Showing papers on "Non-equilibrium thermodynamics published in 2022"
35 citations
TL;DR: In this article , the authors predict conditions under which a sufficiently large imbalance in intermolecular interactions can emerge intrinsically from the accumulation of protein structural transitions, driving even single component condensates into nonequilibrium liquid core/gel-shell or gel-core/liquid-shell multiphase architectures.
Abstract: Significance Biomolecular condensates are highly diverse systems spanning not only homogeneous liquid droplets but also gels, glasses, and even multiphase architectures that contain various coexisting liquid-like and/or gel-like inner phases. Multiphase architectures form when the different biomolecular components in a multicomponent condensate establish sufficiently imbalanced intermolecular forces to sustain different coexisting phases. While such a requirement seems, at first glance, impossible to fulfil for a condensate formed exclusively of chemically identical proteins (i.e., single component), our simulations predict conditions under which this may be possible. During condensate aging, a sufficiently large imbalance in intermolecular interactions can emerge intrinsically from the accumulation of protein structural transitions—driving even single-component condensates into nonequilibrium liquid-core/gel-shell or gel-core/liquid-shell multiphase architectures.
30 citations
TL;DR: In this article , the authors review recent works that use stochastic thermodynamics tools to identify, for active systems, a measure of irreversibility comprising a coarse-grained or informatic entropy production.
Abstract: Active systems evade the rules of equilibrium thermodynamics by constantly dissipating energy at the level of their microscopic components. This energy flux stems from the conversion of a fuel, present in the environment, into sustained individual motion. It can lead to collective effects without any equilibrium equivalent, such as a phase separation for purely repulsive particles, or a collective motion (flocking) for aligning particles. Some of these effects can be rationalized by using equilibrium tools to recapitulate nonequilibrium transitions. An important challenge is then to delineate systematically to which extent the character of these active transitions is genuinely distinct from equilibrium analogs. We review recent works that use stochastic thermodynamics tools to identify, for active systems, a measure of irreversibility comprising a coarse-grained or informatic entropy production. We describe how this relates to the underlying energy dissipation or thermodynamic entropy production, and how it is influenced by collective behavior. Then, we review the possibility to construct thermodynamic ensembles out-of-equilibrium, where trajectories are biased towards atypical values of nonequilibrium observables. We show that this is a generic route to discovering unexpected phase transitions in active matter systems, which can also inform their design.
27 citations
TL;DR: In this paper , the authors studied how mechanical activity shapes soft interfaces that separate an active and a passive fluid and demonstrated the promise of mechanically driven interfaces for creating a new class of soft active matter.
Abstract: Controlling interfaces of phase-separating fluid mixtures is key to the creation of diverse functional soft materials. Traditionally, this is accomplished with surface-modifying chemical agents. Using experiment and theory, we studied how mechanical activity shapes soft interfaces that separate an active and a passive fluid. Chaotic flows in the active fluid give rise to giant interfacial fluctuations and noninertial propagating active waves. At high activities, stresses disrupt interface continuity and drive droplet generation, producing an emulsion-like active state composed of finite-sized droplets. When in contact with a solid boundary, active interfaces exhibit nonequilibrium wetting transitions, in which the fluid climbs the wall against gravity. These results demonstrate the promise of mechanically driven interfaces for creating a new class of soft active matter. Description When active and passive fluids interact Incompatible liquids such as oil and water will phase separate with low interfacial tension. Adkins et al. investigated the dynamics of a one-dimensional interface separating an active nematic phase with a passive isotropic phase (see the Perspective by Palacci). They found a rich behavior of fluctuating interfaces in which the phase-separating fluids could form active emulsions that did not coarsen and in which droplets formed spontaneously. Macroscopic interfaces can also displayed propagating waves with a characteristic wave number and speed. Furthermore, the activity of one of the fluids, in which the addition of energy drove the ordering of that fluid, was able to modify the wetting transitions. The authors also observed active wetting of a solid surface whereby active extensile stresses parallel to the surface drove the fluid to climb a solid wall against gravity. —MSL Active interfaces exhibit giant fluctuations and propagating waves that power wetting transitions and droplet shape shifting.
24 citations
TL;DR: In this paper , a long-range interacting spin chain was realized by measuring space-time-resolved correlation functions in an infinite temperature state, and a whole family of hydrodynamic universality classes, ranging from normal diffusion to anomalous superdiffusion, were observed.
Abstract: Identifying universal properties of nonequilibrium quantum states is a major challenge in modern physics. A fascinating prediction is that classical hydrodynamics emerges universally in the evolution of any interacting quantum system. We experimentally probed the quantum dynamics of 51 individually controlled ions, realizing a long-range interacting spin chain. By measuring space-time-resolved correlation functions in an infinite temperature state, we observed a whole family of hydrodynamic universality classes, ranging from normal diffusion to anomalous superdiffusion, that are described by Lévy flights. We extracted the transport coefficients of the hydrodynamic theory, reflecting the microscopic properties of the system. Our observations demonstrate the potential for engineered quantum systems to provide key insights into universal properties of nonequilibrium states of quantum matter.
23 citations
07 Jan 2022
TL;DR: In this article , a heterogeneous diffusion process (HDP) with position-dependent diffusion coefficient and Poissonian stochastic resetting was studied, and exact results for the mean squared displacement and the probability density function were derived.
Abstract: We study a heterogeneous diffusion process (HDP) with position-dependent diffusion coefficient and Poissonian stochastic resetting. We find exact results for the mean squared displacement and the probability density function. The nonequilibrium steady state reached in the long time limit is studied. We also analyse the transition to the non-equilibrium steady state by finding the large deviation function. We found that similarly to the case of the normal diffusion process where the diffusion length grows like t 1/2 while the length scale ξ(t) of the inner core region of the nonequilibrium steady state grows linearly with time t, in the HDP with diffusion length increasing like t p/2 the length scale ξ(t) grows like t p . The obtained results are verified by numerical solutions of the corresponding Langevin equation.
20 citations
TL;DR: In this article , the authors identify the underlying molecular process responsible for this class of Arrhenius equilibration mechanisms with a slow mode (SAP), universally observed in the liquid dynamics of thin films.
Abstract: The rate at which a nonequilibrium system decreases its free energy is commonly ascribed to molecular relaxation processes, arising from spontaneous rearrangements at the microscopic scale. While equilibration of liquids usually requires density fluctuations at time scales quickly diverging upon cooling, growing experimental evidence indicates the presence of a different, alternative pathway of weaker temperature dependence. Such equilibration processes exhibit a temperature-invariant activation energy, on the order of 100 kJ mol−1. Here, we identify the underlying molecular process responsible for this class of Arrhenius equilibration mechanisms with a slow mode (SAP), universally observed in the liquid dynamics of thin films. The SAP, which we show is intimately connected to high-temperature flow, can efficiently drive melts and glasses toward more stable, less energetic states. Our results show that measurements of liquid dynamics can be used to predict the equilibration rate in the glassy state.
20 citations
TL;DR: In this article , a detailed exposition on the formalism of quantum master equations for open Floquet systems and highlight recent work investigating whether equilibrium statistical mechanics applies to Floquet states is presented. But this work does not consider the effect of dissipation, which is ubiquitous in nature.
Abstract: In Floquet engineering, periodic driving is used to realize novel phases of matter that are inaccessible in thermal equilibrium. For this purpose, the Floquet theory provides us a recipe for obtaining a static effective Hamiltonian. Although many existing works have treated closed systems, it is important to consider the effect of dissipation, which is ubiquitous in nature. Understanding the interplay of periodic driving and dissipation is a fundamental problem of nonequilibrium statistical physics that is receiving growing interest because of the fact that experimental advances have allowed us to engineer dissipation in a controllable manner. In this review, we give a detailed exposition on the formalism of quantum master equations for open Floquet systems and highlight recent work investigating whether equilibrium statistical mechanics applies to Floquet states. Expected final online publication date for the Annual Review of Condensed Matter Physics, Volume 14 is March 2023. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
18 citations
TL;DR: In this paper , the authors classify the mechanisms by which external fields impact the structure and dynamics in colloidal dispersions and augment their nonequilibrium behavior, and highlight the emergence of colloids powered by external fields as model systems to understand living matter.
Abstract: Electric and magnetic fields have enabled both technological applications and fundamental discoveries in the areas of bottom-up material synthesis, dynamic phase transitions, and biophysics of living matter. Electric and magnetic fields are versatile external sources of energy that power the assembly and self-propulsion of colloidal particles. In this Invited Feature Article, we classify the mechanisms by which external fields impact the structure and dynamics in colloidal dispersions and augment their nonequilibrium behavior. The paper is purposely intended to highlight the similarities between electrically and magnetically actuated phenomena, providing a brief treatment of the origin of the two fields to understand the intrinsic analogies and differences. We survey the progress made in the static and dynamic assembly of colloids and the self-propulsion of active particles. Recent reports of assembly-driven propulsion and propulsion-driven assembly have blurred the conceptual boundaries and suggest an evolution in the research of nonequilibrium colloidal materials. We highlight the emergence of colloids powered by external fields as model systems to understand living matter and provide a perspective on future challenges in the area of field-induced colloidal phenomena.
17 citations
TL;DR: In this paper , the temporal characters of laser-driven phase transition from 2H to 1T^{'} have been investigated in the prototype MoTe_{2} monolayer.
Abstract: The temporal characters of laser-driven phase transition from 2H to 1T^{'} has been investigated in the prototype MoTe_{2} monolayer. This process is found to be induced by fundamental electron-phonon interactions, with an unexpected phonon excitation and coupling pathway closely related to the nonequilibrium relaxation of photoexcited electrons. The order-to-order phase transformation is dissected into three substages, involving energy and momentum scattering processes from optical (A_{1}^{'} and E^{'}) to acoustic phonon modes [LA(M)] in subpicosecond timescale. An intermediate metallic state along the nonadiabatic transition pathway is also identified. These results have profound implications on nonequilibrium phase engineering strategies.
16 citations
TL;DR: In this paper , the authors proposed a new concept to remove CO2 from the offshore natural gas industry, which utilises the combined effect from nonequilibrium condensation phenomena in the supersonic flow and cyclonic separation process from swirling flows.
TL;DR: In this article , a single trapped ultracold ion using dissipative channels, along with a postprocessing method developed in the data analysis, was used to build the effective nonequilibrium stochastic evolutions for the energy transfer between two heat baths mediated by a qubit.
Abstract: Dissipation is vital to any cyclic process in realistic systems. Recent research focus on nonequilibrium processes in stochastic systems has revealed a fundamental trade-off, called dissipation-time uncertainty relation, that entropy production rate associated with dissipation bounds the evolution pace of physical processes [Phys. Rev. Lett. 125, 120604 (2020)PRLTAO0031-900710.1103/PhysRevLett.125.120604]. Following the dissipative two-level model exemplified in the same Letter, we experimentally verify this fundamental trade-off in a single trapped ultracold ^{40}Ca^{+} ion using elaborately designed dissipative channels, along with a postprocessing method developed in the data analysis, to build the effective nonequilibrium stochastic evolutions for the energy transfer between two heat baths mediated by a qubit. Since the dissipation-time uncertainty relation imposes a constraint on the quantum speed regarding entropy flux, our observation provides the first experimental evidence confirming such a speed restriction from thermodynamics on quantum operations due to dissipation, which helps us further understand the role of thermodynamical characteristics played in quantum information processing.
TL;DR: In this paper , the authors investigate entanglement dynamics in continuously monitored open quantum systems featuring current-carrying nonequilibrium states, and reveal the double role of weak monitoring in current-driven open quantum system, simultaneously damping transport and enhancing Entanglement.
Abstract: We investigate entanglement dynamics in continuously monitored open quantum systems featuring current-carrying nonequilibrium states. We focus on a prototypical one-dimensional model of boundary-driven noninteracting fermions with monitoring of the local density, whose average Lindblad dynamics features a well-studied ballistic to diffusive crossover in transport. Here we analyze the dynamics of the fermionic negativity, mutual information, and purity along different quantum trajectories. We show that monitoring this boundary-driven system enhances its entanglement negativity at long times, which otherwise decays to zero in the absence of measurements. This result is in contrast with the case of unitary evolution where monitoring suppresses entanglement production. For small values of $\ensuremath{\gamma}$, the stationary-state negativity shows a logarithmic scaling with system size, transitioning to an area-law scaling as $\ensuremath{\gamma}$ is increased beyond a critical value. Similar critical behavior is found in the mutual information, while the late-time purity shows no apparent signature of a transition, being $O(1)$ for all values of $\ensuremath{\gamma}$. Our work unveils the double role of weak monitoring in current-driven open quantum systems, simultaneously damping transport and enhancing entanglement.
TL;DR: In this article , a mid-infrared laser absorption strategy for simultaneously measuring translational, rotational, and vibrational temperatures of carbon monoxide (CO) at high speeds was developed for application to high-temperature nonequilibrium environments relevant to Mars atmosphere entry.
Abstract: A mid-infrared laser absorption strategy for simultaneously measuring translational, rotational, and vibrational temperatures of carbon monoxide (CO) at high speeds was developed for application to high-temperature nonequilibrium environments relevant to Mars atmosphere entry. Rapid-tuning scanned wavelength techniques were used to spectrally resolve the R(0,66), P(0,31), P(2,20), and P(3,14) lines of the CO fundamental vibrational bands at a rate of 1 MHz to infer multiple temperatures of CO behind incident and reflected shock waves in a shock tube. A distributed feedback quantum cascade laser was used to probe the P-branch transitions near and an external cavity quantum cascade laser was used to probe the R-branch transition near , both using bias-tee circuitry. The sensing method is shown to resolve each targeted transition with temporal and spectral resolution sufficient for quantitative multi-temperature measurements over a wide range of temperatures and pressures (2100–5500 K, 0.03–1.02 atm), including behind incident shock waves traveling up to 3.3 km/s. Measured temperature results were compared to equilibrium and nonequilibrium simulations.
TL;DR: In this article , a superadiabatic dynamical density functional theory (DDFT) was developed for the description of inhomogeneous fluids out-of-equilibrium.
Abstract: For classical many-body systems subject to Brownian dynamics, we develop a superadiabatic dynamical density functional theory (DDFT) for the description of inhomogeneous fluids out-of-equilibrium. By explicitly incorporating the dynamics of the inhomogeneous two-body correlation functions, we obtain superadiabatic forces directly from the microscopic interparticle interactions. We demonstrate the importance of these nonequilibrium forces for an accurate description of the one-body density by numerical implementation of our theory for three-dimensional hard-spheres in a time-dependent planar potential. The relaxation of the one-body density in superadiabatic-DDFT is found to be slower than that predicted by standard adiabatic DDFT and significantly improves the agreement with Brownian dynamics simulation data. We attribute this improved performance to the correct treatment of structural relaxation within the superadiabatic-DDFT. Our approach provides fundamental insight into the underlying structure of dynamical density functional theories and makes possible the study of situations for which standard approaches fail.
TL;DR: In this article , a machine learning algorithm that samples rare trajectories and estimates the associated large deviation functions using a many-body control force by leveraging the flexible function representation provided by deep neural networks, importance sampling in trajectory space, and stochastic optimal control theory is proposed.
Abstract: Sampling the collective, dynamical fluctuations that lead to nonequilibrium pattern formation requires probing rare regions of trajectory space. Recent approaches to this problem, based on importance sampling, cloning, and spectral approximations, have yielded significant insight into nonequilibrium systems but tend to scale poorly with the size of the system, especially near dynamical phase transitions. Here we propose a machine learning algorithm that samples rare trajectories and estimates the associated large deviation functions using a many-body control force by leveraging the flexible function representation provided by deep neural networks, importance sampling in trajectory space, and stochastic optimal control theory. We show that this approach scales to hundreds of interacting particles and remains robust at dynamical phase transitions.
TL;DR: In this article , the emergence of nonequilibrium collective motion in disordered nonthermal active matter when persistent motion and crowding effects compete is explored, using simulations of a two-dimensional model of size polydisperse self-propelled particles.
Abstract: We explore the emergence of nonequilibrium collective motion in disordered nonthermal active matter when persistent motion and crowding effects compete, using simulations of a two-dimensional model of size polydisperse self-propelled particles. In stark contrast with monodisperse systems, we find that polydispersity stabilizes a homogeneous active liquid at arbitrary large persistence times, characterized by remarkable velocity correlations and irregular turbulent flows. For all persistence values, the active fluid undergoes a nonequilibrium glass transition at large density. This is accompanied by collective motion, whose nature evolves from near-equilibrium spatially heterogeneous dynamics at small persistence, to a qualitatively different intermittent dynamics when persistence is large. This latter regime involves a complex time evolution of the correlated displacement field.
TL;DR: In this paper , a spin-boson inspired model of electron transfer is investigated, where the diabatic coupling is given by a position-dependent phase, e iWx .
Abstract: We investigate a spin-boson inspired model of electron transfer, where the diabatic coupling is given by a position-dependent phase, e iWx . We consider both equilibrium and nonequilibrium initial conditions. We show that, for this model, all equilibrium results are completely invariant to the sign of W (to infinite order). However, the nonequilibrium results do depend on the sign of W , suggesting that photo-induced electron transfer dynamics are meaningfully affected by Berry forces even in the presence of nuclear friction; furthermore, whenever there is spin-orbit coupling, electronic spin polarization can emerge (at least for some time).
TL;DR: An overview of the physics surrounding quantum friction and a perspective on recent developments can be found in this article , where the authors provide an overview of recent developments in the field of quantum friction.
Abstract: When two or more objects move relative to one another in vacuum, they experience a drag force which, at zero temperature, usually goes under the name of quantum friction. This contactless non-conservative interaction is mediated by the fluctuations of the material-modified quantum electrodynamic vacuum and, hence, is purely quantum in nature. Numerous investigations have revealed the richness of the mechanisms at work, thereby stimulating novel theoretical and experimental approaches and identifying challenges as well as opportunities. In this article, we provide an overview of the physics surrounding quantum friction and a perspective on recent developments.
TL;DR: This work has demonstrated the nonequilibrium generation of catalytic supramolecular assemblies from simple heterocycle melamine driven by a thermodynamically activated ester using a reversible covalent linkage.
Abstract: The development of synthetic nonequilibrium systems has gathered increasing attention due to their potential to illustrate the dynamic, complex, and emergent traits of biological systems. Simple building blocks capable of interacting via dynamic covalent chemistry and physical assembly in a reaction network under nonequilibrium conditions can contribute to our understanding of complex systems of life and its origin. Herein, we have demonstrated the nonequilibrium generation of catalytic supramolecular assemblies from simple heterocycle melamine driven by a thermodynamically activated ester. Utilizing a reversible covalent linkage, an imidazole moiety was recruited by the assemblies to access a catalytic transient state that dissipated energy via accelerated hydrolysis of the activated ester. The nonequilibrium assemblies were further capable of temporally binding to a hydrophobic guest to modulate its photophysical properties. Notably, the presence of an exogenous aromatic base augmented the lifetime of the catalytic microphases, reflecting their higher kinetic stability.
TL;DR: In this paper , a spin-boson inspired model of electron transfer was investigated, where the diabatic coupling was given by a position-dependent phase, eiWx.
Abstract: We investigate a spin-boson inspired model of electron transfer, where the diabatic coupling is given by a position-dependent phase, eiWx. We consider both equilibrium and nonequilibrium initial conditions. We show that, for this model, all equilibrium results are completely invariant to the sign of W (to infinite order). However, the nonequilibrium results do depend on the sign of W, suggesting that photo-induced electron transfer dynamics with spin-orbit coupling can exhibit electronic spin polarization (at least for some time).
TL;DR: In this paper , the speed of the expectation value of an observable defined on an arbitrary graph, which can describe general many-body systems, is bounded by the "gradient" of the observable, in contrast with conventional speed limits depending on the entire range of observable.
Abstract: Speed of state transitions in macroscopic systems is a crucial concept for foundations of nonequilibrium statistical mechanics as well as various applications in quantum technology represented by optimal quantum control. While extensive studies have made efforts to obtain rigorous constraints on dynamical processes since Mandelstam and Tamm, speed limits that provide tight bounds for macroscopic transitions have remained elusive. Here, by employing the local conservation law of probability, the fundamental principle in physics, we develop a general framework for deriving qualitatively tighter speed limits for macroscopic systems than many conventional ones. We show for the first time that the speed of the expectation value of an observable defined on an arbitrary graph, which can describe general many-body systems, is bounded by the "gradient" of the observable, in contrast with conventional speed limits depending on the entire range of the observable. This framework enables us to derive novel quantum speed limits for macroscopic unitary dynamics. Unlike previous bounds, the speed limit decreases when the expectation value of the transition Hamiltonian increases; this intuitively describes a new tradeoff relation between time and quantum phase difference. Our bound is dependent on instantaneous quantum states and thus can achieve the equality condition, which is conceptually distinct from the Lieb-Robinson bound. Our work elucidates novel speed limits on the basis of local conservation law, providing fundamental limits to various types of nonequilibrium quantum macroscopic phenomena.
TL;DR: In this paper , the authors studied the nonequilibrium thermodynamics of a heat engine operating between two finite-sized reservoirs with well-defined temperatures, and found that the uniform temperature of the two reservoirs at final time τ is bounded from below by the entropy production σ min √ 1/τ.
Abstract: We study the nonequilibrium thermodynamics of a heat engine operating between two finite-sized reservoirs with well-defined temperatures. Within the linear response regime, it is found that the uniform temperature of the two reservoirs at final time τ is bounded from below by the entropy production σ_{min}∝1/τ. We discover a general power-efficiency tradeoff depending on the ratio of heat capacities (γ) of the reservoirs for the engine, and a universal efficiency at maximum average power of the engine for arbitrary γ is obtained. For practical purposes, the operation protocol of an ideal gas heat engine to achieve the optimal performance associated with σ_{min} is demonstrated. Our findings can be used to develop a general optimization scenario for thermodynamic cycles with finite-sized reservoirs in real-world circumstances.
TL;DR: In this article , the behavior of the metal-insulator transition in TiS3 nanowire field effect transistors was investigated in the strongly nonequilibrium limit, and the existence of a critical fixed point, separating insulating and metallic regions in the transfer curves of the device, was identified.
Abstract: We investigate the behavior of the metal-insulator transition (MIT) in TiS3 nanowire field-effect transistors, in the strongly nonequilibrium limit that has, thus far, largely been neglected. Under high electric fields within the TiS3 channel (≤115 kV/cm), we observe the emergence of a critical fixed point, separating insulating and metallic regions in the transfer curves of the device. The critical gate voltage that defines this fixed point evolves systematically with the drain bias (field), allowing us to map out a phase diagram that identifies the conditions for metallicity or for insulating behavior. Dependent upon the choice of the gate voltage used to tune the carrier concentration in the nanowire, the existence of the field-induced MIT allows the TiS3 to be either insulating or metallic over an extensive range of temperature. The possible connection of this strongly nonequilibrium state to some form of charge density wave is discussed.
TL;DR: In this article , the effects of Mg content on the microstructures and second phases of the as-cast Al-Zn-Mg-Cu alloys were investigated, and the results showed that the nonequilibrium eutectic structure consists of α(Al), Al7Cu2Fe, η(MgZn2) and T(AlCuMg Zn) intermetallic compounds.
Abstract: The effects of Mg content on the microstructures and second phases of the as-cast Al–Zn–Mg–Cu alloys were investigated. The results show that the nonequilibrium eutectic structure consists of α(Al), Al7Cu2Fe, η(MgZn2) and T(AlCuMgZn) intermetallic compounds. The alloys with the highest Mg content generate nonequilibrium eutectic structures. The maximum value of nonequilibrium eutectic structures is 10.13 ± 0.62%. As the Mg content increases, the number of tertiary dendrites in the α(Al) matrix increases significantly, and more Mg can be dissolved into the Al- matrix. In addition, as the Mg content increases, the crystallization temperature range decreases from 169.8 K to 157.3 K. When the Mg content is higher than 2.6 wt%, the microstructure evolution of the Al–Zn–Mg–Cu aluminum alloy is as follows: Liq. → Liq. + α(Al) → Liq. + α(Al) + Al7Cu2Fe → α(Al) + Al7Cu2Fe + η(MgZn2) + T(AlCuMgZn). These results play a certain role in promoting the basic research of Al–Zn–Mg–Cu aluminum alloys with high Mg content.
TL;DR: An overview of nonequilibrium dynamics in quantum Hall Tomonaga-luttinger liquids is presented in this article , where a circuit model for collective excitations (bosons) in the system, transport eigenmodes in interaction and disorderdominated regimes are discussed with time-resolved charge measurements for the integer and fractional quantum Hall systems.
Abstract: Tomonaga–Luttinger liquids exhibit unique features that cannot be seen in ordinary Fermi liquids. Recent advancement in measurement techniques on 1D quantum Hall edge channels allows to reveal unique characteristics, such as spin‐charge separation and nonthermal metastable states. In this review, an overview of nonequilibrium dynamics in quantum‐Hall Tomonaga–Luttinger liquids is presented. After the introduction of a circuit model for collective excitations (bosons) in the system, transport eigenmodes in interaction‐ and disorder‐dominated regimes are discussed with time‐resolved charge measurements for the integer and fractional quantum Hall systems. Moreover, nonthermal steady states associated with the integrable model are studied with energy distribution functions obtained with a quantum dot spectrometer. These nontrivial dynamics can be extended to other 1D systems, including 2D topological insulators.
TL;DR: In this article , a surface-patterned system engendering periodic three-dimensional disclinations, which can be excited by light irradiation and undergo a programmable transformation between different topological states, is presented.
Abstract: Significance Topological defects are marvels of nature. Understanding their structures is important for their applications in, for example, directed self-assembly, sensing, and photonic devices. There is recent interest in active motion and transformation of topological defects in active nematics. In these nonequilibrium systems, however, the motion and transformation of disclinations are difficult to control, thereby hindering their applications. Here, we propose a surface-patterned system engendering periodic three-dimensional disclinations, which can be excited by light irradiation and undergo a programmable transformation between different topological states. Continuum simulations recapitulating these topological structures characterize the bending, breaking, and relinking events of the disclinations during the nonequilibrium process. Our work provides an alternative dynamic system in which active transformation of topological defects can be engineered.
TL;DR: In this paper , the authors reveal the Hessian geometry which underlies chemical reaction networks and demonstrate how it originates from the interplay of stoichiometric and thermodynamic constraints.
Abstract: The theory of chemical kinetics forms the basis to describe the dynamics of chemical reaction networks. Owing to physical and thermodynamic constraints, the networks possess various structures, which can be utilized to characterize important properties of the networks. In this work, we reveal the Hessian geometry which underlies chemical reaction networks and demonstrate how it originates from the interplay of stoichiometric and thermodynamic constraints. Our derivation is based on kinetics, we assume the law of mass action and characterize the equilibrium states by the detailed balance condition. The obtained geometric structure is then related to thermodynamics via the Hessian geometry appearing in a pure thermodynamic derivation. We demonstrate, based on the fact that both equilibrium and complex balanced states form toric varieties, how the Hessian geometric framework can be extended to nonequilibrium complex balanced steady states. We conclude that Hessian geometry provides a natural framework to capture the thermodynamic aspects of chemical reaction networks.
TL;DR: In this article , the temperature dependence of the diffusion coefficient of a Brownian particle is studied in the context of Langevin dynamics, and it is shown that the coefficient exhibits an intriguingly non-monotonic dependence on temperature.
Abstract: The diffusion of small particles is omnipresent in many processes occurring in nature. As such, it is widely studied and exerted in almost all branches of sciences. It constitutes such a broad and often rather complex subject of exploration that we opt here to narrow our survey to the case of the diffusion coefficient for a Brownian particle that can be modeled in the framework of Langevin dynamics. Our main focus centers on the temperature dependence of the diffusion coefficient for several fundamental models of diverse physical systems. Starting out with diffusion in equilibrium for which the Einstein theory holds, we consider a number of physical situations outside of free Brownian motion and end by surveying nonequilibrium diffusion for a time-periodically driven Brownian particle dwelling randomly in a periodic potential. For this latter situation the diffusion coefficient exhibits an intriguingly non-monotonic dependence on temperature.
TL;DR: In this article , a review of methods to calculate the microscopic pressure tensor at both microscopic and macroscopic levels is presented, and connections between different pressure forms for equilibrium and nonequilibrium systems are established.
Abstract: The pressure tensor (equivalent to the negative stress tensor) at both microscopic and macroscopic levels is fundamental to many aspects of engineering and science, including fluid dynamics, solid mechanics, biophysics, and thermodynamics. In this Perspective, we review methods to calculate the microscopic pressure tensor. Connections between different pressure forms for equilibrium and nonequilibrium systems are established. We also point out several challenges in the field, including the historical controversies over the definition of the microscopic pressure tensor; the difficulties with many-body and long-range potentials; the insufficiency of software and computational tools; and the lack of experimental routes to probe the pressure tensor at the nanoscale. Possible future directions are suggested.