whose solution is compared with the one of the state evolution of approximate message passing (AMP). Our results show that, remarkably, the algorithmic threshold of the Langevin algorithm is sub-optimal with respect to the one given by AMP. We conjecture this phenomenon to be due to the residual glassiness present in that region of parameters. Finally we show how a landscape-annealing protocol, that uses the Langevin algorithm but violate the Bayes-optimality condition, can approach the performance of AMP., 11 pages and 5 figures + appendix

Published
2020

9. Unexpected trapping of swimming microalgae in foam

Author

Roveillo, Quentin, Dervaux, Julien, Wang, Yuxuan, Rouyer, Florence, Zanchi, Drazen, Seuront, Laurent, Elias, Florence, Matière et Systèmes Complexes (MSC (UMR_7057)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), CNRS UMR 7057 - Laboratoire Matières et Systèmes Complexes (MSC) (MSC), Centre National de la Recherche Scientifique (CNRS), Tsinghua University [Beijing], Laboratoire Navier (NAVIER UMR 8205), École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel (UNIV GUSTAVE EIFFEL), Processus d'Activation Sélective par Transfert d'Energie Uni-électronique ou Radiatif (UMR 8640) (PASTEUR), Université Pierre et Marie Curie - Paris 6 (UPMC)-Département de Chimie - ENS Paris, École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS), Laboratoire d’Océanologie et de Géosciences (LOG) - UMR 8187 (LOG), Université de Lille-Université du Littoral Côte d'Opale-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Tsinghua University [Beijing] (THU), École des Ponts ParisTech (ENPC)-Centre National de la Recherche Scientifique (CNRS)-Université Gustave Eiffel, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Institut national des sciences de l'Univers (INSU - CNRS), Matière et Systèmes Complexes (MSC), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Département de Chimie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut de Chimie du CNRS (INC)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Institut national des sciences de l'Univers (INSU - CNRS)-Université du Littoral Côte d'Opale (ULCO)-Université de Lille-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche pour le Développement (IRD [France-Nord])

Subjects
[PHYS]Physics [physics], lipids (amino acids, peptides, and proteins), cardiovascular diseases, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

Massive foam formation in aquatic environments is a seasonal threat that drastically impacts the stability of marine ecosystems. Because liquid foams are known to filter passive solid particles, with large particles remaining trapped by confinement in the network of liquid channels and small particles being freely advected by the gravity-driven flow, we hypothesized that a similar e↵ect could explain the major shifts in phytoplankton populations observed during foaming episodes. The model unicellular motile algae Chlamydomonas reinhardtii (CR) was incorporated in a bio-compatible foam, and the number of cells escaping the foam at the bottom was measured in time. Comparing the escape dynamics of living and dead CR cells, we found that dead cells are totally advected by the liquid flow towards the bottom of the foam, as expected since the CR diameter remains smaller than the typical foam channel diameter. In contrast, living motile CR cells escape the foam at a significantly lower rate: after two hours, up to 60 % of the injected cells may remain blocked in the foam, while 95 % of the initial liquid volume in the foam has been drained out of the foam. Microscopic observation of the swimming CR cells in a chamber mimicking the cross-section of foam internal channels revealed that swimming CR cells accumulate near channels corners. A theoretical analysis based on the probability density measurements in the micro chambers have shown that this trapping at the microscopic scale contributes to explain the macroscopic retention of the microswimmers in the foam.

Published
2020

10. The ping-pong ball water cannon

Author

Andreotti, Bruno, Toutain, Wladimir, Noûs, Camille, El Rhandour-Essmaili, Sofia, Pérignon-Hubert, Guillaume, Daerr, Adrian, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Matière et Systèmes Complexes (MSC (UMR_7057)), and Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
[PHYS.PHYS.PHYS-FLU-DYN]Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn], teaching of research, shock wave, fluid mechanics, Scientific method, hydraulic catapult, liquid projection Mathematical subject classification (2010) 00X99, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], liquid projection, pressure focussing, [PHYS.PHYS.PHYS-ED-PH]Physics [physics]/Physics [physics]/Physics Education [physics.ed-ph]
Abstract

16 pages, 7 figures. En fichiers annexes 4 séquences vidéo accompagnées de légendes.; International audience; Der Kurs "Phy Ex" wurde von Yves Couder an der Universität Paris VII konzipiert und erschaffen, um Experimentalphysik und wissenschaftliche Methodik durch Forschungsprojekte zu vermitteln. Dieser Beitrag präsentiert die Lehrmethode anhand des Projekts zweier Studenten im ersten Semester 2019/2020: die Tischtennisball-Wasserkanone. Ziel dieses Projekts war es, die dem folgenden Experiment zugrundeliegenden physikalischen Mechanismen zu identifizieren: man lasse ein Wasserglas, in welchem ein Tischtennisball schwimmt, senkrecht zu Boden fallen. Gleich nach dem Aufprall wird der Ball hochkatapultiert, mit einer Geschwindigkeit die die Fallgeschwindigkeit deutlich überschreiten kann. Wir geben die von den Studenten durchgeführte Dimensionsanalyse und Größenordnugsabschätzung wieder, und beschreiben dann die sukzessiven Versuchsanordnungen und die daraus gewonnenen Beobachtungen: (1) die Kanone funktioniert nur wenn dem Aufprall ein freier Fall vorausgeht, (2) eine Impulsbilanz basierend auf der Integration des Druckimpulses beim Aufprall sagt die Auswurfsgeschwindigkeit größenordnungsmäßig richtig voraus, und (3) die Impulsübertragung auf den Ball lässt sich durch Rühren der Flüssigkeit oder Erhöhung der Benetzbarkeit des Balls deutlich steigern. Die im Laufe des Projekts formulierte und durch direkte Hochgeschwindigkeitsfotographie bestätigte Erklärung besagt, dass der Ball im freien Fall durch Kapillarkräfte --- oder in sich drehender Flüssigkeit durch den zentralen Unterdruck --- tiefer in die Flüssigkeit gezogen wird, während der sonst dominante Auftrieb vorübergehend aufgehoben ist. Der enorme Überdruck beim Aufprall bewirkt dann eine Rückkehr in Richtung Auftriebsgleichgewicht, bei der der Ball derartig beschleunigt wird, dass er die Flüssigkeit mit hoher Geschwindigkeit verlässt. Der Mechanismus dieser letzten Etappe ist der gleiche, der zur Bildung eines schnellen Flüssigkeitsstrahls beim Zusammenbruch eines Hohlraums in einer Flüssigkeit führt.; The course "Phy Ex" was created by Yves Couder in the Paris VII university to teach experimental physics through projects. In this article, we present this teaching method through a particular project that took place in the autumn semester 2019: the ping-pong ball water cannon. In this experiment, a glass containing water and a floating table tennis ball is dropped from some height to the ground. Following the impact, the ball is ejected vertically upwards at speeds that can be several times the impact speed. We report the student team's initial dimensional and order-of-magnitude analysis, and describe the successive experimental setups that showed (1) that free flight is essential for the phenomenon to occur, (2) that the order of magnitude of the ball ejection momentum is correctly predicted by a momentum balance based on integrating the pressure impulse during impact and (3) that making the ball surface more wettable, or stirring the liquid, drastically increases the momentum transfer. The proposed explanation, confirmed by direct high-speed video observations, is that the immersion depth of the ball increases during free fall due to capillary forces or vortex depression-in the absence of buoyancy-and that the enormous excess pressure on the bottom of the ball during impact drives the ball up towards its buoyancy equilibrium. The transfered momentum is sufficient to expel the ball at high velocity, very similar to the formation of liquid jets in collapsing cavities in liquids.; Yves Couder a créé un enseignement de physique expérimentale par projets, «Phy Ex», à l'université de Paris VII. Cet article présentela méthode d'enseignement à travers le projet d'un binôme d'étudiants au premier semestre 2019/2020: le canon à eau propulsant une balle deping-pong. Le projet consistait à identifier les mécanismes physiques en jeu dans l'expérience suivante: on fait tomber verticalement unverre en plastique contenant de l'eau avec une balle de ping-pong à sa surface. Lorsque le verre percute le sol, la balle de ping-pong estéjectée vers le haut à une vitesse pouvant largement dépasser la vitesse de chute. Nous résumons l'analyse dimensionnelle et d'ordre degrandeur faite par le binôme d'étudiants en amont des expériences. Puis nous décrivons les montages successifs qui montrent (1) que laphase de chute libre précédant l'impact est essentielle dans ce phénomène, (2) que l'ordre de grandeur de la vitesse d'éjection estcorrectement prédit par un bilan de quantité de mouvement basé sur l'intégration du pic de pression résultant de l'impact, et (3) querendre la balle plus mouillante, ou que mettre l'eau en rotation avant la chute, résulte en une augmentation importante de la quantité demouvement transmise à la balle. L'image physique ayant émergé au cours de ce projet, et qui s'appuie également sur des images vidéo prises àl'aide d'une caméra rapide, est que la profondeur d'immersion de la balle augmente pendant la brève période de chute libre par l'actiondes forces capillaires ou par la dépression au cœur d'un vortex en présence de rotation --- la poussée d'Archimède habituellement dominanteétant nulle pendant la chute --- et que la pression considérable sur la partie immergée de la balle pendant la décélération au sol repousse laballe vers son équilibre de flottaison. La quantité de mouvement transmise dans ce processus est alors tellement importante que laballe est expulsée vers le haut à grande vitesse, de la même manière que l'effondrement d'une cavité à la surface d'un liquide conduit à laformation d'un jet rapide au centre.

Published
2020

11. Die Tischtennisball-Wasserkanone

Author

Adrian Daerr, Bruno Andreotti, Wladimir Toutain, Camille Noûs, Guillaume Pérignon-Hubert, Sofia El Rhandour-Essmaili, Mécanique, Matière Molle, Morphogénèse, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Matière et Systèmes Complexes (MSC (UMR_7057)), Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Shock wave, [PHYS.PHYS.PHYS-FLU-DYN]Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn], Buoyancy, shock wave, fluid mechanics, 02 engineering and technology, Impulse (physics), engineering.material, [PHYS.PHYS.PHYS-ED-PH]Physics [physics]/Physics [physics]/Physics Education [physics.ed-ph], Physics::Fluid Dynamics, teaching of research, 0203 mechanical engineering, Scientific method, General Materials Science, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], Physics, [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Mechanics of the fluids [physics.class-ph], Momentum transfer, hydraulic catapult, Fluid mechanics, Mechanics, pressure focussing, Vortex, 020303 mechanical engineering & transports, Mechanics of Materials, Ball (bearing), engineering, Tennis ball, liquid projection Mathematical subject classification (2010) 00X99, liquid projection
Abstract

16 pages, 7 figures. En fichiers annexes 4 séquences vidéo accompagnées de légendes.; International audience; Der Kurs "Phy Ex" wurde von Yves Couder an der Universität Paris VII konzipiert und erschaffen, um Experimentalphysik und wissenschaftliche Methodik durch Forschungsprojekte zu vermitteln. Dieser Beitrag präsentiert die Lehrmethode anhand des Projekts zweier Studenten im ersten Semester 2019/2020: die Tischtennisball-Wasserkanone. Ziel dieses Projekts war es, die dem folgenden Experiment zugrundeliegenden physikalischen Mechanismen zu identifizieren: man lasse ein Wasserglas, in welchem ein Tischtennisball schwimmt, senkrecht zu Boden fallen. Gleich nach dem Aufprall wird der Ball hochkatapultiert, mit einer Geschwindigkeit die die Fallgeschwindigkeit deutlich überschreiten kann. Wir geben die von den Studenten durchgeführte Dimensionsanalyse und Größenordnugsabschätzung wieder, und beschreiben dann die sukzessiven Versuchsanordnungen und die daraus gewonnenen Beobachtungen: (1) die Kanone funktioniert nur wenn dem Aufprall ein freier Fall vorausgeht, (2) eine Impulsbilanz basierend auf der Integration des Druckimpulses beim Aufprall sagt die Auswurfsgeschwindigkeit größenordnungsmäßig richtig voraus, und (3) die Impulsübertragung auf den Ball lässt sich durch Rühren der Flüssigkeit oder Erhöhung der Benetzbarkeit des Balls deutlich steigern. Die im Laufe des Projekts formulierte und durch direkte Hochgeschwindigkeitsfotographie bestätigte Erklärung besagt, dass der Ball im freien Fall durch Kapillarkräfte --- oder in sich drehender Flüssigkeit durch den zentralen Unterdruck --- tiefer in die Flüssigkeit gezogen wird, während der sonst dominante Auftrieb vorübergehend aufgehoben ist. Der enorme Überdruck beim Aufprall bewirkt dann eine Rückkehr in Richtung Auftriebsgleichgewicht, bei der der Ball derartig beschleunigt wird, dass er die Flüssigkeit mit hoher Geschwindigkeit verlässt. Der Mechanismus dieser letzten Etappe ist der gleiche, der zur Bildung eines schnellen Flüssigkeitsstrahls beim Zusammenbruch eines Hohlraums in einer Flüssigkeit führt.; The course "Phy Ex" was created by Yves Couder in the Paris VII university to teach experimental physics through projects. In this article, we present this teaching method through a particular project that took place in the autumn semester 2019: the ping-pong ball water cannon. In this experiment, a glass containing water and a floating table tennis ball is dropped from some height to the ground. Following the impact, the ball is ejected vertically upwards at speeds that can be several times the impact speed. We report the student team's initial dimensional and order-of-magnitude analysis, and describe the successive experimental setups that showed (1) that free flight is essential for the phenomenon to occur, (2) that the order of magnitude of the ball ejection momentum is correctly predicted by a momentum balance based on integrating the pressure impulse during impact and (3) that making the ball surface more wettable, or stirring the liquid, drastically increases the momentum transfer. The proposed explanation, confirmed by direct high-speed video observations, is that the immersion depth of the ball increases during free fall due to capillary forces or vortex depression-in the absence of buoyancy-and that the enormous excess pressure on the bottom of the ball during impact drives the ball up towards its buoyancy equilibrium. The transfered momentum is sufficient to expel the ball at high velocity, very similar to the formation of liquid jets in collapsing cavities in liquids.; Yves Couder a créé un enseignement de physique expérimentale par projets, «Phy Ex», à l'université de Paris VII. Cet article présentela méthode d'enseignement à travers le projet d'un binôme d'étudiants au premier semestre 2019/2020: le canon à eau propulsant une balle deping-pong. Le projet consistait à identifier les mécanismes physiques en jeu dans l'expérience suivante: on fait tomber verticalement unverre en plastique contenant de l'eau avec une balle de ping-pong à sa surface. Lorsque le verre percute le sol, la balle de ping-pong estéjectée vers le haut à une vitesse pouvant largement dépasser la vitesse de chute. Nous résumons l'analyse dimensionnelle et d'ordre degrandeur faite par le binôme d'étudiants en amont des expériences. Puis nous décrivons les montages successifs qui montrent (1) que laphase de chute libre précédant l'impact est essentielle dans ce phénomène, (2) que l'ordre de grandeur de la vitesse d'éjection estcorrectement prédit par un bilan de quantité de mouvement basé sur l'intégration du pic de pression résultant de l'impact, et (3) querendre la balle plus mouillante, ou que mettre l'eau en rotation avant la chute, résulte en une augmentation importante de la quantité demouvement transmise à la balle. L'image physique ayant émergé au cours de ce projet, et qui s'appuie également sur des images vidéo prises àl'aide d'une caméra rapide, est que la profondeur d'immersion de la balle augmente pendant la brève période de chute libre par l'actiondes forces capillaires ou par la dépression au cœur d'un vortex en présence de rotation --- la poussée d'Archimède habituellement dominanteétant nulle pendant la chute --- et que la pression considérable sur la partie immergée de la balle pendant la décélération au sol repousse laballe vers son équilibre de flottaison. La quantité de mouvement transmise dans ce processus est alors tellement importante que laballe est expulsée vers le haut à grande vitesse, de la même manière que l'effondrement d'une cavité à la surface d'un liquide conduit à laformation d'un jet rapide au centre.

Published
2020

12. Ultrastable metallic glasses in silico

Author

Ludovic Berthier, Anshul D. S. Parmar, Misaki Ozawa, Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Condensed Matter - Materials Science, Materials science, Amorphous metal, Statistical Mechanics (cond-mat.stat-mech), Configuration entropy, General Physics and Astronomy, Stable equilibrium, Thermodynamics, Materials Science (cond-mat.mtrl-sci), FOS: Physical sciences, Numerical models, Computational Physics (physics.comp-ph), Condensed Matter::Disordered Systems and Neural Networks, 01 natural sciences, [PHYS.PHYS.PHYS-COMP-PH]Physics [physics]/Physics [physics]/Computational Physics [physics.comp-ph], Brittleness, 0103 physical sciences, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], 010306 general physics, Glass transition, Swap (computer programming), Physics - Computational Physics, Monte Carlo algorithm, Condensed Matter - Statistical Mechanics
Abstract

We develop a generic strategy and simple numerical models for multi-component metallic glasses for which the swap Monte Carlo algorithm can produce highly stable equilibrium configurations equivalent to experimental systems cooled more than $10^7$ times slower than in conventional simulations. This paves the way for a deeper understanding of thermodynamic, dynamic, and mechanical properties of metallic glasses. As first applications, we considerably extend configurational entropy measurements down to the experimental glass temperature, and demonstrate a qualitative change of the mechanical response of metallic glasses of increasing stability towards brittleness., Comment: 11 pages, 9 figs

Published
2020
Full Text
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13. Tree-AMP: Compositional Inference with Tree Approximate Message Passing

Author

Baker, Antoine, Aubin, Benjamin, Krzakala, Florent, Zdeborová, Lenka, Aubin, Benjamin, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Signal Processing (eess.SP), FOS: Computer and information sciences, Computer Science - Machine Learning, [INFO.INFO-TS] Computer Science [cs]/Signal and Image Processing, FOS: Physical sciences, Mathematics - Statistics Theory, Machine Learning (stat.ML), Statistics Theory (math.ST), Statistics - Computation, [STAT.CO] Statistics [stat]/Computation [stat.CO], Machine Learning (cs.LG), [STAT.ML]Statistics [stat]/Machine Learning [stat.ML], [INFO.INFO-LG]Computer Science [cs]/Machine Learning [cs.LG], [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, [MATH.MATH-ST]Mathematics [math]/Statistics [math.ST], Statistics - Machine Learning, FOS: Electrical engineering, electronic engineering, information engineering, FOS: Mathematics, [PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn], Electrical Engineering and Systems Science - Signal Processing, [STAT.CO]Statistics [stat]/Computation [stat.CO], [MATH.MATH-ST] Mathematics [math]/Statistics [math.ST], Computation (stat.CO), [INFO.INFO-LG] Computer Science [cs]/Machine Learning [cs.LG], Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, [STAT.ML] Statistics [stat]/Machine Learning [stat.ML], [PHYS.COND.CM-DS-NN] Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn]
Abstract

We introduce Tree-AMP, standing for Tree Approximate Message Passing, a python package for compositional inference in high-dimensional tree-structured models. The package provides a unifying framework to study several approximate message passing algorithms previously derived for a variety of machine learning tasks such as generalized linear models, inference in multi-layer networks, matrix factorization, and reconstruction using non-separable penalties. For some models, the asymptotic performance of the algorithm can be theoretically predicted by the state evolution, and the measurements entropy estimated by the free entropy formalism. The implementation is modular by design: each module, which implements a factor, can be composed at will with other modules to solve complex inference tasks. The user only needs to declare the factor graph of the model: the inference algorithm, state evolution and entropy estimation are fully automated., Comment: Source code available at https://github.com/sphinxteam/tramp and documentation at https://sphinxteam.github.io/tramp.docs

Published
2020
Full Text
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14. Optimized electrical control of a Si/SiGe spin qubit in the presence of an induced frequency shift

Author

Giles Allison, Seigo Tarucha, Noritaka Usami, Jun Yoneda, Shunri Oda, Tetsuo Kodera, Tomohiro Otsuka, Takashi Nakajima, Kenta Takeda, Matthieu R. Delbecq, Kohei M. Itoh, Yusuke Hoshi, RIKEN - Institute of Physical and Chemical Research [Japon] (RIKEN), Tohoku University [Sendai], Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Tokyo University of Science [Tokyo], Nagoya University, Keio University, Tokyo Institute of Technology [Tokyo] (TITECH), and The University of Tokyo (UTokyo)

Subjects
Coherence time, Quantum decoherence, Computer Networks and Communications, FOS: Physical sciences, 02 engineering and technology, Electron, 01 natural sciences, lcsh:QA75.5-76.95, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], 0103 physical sciences, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), Computer Science (miscellaneous), Hardware_ARITHMETICANDLOGICSTRUCTURES, 010306 general physics, Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Spins, Quantum dots, business.industry, Statistical and Nonlinear Physics, Quantum Physics, 021001 nanoscience & nanotechnology, lcsh:QC1-999, Computational Theory and Mathematics, Quantum dot, Qubit, Optoelectronics, lcsh:Electronic computers. Computer science, 0210 nano-technology, Electric dipole spin resonance, business, Qubits, Rabi frequency, lcsh:Physics
Abstract

Electron spins confined in quantum dots are an attractive system to realize high-fidelity qubits owing to their long coherence time. With the prolonged spin coherence time, however, the control fidelity can be limited by systematic errors rather than decoherence, making characterization and suppression of their influence crucial for further improvement. Here we report that the control fidelity of Si/SiGe spin qubits can be limited by the microwave-induced frequency shift of electric dipole spin resonance and it can be improved by optimization of control pulses. As we increase the control microwave amplitude, we observe a shift of the qubit resonance frequency, in addition to the increasing Rabi frequency. We reveal that this limits control fidelity with a conventional amplitude-modulated microwave pulse below 99.8%. In order to achieve a gate fidelity >99.9%, we introduce a quadrature control method, and validate this approach experimentally by randomized benchmarking. Our finding facilitates realization of an ultra-high-fidelity qubit with electron spins in quantum dots.

Published
2018

15. Comparing dynamics: deep neural networks versus glassy systems

Author

Marco Baity-Jesi, Mario Geiger, Gérard Ben Arous, Stefano Spigler, Yann LeCun, Matthieu Wyart, Chiara Cammarota, Levent Sagun, Giulio Biroli, Department of Physics and Astronomy [Philadelphia], University of Pennsylvania [Philadelphia], Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Physique Théorique et Modèles Statistiques (LPTMS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), Institut de Mathématiques (IMA), King‘s College London, Facebook AI Research [Paris] (FAIR), Facebook, Service de Physique Théorique (SPhT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Systèmes Désordonnés et Applications, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), University of Pennsylvania, Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL)

Subjects
Statistics and Probability, FOS: Computer and information sciences, Computer Science - Machine Learning, Computer science, FOS: Physical sciences, Machine Learning (stat.ML), 01 natural sciences, Machine learning, glassy dynamics, loss landscape, 010305 fluids & plasmas, Machine Learning (cs.LG), [STAT.ML]Statistics [stat]/Machine Learning [stat.ML], Statistics - Machine Learning, 0103 physical sciences, [PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn], 010306 general physics, ComputingMilieux_MISCELLANEOUS, business.industry, Statistical and Nonlinear Physics, Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, states, Dynamics (music), Deep neural networks, Artificial intelligence, Statistics, Probability and Uncertainty, business
Abstract

We analyze numerically the training dynamics of deep neural networks (DNN) by using methods developed in statistical physics of glassy systems. The two main issues we address are (1) the complexity of the loss landscape and of the dynamics within it, and (2) to what extent DNNs share similarities with glassy systems. Our findings, obtained for different architectures and datasets, suggest that during the training process the dynamics slows down because of an increasingly large number of flat directions. At large times, when the loss is approaching zero, the system diffuses at the bottom of the landscape. Despite some similarities with the dynamics of mean-field glassy systems, in particular, the absence of barrier crossing, we find distinctive dynamical behaviors in the two cases, showing that the statistical properties of the corresponding loss and energy landscapes are different. In contrast, when the network is under-parametrized we observe a typical glassy behavior, thus suggesting the existence of different phases depending on whether the network is under-parametrized or over-parametrized., 10 pages, 5 figures. Version accepted at ICML 2018

Published
2019

16. A jamming transition from under- to over-parametrization affects generalization in deep learning

Author

Mario Geiger, Giulio Biroli, Levent Sagun, Stéphane d'Ascoli, Matthieu Wyart, Stefano Spigler, Systèmes Désordonnés et Applications, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Statistics and Probability, overparametrization, Computer science, Generalization, General Physics and Astronomy, Jamming, 01 natural sciences, 010305 fluids & plasmas, 0103 physical sciences, Statistical physics, [PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn], 010306 general physics, jamming, generalization, Mathematical Physics, ComputingMilieux_MISCELLANEOUS, Artificial neural network, business.industry, Transition (fiction), Deep learning, Statistical and Nonlinear Physics, neural networks, Modeling and Simulation, Artificial intelligence, business, Parametrization
Abstract

In this paper we first recall the recent result that in deep networks a phase transition, analogous to the jamming transition of granular media, delimits the over- and under-parametrized regimes where fitting can or cannot be achieved. The analysis leading to this result support that for proper initialization and architectures, in the whole over-parametrized regime poor minima of the loss are not encountered during training, because the number of constraints that hinders the dynamics is insufficient to allow for the emergence of stable minima. Next, we study systematically how this transition affects generalization properties of the network (i.e. its predictive power). As we increase the number of parameters of a given model, starting from an under-parametrized network, we observe for gradient descent that the generalization error displays three phases: (i) initial decay, (ii) increase until the transition point?where it displays a cusp?and (iii) slow decay toward an asymptote as the network width diverges. However if early stopping is used, the cusp signaling the jamming transition disappears. Thereby we identify the region where the classical phenomenon of over-fitting takes place as the vicinity of the jamming transition, and the region where the model keeps improving with increasing the number of parameters, thus organizing previous empirical observations made in modern neural networks.

Published
2019

17. Single molecule kinetics uncover roles for E. coli RecQ DNA helicase domains and interaction with SSB

Author

James L. Keck, Vincent Croquette, Debjani Bagchi, Bertrand Ducos, Weiting Zhang, Kelly A. Manthei, Maria Manosas, Samar Hodeib, Universitat de Barcelona (UB), Centro Investigacion Biomedica en Red Bioingenieria, Biomateriales y Nanomedicina - CIBER-BBN (SPAIN), Institut de biologie de l'ENS Paris (IBENS), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Département de Biologie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université - Faculté de Médecine (SU FM), Sorbonne Université (SU), Université Paris Diderot - Paris 7 (UPD7), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Institut de biologie de l'ENS Paris (UMR 8197/1024) (IBENS), Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)

Subjects
DNA, Bacterial, Models, Molecular, 0301 basic medicine, congenital, hereditary, and neonatal diseases and abnormalities, Optical Tweezers, Protein Conformation, Inverted Repeat Sequences, [SDV]Life Sciences [q-bio], Protein domain, Biology, medicine.disease_cause, 03 medical and health sciences, chemistry.chemical_compound, 0302 clinical medicine, Protein structure, Protein Domains, Escherichia coli, Genetics, medicine, RNase D, [SDV.GEN]Life Sciences [q-bio]/Genetics, RecQ Helicases, Escherichia coli Proteins, nutritional and metabolic diseases, Helicase, Processivity, Single Molecule Imaging, Cell biology, DNA-Binding Proteins, Kinetics, enzymes and coenzymes (carbohydrates), 030104 developmental biology, chemistry, biology.protein, Gene Deletion, 030217 neurology & neurosurgery, DNA
Abstract

International audience; Most RecQ DNA helicases share a conserved domain arrangement that mediates their activities in genomic stability. This arrangement comprises a helicase motor domain, a RecQ C-terminal (RecQ-C) region including a winged-helix (WH) domain, and a 'Helicase and RNase D C-terminal' (HRDC) domain. Single-molecule real-time translocation and DNA unwinding by full-length Escherichia coli RecQ and variants lacking either the HRDC or both the WH and HRDC domains was analyzed. RecQ operated under two interconvertible kinetic modes, 'slow' and 'normal', as it unwound duplex DNA and translocated on single-stranded (ss) DNA. Consistent with a crystal structure of bacterial RecQ bound to ssDNA by base stacking, abasic sites blocked RecQ unwinding. Removal of the HRDC domain eliminates the slow mode while preserving the normal mode of activity. Unexpectedly, a RecQ variant lacking both the WH and HRDC domains retains weak helicase activity. The inclusion of E. coli ssDNA-binding protein (SSB) induces a third 'fast' unwinding mode four times faster than the normal RecQ mode and enhances the overall helicase activity (affinity, rate, and processivity). SSB stimulation was, furthermore, observed in the RecQ deletion variants, including the variant missing the WH domain. Our results support a model in which RecQ and SSB have multiple interacting modes.

Published
2018

18. Quantum Bound to Chaos and the Semiclassical Limit

Author

Jorge Kurchan, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
High Energy Physics - Theory, Surface (mathematics), FOS: Physical sciences, Semiclassical physics, Context (language use), Lyapunov exponent, Curvature, 01 natural sciences, symbols.namesake, Quantum mechanics, 0103 physical sciences, Limit (mathematics), [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], 010306 general physics, Quantum, Condensed Matter - Statistical Mechanics, Mathematical Physics, Physics, Statistical Mechanics (cond-mat.stat-mech), 010308 nuclear & particles physics, Statistical and Nonlinear Physics, Nonlinear Sciences::Chaotic Dynamics, Classical mechanics, High Energy Physics - Theory (hep-th), symbols, Chaos, Matter wave, Quantum bounds
Abstract

We discuss the quantum bound on chaos in the context of the free propagation of a particle in an arbitrarily curved surface at low temperatures. The semiclassical calculation of the Lyapunov exponent can be performed in much the same way as the corresponding one for the `Loschmidt echo'.The bound appears here as the impossibility to scatter a wave, by effect of the curvature, over characteristic lengths smaller than the deBroglie wavelength., References added, some typos corrected

Published
2018

19. Dynamics of a qubit while simultaneously monitoring its relaxation and dephasing

Author

Ficheux, Q., Jezouin, S., Leghtas, Z., Huard, B., Laboratoire de Physique de l'ENS Lyon (Phys-ENS), École normale supérieure de Lyon (ENS de Lyon)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon-Centre National de la Recherche Scientifique (CNRS), Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre d'Enseignement et de Recherche en Mathématiques et Calcul Scientifique (CERMICS), École des Ponts ParisTech (ENPC), QUANTum Information Circuits (QUANTIC), Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire de physique de l'ENS - ENS Paris (LPENS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL), École normale supérieure - Lyon (ENS Lyon)-Centre National de la Recherche Scientifique (CNRS)-Université Claude Bernard Lyon 1 (UCBL), Université de Lyon-Université de Lyon, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Centre Automatique et Systèmes (CAS), MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris)

Subjects
Quantum Physics, Computer Science::Emerging Technologies, Condensed Matter - Mesoscale and Nanoscale Physics, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Science, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), FOS: Physical sciences, lcsh:Q, Quantum Physics (quant-ph), Condensed Matter::Mesoscopic Systems and Quantum Hall Effect, lcsh:Science
Abstract

Decoherence originates from the leakage of quantum information into external degrees of freedom. For a qubit the two main decoherence channels are relaxation and dephasing. Here, we report an experiment on a superconducting qubit where we retrieve part of the lost information in both of these channels. We demonstrate that raw averaging the corresponding measurement records provides a full quantum tomography of the qubit state where all three components of the effective spin-1/2 are simultaneously measured. From single realizations of the experiment, it is possible to infer the quantum trajectories followed by the qubit state conditioned on relaxation and/or dephasing channels. The incompatibility between these quantum measurements of the qubit leads to observable consequences in the statistics of quantum states. The high level of controllability of superconducting circuits enables us to explore many regimes from the Zeno effect to underdamped Rabi oscillations depending on the relative strengths of driving, dephasing and relaxation., Comment: Supplemental videos can be found at http://physinfo.fr/publications/Ficheux1710.html and supplemental information can be found as an ancillary file on arxiv

Published
2018

20. Asymmetric adhesion of rod-shaped bacteria controls microcolony morphogenesis

Author

Vincent Croquette, Marie-Cecilia Duvernoy, Catherine Quilliet, Martial Balland, Nicolas Desprat, Maxime Ardre, Sigolene Lecuyer, Christophe Beloin, David Bensimon, Jean-Marc Ghigo, Thierry Mora, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Interdisciplinaire de Physique [Saint Martin d’Hères] (LIPhy), Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Institut de biologie de l'ENS Paris (UMR 8197/1024) (IBENS), Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Solides (LPS), Centre National de la Recherche Scientifique (CNRS)-Université Paris-Sud - Paris 11 (UP11), University of California [Los Angeles] (UCLA), University of California, Génétique des Biofilms, Institut Pasteur [Paris]-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7), This work was supported by the Agence Nationale pour la Recherche ANR-12-JSV5-0007-01 (to M.B.), ANR-10-LABX-62-IBEID (to C.B. and J.-M.G.), and ANR-11-JSV5-005-01 (to N.D.) and by the Fondation pour la Recherche Médicale grant Equipe FRM DEQ20140329508 (to C.B. and J.-M.G.)., We thank Paul Rainey, Roberto Kolter, Oskar Hallatscheck, and Jean-Baptiste Boulé for their comments on the manuscript. We thank Irene Wang for her help with force microscopy calculations. We thank Michael Elowitz for Schnitzcell. We thank José Quintas Da-Silva and Carlos Gonzales for design and construction of the mechanical parts. We thank Mathieu Coppey, Manuel Thery, Frederic Lechenault, and Sebastien Moulinet for stimulating discussions, ANR-12-JSV5-0007,DOCM,Etude des aspects dynamiques de la mecanotransduction cellulaire(2012), ANR-10-LABX-0062,IBEID,Integrative Biology of Emerging Infectious Diseases(2010), ANR-11-JSV5-0005,COOPIRON,Aspects coopératifs de la régulation des sidérophores(2011), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Joseph Fourier - Grenoble 1 (UJF)-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes (UGA), École normale supérieure - Paris (ENS Paris)-École normale supérieure - Paris (ENS Paris)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Institut Pasteur [Paris], ANR-10-LABX-62-IBEID,IBEID,Laboratoire d'Excellence 'Integrative Biology of Emerging Infectious Diseases'(2010), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Institut de biologie de l'ENS Paris (IBENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris-Sud - Paris 11 (UP11)-Centre National de la Recherche Scientifique (CNRS), University of California (UC), Institut Pasteur [Paris] (IP)-Centre National de la Recherche Scientifique (CNRS), HAL UPMC, Gestionnaire, Jeunes Chercheuses et Jeunes Chercheurs - Etude des aspects dynamiques de la mecanotransduction cellulaire - - DOCM2012 - ANR-12-JSV5-0007 - JC - VALID, Integrative Biology of Emerging Infectious Diseases - - IBEID2010 - ANR-10-LABX-0062 - LABX - VALID, Jeunes Chercheuses et Jeunes Chercheurs - Aspects coopératifs de la régulation des sidérophores - - COOPIRON2011 - ANR-11-JSV5-0005 - JCJC - VALID, Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Département de Biologie - ENS Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Cell division, Science, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], education, Morphogenesis, Cellular level, Microscopy, Atomic Force, Time-Lapse Imaging, Bacterial Adhesion, Article, 03 medical and health sciences, Spatio-Temporal Analysis, Cell Wall, Escherichia coli, 14. Life underwater, lcsh:Science, 030304 developmental biology, 0303 health sciences, biology, [PHYS.PHYS.PHYS-BIO-PH] Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], 030306 microbiology, Biofilm, Adhesion, Substrate (biology), biology.organism_classification, [SDV.MP.BAC]Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, Cell biology, Biofilms, Pseudomonas aeruginosa, lcsh:Q, Stress, Mechanical, [SDV.MP.BAC] Life Sciences [q-bio]/Microbiology and Parasitology/Bacteriology, Bacteria
Abstract

Surface colonization underpins microbial ecology on terrestrial environments. Although factors that mediate bacteria–substrate adhesion have been extensively studied, their spatiotemporal dynamics during the establishment of microcolonies remains largely unexplored. Here, we use laser ablation and force microscopy to monitor single-cell adhesion during the course of microcolony formation. We find that adhesion forces of the rod-shaped bacteria Escherichia coli and Pseudomonas aeruginosa are polar. This asymmetry induces mechanical tension, and drives daughter cell rearrangements, which eventually determine the shape of the microcolonies. Informed by experimental data, we develop a quantitative model of microcolony morphogenesis that enables the prediction of bacterial adhesion strength from simple time-lapse measurements. Our results demonstrate how patterns of surface colonization derive from the spatial distribution of adhesive factors on the cell envelope., It is unclear how cell adhesion and elongation coordinate during formation of bacterial microcolonies. Here, Duvernoy et al. monitor microcolony formation in rod-shaped bacteria, and show that patterns of surface colonization derive from the spatial distribution of adhesive factors on the cell envelope.

Published
2018

21. Monitoring bacterial secreted proteins in real time

Author

Péron-Cane, Caroline, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de biologie de l'ENS Paris (IBENS), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Département de Biologie - ENS Paris, École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université, Nicolas Desprat, Alice Lebreton, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de biologie de l'ENS Paris (UMR 8197/1024) (IBENS), Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), and STAR, ABES

Subjects
Dynamique, [SDV.BBM.BP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics, Vacuolar residence, Virulence factors, Résidence vacuolaire, [SDV.BBM.BP] Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics, Listeria monocytogenes, Fluorescence, Secretion, Facteurs de virulence, Sécrétion
Abstract

Upon infection, bacterial pathogens deploy an arsenal of virulence factors promoting the invasion of their host organisms. Although these bacterial effectors have been well characterized, the dynamics of their secretion and of their intracellular localization in the host remain poorly described due to the lack of appropriate tools allowing their visualization in real time. Indeed, common fluorescent tags like GFP (Green Fluorescent Protein) are thought inactive after transport through bacterial secretion systems. To overcome these limitations, we took advantage of FAST (Fluorescence-Activating and absorption Shifting Tag), a tunable fluorescent probe where the fluorescence results from the rapid association with a membrane-permeant fluorogenic ligand. In this work, we showed that FAST can be used to visualize effectors secreted by several bacterial secretion systems (T3SS, T5SS and Sec). By measuring FAST secretion, we quantified the dynamics of formation and rupture of internalization vacuoles occupied by Listeria monocytogenes. Monitoring the location of LLO, a major virulence factor secreted by L. monocytogenes during invasion of epithelial cells, we identified a compartment in which bacteria can replicate, before colonizing the host cytoplasm. In addition to validating a fluorescent tool to monitor the real-time localization of bacterial proteins exported by various secretion systems, this study updates the model of the intracellular cycle of L. monocytogenes during epithelial cell infection., Lors de l’infection, les bactéries pathogènes déploient un arsenal de facteurs de virulence leur permettant d’envahir leurs organismes cibles. Si nombre de ces effecteurs bactériens ont été bien caractérisés, peu d’outils permettent une étude en temps réel de leur dynamique de sécrétion et de localisation au cours de l’infection. Les marqueurs existants, tels que la GFP (Green Fluorescent Protein) ne peuvent a priori pas passer les systèmes de sécrétion bactériens sous leur conformation active. L’utilisation de FAST (Fluorescence-Activating Shifting Tag) — une sonde dont la fluorescence résulte de la formation d’un complexe avec un ligand diffusant librement au travers des membranes biologiques — permet de s’affranchir de cet obstacle. Lors de ces travaux, j’ai montré que FAST peut être utilisé pour la visualisation d’effecteurs sécrétés par plusieurs systèmes de sécrétion bactériens (T3SS, T5SS et Sec). En mesurant la sécrétion de FAST, nous avons quantifié la dynamique de formation et de rupture des vacuoles d’internalisation occupées par Listeria monocytogenes. En recherchant la localisation de la LLO, l’un des principaux facteurs de virulence sécrétés par L. monocytogenes, j’ai identifié un compartiment dans lequel les bactéries peuvent se répliquer après l’invasion des cellules épithéliales, avant de coloniser le cytoplasme de l’hôte. En plus de valider un outil fluorescent permettant la localisation en temps réel de protéines bactériennes exportées par divers systèmes de sécrétion, cette étude complète le modèle du cycle intracellulaire de L. monocytogenes lors de l’infection de cellules épithéliales.

Published
2019

22. Injection Locking and Parametric Locking in a Superconducting Circuit

Author

Danijela Marković, Emmanuel Flurin, Nicolas Roch, Benjamin Huard, J.-D. Pillet, Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École polytechnique (X), Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Circuits électroniques quantiques Alpes (QuantECA ), Institut Néel (NEEL), Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019])-Institut polytechnique de Grenoble - Grenoble Institute of Technology (Grenoble INP )-Centre National de la Recherche Scientifique (CNRS)-Université Grenoble Alpes [2016-2019] (UGA [2016-2019]), Quantronics Group (QUANTRONICS), Service de physique de l'état condensé (SPEC - UMR3680), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS)-Institut Rayonnement Matière de Saclay (IRAMIS), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), and Circuits électroniques quantiques Alpes (NEEL - QuantECA)

Subjects
Superconductivity, Physics, [PHYS]Physics [physics], Mesoscopic physics, Condensed Matter - Mesoscale and Nanoscale Physics, Phase (waves), FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, 021001 nanoscience & nanotechnology, Quantum information processing, Microwave oscillators, 01 natural sciences, Imaging phantom, Injection locking, Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Atomic physics, 010306 general physics, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], Parametric statistics
Abstract

When a signal is injected in a parametric oscillator close enough to its resonance, the oscillator frequency and phase get locked to those of the injected signal. Here, we demonstrate two frequency locking schemes using a Josephson mixer in the parametric down-conversion regime, pumped beyond the parametric oscillation threshold. The circuit then emits radiation out of two spectraly and spatially separated resonators at frequencies determined by the locking schemes that we choose. When we inject the signal close to a resonance, it locks the oscillator emission to the signal frequency by injection locking. When we inject the signal close to the difference of resonances, it locks the oscillator emission by parametric locking. We compare both schemes and investigate the dependence of the parametric locking range on the pump and the injection signal power. Our results can be interpreted using Adler's theory for lasers, which makes a new link between laser physics and superconducting circuits that could enable better understanding of pumped circuits for quantum information applications such as error correction, circulators and photon number detectors.

Published
2019

23. Passed & Spurious: analysing descent algorithms and local minima in Spiked Matrix-Tensor Models

Author

Mannelli, Stefano, Krzakala, Florent, Urbani, Pierfrancesco, Zdeborova, Lenka, Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE23-0023,PAIL,Diagramme de Phase et Algorithme pour l'inference et l'apprentissage(2017), ANR-10-LABX-0039,PALM,Physics: Atoms, Light, Matter(2010), European Project: 714608,SMILE, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics]
Abstract

International audience; In this work we analyse quantitatively the interplay between the loss landscape and performance of descent algorithms in a prototypical inference problem, the spiked matrix-tensor model. We study a loss function that is the negative log-likelihood of the model. We analyse the number of local minima at a fixed distance from the signal/spike with the Kac-Rice formula, and locate trivialization of the landscape at large signal-to-noise ratios. We evaluate in a closed form the performance of a gradient flow algorithm using integro-differential PDEs as developed in physics of disordered systems for the Langevin dynamics. We analyze the performance of an approximate message passing algorithm estimating the maximum likelihood configuration via its state evolution. We conclude by comparing the above results: while we observe a drastic slow down of the gradient flow dynamics even in the region where the landscape is trivial, both the analyzed algorithms are shown to perform well even in the part of the region of parameters where spurious local minima are present.

Published
2019

24. Jamming transition as a paradigm to understand the loss landscape of deep neural networks

Author

Marco Baity-Jesi, Stéphane d'Ascoli, Mario Geiger, Stefano Spigler, Giulio Biroli, Matthieu Wyart, Levent Sagun, Ecole Polytechnique Fédérale de Lausanne (EPFL), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Systèmes Désordonnés et Applications, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Physics, FOS: Computer and information sciences, Computer Science - Machine Learning, Phase transition, Artificial neural network, Activation function, Energy landscape, FOS: Physical sciences, Jamming, space, Function (mathematics), Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, 01 natural sciences, Critical point (mathematics), 010305 fluids & plasmas, Machine Learning (cs.LG), Maxima and minima, go, 0103 physical sciences, Neuronal networks, game, Statistical physics, [PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn], 010306 general physics
Abstract

Deep learning has been immensely successful at a variety of tasks, ranging from classification to artificial intelligence. Learning corresponds to fitting training data, which is implemented by descending a very high-dimensional loss function. Understanding under which conditions neural networks do not get stuck in poor minima of the loss, and how the landscape of that loss evolves as depth is increased, remains a challenge. Here we predict, and test empirically, an analogy between this landscape and the energy landscape of repulsive ellipses. We argue that in fully connected deep networks a phase transition delimits the over- and underparametrized regimes where fitting can or cannot be achieved. In the vicinity of this transition, properties of the curvature of the minima of the loss (the spectrum of the Hessian) are critical. This transition shares direct similarities with the jamming transition by which particles form a disordered solid as the density is increased, which also occurs in certain classes of computational optimization and learning problems such as the perceptron. Our analysis gives a simple explanation as to why poor minima of the loss cannot be encountered in the overparametrized regime. Interestingly, we observe that the ability of fully connected networks to fit random data is independent of their depth, an independence that appears to also hold for real data. We also study a quantity Delta which characterizes how well (Delta < 0) or badly (Delta > 0) a datum is learned. At the critical point it is power-law distributed on several decades, P+(Delta) similar to Delta(theta) for Delta > 0 and P_(Delta) similar to (-Delta)(-gamma) for Delta < 0, with exponents that depend on the choice of activation function. This observation suggests that near the transition the loss landscape has a hierarchical structure and that the learning dynamics is prone to avalanche-like dynamics, with abrupt changes in the set of patterns that are learned.

Published
2019

25. The spiked matrix model with generative priors

Author

Bruno Loureiro, Lenka Zdeborová, Florent Krzakala, Benjamin Aubin, Antoine Maillard, Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Aubin, Benjamin

Subjects
Signal Processing (eess.SP), FOS: Computer and information sciences, [MATH.MATH-PR] Mathematics [math]/Probability [math.PR], Computer Science - Machine Learning, Computer science, [INFO.INFO-TS] Computer Science [cs]/Signal and Image Processing, Inference, Machine Learning (stat.ML), Mathematics - Statistics Theory, 02 engineering and technology, Statistics Theory (math.ST), Library and Information Sciences, Machine Learning (cs.LG), [INFO.INFO-LG]Computer Science [cs]/Machine Learning [cs.LG], [INFO.INFO-TS]Computer Science [cs]/Signal and Image Processing, [STAT.ML]Statistics [stat]/Machine Learning [stat.ML], [MATH.MATH-ST]Mathematics [math]/Statistics [math.ST], Statistics - Machine Learning, Prior probability, 0202 electrical engineering, electronic engineering, information engineering, FOS: Mathematics, FOS: Electrical engineering, electronic engineering, information engineering, Electrical Engineering and Systems Science - Signal Processing, [MATH.MATH-ST] Mathematics [math]/Statistics [math.ST], Signal reconstruction, Probability (math.PR), Approximation algorithm, Estimator, 020206 networking & telecommunications, Mutual information, [INFO.INFO-LG] Computer Science [cs]/Machine Learning [cs.LG], [STAT.ML] Statistics [stat]/Machine Learning [stat.ML], Computer Science Applications, Data set, [MATH.MATH-PR]Mathematics [math]/Probability [math.PR], Asymptotically optimal algorithm, Threshold model, Algorithm, Mathematics - Probability, Information Systems
Abstract

Using a low-dimensional parametrization of signals is a generic and powerful way to enhance performance in signal processing and statistical inference. A very popular and widely explored type of dimensionality reduction is sparsity; another type is generative modelling of signal distributions. Generative models based on neural networks, such as GANs or variational auto-encoders, are particularly performant and are gaining on applicability. In this paper we study spiked matrix models, where a low-rank matrix is observed through a noisy channel. This problem with sparse structure of the spikes has attracted broad attention in the past literature. Here, we replace the sparsity assumption by generative modelling, and investigate the consequences on statistical and algorithmic properties. We analyze the Bayes-optimal performance under specific generative models for the spike. In contrast with the sparsity assumption, we do not observe regions of parameters where statistical performance is superior to the best known algorithmic performance. We show that in the analyzed cases the approximate message passing algorithm is able to reach optimal performance. We also design enhanced spectral algorithms and analyze their performance and thresholds using random matrix theory, showing their superiority to the classical principal component analysis. We complement our theoretical results by illustrating the performance of the spectral algorithms when the spikes come from real datasets., 12 + 56, 8 figures, v2 lighter jpeg figures

Published
2019

26. A Model of Somitogenesis

Author

Martin Distel, Vanessa Mayr, Weiting Zhang, Bertrand Ducos, David Bensimon, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de biologie de l'ENS Paris (UMR 8197/1024) (IBENS), Département de Biologie - ENS Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS), ABCD : Biophysique des Biomolécules, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Children’s Cancer Research Institute [Vienna, Austria], Department of Chemistry and Biochemistry [Los Angeles], University of California [Los Angeles] (UCLA), University of California-University of California, Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Institut de biologie de l'ENS Paris (IBENS), Centre National de la Recherche Scientifique (CNRS)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Département de Biologie - ENS Paris, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Institut National de la Santé et de la Recherche Médicale (INSERM)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Physics, Mesoderm, biology, [PHYS.PHYS]Physics [physics]/Physics [physics], ved/biology, ved/biology.organism_classification_rank.species, Robustness (evolution), Statistical and Nonlinear Physics, biology.organism_classification, 01 natural sciences, 010305 fluids & plasmas, Cell biology, medicine.anatomical_structure, Somitogenesis, 0103 physical sciences, medicine, Segmentation, 010306 general physics, Model organism, Zebrafish, Developmental biology, Mathematical Physics, ComputingMilieux_MISCELLANEOUS, Morphogen
Abstract

A quantitative description of the molecular networks that sustain morphogenesis is one of the main challenges of developmental biology. In particular, a molecular understanding of the segmentation of the antero-posterior axis in vertebrates has yet to be achieved. This process known as somitogenesis is believed to result from the interactions between a well-studied genetic oscillator and a less established posterior-moving determination wavefront. Here we describe a molecular model for somitogenesis that couples a moving morphogen wavefront with the somitogenetic oscillator. The wavefront is due to a switch between stable states that results from reciprocal negative feedbacks of Retinoic Acid (RA) on the activation of a kinase ErK and of ErK on RA synthesis. We suggest a molecular mechanism by which that switch can be triggered by the somitogenetic clock. The model quantitatively accounts for the shortening of the pre-somitic mesoderm (PSM) in zebrafish in response to the decrease during somitogenesis in the concentration of a morphogen (Fgf8). The generality and robustness of the model allows for its validation (or invalidation) in other model organisms.

Published
2019

27. Visualizing the Effect of an Electrostatic Gate with Angle-Resolved Photoemission Spectroscopy

Author

Romaric Le Goff, Hemian Yi, Eberth A. Quezada-Lopez, Emmanuel Baudin, Takashi Taniguchi, Jairo Velasco, Zhehao Ge, Frédéric Joucken, Maria C. Asensio, Kenji Watanabe, José Avila, John Davenport, University of California [Santa Cruz] (UCSC), University of California, Synchrotron SOLEIL (SSOLEIL), Centre National de la Recherche Scientifique (CNRS), Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Nano-Optique, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), National Institute for Materials Science (NIMS), US Army Research Laboratory, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
NanoARPES, Electronic structure, Materials science, Photoemission spectroscopy, Band gap, FOS: Physical sciences, Bioengineering, Angle-resolved photoemission spectroscopy, 02 engineering and technology, Electrostatic gating, Electric field, General Materials Science, Electronic band structure, Condensed Matter - Materials Science, business.industry, Mechanical Engineering, Materials Science (cond-mat.mtrl-sci), Heterojunction, General Chemistry, 021001 nanoscience & nanotechnology, Condensed Matter Physics, ARPES, Bilayer graphene, [PHYS.COND.CM-MS]Physics [physics]/Condensed Matter [cond-mat]/Materials Science [cond-mat.mtrl-sci], Optoelectronics, 0210 nano-technology, business, Van der Waals heterostructure
Abstract

[EN] Electrostatic gating is pervasive in materials science, yet its effects on the electronic band structure of materials has never been revealed directly by angle-resolved photoemission spectroscopy (ARPES), the technique of choice to noninvasively probe the electronic band structure of a material. By means of a state-of-the-art ARPES setup with submicron spatial resolution, we have investigated a heterostructure composed of Bernal-stacked bilayer graphene (BLG) on hexagonal boron nitride and deposited on a graphite flake. By voltage biasing the latter, the electric field effect is directly visualized on the valence band as well as on the carbon 1s core level of BLG. The band gap opening of BLG submitted to a transverse electric field is discussed and the importance of intra layer screening is put forward. Our results pave the way for new studies that will use momentum-resolved electronic structure information to gain insight on the physics of materials submitted to the electric field effect., ANR-14-CE08-018-05 funding “GoBN". J.V.J acknowledges support from UCOP. Atomic Force Microscope images were taken with an instrument acquired from Contract W911NF-17-1-0473 from the Army Research Office. BLG/hBN/graphite stacks were assembled in a glove box that was acquired from Contract W911NF-17-1-0473 from the Army Research Office.

Published
2019

28. A kinetic-Monte Carlo perspective on active matter

Author

Werner Krauth, Juliane U. Klamser, Sebastian C. Kapfer, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Max-Planck-Institut für Physik komplexer Systeme (MPI-PKS), Max-Planck-Gesellschaft, Systèmes Classiques ou Quantiques en Interaction, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
General Physics and Astronomy, Thermodynamics, FOS: Physical sciences, Gaussian processes, Disjoint sets, Condensed Matter - Soft Condensed Matter, 010402 general chemistry, 01 natural sciences, Classical statistical mechanics, Stochastic processes, Phase (matter), 0103 physical sciences, Thermodynamic states and processes, Kinetic Monte Carlo, Physical and Theoretical Chemistry, Condensed Matter - Statistical Mechanics, Phase diagram, Physics, Range (particle radiation), 010304 chemical physics, Statistical Mechanics (cond-mat.stat-mech), Isotropy, Probability theory, Monte Carlo methods, 0104 chemical sciences, Active matter, Phase transitions, Soft Condensed Matter (cond-mat.soft), [PHYS.PHYS.PHYS-CHEM-PH]Physics [physics]/Physics [physics]/Chemical Physics [physics.chem-ph], Soft matter, Random walks, Hexatic phase
Abstract

We study non-equilibrium phases for interacting two-dimensional self-propelled particles with isotropic pair-wise interactions using a persistent kinetic Monte Carlo (MC) approach. We establish the quantitative phase diagram, including the motility-induced phase separation (MIPS) that is a commonly observed collective phenomena in active matter. In addition, we demonstrate for several different potential forms the presence of two-step melting, with an intermediate hexatic phase, in regions far from equilibrium. Increased activity can melt a two-dimensional solid and the melting lines remain disjoint from MIPS. We establish this phase diagram for a range of the inter-particle potential stiffnesses, and identify the MIPS phase even in the hard-disk limit. We establish that the full description of the phase behavior requires three independent control parameters., Comment: 11 pages, 10 figures

Published
2019

29. Can the glass transition be explained without a growing static length scale?

Author

Gilles Tarjus, Giulio Biroli, Ludovic Berthier, Jean-Philippe Bouchaud, Laboratoire Charles Coulomb (L2C), Université de Montpellier (UM)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Systèmes Désordonnés et Applications, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Length scale, Physics, Speedup, 010304 chemical physics, Statistical Mechanics (cond-mat.stat-mech), Monte Carlo method, Nucleation, General Physics and Astronomy, FOS: Physical sciences, 010402 general chemistry, 01 natural sciences, 0104 chemical sciences, Metastability, 0103 physical sciences, Statistical physics, Physical and Theoretical Chemistry, [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], Glass transition, Supercooling, Condensed Matter - Statistical Mechanics, Monte Carlo algorithm
Abstract

It was recently discovered that SWAP, a Monte Carlo algorithm that involves the exchange of pairs of particles of differing diameters, can dramatically accelerate the equilibration of simulated supercooled liquids in regimes where the normal dynamics is glassy. This spectacular effect was subsequently interpreted as direct evidence against a static, cooperative explanation of the glass transition such as the one offered by the random first-order transition (RFOT) theory. We review several empirical facts that support the opposite view, namely, that a local mechanism cannot explain the glass transition phenomenology. We explain the speedup induced by SWAP within the framework of the RFOT theory. We suggest that the efficiency of SWAP stems from a postponed onset of glassy dynamics, which allows the efficient exploration of configuration space even in the regime where the physical dynamics is dominated by activated events across free-energy barriers. We describe this effect in terms of `crumbling metastability' and use the example of nucleation to illustrate the possibility of circumventing free-energy barriers of thermodynamic origin by a change of the local dynamical rules., Comment: 15 pages, 3 figures; v2: improved discussions and clarifications

Published
2019

30. Two recipes for repelling hot water

Author

Antonio Checco, Pierre Lecointre, Christophe Clanet, Gaëlle Lehoucq, Timothée Mouterde, David Quéré, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Micromegas : Nano-Fluidique, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Thales Research and Technology [Palaiseau], THALES, Brookhaven National Laboratory [Upton, NY] (BNL), U.S. Department of Energy [Washington] (DOE)-UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Laboratoire d'hydrodynamique (LadHyX), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
0301 basic medicine, Materials science, Science, FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, Condensed Matter - Soft Condensed Matter, Article, General Biochemistry, Genetics and Molecular Biology, 03 medical and health sciences, [SPI]Engineering Sciences [physics], lcsh:Science, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Multidisciplinary, Solid surface, Drop (liquid), [SPI.FLUID]Engineering Sciences [physics]/Reactive fluid environment, Fluid Dynamics (physics.flu-dyn), Physics - Fluid Dynamics, General Chemistry, 021001 nanoscience & nanotechnology, 6. Clean water, 030104 developmental biology, Chemical physics, Soft Condensed Matter (cond-mat.soft), lcsh:Q, 0210 nano-technology
Abstract

Although a hydrophobic microtexture at a solid surface most often reflects rain owing to the presence of entrapped air within the texture, it is much more challenging to repel hot water. As it contacts a colder material, hot water generates condensation within the cavities at the solid surface, which eventually builds bridges between the substrate and the water, and thus destroys repellency. Here we show that both “small” (~100 nm) and “large” (~10 µm) model features do reflect hot drops at any drop temperature and in the whole range of explored impact velocities. Hence, we can define two structural recipes for repelling hot water: drops on nanometric features hardly stick owing to the miniaturization of water bridges, whereas kinetics of condensation in large features is too slow to connect the liquid to the solid at impact., It has previously been reported that hot drops impacting on a colder surface can lead to loss of surface hydrophobicity unless the surface features are very small. Here the authors find that both small and large features but not intermediate ones are able to preserve hydrophobicity.

Published
2019

31. Dispersion relation for unidirectional surface gravity waves

Author

Tikan, Alexey, Bonnefoy, Félicien, Michel, Guillaume, Prabhudesai, Gaurav, Cazaubiel, Annette, Copie, François, Falcon, Eric, Randoux, Stephane, Suret, Pierre, Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Physique Non-Linéaire, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Matière et Systèmes Complexes (MSC (UMR_7057)), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), E. Falcon, M. Lefranc, F. Pétrélis, C.-T. Pham, Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), and Matière et Systèmes Complexes (MSC)

Subjects
[PHYS.PHYS.PHYS-FLU-DYN]Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Mechanics of the fluids [physics.class-ph], [NLIN.NLIN-SI]Nonlinear Sciences [physics]/Exactly Solvable and Integrable Systems [nlin.SI], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]
Abstract

ISBN 9782953859683; International audience

Published
2019

32. Observation de la modulation non-linéaire contra-propagative des bords d’un train d’onde de gravité à la surface d’un fluide

Author

Bonnefoy, Félicien, Suret, Pierre, Tikan, Alexey, Copie, François, Prabhudesai, Gaurav, Michel, Guillaume, Cazaubiel, Annette, Falcon, Eric, El, Gennady, Randoux, Stephane, Laboratoire de recherche en Hydrodynamique, Énergétique et Environnement Atmosphérique (LHEEA), École Centrale de Nantes (ECN)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique des Lasers, Atomes et Molécules - UMR 8523 (PhLAM), Université de Lille-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Matière et Systèmes Complexes (MSC (UMR_7057)), Université Paris Diderot - Paris 7 (UPD7)-Centre National de la Recherche Scientifique (CNRS), University of Northumbria at Newcastle [United Kingdom], E. Falcon, M. Lefranc, F. Pétrélis, C.-T. Pham, Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Physique Non-Linéaire, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7), École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Matière et Systèmes Complexes (MSC)

Subjects
[PHYS.PHYS.PHYS-FLU-DYN]Physics [physics]/Physics [physics]/Fluid Dynamics [physics.flu-dyn], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Mechanics of the fluids [physics.class-ph], [NLIN.NLIN-SI]Nonlinear Sciences [physics]/Exactly Solvable and Integrable Systems [nlin.SI], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph]
Abstract

ISBN 9782953859683; International audience; Nous étudions expérimentalement la propagation d’un train d’onde sinusoïdal, d’extension finie dans le temps, au sein d’un bassin de houle de grande longueur (150 m) devant la longueur d’onde (1 m). Un batteur engendre, à une extrémité du bassin, un train de vagues monochromatique d’amplitude finie, constante, et de grande durée devant la période. Nous observons alors que les deux bords de ce train d’onde se modulent au cours de la propagation. Le cadre de cette expérience est celui de l’équation de Schrödinger non linéaire focalisante en lien avec le problème du dambreak [1, 2]. A grande distance du batteur, le champ de vague est décrit théoriquement par un régime faiblement dispersif où les effets non linéaires dominent et sont responsables de la modulation non linéaire se propageant depuis les bords du paquet. La solution théorique correspond dans ce cas en une solution périodique lentement modulée en temps. En comparant les mesures obtenues dans le bassin et la solution théorique, notre expérience révèleque le train d’onde non linéaire n’est pas déstabilisé par l’instabilité de Benjamin-Feir mais développe une modulation non linéaire se propageant à vitesse finie sous la forme de deux trains d’onde contra-propagatifs (dits de dambreak dispersifs) en bon accord avec le scénario théorique attendu [3]. Ces observations corroborent celles qui ont été faites en optique [4, 5].

Published
2019

33. Structural Instability of Driven Josephson Circuits Prevented by an Inductive Shunt

Author

Michel Devoret, Zaki Leghtas, Raphaël Lescanne, Lucas Verney, Mazyar Mirrahimi, QUANTum Information Circuits (QUANTIC), Mines Paris - PSL (École nationale supérieure des mines de Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria)-Laboratoire de physique de l'ENS - ENS Paris (LPENS), Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Cité (UPCité)-Département de Physique de l'ENS-PSL, Université Paris sciences et lettres (PSL), Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Departments of Applied Physics [New Haven], Yale University [New Haven], Centre Automatique et Systèmes (CAS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL), Yale Quantum Institute, MINES ParisTech - École nationale supérieure des mines de Paris, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Inria de Paris, Institut National de Recherche en Informatique et en Automatique (Inria)-Institut National de Recherche en Informatique et en Automatique (Inria), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-MINES ParisTech - École nationale supérieure des mines de Paris

Subjects
Superconductivity, Quantum information, FOS: Physical sciences, General Physics and Astronomy, 02 engineering and technology, Hardware_PERFORMANCEANDRELIABILITY, Topology, 01 natural sciences, Instability, Superconductivity (cond-mat.supr-con), [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, 010306 general physics, [PHYS.COND.CM-MSQHE]Physics [physics]/Condensed Matter [cond-mat]/Mesoscopic Systems and Quantum Hall Effect [cond-mat.mes-hall], Electronic circuit, Parametric statistics, Quantum computer, Physics, Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Condensed Matter - Superconductivity, Transmon, 021001 nanoscience & nanotechnology, [PHYS.COND.CM-S]Physics [physics]/Condensed Matter [cond-mat]/Superconductivity [cond-mat.supr-con], Complex dynamics, Qubit, Nonlinear dynamics, Quantum Physics (quant-ph), 0210 nano-technology, Shunt (electrical)
Abstract

Superconducting circuits are a versatile platform to implement a multitude of Hamiltonians which perform quantum computation, simulation and sensing tasks. A key ingredient for realizing a desired Hamiltonian is the irradiation of the circuit by a strong drive. These strong drives provide an in-situ control of couplings, which cannot be obtained by near-equilibrium Hamiltonians. However, as shown in this paper, out-of-equilibrium systems are easily plagued by complex dynamics leading to instabilities. Predicting and preventing these instabilities is crucial, both from a fundamental and application perspective. We propose an inductively shunted transmon as the elementary circuit optimized for strong parametric drives. Developing a novel numerical approach that avoids the built-in limitations of perturbative analysis, we demonstrate that adding the inductive shunt significantly extends the range of pump powers over which the circuit behaves in a stable manner., Comment: 11 pages, 7 figures

Published
2019

34. Equilibration of quasi-integrable systems

Author

Jorge Kurchan, Tomer Goldfriend, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Systèmes Classiques ou Quantiques en Interaction, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Canonical ensemble, Physics, Integrable system, Statistical Mechanics (cond-mat.stat-mech), Fluctuation theorem, FOS: Physical sciences, Nonlinear Sciences - Chaotic Dynamics, 01 natural sciences, Energy sharing, 010305 fluids & plasmas, Numerical integration, Classical statistical mechanics, Nonlinear Sciences::Exactly Solvable and Integrable Systems, 0103 physical sciences, Large deviations theory, Statistical physics, Chaotic Dynamics (nlin.CD), [PHYS.COND.CM-SM]Physics [physics]/Condensed Matter [cond-mat]/Statistical Mechanics [cond-mat.stat-mech], 010306 general physics, Quasistatic process, Condensed Matter - Statistical Mechanics
Abstract

We study the slow relaxation of isolated quasi-integrable systems, focusing on the classical problem of Fermi-Pasta-Ulam-Tsingou (FPU) chain. It is well-known that the initial energy sharing between different linear-modes can be inferred by the integrable Toda chain. Using numerical simulations, we show explicitly how the relaxation of the FPU chain toward equilibration is determined by a slow drift within the space of Toda's integrals of motion. We analyze the whole spectrum of Toda-modes and show how they dictate, via a Generalized Gibbs Ensemble (GGE), the quasi-static states along the FPU evolution. This picture is employed to devise a fast numerical integration, which can be generalized to other quasi-integrable models. In addition, the GGE description leads to a fluctuation theorem, describing the large deviations as the system flows in the entropy landscape., 13 pages, 9 figures

Published
2019

35. Functional Diversity in the Retina Improves the Population Code

Author

Felix Lebois, Rava Azeredo da Silveira, Avi Ziskind, Michael J. Berry, Princeton University, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Department of Physics, Princeton University (DPPU), Princeton Neuroscience Institute [Princeton], Laboratoire de Physique Statistique de l'ENS (LPS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Biophysique et Neuroscience Théoriques, and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris)

Subjects
Retinal Ganglion Cells, Computer science, Cognitive Neuroscience, [SDV]Life Sciences [q-bio], Models, Neurological, Population, Action Potentials, Retinal ganglion, Retina, 03 medical and health sciences, 0302 clinical medicine, Arts and Humanities (miscellaneous), Biological neural network, Feature (machine learning), Animals, Humans, Set (psychology), education, 030304 developmental biology, [PHYS]Physics [physics], 0303 health sciences, education.field_of_study, business.industry, Population size, Pattern recognition, Artificial intelligence, Neural coding, business, Photic Stimulation, 030217 neurology & neurosurgery, Coding (social sciences)
Abstract

International audience; Within a given brain region, individual neurons exhibit a wide variety of different feature selectivities. Here, we investigated the impact of this extensive functional diversity on the population neural code. Our approach was to build optimal decoders to discriminate among stimuli using the spiking output of a real, measured neural population and compare its performance against a matched, homogeneous neural population with the same number of cells and spikes. Analyzing large populations of retinal ganglion cells, we found that the real, heterogeneous population can yield a discrimination error lower than the homogeneous population by several orders of magnitude and consequently can encode much more visual information. This effect increases with population size and with graded degrees of heterogeneity. We complemented these results with an analysis of coding based on the Chernoff distance, as well as derivations of inequalities on coding in certain limits, from which we can conclude that the beneficial effect of heterogeneity occurs over a broad set of conditions. Together, our results indicate that the presence of functional diversity in neural populations can enhance their coding fidelity appreciably. A noteworthy outcome of our study is that this effect can be extremely strong and should be taken into account when investigating design principles for neural circuits.

Published
2019

36. Perceptual decision making: Biases in post-error reaction times explained by attractor network dynamics

Author

Berlemont, Kevin, Nadal, Jean-Pierre, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Biophysique et Neuroscience Théoriques, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Centre d'Analyse et de Mathématique sociales (CAMS), and École des hautes études en sciences sociales (EHESS)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], [SCCO.NEUR]Cognitive science/Neuroscience, reaction times, post- error slowing, post-error slowing, [SDV.NEU]Life Sciences [q-bio]/Neurons and Cognition [q-bio.NC], [PHYS.COND.CM-DS-NN]Physics [physics]/Condensed Matter [cond-mat]/Disordered Systems and Neural Networks [cond-mat.dis-nn], attractor networks, perceptual decision making
Abstract

International audience; Perceptual decision making is the subject of many experimental and theoretical studies. Whereas most modeling analysis are based on statistical processes of accumulation of evidence, less attention is being devoted to the modeling with attractor network dynamics, even though they describe well psychophysical and neurophysiological data. In particular, very few works confront attractor models predictions with data from continuous sequences of trials. Recently however, a biophysical competitive attractor network model has been used to describe such sequences of decision trials, and has been shown to reproduce repetition biases observed in perceptual decision experiments. Here we propose an extension of the reduced attractor network model of Wong and Wang (2006) to get more insights into such effects. We make explicit the conditions under which such network can perform a succession of decisions, and show that the model provides a mathematical framework for studying the effects of a trial on the decision made on the next one. We study in details the reaction times properties during a sequence of decision trials, and show that the model reproduces behavioral data, both qualitatively and quantitatively. In particular, we find that the decision made on the current trial is biased toward the one made on the previous trial. More remarkably, we show that, in the absence of any feedback about the correctness of the decision, the network exhibits post-error slowing, a subtle effect in agreement with empirical data.

Published
2019

37. MicroMegascope based dynamic Surface Force Apparatus

Author

Antoine Lainé, Laetitia Jubin, Lydéric Bocquet, Antoine Niguès, Alessandro Siria, Luca Canale, Stephen H. Donaldson, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Micromegas : Nano-Fluidique, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-10-LABX-0010,ENS-ICFP,ENS- International Center for Fundamental Physics and its interfaces(2010), European Project: 637748,H2020,ERC-2014-STG,NanoSOFT(2015), and European Project: 785911,Shadoks

Subjects
Materials science, Physics - Instrumentation and Detectors, Acoustics, FOS: Physical sciences, Bioengineering, 02 engineering and technology, Condensed Matter - Soft Condensed Matter, 010402 general chemistry, 01 natural sciences, General Materials Science, Soft matter, [PHYS.PHYS.PHYS-INS-DET]Physics [physics]/Physics [physics]/Instrumentation and Detectors [physics.ins-det], Electrical and Electronic Engineering, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Mechanical Engineering, Mechanical impedance, Surface forces apparatus, Instrumentation and Detectors (physics.ins-det), General Chemistry, 021001 nanoscience & nanotechnology, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], 0104 chemical sciences, Characterization (materials science), Shear (sheet metal), Interferometry, Mechanics of Materials, Force dynamics, Nanotribology, Soft Condensed Matter (cond-mat.soft), 0210 nano-technology
Abstract

International audience; Surface Force Apparatus (SFA) allows to accurately resolve the interfacial properties of fluids confined between extended surfaces. The accuracy of the SFA makes it an ubiquitous tool for the nanoscale mechanical characterization of soft matter systems. The SFA traditionally measures force-distance profiles through interferometry with subnanometric distance precision. However, these techniques often require a dedicated and technically demanding experimental setup, and there remains a need for versatile and simple force-distance measurement tools. Here we present a MicroMegascope based dynamic Surface Force Apparatus capable of accurate measurement of the dynamic force profile of a liquid confined between a millimetric sphere and a planar substrate. Normal and shear mechanical impedance is measured within the classical Frequency Modulation framework. We measure rheological and frictional properties from micrometric to molecular confinement. We also highlight the resolution of small interfacial features such as ionic liquid layering. This apparatus shows promise as a versatile force-distance measurement device for exotic surfaces or extreme environments.

Published
2019

38. Peeling a soft viscoelastic adhesive: experiments and scaling laws

Author

Perrin, Hugo, Eddi, Antonin, Karpitschka, Stefan, Snoeijer, Jacco, Andreotti, Bruno, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP), Max Planck Institute for Dynamics and Self-Organization (MPIDS), Max-Planck-Gesellschaft, University of Twente [Netherlands], Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Physique et mécanique des milieux hétérogenes (PMMH (UMR_7636)), and Université Paris Diderot - Paris 7 (UPD7)-ESPCI ParisTech-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], genetic structures, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

International audience; The functionality of adhesives relies on their response under the application of a load. Yet, it has remained a challenge to quantitatively relate the macroscopic dynamics of peeling to the dissipative processes inside the adhesive layer. Here we investigate the peeling of a reversible adhesive made of a polymer gel, measuring the relationship between the peeling force, the peeling velocity, and the geometry of the interface at small-scale. Experiments are compared to a theory based on the linear viscoelastic response of the adhesive, augmented with an elastocapillary regularization approach. This theory, fully quantitative in the limit of small surface deformations, demonstrates the emergence of a "wetting" angle at the contact line and exhibits scaling laws for peeling which are in good agreement with the experimental results. Our findings provide a new strategy for design of reversible adhesives, by quantitatively combining wetting, geometry and dissipation.

Published
2019

39. Ballistics of self-jumping microdroplets

Author

Atikur Rahman, Pierre Lecointre, Timothée Mouterde, David Quéré, Charles T. Black, Antonio Checco, Christophe Clanet, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Micromegas : Nano-Fluidique, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), Brookhaven National Laboratory [Upton, NY] (BNL), U.S. Department of Energy [Washington] (DOE)-UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), State University of New York (SUNY)-State University of New York (SUNY), Center for Functional Nanomaterials, State University of New York (SUNY)-State University of New York (SUNY)-U.S. Department of Energy [Washington] (DOE)-UT-Battelle, LLC-Stony Brook University [SUNY] (SBU), Laboratoire d'hydrodynamique (LadHyX), École polytechnique (X)-Centre National de la Recherche Scientifique (CNRS), Physique et mécanique des milieux hétérogenes (UMR 7636) (PMMH), Ecole Superieure de Physique et de Chimie Industrielles de la Ville de Paris (ESPCI Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Université de Paris (UP)

Subjects
[PHYS]Physics [physics], Fluid Flow and Transfer Processes, Materials science, media_common.quotation_subject, Computational Mechanics, Ballistics, 02 engineering and technology, Mechanics, 021001 nanoscience & nanotechnology, Inertia, 01 natural sciences, Slow flight, 010305 fluids & plasmas, Physics::Fluid Dynamics, Lift (force), Viscosity, Modeling and Simulation, 0103 physical sciences, Jump, Takeoff, 0210 nano-technology, ComputingMilieux_MISCELLANEOUS, Microscale chemistry, media_common
Abstract

Droplets merging on hydrophobic nanocones jump off, and the takeoff speed is found to be maximum at microscale, below and above which viscosity and inertia, respectively, cap this speed. Microdroplets successively experience strong lift off, slow flight, and smooth landing, which impedes bouncing.

Published
2019

40. Beyond the Tradeoff: Dynamic Selectivity in Ionic Transport and Current Rectification

Author

Alessandro Siria, Lydéric Bocquet, Anthony R. Poggioli, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Micromegas : Nano-Fluidique, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Materials science, Ionic bonding, 010402 general chemistry, 7. Clean energy, 01 natural sciences, Quantitative Biology::Subcellular Processes, symbols.namesake, 0103 physical sciences, Materials Chemistry, Surface charge, Physical and Theoretical Chemistry, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], Debye length, ComputingMilieux_MISCELLANEOUS, Debye, [PHYS]Physics [physics], Physics::Biological Physics, 010304 chemical physics, Conductance, 0104 chemical sciences, Surfaces, Coatings and Films, Nanopore, Membrane, Chemical physics, symbols, Selectivity, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft]
Abstract

Traditionally, ion selectivity in nanopores and nanoporous membranes is understood to be a consequence of Debye overlap, in which the Debye screening length is comparable to the nanopore radius somewhere along the length of the nanopore(s). This criterion sets a significant limitation on the size of ion-selective nanopores, as the Debye length is on the order of 1-10 nm for typical ionic concentrations. However, the analytical results we present here demonstrate that surface conductance generates a dynamical selectivity in ion transport, and this selectivity is controlled by so-called Dukhin, rather than Debye, overlap. The Dukhin length, defined as the ratio of surface to bulk conductance, reaches values of hundreds of nanometers for typical surface charge densities and ionic concentrations, suggesting the possibility of designing large-nanopore (10-100 nm), high-conductance membranes exhibiting significant ion selectivity. Such membranes would have potentially dramatic implications for the efficiency of osmotic energy conversion and separation techniques. Furthermore, we demonstrate that this mechanism of dynamic selectivity leads ultimately to the rectification of ionic current, rationalizing previous studies, showing that Debye overlap is not a necessary condition for the occurrence of rectifying behavior in nanopores.

Published
2019

41. SNAREpin Assembly: Kinetic and Thermodynamic Approaches

Author

Frederic Pincet, Feng Li, Yale University School of Medicine, Sorbonne Université (SU), Sorbonne Université - Faculté de Médecine (SU FM), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Mécanismes Moléculaires Membranaires, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), and Rutilio Fratti

Subjects
0303 health sciences, [SDV.BBM.BS]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Structural Biology [q-bio.BM], Chemistry, Protein assembly, Protein interaction, Kinetics, Critical factors, Isothermal titration calorimetry, Characterization (materials science), [SDV.BBM.BP]Life Sciences [q-bio]/Biochemistry, Molecular Biology/Biophysics, 03 medical and health sciences, 0302 clinical medicine, VAMP2, Chemical physics, SNARE, Fluorescence polarization, SNAP25, Syntaxin, 030217 neurology & neurosurgery, Fluorescence anisotropy, 030304 developmental biology
Abstract

International audience; Proteins constantly interact and often form molecular complexes. The dynamics of most biological processes strongly rely on the kinetics and thermodynamics of assembly and disassembly of these complexes. Consequently an accurate characterization of these kinetics and thermodynamics that underlie them provides key information to better understand these processes. Here, we present two efficient techniques to quantify the assembly and disassembly of protein complexes: isothermal titration calorimetry and fluorescence anisotropy. As an example we focus on the formation of SNAREpins and also present how to prepare SNARE proteins to use in these experimental setups. We then show how to use these techniques to determine the critical factors that activate assembly kinetics.

Published
2019

42. Three-wave interactions among surface gravity waves in a cylindrical container

Author

Guillaume Michel, HAL-UPMC, Gestionnaire, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Slosh dynamics, Computational Mechanics, FOS: Physical sciences, Container (type theory), 01 natural sciences, 010305 fluids & plasmas, [PHYS] Physics [physics], 0103 physical sciences, Fluid dynamics, [PHYS.MECA.MEFL] Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], [PHYS.MECA.MEFL]Physics [physics]/Mechanics [physics]/Fluid mechanics [physics.class-ph], 010306 general physics, Nonlinear waves, [PHYS]Physics [physics], Fluid Flow and Transfer Processes, Physics, Fluid Dynamics (physics.flu-dyn), Resonance, Fluid Dynamics, Physics - Fluid Dynamics, Mechanics, Physical Systems, Surface gravity, Surface waves, Nonlinear system, Surface wave, Modeling and Simulation, Free surface
Abstract

The motion of a container filled with fluid perturbs the free surface and may result in spilling. In practice, most of the energy is localized in the modes of lowest frequencies (the gravest modes), and sloshing can be predicted once the dynamics of these modes is known. In this Rapid Communication, we investigate the nonlinear interactions between such grave modes in a cylindrical container. We first show that energy can be transferred from modes to modes with three-wave interactions: we derive the resonance conditions and characterize the early stage of this interaction. This result strongly contrasts with resonant interactions between surface gravity waves in extended domains such as the ocean, which involve at least four waves and are thus less efficient. An experiment is then performed to provide evidence of these nonlinear interactions., Comment: 7 pages, 3 figures

Published
2019

43. Interfacial transport with mobile surface charges and consequences for ionic transport in carbon nanotubes

Author

Timothée Mouterde, Lydéric Bocquet, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
Materials science, Biophysics, Ionic bonding, FOS: Physical sciences, 02 engineering and technology, Carbon nanotube, Slip (materials science), Condensed Matter - Soft Condensed Matter, 01 natural sciences, law.invention, Physics::Fluid Dynamics, Electrokinetic phenomena, law, Electric field, 0103 physical sciences, General Materials Science, Boundary value problem, Surface charge, [PHYS.COND]Physics [physics]/Condensed Matter [cond-mat], 010306 general physics, ComputingMilieux_MISCELLANEOUS, [PHYS]Physics [physics], Conductance, Surfaces and Interfaces, General Chemistry, 021001 nanoscience & nanotechnology, Chemical physics, Soft Condensed Matter (cond-mat.soft), 0210 nano-technology, [PHYS.COND.CM-SCM]Physics [physics]/Condensed Matter [cond-mat]/Soft Condensed Matter [cond-mat.soft], Biotechnology
Abstract

In this paper, we explore the effect of a finite surface charge mobility on the interfacial transport: conductance, streaming currents, electro- and diffusio-osmotic flows. We first show that the surface charge mobility modifies the hydrodynamic boundary condition for the fluid, which introduces a supplementary term depending on the applied electric field. In particular, the resulting slip length is found to decrease inversely with the surface charge. We then derive expressions for the various transport mobilities, high-lighting that the surface charge mobility merely moderates the amplification effect of interfacial slippage, to the noticeable exception of diffusio-osmosis and surface conductance. Our calculations, obtained within Poisson-Boltzmann framework, highlight the importance of non-linear electrostatic contributions to predict the small concentration/large charge limiting regimes for the transport mobilities. We discuss these predictions in the context of recent electrokinetic experiments with carbon nanotubes.

Published
2019
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44. Anisotropic cellular forces support mechanical integrity of the Stratum Corneum barrier

Author

Mark Donovan, Yves Pomeau, Shuo Guo, Gustavo S. Luengo, Yegor A. Domanov, Eric Perez, Bertrand Ducos, Christine Gourier, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Mécanismes Moléculaires Membranaires, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), L'Oréal Research, L'OREAL, L'Oréal Recherche France (L'Oréal Recherche), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Dept. of Mathematics, University of Arizona (Dept. of Mathematics, University of Arizona), University of Arizona, Université Paris Diderot - Paris 7 (UPD7)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)

Subjects
Materials science, [PHYS.PHYS.PHYS-BIO-PH]Physics [physics]/Physics [physics]/Biological Physics [physics.bio-ph], Population, Biomedical Engineering, Biomaterials, 030207 dermatology & venereal diseases, 03 medical and health sciences, 0302 clinical medicine, Materials Testing, Stratum corneum, medicine, Humans, [PHYS.MECA.BIOM]Physics [physics]/Mechanics [physics]/Biomechanics [physics.med-ph], Anisotropy, education, Cell adhesion, ComputingMilieux_MISCELLANEOUS, 030304 developmental biology, Mechanical Phenomena, Skin, 0303 health sciences, education.field_of_study, Corneocyte, Adhesion, Biomechanical Phenomena, medicine.anatomical_structure, Mechanics of Materials, Biophysics, Adhesive, Layer (electronics)
Abstract

International audience; The protective function of biological surfaces that are exposed to the exterior of living organisms is the result of a complex arrangement and interaction of cellular components. This is the case for the most external cornified layer of skin, the stratum corneum (SC). This layer is made of corneocytes, the elementary ‘flat bricks’ that are held together through adhesive junctions. Despite the well-known protective role of the SC under high mechanical stresses and rapid cell turnover, the subtleties regarding the adhesion and mechanical interaction among the individual corneocytes are still poorly known. Here, we explore the adhesion of single corneocytes at different depths of the SC, by pulling them using glass microcantilevers, and measuring their detachment forces. We measured their interplanar adhesion between SC layers, and their peripheral adhesion among cells within a SC layer. Both adhesions increased considerably with depth. At the SC surface, with respect to adhesion, the corneocyte population exhibited a strong heterogeneity, where detachment forces differed by more than one order of magnitude for corneocytes located side by side. The measured detachment forces indicated that in the upper-middle layers of SC, the peripheral adhesion was stronger than the interplanar one. We conclude that the stronger peripheral adhesion of corneocytes in the SC favors an efficient barrier which would be able to resist strong stresses.

Published
2019

45. Eigenstate thermalization hypothesis and out of time order correlators

Author

Jorge Kurchan, Laura Foini, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS ( LPS ), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris ( FRDPENS ), Centre National de la Recherche Scientifique ( CNRS ) -École normale supérieure - Paris ( ENS Paris ) -Centre National de la Recherche Scientifique ( CNRS ) -École normale supérieure - Paris ( ENS Paris ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS ), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
High Energy Physics - Theory, chaos, FOS: Physical sciences, Lyapunov exponent, Correlation function (quantum field theory), operator: local, 01 natural sciences, 010305 fluids & plasmas, [ PHYS.HTHE ] Physics [physics]/High Energy Physics - Theory [hep-th], thermal, symbols.namesake, Chaotic systems, 0103 physical sciences, [ PHYS.PHYS.PHYS-GEN-PH ] Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], correlation function, 010306 general physics, Eigenstate thermalization hypothesis, Condensed Matter - Statistical Mechanics, Eigenvalues and eigenvectors, Mathematical physics, Physics, Quantum Physics, Statistical Mechanics (cond-mat.stat-mech), [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], Statistical Physics, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], Hamiltonian, Nonlinear Sciences::Chaotic Dynamics, High Energy Physics - Theory (hep-th), Exponent, symbols, Hamiltonian (quantum mechanics), Quantum Physics (quant-ph)
Abstract

International audience; The eigenstate thermalization hypothesis (ETH) implies a form for the matrix elements of local operators between eigenstates of the Hamiltonian, expected to be valid for chaotic systems. Another signal of chaos is a positive Lyapunov exponent, defined on the basis of Loschmidt echo or out of time order correlators. For this exponent to be positive, correlations between matrix elements unrelated by symmetry, usually neglected, have to exist. The same is true for the peak of the dynamic heterogeneity length χ4, relevant for systems with slow dynamics. These correlations, as well as those between elements of different operators, are encompassed in a generalized form of ETH.

Published
2019

46. JUNO, the receptor of sperm IZUMO1, is expressed by the human oocyte and is essential for human fertilisation

Author

J E Lee, Virginie Barraud-Lange, Ahmed Ziyyat, Eric Rubinstein, Camille Jean, Farhad Haghighi-Rad, Yingying Zhu, Jean-Philippe Wolf, Claude Boucheix, M Chalbi, Paul M. Yip, Christine Gourier, Université Paris Descartes - Faculté de Médecine (UPD5 Médecine), Université Paris Descartes - Paris 5 (UPD5), Université Paris-Sud - Paris 11 - Faculté de médecine (UP11 UFR Médecine), Université Paris-Sud - Paris 11 (UP11), Huazhong University of Science and Technology [Wuhan] (HUST), Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Mécanismes Moléculaires Membranaires, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7), and University of Toronto

Subjects
0301 basic medicine, Male, medicine.drug_class, medicine.medical_treatment, [SDV]Life Sciences [q-bio], Egg protein, Cell Culture Techniques, Immunoglobulins, Receptors, Cell Surface, Fertilization in Vitro, Biology, Monoclonal antibody, 03 medical and health sciences, Mice, 0302 clinical medicine, medicine, Animals, Humans, Fertilisation, ComputingMilieux_MISCELLANEOUS, Sperm-Ovum Interactions, In vitro fertilisation, Hybridomas, Rehabilitation, Cell Membrane, Egg Proteins, Obstetrics and Gynecology, Antibodies, Monoclonal, Membrane Proteins, Oocyte, Sperm, Spermatozoa, Recombinant Proteins, Cell biology, 030104 developmental biology, medicine.anatomical_structure, HEK293 Cells, Reproductive Medicine, Fertilization, Oocytes, Gamete, Female, Carrier Proteins, 030217 neurology & neurosurgery, Immunostaining
Abstract

Study question Is JUNO protein present at the surface membrane of human oocytes and involved in the fertilisation process? Summary answer JUNO protein is expressed on the plasma membrane of human oocytes and its inhibition by a monoclonal antibody completely blocks gamete fusion. What is known already Fusion of gamete membranes is the culminating event of the fertilisation process, but its molecular mechanisms are poorly understood. Until now, three molecules have been shown to be essential: CD9 tetraspanin in the oocyte, Izumo1 protein on the sperm and Juno, its corresponding receptor on the oocyte. Oocyte CD9 and sperm IZUMO1 have been identified in human gametes and their interaction is also well-conserved among several mammalian species. The presence of JUNO on human oocytes, however, has not yet been reported, nor has its role in fertilisation been investigated. Study design, size, duration We selected an anti-human JUNO antibody in order to investigate the presence of JUNO on the oocyte membrane surface and studied its potential involvement in gamete membrane interaction during fertilisation. Participants/materials, setting, methods Monoclonal antibodies against human JUNO (anti-hJUNO mAb) were produced by immunisation of mice with HEK cells transfected with the putative human JUNO sequence (HEK-hJUNO). These antibodies were used for immunostaining experiments and in vitro fertilisation assays with human gametes (GERMETHEQUE Biobank). Main results and the role of chance Three hybridoma supernatants, verified by immunostaining, revealed specifically HEK-hJUNO cells. The three purified monoclonal antibodies, FJ2E4 (IgG1), FJ8E8 (IgG1) and FJ4F5 (IgG2a), recognised the soluble recombinant human JUNO protein and, in a western blot of HEK-hJUNO extracts, a protein with an expected MW of 25 kDa. In addition, soluble recombinant human IZUMO protein inhibited the binding of anti-hJUNO mAbs to cells expressing hJUNO. Using these anti-hJUNO mAbs in immunostaining, we identified the presence of JUNO protein at the plasma membrane of human oocytes. Furthermore, we revealed a progressive expression of JUNO according to oocyte maturity. Finally, we showed that human zona-free oocytes, inseminated in the presence of anti-hJUNO mAb, were not fertilised by human sperm. These results suggest that, as seen in the mouse, JUNO is indeed involved in human gamete membrane fusion during fertilisation. Large-scale data N/A. Limitations, reasons for caution In accordance with French bioethics laws, functional tests were performed using zona-free oocytes, which of course does not fully encompass all normal in vivo physiological conditions. However, these in vitro tests do provide direct information regarding sperm-oocyte membrane interactions. Wider implications of the findings Mechanisms of gamete fusion appear to be homologous between mice and humans. However, some differences do exist and analysing the human mechanisms is essential. In fact, this is the first report describing the presence of JUNO on human oocytes and its involvement in human fertilisation. This discovery allows further examination of the understanding of molecular mechanisms that drive gamete fusion: a crucial challenge at a time when infertility affects 16% of reproductively active couples. Study funding/competing interests This work was supported by the Agence Nationale pour la Recherche, Grant no. ANR-13-BVS5-0004, and by Association Institut du Cancer et d'Immunogenetique (ICIG). There are no competing interests.

Published
2019

47. Correlation functions with single photon emitters under noisy resonant continuous excitation

Author

Emmanuel Baudin, Ph. Roussignol, Raphaël Proux, Carole Diederichs, Maria Maragkou, Laboratoire Pierre Aigrain (LPA), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Nano-Optique, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Photon, Computation, two-level models, FOS: Physical sciences, 01 natural sciences, 010305 fluids & plasmas, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], 0103 physical sciences, Astronomical interferometer, Figure of merit, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Physics, Quantum optics, Quantum Physics, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Photon correlation spectroscopy, Autocorrelation, 3. Good health, Computational physics, Single photons sources, Interferometry, Fluctuations & noise, Quantum Physics (quant-ph), Excitation, Photon statistics
Abstract

To characterize the statistics and indistinguishability of a source, it is common to measure the correlation functions of the emitted field using various interferometers. Here, we present a theoretical framework for the computation of the correlation functions of a two-level system that is resonantly driven by a realistic noisy cw excitation laser. Analytic expressions of the first and second-order auto-correlation functions are obtained where the various contributions of the noisy excitation source are correctly taken into account. We predict that, even in the low power regime, the noise source has a strong influence on the two-level system dynamics, which is not anticipated by simpler models. The characterization of photon indistinguishability in the pulsed excitation regime is usually done by measuring the value of the zero-delay intensity correlation obtained with a Hong-Ou-Mandel interferometer. We show that this figure is irrelevant in the cw excitation regime and we introduce the coalescence time window, a figure of merit based on a probabilistic interpretation of the notion of photon indistinguishability. We finally use the coalescence time window to quantify how noisy cw excitation influences photon indistinguishability., Comment: 15 pages, 9 figures, 2 tables

Published
2019

48. Synaptotagmin oligomers are necessary and can be sufficient to form a Ca 2+ -sensitive fusion clamp

Author

Shyam S. Krishnakumar, Jeff Coleman, Frederic Pincet, James E. Rothman, Manindra Bera, Sathish Ramakrishnan, Yale University School of Medicine, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Mécanismes Moléculaires Membranaires, Laboratoire de physique de l'ENS - ENS Paris (LPENS (UMR_8023)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)-École normale supérieure - Paris (ENS Paris), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Université Paris Diderot - Paris 7 (UPD7)

Subjects
Electron Microscope Tomography, SNARE proteins, Biophysics, medicine.disease_cause, SYT1, Biochemistry, Membrane Fusion, Synaptotagmin 1, 03 medical and health sciences, Structural Biology, Genetics, medicine, Research Letter, Animals, [SDV.BBM]Life Sciences [q-bio]/Biochemistry, Molecular Biology, single-vesicle analysis, Molecular Biology, 030304 developmental biology, 0303 health sciences, Mutation, Fusion, calcium, Chemistry, Vesicle, Bilayer, 030302 biochemistry & molecular biology, Cryoelectron Microscopy, fusion clamp, Cell Biology, Research Letters, Synaptotagmin, Clamp, Synaptotagmin I, single‐vesicle analysis, Synaptic Vesicles, Protein Multimerization
Abstract

International audience; The buttressed-ring hypothesis, supported by recent cryo-electron tomography analysis of docked synaptic-like vesicles in neuroendocrine cells, postulates that prefusion SNAREpins are stabilized and organized by Synaptotagmin (Syt) ring-like oligomers. Here, we use a reconstituted single-vesicle fusion analysis to test the prediction that destabilizing the Syt1 oligomers destabilizes the clamp and results in spontaneous fusion in the absence of Ca 2+. Vesicles in which Syt oligomerization is compromised by a ring-destabilizing mutation dock and diffuse freely on the bilayer until they fuse spontaneously, similar to vesicles containing only v-SNAREs. In contrast, vesicles containing wild-type Syt are immobile as soon as they attach to the bilayer and remain frozen in place, up to at least 1 h until fusion is triggered by Ca 2+ .

Published
2019

49. Emergence and spontaneous breaking of approximate $O(4)$ symmetry at a weakly first-order deconfined phase transition

Author

Serna, Pablo, Nahum, Adam, Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire de Physique Statistique de l'ENS ( LPS ), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris ( FRDPENS ), and Centre National de la Recherche Scientifique ( CNRS ) -École normale supérieure - Paris ( ENS Paris ) -Centre National de la Recherche Scientifique ( CNRS ) -École normale supérieure - Paris ( ENS Paris ) -Université Pierre et Marie Curie - Paris 6 ( UPMC ) -Université Paris Diderot - Paris 7 ( UPD7 ) -Centre National de la Recherche Scientifique ( CNRS )

Subjects
High Energy Physics - Theory, Strongly Correlated Electrons (cond-mat.str-el), Statistical Mechanics (cond-mat.stat-mech), dimension: 3, [PHYS.HTHE]Physics [physics]/High Energy Physics - Theory [hep-th], High Energy Physics::Lattice, critical phenomena: deconfinement, FOS: Physical sciences, spontaneous symmetry breaking, Electronic structure and strongly correlated systems, [PHYS.PHYS.PHYS-GEN-PH]Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], [ PHYS.HTHE ] Physics [physics]/High Energy Physics - Theory [hep-th], Condensed Matter - Strongly Correlated Electrons, High Energy Physics - Theory (hep-th), sigma model: O(4), renormalization group: flow, [ PHYS.PHYS.PHYS-GEN-PH ] Physics [physics]/Physics [physics]/General Physics [physics.gen-ph], emergence, flavor: 2, symmetry: lattice, numerical calculations: Monte Carlo, Condensed Matter - Statistical Mechanics
Abstract

We investigate approximate emergent nonabelian symmetry in a class of weakly first order `deconfined' phase transitions using Monte Carlo simulations and a renormalization group analysis. We study a transition in a 3D classical loop model that is analogous to a deconfined 2+1D quantum phase transition in a magnet with reduced lattice symmetry. The transition is between the N\'eel phase and a twofold degenerate valence bond solid (lattice-symmetry-breaking) phase. The combined order parameter at the transition is effectively a four-component superspin. It has been argued that in some weakly first order `pseudocritical' deconfined phase transitions, the renormalization group flow can take the system very close to the ordered fixed point of the symmetric $O(N)$ sigma model, where $N$ is the total number of `soft' order parameter components, despite the fact that $O(N)$ is not a microscopic symmetry. This yields a first order transition with unconventional phenomenology. We argue that this occurs in the present model, with $N=4$. This means that there is a regime of lengthscales in which the transition resembles a `spin-flop' transition in the ordered $O(4)$ sigma model. We give numerical evidence for (i) the first order nature of the transition, (ii) the emergence of $O(4)$ symmetry to an accurate approximation, and (iii) the existence of a regime in which the emergent $O(4)$ is `spontaneously broken', with distinctive features in the order parameter probability distribution. These results may be relevant for other models studied in the literature, including 2+1D QED with two flavours, the `easy-plane' deconfined critical point, and the N\'eel--VBS transition on the rectangular lattice., Comment: 16 pages. v2: updated to journal version

Published
2019

50. Generalisation dynamics of online learning in over-parameterised neural networks

Author

Goldt, Sebastian, Advani, Madhu S., Saxe, Andrew M., Krzakala, Florent, Zdeborová, Lenka, Institut de Physique Théorique - UMR CNRS 3681 (IPHT), Commissariat à l'énergie atomique et aux énergies alternatives (CEA)-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Harvard University [Cambridge], Department of Experimental Psychology, University of Oxford [Oxford], Laboratoire de Physique Statistique de l'ENS (LPS), Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS Paris), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), ANR-17-CE23-0023,PAIL,Diagramme de Phase et Algorithme pour l'inference et l'apprentissage(2017), European Project: 725937,Neuroabstraction, European Project: 714608,SMILE, Harvard University, University of Oxford, École normale supérieure - Paris (ENS-PSL), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-École normale supérieure - Paris (ENS-PSL), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Université Paris Diderot - Paris 7 (UPD7)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)

Subjects
[PHYS]Physics [physics], FOS: Computer and information sciences, Computer Science - Machine Learning, Statistical Mechanics (cond-mat.stat-mech), Statistics - Machine Learning, Physics::Physics Education, FOS: Physical sciences, Machine Learning (stat.ML), Disordered Systems and Neural Networks (cond-mat.dis-nn), Condensed Matter - Disordered Systems and Neural Networks, Condensed Matter - Statistical Mechanics, Machine Learning (cs.LG)
Abstract

Deep neural networks achieve stellar generalisation on a variety of problems, despite often being large enough to easily fit all their training data. Here we study the generalisation dynamics of two-layer neural networks in a teacher-student setup, where one network, the student, is trained using stochastic gradient descent (SGD) on data generated by another network, called the teacher. We show how for this problem, the dynamics of SGD are captured by a set of differential equations. In particular, we demonstrate analytically that the generalisation error of the student increases linearly with the network size, with other relevant parameters held constant. Our results indicate that achieving good generalisation in neural networks depends on the interplay of at least the algorithm, its learning rate, the model architecture, and the data set., Comment: 25 pages, 13 figures

Published
2019
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