Author: "Fabrice Gerbier" - Searchworks@Jio Institute Digital Library Search Results

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78 results on '"Fabrice Gerbier"'

1. Spin-gap spectroscopy in a bosonic flux ladder

Author: Marcello Calvanese Strinati, Fabrice Gerbier, and Leonardo Mazza
Subjects: flux ladders, synthetic gauge fields, Meissner and vortex phases, matrix-product states, Science, Physics, QC1-999
Abstract: Ultracold bosonic atoms trapped in a two-leg ladder pierced by a magnetic field provide a minimal and quasi-one-dimensional instance to study the interplay between orbital magnetism and interactions. Using time-dependent matrix-product-state simulations, we investigate the properties of the so-called ‘Meissner’ and ‘vortex’ phases which appear in such a system, focusing on the experimentally accessible observables. We discuss how to experimentally monitor the phase transition, and show that the response to the modulation of the density imbalance between the two legs of the ladder is qualitatively different in the two phases. We argue that this technique can be used as a tool for many-body spectroscopy, allowing us to quantitatively measure the spin gap in the Meissner phase. We finally discuss its experimental implementation.
Published: 2018
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2. Spin fragmentation of Bose–Einstein condensates with antiferromagnetic interactions

Author: Luigi De Sarlo, Lingxuan Shao, Vincent Corre, Tilman Zibold, David Jacob, Jean Dalibard, and Fabrice Gerbier
Subjects: Science, Physics, QC1-999
Abstract: We study spin fragmentation of an antiferromagnetic spin 1 condensate in the presence of a quadratic Zeeman (QZ) effect breaking spin rotational symmetry. We describe how the QZ effect turns a fragmented spin state, with large fluctuations of the Zeeman populations, into a regular polar condensate, where the atoms all condense in the m = 0 state along the field direction. We calculate the average value and variance of the population of the Zeeman state m = 0 to illustrate clearly the crossover from a fragmented to an unfragmented state. The typical width of this crossover is q ∼ k _B T / N , where q is the QZ energy, T the spin temperature and N the atom number. This shows that the spin fluctuations are a mesoscopic effect that will not survive in the thermodynamic limit N → ∞, but are observable for a sufficiently small atom number.
Published: 2013
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3. Adiabatic Quantum Zeno Dynamics of Bosonic Atom Pairs with Large Inelastic Losses

Author: Manel Bosch Aguilera, Alexis Ghermaoui, Rémy Vatré, Raphaël Bouganne, Jérôme Beugnon, and Fabrice Gerbier
Subjects: Quantum Physics, Quantum Gases (cond-mat.quant-gas), FOS: Physical sciences, Condensed Matter - Quantum Gases, Quantum Physics (quant-ph)
Abstract: We report on experiments exploring the non-Hermitian dynamics of pairs of two-level atoms tightly confined in an optical lattice and driven by a near-resonant laser. Although spontaneous emission is negligible for the long-lived excited state, two-body dissipation arises from strong inelastic collisions between two atoms in the excited state. We demonstrate quasi-adiabatic control of the internal state of the pairs in the quantum Zeno regime where inelastic losses dominate. Preparing each atom pair in the longest-lived eigenstate of the non-Hermitian Hamiltonian describing the dissipative dynamics, we measure a lifetime enhanced by more than two orders of magnitude in comparison to the bare two-body lifetime. The measured enhancement factor is in quantitative agreement with the expected lifetime of the prepared ``non-Hermitian dressed state''., Comment: Supplementary Information available as ancillary file
Published: 2022
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4. Observation of fragmentation of a spinor Bose-Einstein condensate

Author: Jean Dalibard, Bertrand Evrard, Fabrice Gerbier, and An Qu
Subjects: Condensed Matter::Quantum Gases, Physics, Multidisciplinary, Spinor, Condensed Matter::Other, Fragmentation (computing), 01 natural sciences, 010305 fluids & plasmas, law.invention, law, Continuous symmetry, Quantum mechanics, 0103 physical sciences, 010306 general physics, Bose–Einstein condensate
Abstract: Weakly interacting Bose gases usually form Bose-Einstein condensates in which most particles occupy the same single-particle state. However, when this state cannot realize a continuous symmetry of the many-body Hamiltonian, a fragmented condensate exhibiting the expected symmetry may emerge. Here, we produced a three-fragment condensate for a mesoscopic spin-1 gas of about 100 atoms, with anti-ferromagnetic interactions and vanishing collective spin. Using a spin-resolved detection approaching single-atom resolution, we show that the reconstructed state is close to the expected many-body ground state, whereas one-body observables are the same as for a completely mixed state. Our results highlight how the interplay between symmetry and interactions generates entanglement in a mesoscopic quantum system.
Published: 2021

5. Coherent seeding of the dynamics of a spinor Bose-Einstein condensate: From quantum to classical behavior

Author: Jean Dalibard, Fabrice Gerbier, Bertrand Evrard, An Qu, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Condensed Matter::Quantum Gases, Physics, Spinor, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Dynamics (mechanics), FOS: Physical sciences, Semiclassical physics, 01 natural sciences, 010305 fluids & plasmas, law.invention, Magnetic field, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), law, Quantum mechanics, 0103 physical sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Seeding, Condensed Matter - Quantum Gases, 010306 general physics, Quantum, Bose–Einstein condensate, Quantum fluctuation
Abstract: International audience; We present experiments revealing the competing effect of quantum fluctuations and of a coherent seed in the dynamics of a spin-1 Bose-Einstein condensate, and discuss the relevance of a mean-field description of our system. We first explore a near-equilibrium situation, where the mean-field equations can be linearized around a fixed point corresponding to all atoms in the same Zeeman state $m=0$. Preparing the system at this classical fixed point, we observe a reversible dynamics triggered by quantum fluctuations, which cannot be understood within a classical framework. We demonstrate that the classical description becomes accurate provided a coherent seed of a few atoms only is present in the other Zeeman states $m= \pm 1$. In a second regime characterized by a strong non-linearity of the mean-field equations, we observe a collapse dynamics driven by quantum fluctuations. This behavior cannot be accounted for by a classical description and persists for a large range of initial states. We show that all our experimental results can be explained with a semi-classical description (truncated Wigner approximation), using stochastic classical variables to model the quantum noise.
Published: 2021
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6. From many-body oscillations to thermalization in an isolated spinor gas

Author: An Qu, Jean Dalibard, Bertrand Evrard, Fabrice Gerbier, Chaire Atomes et rayonnement, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Physics, Spinor, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Spectrum (functional analysis), Chaotic, General Physics and Astronomy, FOS: Physical sciences, Observable, 01 natural sciences, Nonlinear system, symbols.namesake, Thermalisation, Classical mechanics, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), 0103 physical sciences, symbols, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, 010306 general physics, Hamiltonian (quantum mechanics), Condensed Matter - Quantum Gases, Eigenstate thermalization hypothesis
Abstract: The dynamics of a many-body system can take many forms, from a purely reversible evolution to fast thermalization. Here we show experimentally and numerically that an assembly of spin 1 atoms all in the same spatial mode allows one to explore this wide variety of behaviors. When the system can be described by a Bogoliubov analysis, the relevant energy spectrum is linear and leads to undamped oscillations of many-body observables. Outside this regime, the non-linearity of the spectrum leads to irreversibity, characterized by a universal behavior. When the integrability of the Hamiltonian is broken, a chaotic dynamics emerges and leads to thermalization, in agreement with the Eigenstate Thermalization Hypothesis paradigm., Supplementary material available as ancillary file
Published: 2021
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7. Strong correlations in lossy one-dimensional quantum gases: from the quantum Zeno effect to the generalized Gibbs ensemble

Author: Davide Rossini, R. Bouganne, Leonardo Mazza, Fabrice Gerbier, Rémy Vatré, Manel Bosch Aguilera, Alexis Ghermaoui, Jérôme Beugnon, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Physics, Canonical ensemble, Strongly Correlated Electrons (cond-mat.str-el), [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], FOS: Physical sciences, Rate equation, State (functional analysis), 01 natural sciences, Action (physics), 3. Good health, 010305 fluids & plasmas, Simple set, Condensed Matter - Strongly Correlated Electrons, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), Quantum mechanics, Metastability, 0103 physical sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Connection (algebraic framework), 010306 general physics, Condensed Matter - Quantum Gases, Quantum Zeno effect
Abstract: We consider strong two-body losses in bosonic gases trapped in one-dimensional optical lattices. We exploit the separation of time scales typical of a system in the many-body quantum Zeno regime to establish a connection with the theory of the time-dependent generalized Gibbs ensemble. Our main result is a simple set of rate equations that capture the simultaneous action of coherent evolution and two-body losses. This treatment gives an accurate description of the dynamics of a gas prepared in a Mott insulating state and shows that its long-time behaviour deviates significantly from mean-field analyses. The possibility of observing our predictions in an experiment with $^{174}$Yb in a metastable state is also discussed., Comment: 5 pages and 3 figures + Appendices
Published: 2021
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8. Probing spin correlations in a Bose-Einstein condensate near the single atom level

Author: Bertrand Evrard, An Qu, Jean Dalibard, Fabrice Gerbier, Chaire Atomes et rayonnement, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Vacuum state, General Physics and Astronomy, FOS: Physical sciences, 01 natural sciences, Resonance (particle physics), law.invention, symbols.namesake, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], law, 0103 physical sciences, Atom, 010306 general physics, Wave function, Quantum fluctuation, Spin-½, Physics, Condensed Matter::Quantum Gases, Quantum Physics, Zeeman effect, Quantum Gases (cond-mat.quant-gas), symbols, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Atomic physics, Condensed Matter - Quantum Gases, Quantum Physics (quant-ph), Bose–Einstein condensate
Abstract: Using parametric conversion induced by a Shapiro-type resonance, we produce and characterize a two-mode squeezed vacuum state in a sodium spin 1 Bose-Einstein condensate. Spin-changing collisions generate correlated pairs of atoms in the $m=\pm 1$ Zeeman states out of a condensate with initially all atoms in $m=0$. A novel fluorescence imaging technique with sensitivity $\Delta N \sim 1.6$ atom enables us to demonstrate the role of quantum fluctuations in the initial dynamics and to characterize the full distribution of the final state. Assuming that all atoms share the same spatial wave function, we infer a squeezing parameter of 15.3\,dB., Comment: Supplementary material available as ancillary file
Published: 2020
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9. Spontaneous formation and relaxation of spin domains in antiferromagnetic spin-1 condensates

Author: Jean Dalibard, Karina Jimenez-Garcia, Bertrand Evrard, A. Invernizzi, Fabrice Gerbier, C. Frapolli, Chaire Atomes et rayonnement, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution)), Laboratoire Kastler Brossel (LKB (Jussieu)), 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Sorbonne Université (SU), Centro de Investigacion y de Estudios Avanzados del Instituto Politécnico Nacional (CINVESTAV), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))-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)-Collège de France (CdF (institution))
Subjects: 0301 basic medicine, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Science, General Physics and Astronomy, FOS: Physical sciences, 02 engineering and technology, General Biochemistry, Genetics and Molecular Biology, Article, 03 medical and health sciences, Magnetization, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Phase (matter), Quantum system, Antiferromagnetism, Spin (physics), lcsh:Science, Physics, Condensed Matter::Quantum Gases, Multidisciplinary, Condensed matter physics, Relaxation (NMR), General Chemistry, 021001 nanoscience & nanotechnology, 3. Good health, Magnetic field, 030104 developmental biology, Ferromagnetism, Quantum Gases (cond-mat.quant-gas), [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, lcsh:Q, Condensed Matter::Strongly Correlated Electrons, 0210 nano-technology, Condensed Matter - Quantum Gases
Abstract: Quantum systems of many interacting particles at low temperatures generally organize themselves into ordered phases of matter, whose nature and symmetries are captured by an order parameter. In the simplest cases, this order parameter is spatially uniform. For example, a system of localized spins with ferromagnetic interactions align themselves to a common direction and build up a macroscopic magnetization on large distances. However, non-uniform situations also exist in nature, for instance in antiferromagnetism where the magnetization alternates in space. The situation becomes even richer when the spin-carrying particles are mobile, for instance in the so-called stripe phases emerging for itinerant electrons in strongly-correlated materials. Understanding such inhomogeneously ordered states is of central importance in many-body physics. In this work, we study experimentally the magnetic ordering of itinerant spin-1 bosons in inhomegeneous spin domains at nano-Kelvin temperatures. We demonstrate that spin domains form spontaneously after a phase separation transition, \textit{i.e.} in the absence of external magnetic force, purely because of the antiferromagnetic interactions between the atoms. Furthermore, we explore how the equilibrium domain configuration emerges from an initial state prepared far-from-equilibrium., Supplementary material available as ancillary file
Published: 2019
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10. Spin-gap spectroscopy in a bosonic flux ladder

Author: Leonardo Mazza, Fabrice Gerbier, Marcello Calvanese Strinati, Scuola Normale Super Pisa, NEST, Pisa, Italy, 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), Laboratoire Kastler Brossel (LKB (Jussieu)), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Phase transition, Magnetism, Phase (waves), General Physics and Astronomy, FOS: Physical sciences, 01 natural sciences, 010305 fluids & plasmas, synthetic gauge fields, flux ladders, 0103 physical sciences, 010306 general physics, Spectroscopy, Spin-½, Physics, [PHYS]Physics [physics], Quantum Physics, Condensed matter physics, Observable, Meissner and vortex phases, 3. Good health, Vortex, Magnetic field, matrix-product states, Quantum Gases (cond-mat.quant-gas), Condensed Matter - Quantum Gases, Quantum Physics (quant-ph)
Abstract: Ultracold bosonic atoms trapped in a two-leg ladder pierced by a magnetic field provide a minimal and quasi-one-dimensional instance to study the interplay between orbital magnetism and interactions. Using time-dependent matrix-product-states simulations, we investigate the properties of the so-called "Meissner" and "vortex" phases which appear in such system, focusing on experimentally accessible observables. We discuss how to experimentally monitor the phase transition, and show that the response to a modulation of the density imbalance between the two legs of the ladder is qualitatively different in the two phases. We argue that this technique can be used as a tool for many-body spectroscopy, allowing to quantitatively measure the spin gap in the Meissner phase. We finally discuss its experimental implementation, Comment: 23 pages, 11 figures. Updated version after publication in New J. Phys
Published: 2018
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11. Relaxation and hysteresis near Shapiro resonances in a driven spinor condensate

Author: Karina Jimenez-Garcia, Fabrice Gerbier, Jean Dalibard, An Qu, Bertrand Evrard, Laboratoire Kastler Brossel (LKB (Jussieu)), 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)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Chaire Atomes et rayonnement, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-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)-Sorbonne Université (SU)-Collège de France (CdF (institution))-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)-Collège de France (CdF (institution))
Subjects: Physics, Condensed Matter::Quantum Gases, Work (thermodynamics), Spinor, Spinor Bose-Einstein condensates, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Theoretical models, Non-equilibrium thermodynamics, FOS: Physical sciences, 01 natural sciences, 010305 fluids & plasmas, Hysteresis, Quantum Gases (cond-mat.quant-gas), Quantum electrodynamics, Condensed Matter::Superconductivity, 0103 physical sciences, Relaxation (physics), 010306 general physics, Condensed Matter - Quantum Gases, Quantum
Abstract: International audience; Driving a many-body quantum system in a periodic manner gives access to its fundamental properties, both in terms of energy spectrum and relaxation mechanisms. It also leads to important applications, as shown by Superconducting Josephson Junctions (SCJJs): Thanks to the so-called Shapiro resonances that occur in the presence of a microwave drive, SCJJs constitute metrological devices relating the drive frequency to the voltage across the junction. Here we present a detailed experimental study of an atomic analog of a driven SCJJ, based on a spinor Bose-Einstein condensate of sodium atoms. We analyze the short-time evolution of the system in terms of a slow Hamiltonian dynamics, superimposed with a rapid micro-motion. After a long-time evolution, we observe that the system may relax to a non-equilibrium steady state and exhibit a hysteretic behavior. We compare our experimental results with simple phenomenological models of dissipation, that can roughly be described as amplitude or phase damping. We find that the amplitude damping model is able to reproduce quantitatively our observations, while the phase damping model fails qualitatively in certain regimes. Our study therefore constitutes an accurate benchmark for the development of an ab initio microscopic theory of the relaxation processes in this driven many-body system.
Published: 2018
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12. Revealing the Topology of Quasicrystals with a Diffraction Experiment

Author: M. Bosch Aguilera, A. Dareau, R. Bouganne, Fabrice Gerbier, Eric Akkermans, E. Levy, Jérôme Beugnon, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Diffraction, Fibonacci number, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], FOS: Physical sciences, Physics::Optics, General Physics and Astronomy, 02 engineering and technology, Topology, 01 natural sciences, Stability (probability), [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Mesoscale and Nanoscale Physics (cond-mat.mes-hall), 0103 physical sciences, Topological invariants, 010306 general physics, Topology (chemistry), Physics, Condensed Matter - Materials Science, Quantum Physics, Condensed Matter - Mesoscale and Nanoscale Physics, Materials Science (cond-mat.mtrl-sci), Quasicrystal, 021001 nanoscience & nanotechnology, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Quantum Physics (quant-ph), 0210 nano-technology, Optics (physics.optics), Physics - Optics
Abstract: Topological properties of crystals and quasicrystals is a subject of recent and growing interest. This Letter reports an experiment where, for certain quasicrystals, these properties can be directly retrieved from diffraction. We directly observe, using an interferometric approach, all the topological invariants of finite-length Fibonacci chains in their diffraction pattern. We also demonstrate quantitatively the stability of these topological invariants with respect to structural disorder., Supplementary Material available as ancillary files
Published: 2017
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13. Stepwise Bose-Einstein condensation in a spinor gas

Author: A. Invernizzi, Jean Dalibard, Tilman Zibold, C. Frapolli, Karina Jimenez-Garcia, Fabrice Gerbier, Laboratoire Kastler Brossel (LKB (Lhomond)), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Kastler Brossel (LKB (Jussieu)), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS), Laboratoire Kastler Brossel (LKB [Collège de France]), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], General Physics and Astronomy, FOS: Physical sciences, DALIBARD Jean, 01 natural sciences, 010305 fluids & plasmas, Magnetization, symbols.namesake, x2hal, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Phase (matter), 0103 physical sciences, traité, 010306 general physics, Spin-½, Phase diagram, Physics, Condensed Matter::Quantum Gases, Zeeman effect, Condensed matter physics, Condensation, Sous embargo, Preprint/Postprint du document, Ideal gas, 3. Good health, Quantum Gases (cond-mat.quant-gas), symbols, Zeeman energy, Chaires, Condensed Matter - Quantum Gases, Document sous DOI (Digital Object Identifier), web-atomes-rayonnement
Abstract: We observe multi-step condensation of sodium atoms with spin $F=1$, where the different Zeeman components $m_F=0,\pm 1$ condense sequentially as the temperature decreases. The precise sequence changes drastically depending on the magnetization $m_z$ and on the quadratic Zeeman energy $q$ (QZE) in an applied magnetic field. For large QZE, the overall structure of the phase diagram is the same as for an ideal spin 1 gas, although the precise locations of the phase boundaries are significantly shifted by interactions. For small QZE, antiferromagnetic interactions qualitatively change the phase diagram with respect to the ideal case, leading for instance to condensation in $m_F=\pm 1$, a phenomenon that cannot occur for an ideal gas with $q>0$., 6 pages, 3 figures; Supplementary Material available as ancillary arxiv files
Published: 2017
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14. Hofstadter optical lattice for ultracold Ytterbium atoms

Author: D. Doring, A. Dareau, Q. Beaufils, M. Scholl, R. Bouganne, Jérôme Beugnon, M. Bosch Aguilera, and Fabrice Gerbier
Subjects: Condensed Matter::Quantum Gases, Ytterbium, Physics, Optical lattice, Rabi cycle, chemistry.chemical_element, 01 natural sciences, 010305 fluids & plasmas, Atomic motion, chemistry, Excited state, Metastability, 0103 physical sciences, Atom optics, Physics::Atomic Physics, Atomic physics, 010306 general physics, Ground state
Abstract: Recently, a new generation of experiments with ultracold quantum gases has emerged where the many-body properties are probed and manipulated using ultra-narrow “clock” transitions. We describe here our experimental project, which aims at engineering a special kind of optical lattice realizing an effective magnetic field coupling to the atomic motion - the Hofstadter optical lattice. Our specific experimental scheme uses the ultra-narrow optical transition linking the ground state to a metastable excited state of 174 Ytterbium atoms. We present the current status of the experiment, including the observation of coherent Rabi oscillations between the ground and excited states.
Published: 2016
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15. Spin-nematic order in antiferromagnetic spinor condensates

Author: Tilman Zibold, Vincent Corre, Jean Dalibard, Andrea Invernizzi, Fabrice Gerbier, Camille Frapolli, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), Chaire Atomes et rayonnement, Laboratoire Kastler Brossel (LKB [Collège de France]), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution)), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Atomes et rayonnement, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, [PHYS]Physics [physics], Spinor, Condensed matter physics, Spin polarization, FOS: Physical sciences, Spin engineering, 01 natural sciences, 010305 fluids & plasmas, Ferromagnetism, Mean field theory, Quantum Gases (cond-mat.quant-gas), Quantum mechanics, 0103 physical sciences, Antiferromagnetism, Condensed Matter::Strongly Correlated Electrons, Tensor, Condensed Matter - Quantum Gases, 010306 general physics, Spin-½
Abstract: Large spin systems can exhibit unconventional types of magnetic ordering different from the ferromagnetic or N\'eel-like antiferromagnetic order commonly found in spin 1/2 systems. Spin-nematic phases, for instance, do not break time-reversal invariance and their magnetic order parameter is characterized by a second rank tensor with the symmetry of an ellipsoid. Here we show direct experimental evidence for spin-nematic ordering in a spin-1 Bose-Einstein condensate of sodium atoms with antiferromagnetic interactions. In a mean field description this order is enforced by locking the relative phase between spin components. We reveal this mechanism by studying the spin noise after a spin rotation, which is shown to contain information hidden when looking only at averages. The method should be applicable to high spin systems in order to reveal complex magnetic phases., Comment: published version
Published: 2016
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16. Shortcut to adiabaticity in spinor condensates

Author: Tilman Zibold, Luigi De Sarlo, Bruno Juliá-Díaz, Artur Polls, Fabrice Gerbier, David López Núñez, J. Martorell, Arnau Sala, Universitat de Barcelona, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-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-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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Atoms, Bose gas, FOS: Physical sciences, Bose-Einstein condensation, 01 natural sciences, Àtoms, 010305 fluids & plasmas, symbols.namesake, Quantum mechanics, 0103 physical sciences, Condensació de Bose-Einstein, 010306 general physics, Adiabatic process, Harmonic oscillator, ComputingMilieux_MISCELLANEOUS, Boson, Physics, [PHYS]Physics [physics], Condensed Matter::Quantum Gases, Zeeman effect, Spinor, Exponential function, Quantum Gases (cond-mat.quant-gas), symbols, Hamiltonian (quantum mechanics), Condensed Matter - Quantum Gases
Abstract: We devise a method to shortcut the adiabatic evolution of a spin-1 Bose gas with an external magnetic field as the control parameter. An initial many-body state with almost all bosons populating the Zeeman sublevel $m=0$, is evolved to a final state very close to a macroscopic spin-singlet condensate, a fragmented state with three macroscopically occupied Zeeman states. The shortcut protocol, obtained by an approximate mapping to a harmonic oscillator Hamiltonian, is compared to linear and exponential variations of the control parameter. We find a dramatic speedup of the dynamics when using the shortcut protocol., Comment: 10 pages, 7 figures
Published: 2016
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17. Colloquium: Artificial gauge potentials for neutral atoms

Author: Fabrice Gerbier, Jean Dalibard, Patrik Öhberg, and Gediminas Juzeliūnas
Subjects: Condensed Matter::Quantum Gases, Physics, Optical lattice, Field (physics), Condensed matter physics, Magnetism, General Physics and Astronomy, 01 natural sciences, Charged particle, 010305 fluids & plasmas, Magnetic field, symbols.namesake, Coupling (physics), Quantum mechanics, 0103 physical sciences, symbols, Physics::Atomic Physics, Matter wave, 010306 general physics, Aharonov–Bohm effect
Abstract: When a neutral atom moves in a properly designed laser field, its center-of-mass motion may mimic the dynamics of a charged particle in a magnetic field, with the emergence of a Lorentz-like force. In this Colloquium the physical principles at the basis of this artificial (synthetic) magnetism are presented. The corresponding Aharonov-Bohm phase is related to the Berry's phase that emerges when the atom adiabatically follows one of the dressed states of the atom-laser interaction. Some manifestations of artificial magnetism for a cold quantum gas, in particular, in terms of vortex nucleation are discussed. The analysis is then generalized to the simulation of non-Abelian gauge potentials and some striking consequences are presented, such as the emergence of an effective spin-orbit coupling. Both the cases of bulk gases and discrete systems, where atoms are trapped in an optical lattice, are addressed.
Published: 2011
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18. Suppression of the critical temperature for superfluidity near the Mott transition

Author: Matthias Troyer, Boris Svistunov, Stefan Trotzky, Lode Pollet, Immanuel Bloch, Ute Schnorrberger, Nikolai Prokof'ev, and Fabrice Gerbier
Subjects: Superfluidity, Quantum phase transition, Quantum technology, Physics, Open quantum system, Condensed matter physics, Quantum dynamics, Quantum Monte Carlo, General Physics and Astronomy, Quantum simulator, Mott transition
Abstract: A major goal in the fields of ultracold quantum gases and quantum simulations is measuring the phase diagram of strongly interacting many-body systems. This has now been achieved in an optical-lattice-based quantum simulator. The simulation is validated through an ab initio comparison with large-scale numerical quantum Monte Carlo simulations.
Published: 2010
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19. Non-linear relaxation of interacting bosons coherently driven on a narrow optical transition

Author: M. Scholl, Jérôme Beugnon, A. Dareau, R. Bouganne, Q. Beaufils, M. Bosch Aguilera, Fabrice Gerbier, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Condensed Matter::Quantum Gases, Physics, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Condensed matter physics, Dephasing, FOS: Physical sciences, General Physics and Astronomy, Quantum number, 01 natural sciences, 010305 fluids & plasmas, 3. Good health, Momentum, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), Excited state, 0103 physical sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Relaxation (physics), Condensed Matter - Quantum Gases, 010306 general physics, Excitation, Boson, Doppler broadening
Abstract: We study the dynamics of a two-component Bose-Einstein condensate (BEC) of $^{174}$Yb atoms coherently driven on a narrow optical transition. The excitation transfers the BEC to a superposition of states with different internal and momentum quantum numbers. We observe a crossover with decreasing driving strength between a regime of damped oscillations, where coherent driving prevails, and an incoherent regime, where relaxation takes over. Several relaxation mechanisms are involved: inelastic losses involving two excited atoms, leading to a non-exponential decay of populations; Doppler broadening due to the finite momentum width of the BEC and inhomogeneous elastic interactions, both leading to dephasing and to damping of the oscillations. We compare our observations to a two-component Gross-Pitaevskii (GP) model that fully includes these effects. For small or moderate densities, the damping of the oscillations is mostly due to Doppler broadening. In this regime, we find excellent agreement between the model and the experimental results. For higher densities, the role of interactions increases and so does the damping rate of the oscillations. The damping in the GP model is less pronounced than in the experiment, possibly a hint for many-body effects not captured by the mean-field description., Comment: 7 pages, 4 figures; supplementary material available as ancillary file
Published: 2018
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20. One-dimensional behavior of elongated Bose-Einstein condensates

Author: S. Richard, J. Retter, Mathilde Hugbart, Alain Aspect, Joseph H. Thywissen, Fabrice Gerbier, and Philippe Bouyer
Subjects: Condensed Matter::Quantum Gases, Physics, Condensed matter physics, Condensed Matter::Other, Condensed Matter (cond-mat), FOS: Physical sciences, General Physics and Astronomy, Condensed Matter, Coherence length, law.invention, law, Quantum mechanics, Thomas–Fermi model, Bose–Einstein condensate
Abstract: We study the properties of elongated Bose-Einstein condensates. First, we show that the dimensions of the condensate after expansion differs from the 3D Thomas-Fermi regime. We also study the coherence length of such elongated condensates., Comment: proceeding of Quantum Gases in Low Dimension, Les Houches 2003, 8 pages, 5 figures
Published: 2004
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21. Condensat de Bose-Einstein dans un piège anisotrope. Cohérence en phase et propriétés thermodynamiques

Author: Fabrice Gerbier
Subjects: Physics, General Physics and Astronomy, Humanities
Abstract: Cet ouvrage s'interesse aux proprietes d'un condensat de Bose-Einstein atomique dans un piege tres anisotrope. Apres une breve introduction theorique, nous presentons succinctement le dispositif et les techniques experimentales qui ont permis de realiser ces travaux, en insistant particulierement sur l'analyse des images du nuage atomique ultrafroid apres temps de vol. Nous nous interessons ensuite au comportement du nuage thermique a des temperature proches de la temperature critique. Nous mettons en particulier en evidence un decalage de la temperature critique et une reduction de la fraction condensee dus aux interactions, en bon accord avec une description de type Hartree-Fock du nuage mixte. Enfin, nous consacrons un part importante de cet ouvrage a l'etude des fluctuations de phase dans un condensat tres allonge (“quasi-1D”), etude basee sur la mesure de la distribution en impulsion par spectroscopie de Bragg. Nous montrons experimentalement et theoriquement qu'en presence de fluctuations de phase importantes, la distribution en impulsion est tres proche d'une lorentzienne, et notablement elargie par rapport a la distribution etroite et quasiment gaussienne attendue pour un vrai condensat. Nos mesures de la largeur en impulsion, et l'observation de fluctuations de densite fortement reduites par rapport a une distribution thermique “ordinaire”, confirment ainsi la validite de l'approche de Bogoliubov pour decrire les quasi-condensats en dimensionnalite reduite.
Published: 2004
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22. Production of CW and mode-locked atom lasers

Author: Y. Le Coq, Joseph H. Thywissen, G. Delannoy, Sadiqali A. Rangwala, Alain Aspect, S. Richard, Fabrice Gerbier, and Philippe Bouyer
Subjects: Condensed matter physics, law, Chemistry, Atom, General Physics and Astronomy, Atomic physics, Laser, law.invention
Abstract: Nous etudions les proprietes des faisceaux coherents atomique a partir d'un condensat de Bose Einstein. Grâce a un controle precis du coupleur de sortie, il est possible, comme en optique, de produire des faisceaux laser monomodes, multiples ou mode-lockes. De plus, on peut montrer que la propagation du faisceau peut etre decrite par des matrices ABCD similaires a celles qui sont utilisees en optique. Neanmoins, les interactions entre atomes, qui sont inexistantes entre les photons, conduisent quelques differences entre les proprietes de collimation des lasers atomes et photoniques.
Published: 2002
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23. Doppler Spectroscopy of an Ytterbium Bose-Einstein Condensate on the Clock Transition

Author: A. Dareau, M. Scholl, Q. Beaufils, Jérôme Beugnon, D. Doring, Fabrice Gerbier, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Ytterbium, Doppler spectroscopy, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Atomic Physics (physics.atom-ph), Absolute frequency, chemistry.chemical_element, FOS: Physical sciences, Physics::Optics, law.invention, Physics - Atomic Physics, Optics, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], law, Optical clock, Physics::Atomic Physics, Spectroscopy, Physics, Condensed Matter::Quantum Gases, business.industry, Laser, Atomic and Molecular Physics, and Optics, 3. Good health, chemistry, Quantum Gases (cond-mat.quant-gas), Clock transition, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Atomic physics, business, Condensed Matter - Quantum Gases, Bose–Einstein condensate
Abstract: International audience; We describe Doppler spectroscopy of Bose-Einstein condensates of ytterbium atoms using a narrow optical transition. We address the optical clock transition around 578 nm between the ${^1}S_0$ and ${^3}P_0$ states with a laser system locked on a high-finesse cavity. We show how the absolute frequency of the cavity modes can be determined within a few tens of kHz using high-resolution spectroscopy on molecular iodine. We show that optical spectra reflect the velocity distribution of expanding condensates in free fall or after releasing them inside an optical waveguide. We demonstrate sub-kHz spectral linewidths, with long-term drifts of the resonance frequency well below 1 kHz/hour. These results open the way to high-resolution spectroscopy of many-body systems.
Published: 2014
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24. Design of laser-coupled honeycomb optical lattices supporting Chern insulators

Author: Fabrice Gerbier, Egidijus Anisimovas, Tomas Andrijauskas, Nathan Goldman, Laboratoire Kastler Brossel (LKB (Lhomond)), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Center for Nonlinear Phenomena and Complex Systems, and Université libre de Bruxelles (ULB)
Subjects: Physics, Optical lattice, Condensed matter physics, FOS: Physical sciences, Crystal structure, Laser, Atomic and Molecular Physics, and Optics, law.invention, Phase factor, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), law, Excited state, Lattice (order), Condensed Matter - Quantum Gases, Ground state, Quantum tunnelling
Abstract: We introduce an explicit scheme to realize Chern insulating phases employing cold atoms trapped in a state-dependent optical lattice and laser-induced tunneling processes. The scheme uses two internal states, a ground state and a long-lived excited state, respectively trapped in separate triangular and honeycomb optical lattices. A resonant laser coherently coupling the two internal states enables hopping between the two sublattices with a Peierls-like phase factor. Although laser-induced hopping by itself does not lead to topological bands with non-zero Chern numbers, we find that such bands emerge when adding an auxiliary lattice that perturbs the lattice structure, effectively turning it at low energies into a realization of the Haldane model: A two-dimensional honeycomb lattice breaking time-reversal symmetry. We investigate the parameters of the resulting tight-binding model using first-principles band structure calculations to estimate the relevant regimes for experimental implementation., 9 pages, 7 figures, final version
Published: 2014
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25. Experimental study of coupling Bose–Einstein condensates into weakly non-trapping and trapping states

Author: G. Delannoy, Fabrice Gerbier, Alain Aspect, Signe Seidelin, Joseph H. Thywissen, S. Richard, Philippe Bouyer, Sadiqali A. Rangwala, and Y. Le Coq
Subjects: Condensed Matter::Quantum Gases, Physics, Oscillation, General Physics and Astronomy, Trapping, Instability, law.invention, Atom laser, Coupling (physics), Frequency comb, law, Ultracold atom, Physics::Atomic Physics, Atomic physics, Bose–Einstein condensate
Abstract: We study the production of an atom laser from a Bose–Einstein condensate using radio-frequency out-coupling. Single frequency coupling from the Bose–Einstein condensate leads to unstable production of an atom laser due to the extreme sensitivity of this process to magnetic field fluctuations. The extent of this experimental instability is quantified. Stable, repeatable production of an atom laser is achieved by the frequency modulation of the coupling, which forms a frequency comb across the condensate. Different regimes of modulated coupling are discussed. In addition the coupling of atoms into a weakly trapping state is studied. The oscillation frequency of this state in the vertical direction is measured. Preliminary results indicating qualitative difference between condensate and thermal cloud coupling are presented.
Published: 2001
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26. Realizing non-Abelian gauge potentials in optical square lattices: an application to atomic Chern insulators

Author: Maciej Lewenstein, Nathan Goldman, Fabrice Gerbier, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Physics, Optical lattice, Quantum Physics, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], FOS: Physical sciences, Quantum Hall effect, Condensed Matter Physics, Quantum number, 01 natural sciences, Square lattice, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), Topological insulator, Lattice (order), Quantum mechanics, 0103 physical sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Physics::Atomic Physics, Quantum Physics (quant-ph), 010306 general physics, Ground state, Condensed Matter - Quantum Gases, Quantum tunnelling
Abstract: We describe a scheme to engineer non-Abelian gauge potentials on a square optical lattice using laser-induced transitions. We emphasize the case of two-electron atoms, where the electronic ground state g is laser coupled to a metastable state e within a state-dependent optical lattice. In this scheme, the alternating pattern of lattice sites hosting g and e states depict a checkerboard structure, allowing for laser-assisted tunneling along both spatial directions. In this configuration, the nuclear spin of the atoms can be viewed as a "flavor" quantum number undergoing non-Abelian tunneling along nearest-neighbor links. We show that this technique can be useful to simulate the equivalent of the Haldane quantum Hall model using cold atoms trapped in square optical lattices, offering an interesting route to realize Chern insulators. The emblematic Haldane model is particularly suited to investigate the physics of topological insulators, but requires, in its original form, complex hopping terms beyond nearest-neighboring sites. In general, this drawback inhibits a direct realization with cold atoms, using standard laser-induced tunneling techniques. We demonstrate that a simple mapping allows to express this model in terms of matrix hopping operators, that are defined on a standard square lattice. This mapping is investigated for two models that lead to anomalous quantum Hall phases. We discuss the practical implementation of such models, exploiting laser-induced tunneling methods applied to the checkerboard optical lattice., 12 pages, 6 figures. Revised and extended version accepted for publication in Journal of Physics B: Atomic, Molecular and Optical Physics
Published: 2013
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27. Measuring topology in a laser-coupled honeycomb lattice: From Chern insulators to topological semi-metals

Author: Egidijus Anisimovas, Nathan Goldman, Patrik Öhberg, Ian B. Spielman, Gediminas Juzeliunas, Fabrice Gerbier, Université libre de Bruxelles (ULB), Vilnius University [Vilnius], Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution)), Institute of Photonics and Quantum Sciences, Heriot-Watt University [Edinburgh] (HWU), National Institute of Standards and Technology [Gaithersburg] (NIST), University of Maryland [College Park], and University of Maryland System
Subjects: Physics, Condensed Matter::Quantum Gases, [PHYS]Physics [physics], Quantum Physics, Optical lattice, Chern class, FOS: Physical sciences, General Physics and Astronomy, Fermion, Parameter space, Topology, 01 natural sciences, Magnetic flux, 010305 fluids & plasmas, Gapless playback, Quantum Gases (cond-mat.quant-gas), Lattice (order), 0103 physical sciences, Topological order, Quantum Physics (quant-ph), Condensed Matter - Quantum Gases, 010306 general physics
Abstract: Ultracold fermions trapped in a honeycomb optical lattice constitute a versatile setup to experimentally realize the Haldane model [Phys. Rev. Lett. 61, 2015 (1988)]. In this system, a non-uniform synthetic magnetic flux can be engineered through laser-induced methods, explicitly breaking time-reversal symmetry. This potentially opens a bulk gap in the energy spectrum, which is associated with a non-trivial topological order, i.e., a non-zero Chern number. In this work, we consider the possibility of producing and identifying such a robust Chern insulator in the laser-coupled honeycomb lattice. We explore a large parameter space spanned by experimentally controllable parameters and obtain a variety of phase diagrams, clearly identifying the accessible topologically non-trivial regimes. We discuss the signatures of Chern insulators in cold-atom systems, considering available detection methods. We also highlight the existence of topological semi-metals in this system, which are gapless phases characterized by non-zero winding numbers, not present in Haldane's original model., 30 pages, 12 figures, 4 Appendices
Published: 2013
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28. Identifying topological edge states in 2D optical lattices using light scattering

Author: Fabrice Gerbier, Jérôme Beugnon, Nathan Goldman, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Angular momentum, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], FOS: Physical sciences, General Physics and Astronomy, Topology, 01 natural sciences, Light scattering, 010305 fluids & plasmas, law.invention, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], law, Dispersion relation, Quantum mechanics, 0103 physical sciences, General Materials Science, Physical and Theoretical Chemistry, 010306 general physics, Spectroscopy, Physics, Optical lattice, Quantum Physics, Fermi energy, Laser, Magnetic field, Quantum Gases (cond-mat.quant-gas), [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Quantum Physics (quant-ph), Condensed Matter - Quantum Gases
Abstract: We recently proposed in a Letter [Physical Review Letters 108 255303] a novel scheme to detect topological edge states in an optical lattice, based on a generalization of Bragg spectroscopy. The scope of the present article is to provide a more detailed and pedagogical description of the system - the Hofstadter optical lattice - and probing method. We first show the existence of topological edge states, in an ultra-cold gas trapped in a 2D optical lattice and subjected to a synthetic magnetic field. The remarkable robustness of the edge states is verified for a variety of external confining potentials. Then, we describe a specific laser probe, made from two lasers in Laguerre-Gaussian modes, which captures unambiguous signatures of these edge states. In particular, the resulting Bragg spectra provide the dispersion relation of the edge states, establishing their chiral nature. In order to make the Bragg signal experimentally detectable, we introduce a "shelving method", which simultaneously transfers angular momentum and changes the internal atomic state. This scheme allows to directly visualize the selected edge states on a dark background, offering an instructive view on topological insulating phases, not accessible in solid-state experiments., 17 pages, 10 figures. Revised and extended version, to appear in EJP Special Topic for the special issue on "Novel Quantum Phases and Mesoscopic Physics in Quantum Gases". Extended version of arXiv:1203.1246
Published: 2013
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29. Spin fragmentation of Bose-Einstein condensates with antiferromagnetic interactions

Author: Tilman Zibold, Vincent Corre, Jean Dalibard, Fabrice Gerbier, Lingxuan Shao, Luigi De Sarlo, David Jacob, Laboratoire Kastler Brossel (LKB (Jussieu)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), Chaire Atomes et rayonnement, Laboratoire Kastler Brossel (LKB [Collège de France]), Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-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)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))-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)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution)), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Collège de France - Chaire Atomes et rayonnement, Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Collège de France (CdF (institution))-Sorbonne Université (SU)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Spin states, Population, General Physics and Astronomy, FOS: Physical sciences, 01 natural sciences, 010305 fluids & plasmas, law.invention, symbols.namesake, law, 0103 physical sciences, Antiferromagnetism, Physics::Atomic Physics, 010306 general physics, education, [PHYS]Physics [physics], Physics, Condensed Matter::Quantum Gases, education.field_of_study, Mesoscopic physics, Zeeman effect, Condensed matter physics, Observable, 3. Good health, Quantum Gases (cond-mat.quant-gas), Thermodynamic limit, symbols, Condensed Matter::Strongly Correlated Electrons, Condensed Matter - Quantum Gases, Bose–Einstein condensate
Abstract: We study spin fragmentation of an antiferromagnetic spin 1 condensate in the presence of a quadratic Zeeman (QZ) effect breaking spin rotational symmetry. We describe how the QZ effect turns a fragmented spin state, with large fluctuations of the Zeemans populations, into a regular polar condensate, where atoms all condense in the $m=0$ state along the field direction. We calculate the average value and variance of the Zeeman state $m=0$ to illustrate clearly the crossover from a fragmented to an unfragmented state. The typical width of this crossover is $q \sim k_B T/N$, where $q$ is the QZ energy, $T$ the spin temperature and $N$ the atom number. This shows that spin fluctuations are a mesoscopic effect that will not survive in the thermodynamic limit $N\rightarrow \infty$, but are observable for sufficiently small atom number., Comment: submitted to NJP
Published: 2013
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30. An all-solid-state laser source at 671 nm for cold-atom experiments with lithium

Author: Gérard Trénec, Jacques Vigué, Ulrich Eismann, Frédéric Chevy, Andrius Zukauskas, Fabrice Gerbier, Carlota Canalias, Christophe Salomon, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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-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), Department of Applied Physics, Royal Institute of Technology [Stockholm] (KTH ), Interférométrie (LCAR), Laboratoire Collisions Agrégats Réactivité (LCAR), Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS), ERC (FerLoDim project), EuroQUAM (FerMix), IFRAF, IUF, ESF, ANR, SCALA, DARPA (OLE project), CNRS INP, BNM (grant 04-3-004), ANR (grant ANR-05-BLAN-0094) and Région Midi-Pyrénées, ERC (FerLoDim project), EuroQUAM (FerMix), ANR (grant ANR-05-BLAN-0094) and Région Midi-Pyrénées, IFRAF, IUF, ESF, ANR, SCALA, DARPA (OLE project), CNRS INP, BNM (grant 04-3-004), ANR-06-NANO-0014,FABIOLA,Fermions And Bosons In Optical LAttices(2006), European Project, 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)-Université Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Université Toulouse III - Paul Sabatier (UT3), Université de Toulouse (UT)-Université de Toulouse (UT)-Centre National de la Recherche Scientifique (CNRS)-Institut de Recherche sur les Systèmes Atomiques et Moléculaires Complexes (IRSAMC), Université de Toulouse (UT)-Université de Toulouse (UT)-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)-Centre National de la Recherche Scientifique (CNRS), Institut National des Sciences Appliquées - Toulouse (INSA Toulouse), Institut National des Sciences Appliquées (INSA)-Institut National des Sciences Appliquées (INSA)-Université Toulouse III - Paul Sabatier (UT3), and Université Fédérale Toulouse Midi-Pyrénées-Université Fédérale Toulouse Midi-Pyrénées-Centre National de la Recherche Scientifique (CNRS)-Institut National des Sciences Appliquées - Toulouse (INSA Toulouse)
Subjects: Materials science, Laser cooling of atoms, Physics and Astronomy (miscellaneous), [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Atomic Physics (physics.atom-ph), Laser source, Potassium titanyl phosphate, FOS: Physical sciences, General Physics and Astronomy, chemistry.chemical_element, Physics::Optics, Ring laser, 02 engineering and technology, 7. Clean energy, 01 natural sciences, Physics - Atomic Physics, 010309 optics, chemistry.chemical_compound, 020210 optoelectronics & photonics, Ultracold atom, Laser cooling, 0103 physical sciences, 0202 electrical engineering, electronic engineering, information engineering, Quantum optics, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], [PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], business.industry, Diode-pumped solid state lasers, General Engineering, PACS 37.10.De, PACS 42.55.Xi, PACS 42.60.By, PACS 42.60.Pk, PACS 42.62.Fi, PACS 42.65.Ky, PACS 42.72.Ai, PACS 42.72.Bj, Lithium atoms, Frequency doubling, chemistry, Quantum Gases (cond-mat.quant-gas), Optoelectronics, Lithium, Condensed Matter - Quantum Gases, business, Beam (structure), Physics - Optics, Optics (physics.optics)
Abstract: International audience; We present an all solid-state narrow line\-width laser source emitting $670\,\mathrm{mW}$ output power at $671\,\mathrm{nm}$ delivered in a diffraction-limited beam. The \linebreak source is based on a fre\-quency-doubled diode-end-\linebreak pumped ring laser operating on the ${^4F}_{3/2} \rightarrow {^4I}_{13/2}$ transition in Nd:YVO$_4$. By using periodically-poled po\-tassium titanyl phosphate (ppKTP) in an external build\-up cavity, doubling efficiencies of up to 86\% are obtained. Tunability of the source over $100\,\rm GHz$ is accomplished. We demonstrate the suitability of this robust frequency-stabilized light source for laser cooling of lithium atoms. Finally a simplified design based on intra-cavity doubling is described and first results are presented.
Published: 2012
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31. Detecting Chiral Edge States in the Hofstadter Optical Lattice

Author: Fabrice Gerbier, Nathan Goldman, Jérôme Beugnon, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Physics, Quantum Physics, Optical lattice, Angular momentum, Condensed matter physics, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], FOS: Physical sciences, General Physics and Astronomy, 01 natural sciences, Signal, Spectral line, 010305 fluids & plasmas, Magnetic field, symbols.namesake, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), 0103 physical sciences, symbols, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Condensed Matter - Quantum Gases, Quantum Physics (quant-ph), 010306 general physics, Signature (topology), Raman spectroscopy, Spectroscopy
Abstract: We propose a realistic scheme to detect topological edge states in an optical lattice subjected to a synthetic magnetic field, based on a generalization of Bragg spectroscopy sensitive to angular momentum. We demonstrate that using a well-designed laser probe, the Bragg spectra provide an unambiguous signature of the topological edge states that establishes their chiral nature. This signature is present for a variety of boundaries, from a hard wall to a smooth harmonic potential added on top of the optical lattice. Experimentally, the Bragg signal should be very weak. To make it detectable, we introduce a "shelving method", based on Raman transitions, which transfers angular momentum and changes the internal atomic state simultaneously. This scheme allows to detect the weak signal from the selected edge states on a dark background, and drastically improves the detectivity. It also leads to the possibility to directly visualize the topological edge states, using in situ imaging, offering a unique and instructive view on topological insulating phases., Comment: 4 pages, 4 figures, Supplementary material (Appendices A-D). Revised version, accepted in the Physical Review Letters
Published: 2012
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32. Phase diagram of spin 1 antiferromagnetic Bose-Einstein condensates

Author: Emmanuel Mimoun, Luigi De Sarlo, Vincent Corre, Tilman Zibold, Jean Dalibard, David Jacob, Fabrice Gerbier, Lingxuan Shao, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-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-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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Condensed Matter::Quantum Gases, Phase transition, Zeeman effect, Condensed matter physics, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], FOS: Physical sciences, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, symbols.namesake, Magnetization, Quantum Gases (cond-mat.quant-gas), 0103 physical sciences, symbols, Antiferromagnetism, Zeeman energy, Condensed Matter - Quantum Gases, 010306 general physics, Critical field, Phase diagram, Spin-½
Abstract: We study experimentally the equilibrium phase diagram of a spin 1 Bose-Einstein condensate with antiferromagnetic interactions, in a regime where spin and spatial degrees of freedom are decoupled. For a given total magnetization mz, we observe for low magnetic fields an "antiferromagnetic" phase where atoms condense in the m=+/-1 Zeeman states, and occupation of the m=0 state is suppressed. Conversely, for large enough magnetic fields, a phase transition to a "broken axisymmetry" phase takes place: The m=0 component becomes populated and rises sharply above a critical field Bc(mz). This behavior results from the competition between antiferromagnetic spin-dependent interactions (dominant at low fields) and the quadratic Zeeman energy (dominant at large fields). We compare the measured Bc as well as the global shape of the phase diagram with mean-field theory, and find good quantitative agreement., Comment: 8 pages, 6 figures
Published: 2012
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33. Direct imaging of topological edge states in cold-atom systems

Author: Nathan Goldman, Peter Zoller, Maciej Lewenstein, Jean Dalibard, Alexandre Dauphin, Ian B. Spielman, Fabrice Gerbier, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], quantum Hall effects, Topological degeneracy, FOS: Physical sciences, Quantum Hall effect, Topology, 01 natural sciences, Topological entropy in physics, Topological quantum computer, Symmetry protected topological order, Phase Transition, 010305 fluids & plasmas, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum mechanics, 0103 physical sciences, optical lattices, Topological order, 010306 general physics, Topological quantum number, Physics, Quantum Physics, Multidisciplinary, Physique, Cold Temperature, chiral edge states, Models, Chemical, Quantum Gases (cond-mat.quant-gas), Topological insulator, Physical Sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Quantum Theory, Gases, Condensed Matter - Quantum Gases, Quantum Physics (quant-ph), degenerate atomic gases
Abstract: Detecting topological order in cold-atom experiments is an ongoing challenge, the resolution of which offers novel perspectives on topological matter. In material systems, unambiguous signatures of topological order exist for topological insulators and quantum Hall devices. In quantum Hall systems, the quantized conductivity and the associated robust propagating edge modes—guaranteed by the existence of nontrivial topological invariants—have been observed through transport and spectroscopy measurements. Here, we show that optical-lattice-based experiments can be tailored to directly visualize the propagation of topological edge modes. Our method is rooted in the unique capability for initially shaping the atomic gas and imaging its time evolution after suddenly removing the shaping potentials. Our scheme, applicable to an assortment of atomic topological phases, provides a method for imaging the dynamics of topological edge modes, directly revealing their angular velocity and spin structure., SCOPUS: ar.j, info:eu-repo/semantics/published
Published: 2012
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34. Production of Sodium Bose--Einstein condensates in an optical dimple trap

Author: Fabrice Gerbier, Jean Dalibard, Emmanuel Mimoun, David Jacob, Martin Weitz, L. De Sarlo, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), University of Bonn, 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), and Universität Bonn = University of Bonn
Subjects: Atomic Physics (physics.atom-ph), FOS: Physical sciences, General Physics and Astronomy, 7. Clean energy, 01 natural sciences, Physics - Atomic Physics, law.invention, 010309 optics, Trap (computing), laser cooling, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], law, Dimple, 0103 physical sciences, Atom, Laser power scaling, Physics::Atomic Physics, 010306 general physics, Quantum, Physics, Condensed Matter::Quantum Gases, Quantum Physics, Bose--Einstein condensation, Dipole, 67.85.Hj, 37.10.De, 37.10.Jk, Quantum Gases (cond-mat.quant-gas), optical trapping, Atomic physics, Condensed Matter - Quantum Gases, Quantum Physics (quant-ph), Bose–Einstein condensate, Evaporative cooler
Abstract: International audience; We report on the realization of a sodium Bose--Einstein condensate (BEC) in a combined red-detuned optical dipole trap, formed by two beams crossing in a horizontal plane and a third, tightly focused dimple trap propagating vertically. We produce a BEC in three main steps: loading of the crossed dipole trap from laser-cooled atoms, an intermediate evaporative cooling stage which results in efficient loading of the auxiliary dimple trap, and a final evaporative cooling stage in the dimple trap. Our protocol is implemented in a compact setup and allows us to reach quantum degeneracy even with relatively modest initial atom numbers and available laser power.
Published: 2011
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35. Heating rates for an atom in a far-detuned optical lattice

Author: Yvan Castin, Fabrice Gerbier, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), DARPA OLE, 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), and 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)-Centre National de la Recherche Scientifique (CNRS)
Subjects: [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], heating rate, FOS: Physical sciences, PACS 37.10.Jk,03.75.Gg, 01 natural sciences, 7. Clean energy, 010305 fluids & plasmas, Lattice constant, Lattice (order), 0103 physical sciences, Master equation, Atom, optical lattices, Physics::Atomic Physics, Laser detuning, 010306 general physics, Electronic band structure, Mechanical energy, Condensed Matter::Quantum Gases, Physics, Bose-Einstein condensate, Optical lattice, Atomic and Molecular Physics, and Optics, Quantum Gases (cond-mat.quant-gas), Atomic physics, Condensed Matter - Quantum Gases
Abstract: We calculate single atom heating rates in a far detuned optical lattice, in connection with recent experiments. We first derive a master equation, including a realistic atomic internal structure and a quantum treatment of the atomic motion in the lattice. The experimental feature that optical lattices are obtained by superimposing laser standing waves of different frequencies is also included, which leads to a micromotional correction to the light shift that we evaluate. We then calculate, and compare to experimental results, two heating rates, the "total" heating rate (corresponding to the increase of the total mechanical energy of the atom in the lattice), and the ground bande heating rate (corresponding to the increase of energy within the ground energy band of the lattice)., Comment: 11 pages, 3 figures, 1 table
Published: 2010
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36. Fast production of ultracold sodium gases using light-induced desorption and optical trapping

Author: Fabrice Gerbier, Emmanuel Mimoun, David Jacob, Jean Dalibard, Luigi De Sarlo, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-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-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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Condensed Matter::Quantum Gases, Physics, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Evaporation, FOS: Physical sciences, Trapping, Isotopes of sodium, 01 natural sciences, 7. Clean energy, Electromagnetic radiation, Atomic and Molecular Physics, and Optics, 010309 optics, Dipole, Optical tweezers, Quantum Gases (cond-mat.quant-gas), Extinction (optical mineralogy), Desorption, 0103 physical sciences, Physics::Atomic Physics, Atomic physics, Condensed Matter - Quantum Gases, 010306 general physics
Abstract: International audience; In this paper, we report on the production of a Bose--Einstein condensate (BEC) of sodium using light--induced desorption as an atomic source. We load about 2X10^7 atoms in a MOT from this source with a ~6 s loading time constant. The MOT lifetime can be kept around 27 s by turning off the desorbing light after loading. We show that the pressure drops down by a factor of 40 in less than 100 ms after the extinction of the desorbing light, restoring the low background pressure for evaporation. Using this technique, a \na BEC with 10^4 atoms is produced after a 6 s evaporation in an optical dipole trap.
Published: 2010
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37. Solid-state laser system for laser cooling of sodium

Author: L. De Sarlo, Jean Jacques Zondy, Jean Dalibard, Fabrice Gerbier, Emmanuel Mimoun, Laboratoire Kastler Brossel (LKB (Lhomond)), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Laboratoire commun de métrologie LNE-CNAM (LCM), Laboratoire National de Métrologie et d'Essais [Trappes] (LNE )-Conservatoire National des Arts et Métiers [CNAM] (CNAM), HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Materials science, Physics and Astronomy (miscellaneous), General Physics and Astronomy, Physics::Optics, FOS: Physical sciences, 7. Clean energy, 01 natural sciences, law.invention, 010309 optics, law, Solid-state laser, Laser cooling, 0103 physical sciences, Physics::Atomic Physics, 010306 general physics, ComputingMilieux_MISCELLANEOUS, Quantum optics, Quantum Physics, Dye laser, [PHYS.PHYS.PHYS-ATOM-PH]Physics [physics]/Physics [physics]/Atomic Physics [physics.atom-ph], business.industry, General Engineering, Nonlinear optics, Laser, Condensed Matter - Other Condensed Matter, Wavelength, Optoelectronics, Laser beam quality, business, Quantum Physics (quant-ph), Physics - Optics, Optics (physics.optics), Other Condensed Matter (cond-mat.other)
Abstract: We demonstrate a frequency-stabilized, all-solid laser source at 589 nm with up to 800 mW output power. The laser relies on sum-frequency generation from two laser sources at 1064 nm and 1319 nm through a PPKTP crystal in a doubly resonant cavity. We obtain conversion efficiencies as high as 2 W/W2 after careful optimization of the cavity parameters. The output wavelength is tunable over 60 GHz, which is sufficient to lock on the sodium D2 line. The robustness, beam quality, spectral narrowness and tunability of our source make it an alternative to dye lasers for atomic physics experiments with sodium atoms.
Published: 2010
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38. Cooling fermionic atoms in optical lattices by shaping the confinement

Author: Michael M. Kohl, Lorenzo De Leo, Fabrice Gerbier, Jean-Sébastien Bernier, Antoine Georges, Christophe Salomon, and Corinna Kollath
Subjects: Physics, Optical lattice, 0103 physical sciences, Entropy (information theory), Antiferromagnetism, Quantum phases, Atomic physics, 010306 general physics, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas
Abstract: We propose an experimental procedure to cool fermionic atoms loaded into an optical lattice. The central idea is to spatially divide the system into entropy-rich and -poor regions by shaping the confining potential profile. Atoms in regions of high entropy per particle are subsequently isolated from the system. We discuss how to experimentally carry out this proposal and perform a quantitative study of its efficiency. We find that the entropy per particle, $s$, can typically be reduced by a factor of 10 such that entropies lower than $s/{k}_{B}\ensuremath{\sim}0.2$ can be reached. Cooling into highly sought-after quantum phases (such as an antiferromagnet) can thus be achieved. We show that this procedure is robust against variations of the experimental conditions.
Published: 2009
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39. Sum-frequency generation of 589 nm light with near-unit efficiency

Author: Emmanuel Mimoun, Luigi De Sarlo, Jean Jacques Zondy, Jean Dalibard, Fabrice Gerbier, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), Laboratoire commun de métrologie LNE-CNAM (LCM), Laboratoire National de Métrologie et d'Essais [Trappes] (LNE )-Conservatoire National des Arts et Métiers [CNAM] (CNAM), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), and HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)-HESAM Université - Communauté d'universités et d'établissements Hautes écoles Sorbonne Arts et métiers université (HESAM)
Subjects: Photon, Materials science, Infrared Rays, Laser source, FOS: Physical sciences, Trapping, Sensitivity and Specificity, 7. Clean energy, 01 natural sciences, 010309 optics, Optics, 0103 physical sciences, 010306 general physics, Lighting, Quantum Physics, [PHYS.PHYS.PHYS-OPTICS]Physics [physics]/Physics [physics]/Optics [physics.optics], Sum-frequency generation, business.industry, Lasers, Far-infrared laser, Reproducibility of Results, Second-harmonic generation, Equipment Design, Atomic and Molecular Physics, and Optics, Power (physics), Equipment Failure Analysis, Condensed Matter - Other Condensed Matter, Energy Transfer, Computer-Aided Design, business, Quantum Physics (quant-ph), Physics - Optics, Optics (physics.optics), Other Condensed Matter (cond-mat.other)
Abstract: We report on a laser source at 589 nm based on sum-frequency generation of two infrared laser at 1064 nm and 1319 nm. Output power as high as 800 mW are achieved starting from 370 mW at 1319 nm and 770 mW at 1064 nm, corresponding to converting roughly 90% of the 1319 nm photons entering the cavity. The power and frequency stability of this source are ideally suited for cooling and trapping of sodium atoms.
Published: 2008
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40. Quantum Spin Dynamics of Mode-Squeezed Luttinger Liquids in Two-Component Atomic Gases

Author: Mikhail D. Lukin, Stefan Trotzky, Simon Fölling, Eugene Demler, Fabrice Gerbier, Patrick Cheinet, Vladimir Gritsev, Artur Widera, Immanuel Bloch, QUANTUM group, Institute for Physics (QUANTUM), Johannes Gutenberg - Universität Mainz (JGU), Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), Department of Physics, Harvard University [Cambridge], Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), and Harvard University
Subjects: Physics, Condensed Matter::Quantum Gases, Condensed matter physics, Time evolution, General Physics and Astronomy, FOS: Physical sciences, Spin engineering, 01 natural sciences, 010305 fluids & plasmas, Condensed Matter - Other Condensed Matter, Ramsey interferometry, Luttinger liquid, Quantum mechanics, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Mathematics::Metric Geometry, 010306 general physics, Feshbach resonance, Spin (physics), Quantum fluctuation, Squeezed coherent state, Other Condensed Matter (cond-mat.other)
Abstract: We report on the observation of the phase dynamics of interacting one-dimensional ultracold bosonic gases with two internal degrees of freedom. By controlling the non-linear atomic interactions close to a Feshbach resonance we are able to induce a phase diffusive many-body spin dynamics. We monitor this dynamical evolution by Ramsey interferometry, supplemented by a novel, many-body echo technique. We find that the time evolution of the system is well described by a Luttinger liquid initially prepared in a multimode squeezed state. Our approach allows us to probe the non-equilibrium evolution of one-dimensional many-body quantum systems., Comment: 4 pages, 3 figures Updated version, minor changes
Published: 2008
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41. Expansion of a quantum gas released from an optical lattice

Author: Simon Fölling, Barbara Capogrosso-Sansone, Artur Widera, Lode Pollet, Immanuel Bloch, Stefan Trotzky, Jeff D. Thompson, U. Schnorrberger, Fabrice Gerbier, Nikolai Prokof'ev, Boris Svistunov, Matthias Troyer, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), QUANTUM group, Institute for Physics (QUANTUM), Johannes Gutenberg - Universität Mainz (JGU), Department of Physics [Harvard], Harvard University [Cambridge], Institut fuer Angewandte Physik, Rheinische Friedrich-Wilhelms-Universität Bonn, Theoretische Physik, ETH Zurich, Eidgenössische Technische Hochschule - Swiss Federal Institute of Technology [Zürich] (ETH Zürich), Department of Physics, University of Massachusetts [Boston] (UMass Boston), University of Massachusetts System (UMASS)-University of Massachusetts System (UMASS), National Research Center 'Kurchatov Institute' (NRC KI), 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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS), Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), and Harvard University
Subjects: Physics, Condensed Matter::Quantum Gases, Optical lattice, Condensed matter physics, Quantum Monte Carlo, Quantum dynamics, Quantum annealing, General Physics and Astronomy, Quantum simulator, FOS: Physical sciences, 01 natural sciences, Molecular physics, 010305 fluids & plasmas, 3. Good health, Condensed Matter - Other Condensed Matter, Particle in a one-dimensional lattice, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Physics::Atomic Physics, 010306 general physics, Quantum dissipation, Lattice model (physics), Other Condensed Matter (cond-mat.other)
Abstract: We analyze the interference pattern produced by ultracold atoms released from an optical lattice. Such interference patterns are commonly interpreted as the momentum distributions of the trapped quantum gas. We show that for finite time-of-flights the resulting density distribution can, however, be significantly altered, similar to a near-field diffraction regime in optics. We illustrate our findings with a simple model and realistic quantum Monte Carlo simulations for bosonic atoms, and compare the latter to experiments., Comment: 5 pages, 3 figures
Published: 2008
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42. Boson Mott insulators at finite temperatures

Author: Fabrice Gerbier, Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-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-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 Pierre et Marie Curie - Paris 6 (UPMC)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Condensed Matter::Quantum Gases, Condensed matter physics, Condensed Matter::Other, Mott insulator, General Physics and Astronomy, FOS: Physical sciences, 01 natural sciences, 010305 fluids & plasmas, Mott transition, Superfluidity, Condensed Matter - Other Condensed Matter, Phase (matter), [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Condensed Matter::Strongly Correlated Electrons, Metal–insulator transition, 010306 general physics, Adiabatic process, Phase diagram, Boson, Other Condensed Matter (cond-mat.other)
Abstract: International audience; We discuss the finite temperature properties of ultracold bosons in optical lattices in the presence of an additional, smoothly varying potential, as in current experiments. Three regimes emerge in the phase diagram: a low-temperature Mott regime similar to the zero-temperature quantum phase, an intermediate regime where MI features persist, but where superfluidity is absent, and a thermal regime where features of the Mott insulator state have disappeared. We obtain the thermodynamic functions of the Mott phase in the latter cases. The results are used to estimate the temperatures achieved by adiabatic loading in current experiments. We point out the crucial role of the trapping potential in determining the final temperature, and suggest a scheme for further cooling by adiabatic decompression.
Published: 2007
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43. Spin-1 condensates at thermal equilibrium: A SU(3) coherent state approach

Author: C. Frapolli, Vincent Corre, L. Shao, Fabrice Gerbier, Tilman Zibold, Jean Dalibard, Laboratoire Kastler Brossel (LKB [Collège de France]), 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)-Fédération de recherche du Département de physique de l'Ecole Normale Supérieure - ENS Paris (FRDPENS), and Université Paris sciences et lettres (PSL)-Université Paris sciences et lettres (PSL)-Centre National de la Recherche Scientifique (CNRS)-Centre National de la Recherche Scientifique (CNRS)-Sorbonne Université (SU)-Collège de France (CdF (institution))
Subjects: Condensed Matter::Quantum Gases, Thermal equilibrium, Physics, Statistical ensemble, Partition function (statistical mechanics), Conservation law, education.field_of_study, [PHYS.COND.GAS]Physics [physics]/Condensed Matter [cond-mat]/Quantum Gases [cond-mat.quant-gas], Population, FOS: Physical sciences, General Physics and Astronomy, Probability density function, 01 natural sciences, 010305 fluids & plasmas, [PHYS.QPHY]Physics [physics]/Quantum Physics [quant-ph], Quantum Gases (cond-mat.quant-gas), 0103 physical sciences, [SPI.OPTI]Engineering Sciences [physics]/Optics / Photonic, Coherent states, Statistical physics, Condensed Matter - Quantum Gases, 010306 general physics, education, Spin-½
Abstract: International audience; We propose a theoretical framework based on $SU(3)$ coherent states as a convenient tool to describe the collective state of a Bose-Einstein condensate of spin 1 atoms at thermal equilibrium. We work within the single-mode approximation, which assumes that all atoms condense in the same spatial mode. In this system, the magnetization $m_z$ is conserved to a very good approximation. This conservation law is included by introducing a prior distribution for $m_z$ and constructing a generalized statistical ensemble that preserves its first moments. In the limit of large particle numbers, we construct the partition function at thermal equilibrium and use it to compute various quantities of experimental interest, such as the probability distribution function and moments of the population in each Zeeman state. When $N$ is large but finite (as in typical experiments, where $N\sim 10^3-10^5$), we find that fluctuations of the collective spin can be important.
Published: 2015
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44. Resonant control of spin dynamics in ultracold quantum gases by microwave dressing

Author: Olaf Mandel, Artur Widera, Immanuel Bloch, Simon Fölling, Fabrice Gerbier, QUANTUM (QUANTUM), Johannes Gutenberg - Universität Mainz (JGU), Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), 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), and 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)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Field (physics), Quantum gas, Mott insulator, Resonance, FOS: Physical sciences, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, 3. Good health, law.invention, Condensed Matter - Other Condensed Matter, Radiation pressure, law, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Atomic physics, 010306 general physics, Bose–Einstein condensate, Microwave, Spin-½, Other Condensed Matter (cond-mat.other)
Abstract: We study experimentally interaction-driven spin oscillations in optical lattices in the presence of an off-resonant microwave field. We show that the energy shift induced by this microwave field can be used to control the spin oscillations by tuning the system either into resonance to achieve near-unity contrast or far away from resonance to suppress the oscillations. Finally, we propose a scheme based on this technique to create a flat sample with either singly- or doubly-occupied sites, starting from an inhomogeneous Mott insulator, where singly- and doubly-occupied sites coexist., 4 pages, 5 figures
Published: 2006
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45. Formation of spatial shell structures in the superfluid to Mott insulator transition

Author: Artur Widera, Torben Müller, Immanuel Bloch, Simon Fölling, Fabrice Gerbier, QUANTUM group, Institute for Physics (QUANTUM), Johannes Gutenberg - Universität Mainz (JGU), Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), 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), and 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)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Condensed Matter::Quantum Gases, Optical lattice, Spin states, Condensed matter physics, Mott insulator, FOS: Physical sciences, General Physics and Astronomy, 01 natural sciences, 010305 fluids & plasmas, Mott transition, Condensed Matter - Other Condensed Matter, Superfluidity, Lattice (order), [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Condensed Matter::Strongly Correlated Electrons, Metal–insulator transition, 010306 general physics, Jaynes–Cummings–Hubbard model, Other Condensed Matter (cond-mat.other)
Abstract: International audience; We report on the direct observation of the transition from a compressible superfluid to an incompressible Mott insulator by recording the in-trap density distribution of a Bosonic quantum gas in an optical lattice. Using spatially selective microwave transitions and spin changing collisions, we are able to locally modify the spin state of the trapped quantum gas and record the spatial distribution of lattice sites with different filling factors. As the system evolves from a superfluid to a Mott insulator, we observe the formation of a distinct shell structure, in good agreement with theory.
Published: 2006
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46. Adiabatic loading of a Bose-Einstein condensate in a 3D optical lattice

Author: Fabrice Gerbier, Simon Foelling, Olaf Mandel, Artur Widera, Immanuel Bloch, Tatjana Gericke, Gerbier, Fabrice, Marek Trippenbach, QUANTUM (QUANTUM), and Johannes Gutenberg - Universität Mainz (JGU)
Subjects: Physics, Condensed Matter::Quantum Gases, Optical lattice, Condensed matter physics, FOS: Physical sciences, Limiting, 01 natural sciences, Atomic and Molecular Physics, and Optics, 010305 fluids & plasmas, law.invention, Condensed Matter - Other Condensed Matter, Superfluidity, law, [PHYS.COND.CM-GEN] Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], Lattice (order), 0103 physical sciences, Free expansion, 010306 general physics, Adiabatic process, Bose–Einstein condensate, Quantum tunnelling, Other Condensed Matter (cond-mat.other)
Abstract: We experimentally investigate the adiabatic loading of a Bose-Einstein condensate into an optical lattice potential. The generation of excitations during the ramp is detected by a corresponding decrease in the visibility of the interference pattern observed after free expansion of the cloud. We focus on the superfluid regime, where we show that the limiting time scale is related to the redistribution of atoms across the lattice by single-particle tunneling.
Published: 2006

47. Precision measurement of spin-dependent interaction strengths for spin-1 and spin-2 87Rb atoms

Author: Artur Widera, Simon Foelling, Immanuel Bloch, Tatjana Gericke, Fabrice Gerbier, Olaf Mandel, QUANTUM group, Institute for Physics (QUANTUM), Johannes Gutenberg - Universität Mainz (JGU), Laboratoire Kastler Brossel (LKB (Lhomond)), Université Pierre et Marie Curie - Paris 6 (UPMC)-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)-Centre National de la Recherche Scientifique (CNRS), Johannes Gutenberg - Universität Mainz = Johannes Gutenberg University (JGU), 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), and 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)-Centre National de la Recherche Scientifique (CNRS)
Subjects: Physics, Optical lattice, Spin states, FOS: Physical sciences, General Physics and Astronomy, 01 natural sciences, 3. Good health, 010305 fluids & plasmas, Condensed Matter - Other Condensed Matter, symbols.namesake, Ultracold atom, [PHYS.COND.CM-GEN]Physics [physics]/Condensed Matter [cond-mat]/Other [cond-mat.other], 0103 physical sciences, Atom, symbols, Antiferromagnetism, Atomic physics, 010306 general physics, Hamiltonian (quantum mechanics), Ground state, Hyperfine structure, Other Condensed Matter (cond-mat.other)
Abstract: We report on precision measurements of spin-dependent interaction-strengths in the 87Rb spin-1 and spin-2 hyperfine ground states. Our method is based on the recent observation of coherence in the collisionally driven spin-dynamics of ultracold atom pairs trapped in optical lattices. Analysis of the Rabi-type oscillations between two spin states of an atom pair allows a direct determination of the coupling parameters in the interaction hamiltonian. We deduce differences in scattering lengths from our data that can directly be compared to theoretical predictions in order to test interatomic potentials. Our measurements agree with the predictions within 20%. The knowledge of these coupling parameters allows one to determine the nature of the magnetic ground state. Our data imply a ferromagnetic ground state for 87Rb in the f=1 manifold, in agreement with earlier experiments performed without the optical lattice. For 87Rb in the f=2 manifold the data points towards an antiferromagnetic ground state, however our error bars do not exclude a possible cyclic phase., 11 pages, 5 figures
Published: 2006
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48. Strongly Correlated Quantum Matter in Optical Lattices

Author: Immanuel Bloch, D. van Oosten, Ulrich Schneider, Tim Rom, Th. Best, Fabrice Gerbier, Artur Widera, B. Paredes, Torben Müller, and Simon Fölling
Subjects: Condensed Matter::Quantum Gases, Superfluidity, Physics, Condensed matter physics, Mott insulator, Lattice (order), Atom, Quantum noise, Fermion, Quantum, Boson
Abstract: Ultracold bosonic and fermionic quantum gases in optical lattices can be used as versatile model systems for the investigation of fundamental condensed matter physics hamiltonians. We report on two novel detection techniques, which have allowed us to reveal e.g. the in trap density profile of strongly correlated bosonic quantum gases in the lattice. Thereby we have been able to observe the formation of spatial shell structures in the density of the trapped atom cloud across the superfluid to Mott insulator transition. In addition we use quantum noise correlations in expanding bosonic and fermionic atom clouds released from the lattice to observe quantum statistical Hanbury‐Brown and Twiss type hunching and antibunching of the atoms and show that this can be used to reveal the ordering of the particles in the lattice.
Published: 2006
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49. COHERENT SPIN OSCILLATIONS DRIVEN BY COLLISIONS IN AN OPTICAL LATTICE

Author: Artur Widera, Simon Fölling, Tatjana Gericke, Fabrice Gerbier, Immanuel Bloch, and Olaf Mandel
Subjects: Physics, Optical lattice, Spin polarization, Condensed matter physics, Spin-½
Published: 2005
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50. B. Bose-Einstein Condensation and Fermi Degeneracy

Author: Thorsten Köhler, M. Kemmann, Juha Javanainen, I. Shvarchuck, Keith Burnett, S. Schneider, Thorsten Schumm, J.T.M. Walraven, W. von Klitzing, M. Bartenstein, Matt Mackie, L. Feenstra, Joseph H. Thywissen, Fabrice Gerbier, Dmitry S. Petrov, S. Richard, Thomas Gasenzer, Ch. vom Hagen, Mathilde Hugbart, A. Kasper, Zoran Hadzibabic, Subhadeep Gupta, Kai Dieckmann, Rocío Jáuregui, Israel Bar-Joseph, B. Engeser, Ron Folman, Tobias Tiecke, G.V. Shlyapnikov, G. Toledo Sánchez, Philippe Bouyer, Claudiu A. Stan, Christian H. Schunck, Alain Aspect, Rosario Paredes, Ch. Buggle, Wolfgang Ketterle, Kalle-Antti Suominen, and Jörg Schmiedmayer
Subjects: Physics, Condensed matter physics, law, Electron degeneracy pressure, Degeneracy (biology), Fermi gas, Bose–Einstein condensate, law.invention, Fermi Gamma-ray Space Telescope
Published: 2005
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