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We investigate cosmological structure formation in Fuzzy Dark Matter (FDM) with an attractive self-interaction (SI) with numerical simulations. Such a SI would arise if the FDM boson were an ultra-light axion, which has a strong CP symmetry-breaking scale (decay constant). Although weak, the attractive SI may be strong enough to counteract the quantum 'pressure' and alter structure formation. We find in our simulations that the SI can enhance small-scale structure formation, and soliton cores above a critical mass undergo a phase transition, transforming from dilute to dense solitons., 10 pages, 3 figures, submitted to mnras

Phase transitions with spontaneous symmetry breaking are expected for group field theories as a basic feature of the geometogenesis scenario. The following paper aims to investigate the equilibrium phase for group field theory by using the ergodic hypothesis on which the Gibbs-Boltzmann distributions must break down. The breaking of the ergodicity can be considered dynamically, by introducing a fictitious time inducing a stochastic process described through a Langevin equation, from which the randomness of the tensor field will be a consequence. This type of equation is considered particularly for complex just-renormalizable Abelian model of rank $d=5$, and we study some of their properties by using a renormalization group considering a coarse-graining both in time and space., Comment: 76 pages, 18 figures

We use numerical bootstrap techniques to study correlation functions of traceless symmetric tensors of $O(N)$ with two indexes $t_{ij}$. We obtain upper bounds on operator dimensions for all the relevant representations and several values of $N$. We discover several families of kinks, which do not correspond to any known model and we discuss possible candidates. We then specialize to the case $N=4$, which has been conjectured to describe a phase transition in the antiferromagnetic real projective model ARP$^{3}$. Lattice simulations provide strong evidence for the existence of a second order phase transition, while an effective field theory approach does not predict any fixed point. We identify a set of assumptions that constrain operator dimensions to a closed region overlapping with the lattice prediction. The region is still present after pushing the numerics in the single correlator case or when considering a mixed system involving $t$ and the lowest dimension scalar singlet., 49 pages, 27 figures Fixed minor typos. Added a subsection on "External operator as the lowest dimensional operator of its kind". Included bounds using this additional assumption in figures 8a and 8b

In the present work, we investigate the effects of dark matter (DM) on hybrid star properties. We assume that dark matter is mixed with both hadronic and quark matter and interacts with them through the exchange of a Higgs boson. The hybrid star properties are obtained from equations of state calculated with a Maxwell prescription. For the hadronic matter, we use the NL3* parameter set, and for the quark matter, the MIT bag model with a vector interaction. We see that dark matter does not influence the phase transition points (pressure and chemical potential) but shifts the discontinuity on the energy density, which ultimately reduces the minimum mass star that contains a quark core. Moreover, it changes considerably the star family mass-radius diagrams and moves the merger polarizability curves inside the confidence lines. Another interesting feature is the influence of DM in the quark core of the hybrid stars constructed. Our results show an increase of the core radius for higher values of the dark particle Fermi momentum.

We discuss the gravitational wave spectrum produced by first-order phase transitions seeded by domain wall networks. This setup is important for many two-step phase transitions as seen for example in the singlet extension of the standard model. Whenever the correlation length of the domain wall network is larger than the typical bubble size, this setup leads to a gravitational wave signal that is shifted to lower frequencies and with an enhanced amplitude compared to homogeneous phase transitions without domain walls. We discuss our results in light of the recent PTA hints for gravitational waves., 20 pages, 6 figures

Carnot cycles of samples of harmonically confined ultracold 87Rb fluids, near and across Bose–Einstein condensation (BEC), are analyzed. This is achieved through the experimental determination of the corresponding equation of state in terms of the appropriate global thermodynamics for non-uniform confined fluids. We focus our attention on the efficiency of the Carnot engine when the cycle occurs for temperatures either above or below the critical temperature and when BEC is crossed during the cycle. The measurement of the cycle efficiency reveals a perfect agreement with the theoretical prediction (1−TL/TH), with TH and TL serving as the temperatures of the hot and cold heat exchange reservoirs. Other cycles are also considered for comparison.

Phase transitions in a non-perturbative regime can be studied by ab initio Lattice Field Theory methods. The status and future research directions for LFT investigations of Quantum Chromo-Dynamics under extreme conditions are reviewed, including properties of hadrons and of the hypothesized QCD axion as inferred from QCD topology in different phases. We discuss phase transitions in strong interactions in an extended parameter space, and the possibility of model building for Dark Matter and Electro-Weak Symmetry Breaking. Methodological challenges are addressed as well, including new developments in Artificial Intelligence geared towards the identification of different phases and transitions., Comment: 94 pages, 23 figures, GGI workshop "Phase Transitions in Particle Physics" review - v2: minor revisions and typo corrected, matches accepted version on PPNP

Cluster states were introduced in the context of measurement based quantum computing. In one dimension, the cluster Hamiltonian possesses topologically protected states. We investigate the Floquet dynamics of the cluster spin chain in an external field, interacting with a particle. We explore the entanglement properties of the topological and magnetic phases, first in the integrable spin lattice case, and then in the interacting quantum walk case. We find, in addition to thermalization, dynamical phase transitions separating low- and high-entanglement nonthermal states, reminiscent of the ones present in the integrable case, but differing in their magnetic properties. The nonergodic phases are characterized by the emergence of magnetic order, persistent at long times., Comment: 16 pages, 9 figures; accepted version

International audience; In this letter, we address the low-temperature expansion for the $p=2$ spin dynamics with sixtic confining potential. The dynamics are described by a Langevin equation for a real vector $q_i$ of size $N$, where disorder is materialized by a Wigner matrix. We identify the radius of convergence of the expansion as the critical temperature, and we investigate the large time behavior of the averaging square length $a(t)\equiv \sum_i q_i^2(t)/N$, regarding the values of couplings involved in the potential. The methods discussed in this letter may be considered as a generalization which can be used for more complicated models.

We study a novel class of Renormalization Group flows which connect multicritical versions of the two-dimensional Yang-Lee edge singularity described by the conformal minimal models $\mathcal{M}$(2,2n+3). The absence in these models of an order parameter implies that the flows towards and between Lee-Yang edge singularities are all related to the spontaneous breaking of $\mathcal{PT}$ symmetry and comprise a pattern of flows in the space of $\mathcal{PT}$ symmetric theories consistent with the c-theorem and the counting of relevant directions. Additionally, we find that while in a part of the phase diagram the domains of unbroken and broken $\mathcal{PT}$ symmetry are separated by critical manifolds of class $\mathcal{M}$(2,2n+3), other parts of the boundary between the two domains are not critical.

We discuss the gravitational wave spectrum produced by first-order phase transitions seeded by domain wall networks. This setup is important for many two-step phase transitions as seen for example in the singlet extension of the standard model. Whenever the correlation length of the domain wall network is larger than the typical bubble size, this setup leads to a gravitational wave signal that is shifted to lower frequencies and with an enhanced amplitude compared to homogeneous phase transitions without domain walls. We discuss our results in light of the recent PTA hints for gravitational waves.

Gravitational waves from a first-order cosmological phase transition, at temper-atures at the MeV-scale, would arguably be the most exciting explanation of the commonred spectrum reported by the NANOGrav collaboration, not the least because this would bedirect evidence of physics beyond the standard model. Here we perform a detailed analysisof whether such an interpretation is consistent with constraints on the released energy de-riving from big bang nucleosynthesis and the cosmic microwave background. We find that aphase transition in a completely secluded dark sector is strongly disfavoured with respect tothe more conventional astrophysical explanation of the putative gravitational wave signal interms of supermassive black hole binaries. On the other hand, a phase transition in a darksector that subsequently decays, before the time of neutrino decoupling, remains an intriguingpossibility to explain the data. From the model-building perspective, such an option is easilysatisfied for couplings with the visible sector that are small enough to evade current colliderand astrophysical constraints. The first indication that could eventually corroborate such aninterpretation, once the observed common red spectrum is confirmed as a nHz gravitationalwave background, could be the spectral tilt of the signal. In fact, the current data alreadyshow a very slight preference for a spectrum that is softer than what is expected from theleading astrophysical explanation.

We improve the holographic description of isospin-asymmetric baryonic matter within the Witten-Sakai-Sugimoto model by accounting for a realistic pion mass, computing the pion condensate dynamically, and including rho meson condensation by allowing the gauge field in the bulk to be anisotropic. This description takes into account the coexistence of baryonic matter with pion and rho meson condensates. Our main result is the zero-temperature phase diagram in the plane of baryon and isospin chemical potentials. We find that the effective pion mass in the baryonic medium increases with baryon density and that, as a consequence, there is no pion condensation in neutron-star matter. Our improved description also predicts that baryons are disfavored at low baryon chemical potentials even for arbitrarily large isospin chemical potential. Instead, rho meson condensation sets in on top of the pion condensate at an isospin chemical potential of about $9.4\, m_\pi$. We further observe a highly non-monotonic phase boundary regarding the disappearance of pion condensation., Comment: 31 pages, 7 figures, v2: new ansatz for the bulk gauge field, eliminating an unjustified assumption in v1; as a consequence, numerous modifications in text, equations, and plots, with main conclusions unchanged

We consider three-dimensional Quantum Electrodynamics in the presence of a Chern-Simons term at level $k$ and $N_f$ flavors, in the limit of large $N_f$ and $k$ with $k/N_f$ fixed. We consider either bosonic or fermionic matter fields, with and without quartic terms at criticality: the resulting theories are critical and tricritical bosonic QED$_3$, Gross-Neveu and fermionic QED$_3$. For all such theories we compute the effective potentials and the $\beta$ functions of classically marginal couplings, at the leading order in the large $N_f$ limit and to all orders in $k/N_f$ and in the couplings. We determine the RG fixed points and discuss the quantum stability of the corresponding vacua. While critical bosonic and fermionic QED$_3$ are always stable CFTs, we find that tricritical bosonic and Gross-Neveu QED$_3$ exist as stable CFTs only for specific values of $k/N_f$. Finally, we discuss the phase diagrams of these theories as a function of their relevant deformations., Comment: 10 pages, 4 figures

We study a novel class of Renormalization Group flows which connect multicritical versions of the two-dimensional Yang-Lee edge singularity described by the conformal minimal models $\mathcal{M}$(2,2n+3). The absence in these models of an order parameter implies that the flows towards and between Lee-Yang edge singularities are all related to the spontaneous breaking of $\mathcal{PT}$ symmetry and comprise a pattern of flows in the space of $\mathcal{PT}$ symmetric theories consistent with the c-theorem and the counting of relevant directions. Additionally, we find that while in a part of the phase diagram the domains of unbroken and broken $\mathcal{PT}$ symmetry are separated by critical manifolds of class $\mathcal{M}$(2,2n+3), other parts of the boundary between the two domains are not critical.

Three-dimensional gravity is a topological field theory, which can be quantized as the Ponzano-Regge state-sum model built from the $\{3nj\}$-symbols of the recoupling of the $\SU(2)$ representations, in which spins are interpreted as quantized edge lengths in Planck units. It describes the flat spacetime as gluing of three-dimensional cells with a fixed boundary metric encoding length scale. In this paper, we revisit the Ponzano-Regge model formulated in terms of spinors and rewrite the quantum geometry of 3D cells with holomorphic recoupling symbols. These symbols, known as Schwinger's generating function for the $\{6j\}$-symbols, are simply the squared inverse of the partition function of the 2D Ising model living on the boundary of the 3D cells. They can furthermore be interpreted, in their critical regime, as scale-invariant basic elements of geometry. We show how to glue them together into a discrete topological quantum field theory. This reformulation of the path integral for 3D quantum gravity, with a rich pole structure of the elementary building blocks, opens a new door toward the study of phase transitions and continuum limits in 3D quantum gravity, and offers a new twist on the construction of a duality between 3D quantum gravity and a 2d conformal theory., 42 pages + appendices, 18 figures

We study quantum circuits consisting of unitary gates, projective measurements, and control operations that steer the system towards a pure absorbing state. Two types of phase transition occur as the rate of these control operations is increased: a measurement-induced entanglement transition, and a directed percolation transition into the absorbing state (taken here to be a product state). In this work we show analytically that these transitions are generically distinct, with the quantum trajectories becoming disentangled before the absorbing state transition is reached, and we analyze their critical properties. We introduce a simple class of models where the measurements in each quantum trajectory define an Effective Tensor Network (ETN) -- a subgraph of the initial spacetime graph where nontrivial time evolution takes place. By analyzing the entanglement properties of the ETN, we show that the entanglement and absorbing-state transitions coincide only in the limit of infinite local Hilbert-space dimension. Focusing on a Clifford model which allows numerical simulations for large system sizes, we verify our predictions and study the finite-size crossover between the two transitions at large local Hilbert space dimension. We give evidence that the entanglement transition is governed by the same fixed point as in hybrid circuits without feedback., 18 pages, 9 figures; v2: Appendix added, minor revision

Understanding the continuum limit of a theory of discrete random geometries is a beautiful but difficult challenge. In this optic, we review here the insights that can be obtained for Causal Dynamical Triangulations (CDT) by employing the Landau approach to critical phenomena. In particular, concentrating on the cases of two and three dimensions, we will make the case that the configuration of the volume of spatial slices effectively plays the role of an order parameter, helping us to understand the phase structure of CDT. Moreover, consistency with numerical simulations of CDT provides hints that the effective field theory of the model lives in the space of theories invariant under foliation-preserving diffeomorphisms. Among such theories, Horava-Lifshitz gravity has the special status of being a perturbatively renormalizable theory, while General Relativity sits in a subspace with enhanced symmetry. In order to reach either of them, one would likely need to fine tune some of the parameters in the CDT action, or additional ones from some generalization thereof., 44 pages, 11 figures. Invited chapter for the Section "Causal Dynamical Triangulations" of the "Handbook of Quantum Gravity" (Eds. C. Bambi, L. Modesto and I.L. Shapiro, Springer Singapore, expected in 2023); slightly new perspective on old work in collaboration with Joe Henson ( 1410.0845 ) and James P. Ryan ( 1612.09533 )

I analyze the role of infinite idealizations used in the renormalization group (RG hereafter) method in explaining universality across microscopically different physical systems in critical phenomena. I argue that despite the reference to infinite limit systems such as systems with infinite correlation lengths during the RG process, the key to explaining universality in critical phenomena need not involve infinite limit systems. I develop my argument by introducing what I regard as the explanatorily relevant property in RG explanations: linearization* property; I then motivate and prove a proposition about the linearization* property in support of my view. As a result, infinite limit systems in RG explanations are dispensable.

Constant-rate inflation, including ultra-slow-roll as a special case, has been widely applied to the formation of primordial black holes with significant deviation from the standard slow-roll conditions at both the growing and decaying phases of the power spectrum. We derive analytic solutions for the curvature perturbations with respect to the late-time scaling dimensions (conformal weights) constrained by the dilatation symmetry of the de Sitter background and show that the continuity of conformal weights across different rolling phases is protected by the adiabatic condition of the inflaton perturbation. The temporal excitation of subleading states (with the next-to-lowest conformal weights), recorded as the "steepest growth" of the power spectrum, is triggered by the entropy production in the transition from slow-roll to constant-rate phases., Comment: 18 + 4 pages, 6 figures; v2: references added, provided entropy production as a criterion for the steepest growth; v3: minor corrections, version matched with publication

The review presents the development of an approach of constructing approximate solutions to complicated physics problems, starting from asymptotic series, through optimized perturbation theory, to self-similar approximation theory. The close interrelation of underlying ideas of these theories is emphasized. Applications of the developed approach are illustrated by typical examples demonstrating that it combines simplicity with good accuracy.

In strongly correlated quantum systems, conventional techniques for understanding physical behaviour near multicritical points break down. Numerical conformal bootstrap is a promising new method that has proven demonstrably useful in investigating critical phenomena. The method uses the enhanced conformal symmetry exhibited by quantum field theories describing criticality in order to definitively rule out theories based on fundamental symmetry grounds alone. By requiring only that physically plausible conformal field theories (CFTs) satisfy a mathematical self-consistency relation, it allows one to rule out vast amounts of violating CFT data, allowing a rigorous mapping to made of ‘allowed’ CFTs. Such a mapping is powerful due to the concept of universality, whereby the critical behaviour of many disparate physical models is identical and is captured by the same set of critical exponents and the same CFT. This thesis aims to explore the effectiveness of numerical bootstrap. We begin by motivating the bootstrap in a condensed matter context, before reviewing necessary results in the conformal field theory literature and establishing the bootstrap method. A large part of the thesis will be an overview of the working of the method and the approximations made, as well as its applications to simple symmetry groups. We will demonstrate the validity of the method by replicating flagship results, before describing the novel work we have carried out in exploring more complicated global symmetry groups, where more than one fixed point is predicted. Finally, we will conclude and comment on the limitations of the thesis and lines of possible future work.

International audience; To enhance the performance of micro-patterned gaseous detectors (MPGDs) to meet thechallenging requirements of future high energy physics (HEP) experiments, two-dimensional (2D)materials are attractive candidates to address the back flow of positive ions, which affectsdetector performance by distorting electric field lines. In this context, graphene is promisingto work as selective filter for ion back flow suppression, being transparent to electrons while atthe same time blocking ions. Also, graphene membranes can physically separate drift andamplification regions of the detectors, offering additional flexibility in the choice of gasmixtures and allowing independent optimizations of detector sensitivity and electronmultiplication processes. Here we present an approach to integrate graphene grown via chemicalvapor deposition (CVD) on gaseous electron multiplier (GEM) prototypes via a wet transferprocedure in order to suspend graphene over thousands of holes with 60 μm diameter and overcomethe challenges encountered due to process steps involving liquids, mostly related with thecapillary effects during drying and evaporation of them. In order to overcome the risk of damagingthe membrane and decreasing the yield of suspended 2D material membranes, critical point dryer(CPD) and inverted floating method (IFM) procedures are investigated. In addition to thenecessity to cover the full holes in the active area, polymeric residuals have to be minimized inorder to evaluate the graphene transparency at the electron energies (i.e., < 15 eV) typicallyobtained in the operating conditions, measurements in these energy ranges are still not deeplyinvestigated.

International audience; The study of quantum many-body physics in Liouvillian open quantum systems becomes increasingly important with the recent progress in experimental control on dissipative systems and their technological exploitation . A central question in open quantum systems concerns the fate of quantum correlations, and the possibility of controlling them by engineering the competition between the Hamiltonian dynamics and the coupling to a bath. Such a question is challenging from a theoretical point of view, as numerical methods faithfully accounting for quantum correlations are either relying on exact diagonalization, limiting drastically the sizes that can be treated; or on approximations on the range or strength of quantum correlations, associated to the choice of a specific Ansatz for the density matrix. In this work we propose a new method to treat open quantum-spin lattices, based on stochastic quantum trajectories for the solution of the open-system dynamics. Along each trajectory, the hierarchy of equations of motion for many-point spin-spin correlators is truncated to a given finite order, assuming that multivariate $k$-th order cumulants vanish for $k$ exceeding a cutoff $k_c$. This allows tracking the evolution of quantum spin-spin correlations up to order $k_c$ for all length scales. We validate this approach in the paradigmatic case of the phase transitions of the dissipative 2D XYZ lattice, subject to spontaneous decay. We convincingly assess the existence of steady-state phase transitions from paramagnetic to ferromagnetic, and back to paramagnetic, upon increasing one of the Hamiltonian couplings; as well as their classical Ising nature. Moreover, the approach allows us to show the presence of significant quantum correlations in the vicinity of the dissipative critical point, and to unveil the presence of spin squeezing, a tight lower bound to the quantum Fisher information.

We present a review of the Sachdev-Ye-Kitaev (SYK) model of compressible quantum many-body systems without quasiparticle excitations, and its connections to various theoretical studies of non-Fermi liquids in condensed matter physics. The review is placed in the context of numerous experimental observations on correlated electron materials. Strong correlations in metals are often associated with their proximity to a Mott transition to an insulator created by the local Coulomb repulsion between the electrons. We explore the phase diagrams of a number of models of such local electronic correlation, employing a dynamical mean field theory in the presence of random spin exchange interactions. Numerical analyses and analytical solutions, using renormalization group methods and expansions in large spin degeneracy, lead to critical regions which display SYK physics. The models studied include the single-band Hubbard model, the $t$-$J$ model and the two-band Kondo-Heisenberg model in the presence of random spin exchange interactions. We also examine non-Fermi liquids obtained by considering each SYK model with random four-fermion interactions to be a multi-orbital atom, with the SYK-atoms arranged in an infinite lattice. We connect to theories of sharp Fermi surfaces without any low-energy quasiparticles in the absence of spatial disorder, obtained by coupling a Fermi liquid to a gapless boson; a systematic large $N$ theory of such a critical Fermi surface, with SYK characteristics, is obtained by averaging over an ensemble of theories with random boson-fermion couplings. Finally, we present an overview of the links between the SYK model and quantum gravity and end with an outlook on open questions., 72 pages, 25 figures and lots of references. Comments are welcome; (v2) Added references

We investigate how entanglement entropy behaves in a non-conformal scalar field system with a quantum phase transition, by the replica method. We study the $\sigma$-model in 3+1 dimensions which is $O(N)$ symmetric as the mass squared parameter $\mu^{2}$ is positive, and undergoes spontaneous symmetry breaking while $\mu^{2}$ becomes negative. The area law leading divergence of the entanglement entropy is preserved in both of the symmetric and the broken phases. The spontaneous symmetry breaking changes the subleading divergence from log to log squared, due to the cubic interaction on the cone. At the leading order of the coupling constant expansion, the entanglement entropy reaches a cusped maximum at the quantum phase transition point $\mu^{2}=0$, and decreases while $\mu^{2}$ is tuned away from 0 into either phase., Comment: 36 pp., 5 figures

Seismic anisotropy, wave attenuation, and dispersion are critical phenomena of wave propagation in real media. Full-wavefield modeling of wave behavior in such media plays an important role in investigating dynamic features of the earth’s interior and in full-waveform inversion of anisotropic parameters and velocity dispersion. We have developed a numerical scheme to model the full-waveform response from a point source in a vertically varying viscoelastic medium of arbitrary anisotropy. The method is implemented in the frequency domain, so the complexity of anelasticity and anisotropy can be described by a complex elastic stiffness matrix and frequency-dependent moduli can also be readily incorporated. In our scheme, we solve the elastodynamic equations for general anisotropy through finite-element method in the frequency-wavenumber domain and we use the stiffness reduction method to suppress reflections from artificial boundaries along the depth direction. A nonuniform 2D Fourier transform strategy is developed to reconstruct the spatial-domain counterparts from the wavenumber-domain solutions. The time-domain responses are then obtained by taking inverse fast Fourier transform with respect to frequency. We validate the method by comparing the numerical results with the exact solutions for a homogeneous transversely isotropic model and a two-layered model. In the application example, we further proved the feasibility and generality of the scheme using an attenuative, dispersive model with velocity and attenuation anisotropy. Our scheme enjoys significant advantages in incorporating various viscoelastic/dispersive behaviors and general anisotropy, and thus provides a useful tool for numerical simulation of dynamic responses in practical application.

Hasse diagrams (or phase diagrams) for moduli spaces of supersymmetric field theories have been intensively studied in recent years, and many tools to compute them have been developed. The moduli space of instantons, despite being well studied, has proven difficult to deal with. In this note we explore the Hasse diagram of this moduli space from several perspectives — using the partial Higgs mechanism, using brane systems and using quiver subtraction — having to refine previously developed techniques. In particular we introduce the new concept of decorated quiver, which allows to deal with a large class of unitary quivers, including those with adjoint matter.

Physical review / D 107(3), L031504 (2023). doi:10.1103/PhysRevD.107.L031504, Condensed matter physics of gauge theories coupled to fermions can exhibit a rich phase structure, but are nevertheless very difficult to study in Monte Carlo simulations when they are afflicted by a sign problem. As an alternate approach, we use tensor network methods to explore the finite density physics of Abelian gauge theories without dynamical matter. As a concrete example, we consider the U(1) gauge invariant quantum link ladder with spin-12 gauge fields in an external electric field, which causes the winding electric fluxes to condense in the ground state. We demonstrate how the electric flux tubes arrange themselves in the bulk, giving rise to crystalline patterns, whose period can be controlled by tuning the external field. We propose observables to detect the transitions in ground state properties not only in numerical experiments, but also in future cold-atom realizations. A systematic procedure for reaching the thermodynamic limit, as well as extending the studies from ladders to extended geometries is outlined., Published by Inst., Woodbury, NY

The one-dimensional Kardar-Parisi-Zhang (KPZ) equation is becoming an overarching paradigm for the scaling of nonequilibrium, spatially extended, classical and quantum systems with strong correlations. Recent analytical solutions have uncovered a rich structure regarding its scaling exponents and fluctuation statistics. However, the zero surface tension or zero viscosity case eludes such analytical solutions and has remained ill-understood. Using numerical simulations, we elucidate a well-defined universality class for this case that differs from that of the viscous case, featuring intrinsically anomalous kinetic roughening, despite previous expectations for systems with local interactions and time-dependent noise and ballistic dynamics. The latter may be relevant to recent quantum spin chain experiments which measure KPZ and ballistic relaxation under different conditions. We identify the ensuing set of scaling exponents in previous discrete interface growth models related with isotropic percolation, and show it to describe the fluctuations of additional continuum systems related with the noisy Korteweg-de Vries equation. Along this process, we additionally elucidate the universality class of the related inviscid stochastic Burgers equation., 9 pages, 8 figures, Physical Review E (in press, 2022)

Nonstabilizerness, also known as magic, quantifies the number of non-Clifford operations needed in order to prepare a quantum state. As typical measures either involve minimization procedures or a computational cost exponential in the number of qubits $N$, it is notoriously hard to characterize for many-body states. In this work, we show that nonstabilizerness, as quantified by the recently introduced Stabilizer R\'enyi Entropies (SREs), can be computed efficiently for matrix product states (MPSs). Specifically, given an MPS of bond dimension $\chi$ and integer R\'enyi index $n>1$, we show that the SRE can be expressed in terms of the norm of an MPS with bond dimension $\chi^{2n}$. For translation-invariant states, this allows us to extract it from a single tensor, the transfer matrix, while for generic MPSs this construction yields a computational cost linear in $N$ and polynomial in $\chi$. We exploit this observation to revisit the study of ground-state nonstabilizerness in the quantum Ising chain, providing accurate numerical results up to large system sizes. We analyze the SRE near criticality and investigate its dependence on the local computational basis, showing that it is in general not maximal at the critical point., Comment: 11 pages, 7 figures

117987 We show, through the use of the Landauer-Büttiker (LB) formalism and a tight-binding (TB) model, that the transport gap of twinned graphene can be tuned through the application of a uniaxial strain in the direction normal to the twin band. Remarkably, we find that the transport gap Egap bears a square-root dependence on the control parameter x − c , where x is the applied uniaxial strain and c ∼ 19% is a critical strain. We interpret this dependence as evidence of criticality underlying a continuous phase transition, with x − c playing the role of control parameter and the transport gap Egap playing the role of order parameter. For x < c , the transport gap is non-zero and the material is semiconductor, whereas for x > c the transport gap closes to zero and the material becomes conductor, which evinces a semiconductor-to-conductor phase transition. The computed critical exponent of 1/2 places the transition in the meanfield universality class, which enables far-reaching analogies with other systems in the same class. Junta de Andalucía, Consejería de Transformación Económica, Industria, Conocimiento y Universidadades P18-RT- 1485 Ministerio de Ciencia, Innovación y Universidades RTI2018-094325-B-I00

Hybrid quantum-classical algorithms have been proposed to circumvent noise limitations in quantum computers. Such algorithms delegate only a calculation of the expectation value to the quantum computer. Among them, the Variational Quantum Eigensolver (VQE) has been implemented to study molecules and condensed matter systems on small size quantum computers. Condensed matter systems described by the Hubbard model exhibit a rich phase diagram alongside exotic states of matter. In this manuscript, we try to answer the question: how much of the underlying physics of a 1D Hubbard chain is described by a problem-inspired Variational Hamiltonian Ansatz (VHA) in a broad range of parameter values ? We start by probing how much does the solution increases fidelity with increasing ansatz complexity. Our findings suggest that even low fidelity solutions capture energy and number of doubly occupied sites well, while spin-spin correlations are not well captured even when the solution is of high fidelity. Our powerful simulation platform allows us to incorporate a realistic noise model and shows a successful implementation of noise-mitigation strategies - post-selection and the Richardson extrapolation. Finally, we compare our results with an experimental realization of the algorithm on IBM Quantum's ibmq_quito device.

Lateral organization in the plane of the plasma membrane is an important driver of biological processes. The past dozen years have seen increasing experimental support for the notion that lipid organization plays an important role in modulating this heterogeneity. Various biophysical mechanisms rooted in the concept of liquid-liquid phase separation have been proposed to explain diverse experimental observations of heterogeneity in model and cell membranes, with distinct but overlapping applicability. In this review, we focus on evidence for and consequences of the hypothesis that the plasma membrane is poised near an equilibrium miscibility critical point. Critical phenomena explain certain features of the heterogeneity observed in cells and model systems, but also go beyond heterogeneity to predict other interesting phenomena, including responses to composition perturbations., Comment: 49 pages, 4 Figures

Out of equilibrium, the lack of reciprocity is the rule rather than the exception. Non-reciprocal interactions occur, for instance, in networks of neurons, directional growth of interfaces, and synthetic active materials. While wave propagation in non-reciprocal media has recently been under intense study, less is known about the consequences of non-reciprocity on the collective behavior of many-body systems. Here, we show that non-reciprocity leads to time-dependent phases where spontaneously broken symmetries are dynamically restored. The resulting phase transitions are controlled by spectral singularities called exceptional points. We describe the emergence of these phases using insights from bifurcation theory and non-Hermitian quantum mechanics. Our approach captures non-reciprocal generalizations of three archetypal classes of self-organization out of equilibrium: synchronization, flocking and pattern formation. Collective phenomena in these non-reciprocal systems range from active time-(quasi)crystals to exceptional-point enforced pattern-formation and hysteresis. Our work paves the way towards a general theory of critical phenomena in non-reciprocal matter., Comment: Supplementary movies at https://home.uchicago.edu/~vitelli/videos.html

Voltage-gated sodium channels (NavChs) are pore-forming membrane proteins that regulate the transport of sodium ions through the cell membrane. Understanding the structure and function of NavChs is of major biophysical, as well as clinical, importance given their key role in cellular pathophysiology. In this work, we provide a computational framework for modeling system-size-dependent, i.e., cumulative, atomic properties around a NavCh’s pore. We illustrate our methodologies on the bacterial NavAb channel captured in a closed-pore state where we demonstrate that the atomic environment around its pore exhibits a bi-phasic spatial organization dictated by the structural separation of the pore domains (PDs) from the voltage-sensing domains (VSDs). Accordingly, a mathematical model describing packing of atoms around NavAb’s pore is constructed that allows—under certain conservation conditions—for a power-law approximation of the cumulative hydropathic dipole field effect acting along NavAb’s pore. This verified the non-extensitivity hypothesis for the closed-pore NavAb channel and revealed a long-range hydropathic interactions law regulating atom-packing around the NavAb’s selectivity filter. Our model predicts a PDs-VSDs coupling energy of \documentclass[12pt]{minimal} \usepackage{amsmath} \usepackage{wasysym} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{amsbsy} \usepackage{mathrsfs} \usepackage{upgreek} \setlength{\oddsidemargin}{-69pt} \begin{document}$\sim \!282.1$\end{document}∼282.1 kcal/mol corresponding to a global maximum of the atom-packing energy profile. Crucially, we demonstrate for the first time how critical phenomena can emerge in a single-channel structure as a consequence of the non-extensive character of its atomic porous environment. Supplementary Information The online version contains supplementary material available at 10.1007/s10867-021-09565-w.

In the classically unbroken phase, 3d $O(N)$ symmetric $\phi^4$ vector models admit two equivalent descriptions connected by a strong-weak duality closely related to the one found by Chang and Magruder long ago. We determine the exact analytic renormalization dependence of the critical couplings in the weak and strong branches as a function of the renormalization scheme (parametrized by $\kappa$) and for any $N$. It is shown that for $\kappa=\kappa_*$ the two fixed points merge and then, for $\kappa, Comment: 38 pages, 12 figures; v3: version to appear in JHEP

Quantum phase transitions (QPTs) are usually associated with many-body systems with large degrees of freedom approaching the thermodynamic limit. In such systems, the many-body ground state shows abrupt changes at zero temperature when the control parameter of the Hamiltonian is scanned across a quantum critical point. Recently it has been realized that a QPT can also occur in a simple system composed of only a two-level atom and a single-mode bosonic field, described by the quantum Rabi model (QRM). Here we report the first experimental demonstration of a QPT in the QRM using a single trapped ion. We measure the average spin-up state population of the ion and the average phonon number in its spatial oscillation mode as two order parameters and observe the clear evidences of the phase transition via slow quench of the coupling between the ion and its spatial motion. An experimental probe of the phase transitions in a fundamental quantum optics model without imposing the thermodynamic limit opens up a new window for the controlled study of QPTs and quantum critical phenomena., Comment: 15 pages, 9 figures

The current work establishes a pool boiling CHF prediction method based on percolation theory. For the first time, we observe the experimental bubble footprint’s power-law distributions with almost the same exponent in wire heaters’ water pool boiling crisis, which is borne out strongly that boiling crisis is a typical continuum percolative scale-free behavior, and its characteristics seems not to be influenced by the critical heat flux value. The proposed one-dimensional Monte Carlo(MC) method successfully simulates the phase transition of interactive near-wall bubbles. This research enriches and extends applications of continuum percolation theory in boiling phenomena, and could be an instruction for the followed critical heat flux enhancement studies.

Graphical abstract, While swarming behavior is regarded as a critical phenomenon in phase transition and frequently shows the properties of a critical state such as Lévy walk, a general mechanism to explain the critical property in swarming behavior has not yet been found. Here, we address this problem with a simple swarm model, the Self-Propelled Particle (SPP) model, and propose a way to explain this critical behavior by introducing agents making decisions via the data-hypothesis interaction in Bayesian inference, namely, Bayesian and inverse Bayesian inference (BIB). We compare three SPP models, namely, the simple SPP, the SPP with Bayesian-only inference (BO) and the SPP with BIB models. We show that only the BIB model entails coexisting tornado, splash and translation behaviors, and the Lévy walk pattern.

The quantitative characteristics of the products of dispersion and the cascade of dissipative structures arising in metals under shock-wave loading are determined. The fractal dimension df and the Hurst exponent H (standardized range of dissipative structures) of the cascade of hydrodynamic modes, the roughness of the fracture surface, and the dispersion products are determined. Destructive processes occurring in loaded samples are numerically simulated using the Lagrangian technique TIM 3D [1, 2]. It is shown that a cascade of dissipative structures at different scale–temporal levels (nanolevel, mesolevel I, mesolevel II, and macrolevel) is a fractal cluster, and it is a percolation cluster on the threshold of a macrofracture, when there is connectivity in the system of dissipative structures [1, 2]. The self-similarity of dissipative structures is due to the self-organization in nonequilibrium systems; and the dynamic fracture and dispersion processes are examples of scale invariance. The scale invariance of the dissipative structures indicates the nonequilibrium system has reached a critical state.

Various critical phenomena and critical points appearing in many-particle systems under the variation of external conditions (fields), including the temperature, pressure, and magnetic and electric fields are described. Laws of statistical physics are universal for any particular nature of particles and the considered phenomena can be observed in systems of macroparticles (colloids), atoms, molecules, and subnuclear particles (nucleons and quarks).

The phase equilibria and critical phenomena in the Na2SO4–Na2B4O7–H2O system with the boundary subsystems Na2B4O7–H2O (type 1 with the phase separation of the solutions) and Na2SO4–H2O (type 2) at 350–460°C and a pressure of up to 100 MPa are studied. It is shown that there exist two three-phase regions L1–L2–S, which are adjacent to two water–salt subsystems and divided by a fluid region, at temperatures ranging from 440°C (the critical point Q (L1 = L2–S) of the type 2 binary system) to ~455°C (at which these regions unite). The ternary system has two critical curves in saturated solutions. The curves originate from different critical points of the type 2 binary subsystem, point p (G = L–S) and point Q (G = L1–L2–S), respectively, and end at the end ternary critical points pR (G = L1–L2–S) and QN (G–L1 = L2–S), respectively. Between the last two points, there is a four-phase equilibrium (G–L1–L2–S), which, according to the visual observations in the sealed quartz ampules, exists in the temperature range 350–380°C.

This review presents the results of a detailed analysis of the role of isochoric heat capacity as a key thermodynamic property of matter in the investigation of critical and supercritical phenomena. A brief historical background is given on the role and contribution of Russian scientific schools to the experimental investigation of the isochoric heat capacity in the critical region in the development of the nonclassical (scaling) theory of critical phenomena, which drastically changed the understanding of the physical nature of critical and supercritical phenomena. The experimental behavior of the isochoric heat capacity and other thermodynamic properties of fluids in the critical and supercritical regions related to it is investigated in detail. The role of new experimental studies of two-phase isochoric heat capacity near the critical point in the development of a “complete” scaling theory is discussed. This theory allows us to understand the physical nature of the asymmetry of the liquid–gas coexistence curve near the critical point and to estimate the contribution of the chemical potential to the divergence of the two-phase isochoric heat capacity at the critical point. The review also focuses on supercritical phase transitions and the role of isochoric heat capacity in determining the Widom line, which separates the liquid-like and gas-like regions in supercritical states; i.e., it defines the boundaries of the coexistence of liquid-like and gas-like phases in supercritical fluids.

Physics letters / B 834, 137409 (2022). doi:10.1016/j.physletb.2022.137409, Conformal symmetry of QCD is restored at the Wilson-Fisher critical point in noninteger $4-2\epsilon$ space-time dimensions. Correlation functions of multiplicatively renormalizable operators with different anomalous dimensions at the critical point vanish identically. We show that this property allows one to calculate off-diagonal parts of the anomalous dimension matrices for leading-twist operators from a set of two-point correlation functions of gauge-invariant operators which can be evaluated using standard computer algebra techniques. As an illustration, we present the results for the NNLO anomalous dimension matrix for flavor-singlet QCD operators for spin $N\le 8$., Published by North-Holland Publ., Amsterdam

Detection of a gravitational-wave signal of non-astrophysical origin would be a landmark discovery, potentially providing a significant clue to some of our most basic, big-picture scientific questions about the Universe. In this white paper, we survey the leading early-Universe mechanisms that may produce a detectable signal -- including inflation, phase transitions, topological defects, as well as primordial black holes -- and highlight the connections to fundamental physics. We review the complementarity with collider searches for new physics, and multimessenger probes of the large-scale structure of the Universe., Comment: contribution to Snowmass 2021; 3 figures, 67 pages

Previous simulation studies on human connectomes suggested that critical dynamics emerge subcritically in the so-called Griffiths phases. Now we investigate this on the largest available brain network, the 21662 node fruit-fly connectome, using the Kuramoto synchronization model. As this graph is less heterogeneous, lacking modular structure and exhibiting high topological dimension, we expect a difference from the previous results. Indeed, the synchronization transition is mean-field-like, and the width of the transition region is larger than in random graphs, but much smaller than as for the KKI-18 human connectome. This demonstrates the effect of modular structure and dimension on the dynamics, providing a basis for better understanding the complex critical dynamics of humans. We thank Róbert Juhász and Shengfeng Deng for useful comments and discussions. G.Ó. is supported by the National Research, Development and Innovation Office NKFIH under Grant No. K128989 and the Project HPC-EUROPA3 (INFRAIA-2016-1-730897) from the EC Research Innovation Action under the H2020 Programme. We thank access to the Hungarian national supercomputer network NIIF and to BSC Barcelona. G.D. is supported by the project PID2019-105772GB-I00/AEI/10.13039/501100011033 financed by the Ministry of Science, Innovation and Universities (MCIU) and the State Research Agency (AEI)10.

We investigate the strong out-of-equilibrium dynamics occurring when a harmonically trapped ultracold bosonic gas is evaporatively cooled across the Bose--Einstein condensation transition. By imaging the cloud after free expansion, we study how the cooling rate affects the timescales for the growth of the condensate order parameter and the relaxation dynamics of its spatial fluctuations. We find evidence of a delay on the condensate formation related to the collisional properties and a universal condensate growth following the cooling rate. Finally, we measure an exponential relaxation of the spatial fluctuations of the order parameter that also shows a universal scaling. Notably, the scaling for the condensate growth and for the relaxation of its fluctuations follow different power laws., Comment: 10 pages, 6 figures

We extend the effective dynamical quasiparticle model (DQPM) - constructed for the description of non-perturbative QCD phenomena of the strongly interacting quark-gluon plasma (QGP) - to large baryon chemical potentials, $\mu_B$, including a critical end-point and a 1st order phase transition. The DQPM description of quarks and gluons is based on partonic propagators with complex selfenergies where the real part of the selfenergies is related to the quasiparticle mass and the imaginary part to a finite width of their spectral functions. In DQPM the determination of complex selfenergies for the partonic degrees of freedom at zero and finite $\mu_B$ has been performed by adjusting the entropy density to the lQCD data. The temperature-dependent effective coupling (squared) $g^2(T/T_c)$, as well as the parton effective masses and widths are based on this adjustment. The novel extended dynamical quasiparticle model, named "DQPM-CP", makes it possible to describe thermodynamical and transport properties of quarks and gluons in a wide range of $T$ and $\mu_B$, and reproduces the equation-of-state (EoS) of lQCD calculations in the crossover region of finite $T, \mu_B$. We apply a scaling ansatz for the strong coupling constant near the CEP, located at ($T^{CEP}$, $\mu^{CEP}_B) = (0.100, 0.960)$ GeV. We show the EoS as well as the speed of sound for $T>T_c$ and for a wide range of $\mu_B$, which can be of interest for hydrodynamical simulations. Furthermore, we consider two settings for the strange quark chemical potentials (I) $\mu_s=\mu_B/3$ and (II) $\mu_s=0$. The isentropic trajectories of the QGP matter are compared for these two cases. The phase diagram of DQPM-CP is close to PNJL calculations. The leading order pQCD transport coefficients of both approaches differ. This elucidates that the knowledge of the phase diagram alone is not sufficient to describe the dynamical evolution of QGP., Comment: 18 pages, 17 figures