Bulletin of the American Physical Society
APS March Meeting 2022
Volume 67, Number 3
Monday–Friday, March 14–18, 2022; Chicago
Session N08: Systems Far from EquilibriumRecordings Available
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Sponsoring Units: GSNP Chair: Todd Gingrich, Northwestern University Room: McCormick Place W-179B |
Wednesday, March 16, 2022 11:30AM - 11:42AM |
N08.00001: Nonequilibrium Fluctuation Dissipation Relation from Doi-Peliti Field Theory Benjamin P Vollmayr-Lee, Andrew Baish We develop Doi-Peliti field theory for driven, interacting particles coupled to a thermal bath. This mapping of classical particles to a field theory does not require any assumption of large particle numbers or slow modes, and the system may be driven arbitrarily far from equilibrium. We then show how differentiation of the Jarzynski relation results in a nonequilbrium fluctuation dissipation relation. |
Wednesday, March 16, 2022 11:42AM - 11:54AM |
N08.00002: A topological fluctuation theorem Benoit Mahault, Evelyn Tang, Ramin Golestanian Fluctuation theorems specify the non-zero probability to observe negative entropy production, contrary to a naive expectation from the second law of thermodynamics. For closed particle trajectories in a fluid, Stokes theorem can be used to give a geometric characterization of the entropy production. Building on this picture, we formulate a topological fluctuation theorem that depends only on the winding number around each vortex core and is insensitive to other aspects of the force. The probability is robust to local deformations of the particle trajectory, reminiscent of topologically protected modes in various classical and quantum systems. We demonstrate that entropy production is quantized in these strongly fluctuating systems, and it is controlled by a topological invariant. We demonstrate that the theorem holds even when the probability distributions are non-Gaussian functions of the generated heat. |
Wednesday, March 16, 2022 11:54AM - 12:06PM |
N08.00003: Thermodynamic uncertainty relation for Langevin dynamics via time contraction Ray Fu The thermodynamic uncertainty relation (TUR) quantifies the relationship between fluctuation and response in out-of-equilibrium systems, and is the natural counterpart of the fluctuation-dissipation theorem in equilibrium statistical mechanics. For both overdamped and underdamped Langevin dynamics, we derive a TUR by considering a virtual time contration on the discretized equations of motion. The TUR emerges naturally from the contraction principle of large deviation theory and makes no recourse to information-theoretic inequalities. We compare our TUR with known results in the overdamped and underdamped regimes and explore their similarities and differences. |
Wednesday, March 16, 2022 12:06PM - 12:18PM |
N08.00004: Reversal symmetries for cyclic paths in systems far from thermodynamic equilibrium John W Biddle, Jeremy Gunawardena We have examined time-reversal properties of cyclic paths in non-equilibrium systems described by Markov processes. We find that even for systems far from equilibrium, the long-time limit of the ratio of forward to reverse occurrences of a cyclic path is determined only by the thermodynamic force on the cycle itself. In particular, if traversing the cycle does not expend energy, the frequency with which the cyclic path occurs is the same for the forward and reverse directions. This symmetry holds irrespective of the transition rates elsewhere in the system. This is in contrast to time-reversal symmetry for pairs of transitions, which can break down for all transitions in a system if even a single transition rate is disturbed from its equilibrium value, and to steady-state fluxes and probabilities of system states, which in the non-equilibrium case depend in a complex manner on all transition rates. Our results suggest the existence of fluctuation theorems for cycle counts, which is a topic of current research. They also have experimental applications for biological systems, as they can shed light on which processes in a complex system involve expenditure of energy. |
Wednesday, March 16, 2022 12:18PM - 12:30PM |
N08.00005: Emergence and breaking of duality symmetry in the generalized thermodynamic fundamental relations Zhiyue Lu, Hong Qian Thermodynamics provides a universal framework to describe the relationship among macroscopic properties of equilibrated systems. Such a framework has been extended to nanoscale systems by C. Jarzynski, U. Seifert, and T. Hill. Using the theory of large deviation, we find that Hill's nano-thermodynamic can be generalized to systems beyond equilibrium. Generalized thermodynamic results such as entropy, free entropy, fundamental equation, and Hill-Gibbs-Duhem (HGD) equation emerge in the statistics of repeated measurements of an arbitrary stationary system with a priori probability distribution. Moreover, in the repeated measurement limit, a duality symmetry arises between entropy and free entropy -- yielding the fundamental equation and HGD equation as a duality pair. If one further introduces the thermodynamic limit (i.e., for macroscopic systems entropy becoming an Eulerian 1-st order homogeneous function of all extensive variables), the duality symmetry is broken, and the HGD equation reduces to the Gibbs-Duhem equation. The new framework provides an operational approach to derive thermodynamic-like relations for arbitrary stationary systems and offers a unique perspective of the relationship between Hill's nano-thermodynamics and thermodynamics. |
Wednesday, March 16, 2022 12:30PM - 12:42PM |
N08.00006: Scaling of Entropy Production under Coarse Graining Luca Cocconi, Gunnar Pruessner, Guillaume Salbreux Entropy production plays a fundamental role in the study of non-equilibrium systems by offering a quantitative handle on the degree of time-reversal symmetry breaking. It depends crucially on the degree of freedom considered as well as on the scale of description. It was hitherto unknown how the entropy production at one resolution of the degrees of freedom is related to the entropy production at another resolution. This relationship is of particular relevance to coarse grained and continuum descriptions of a given phenomenon. In this work, we derive the scaling of the entropy production under iterative coarse graining on the basis of the correlations of the underlying microscopic transition rates. Our approach unveils a natural criterion to distinguish equilibrium-like and genuinely non-equilibrium macroscopic phenomena based on the sign of the scaling exponent of the entropy production per mesostate. |
Wednesday, March 16, 2022 12:42PM - 12:54PM |
N08.00007: Kibble-Zurek Mechanism for Nonequilibrium Phase Transitions in Driven Systems with Quenched Disorder Charles M Reichhardt, Cynthia Reichhardt, Adolfo Del Campo We examine the density of topological defects for a two-dimensional particle assembly driven over quenched disorder for varied quench rates across a nonequilibrium phase transition from a plastic disordered flowing state to a moving anisotropic crystal. This type of dynamical ordering transition occurs for vortices in type-II superconductors, colloidal particles, and other particle-like systems in the presence of random disorder. We find that the density of topological defects on the ordered side of the transition scales as a power law with the form 1/tqβ, where tq is the time duration of the quench across the transition. This type of scaling is predicted in the Kibble-Zurek mechanism for varied quench rates across a continuous phase transition. We find that the scaling behavior holds for varied strengths of quenched disorder with the same exponent in different systems. The value of the exponent can be connected to the directed percolation universality class. Our results also suggest that the Kibble-Zurek mechanism can be applied in general to nonequilibrium phase transitions. |
Wednesday, March 16, 2022 12:54PM - 1:06PM |
N08.00008: Localization in the Discrete Non-Linear Schroedinger Equation and geometric properties of the microcanonical surface Federico Balducci, Antonello Scardicchio, Claudio Arezzo, Carlo Vanoni, Riccardo Piergallini In this talk I will present some recent results regarding the relaxation to equilibrium in the classical Discrete Non-Linear Schroedinger Equation (DNLSE). This model is well known to show a high-energy-density phase in which ensemble equivalence breaks down, and in which dynamical localization takes place: the charge accumulates on few sites and the exploration of phase space is dramatically slowed down. So far, however, the attention to the DNLSE was focused mainly on 1d geometries, where it is common for non-harmonic chains to present weak ergodicity breaking due to quasi-integrability issues and solitonic modes. In contrast, I will show how also in the mean-field, fully-connected model equilibrium is reached dynamically only after a time exponentially large in the system size. To this end, I will introduce an infinite-temperature expansion that justifies the simplification of keeping only the potential energy term at high energy density. The problem then reduces to the dynamics of a particle on the equipotential surface, whose geometry is non-trivial because of the presence of two conservation laws. I will present exact Morse-theoretic results on the structure of such hypersurface, elucidating how localization emerges when the motion of the particle can be considered Brownian. This in turn implies a phase transition in the lowest eigenvalue (i.e. the gap) of the Laplacian on said surface. |
Wednesday, March 16, 2022 1:06PM - 1:18PM |
N08.00009: Anomalous thermal relaxation in unimolecular chemical reactions Saikat Bera, Matt R Walker, Marija Vucelja Thermal quenching is the process of rapidly cooling or heating a physical system. A curious phenomenon that sometimes occurs during such rapid thermal relaxations is the so-called Mpemba effect. It is the phenomenon where a system prepared at a hot temperature "overtakes" an identical system prepared at a warm temperature and cools down faster to be in equilibrium with a cold environment. There is also the analogous phenomenon in heating, and it is called the inverse Mpemba effect. Here we study the Mpemba effect and its inverse in unimolecular chemical reactions as a function of the chemical reaction rates and the system's energies. We observe both effects in unimolecular chemical reactions of three or more species and provide analytical results. We generalize some of the results to N-species chemical reactions. Potential applications of our work could lead to optimized protocols for obtaining chemical products and better characterizations of biochemical pathways. |
Wednesday, March 16, 2022 1:18PM - 1:30PM |
N08.00010: Perturbation spreading in a non-reciprocal classical isotropic magnet Nisarg Bhatt, Sriram R Ramaswamy, Subroto Mukerjee We consider a classical Heisenberg spin magnet with precessional dynamics governed by an asymmetric exchange coupling along one spatial direction, i.e., different couplings for left and right neighbors [Das et al., EPL 60, 418-424 (2002)]. This breaks both energy and spin conservation while retaining O(3) symmetry. We quantify the effects of a localized perturbation by means of a "decorrelator", the classical equivalent of an out-of-time-ordered correlator, and show that it spreads ballistically and -- for a purely antisymmetric coupling -- symmetrically about the perturbed site. We present results on spreading speed, entropy production and related quantities. |
Wednesday, March 16, 2022 1:30PM - 1:42PM |
N08.00011: Stefan–Maxwell diffusivities of gas mixtures and liquid electrolytes. Maxim Zyskin, Charles W Monroe Stefan–Maxwell diffusivites describe drag created by relative motion of components in continuum multi-species transport models. They are key phenomenological parameters within the concentrated-solution theory of liquid electrolytes, which is important in battery modeling. In general, Stefan–Maxwell coefficients depend on composition, temperature and pressure. Those parameters can be measured experimentally, and we review some of the results and modelling challenges. It is desirable to develop robust microscopic methods that allow Stefan-Maxwell diffusivities to be computed from first principles, rather than relying on experimental data. A method that uses molecular dynamics and computes Stefan–Maxwell diffusivities by exploiting Onsager's regression hypothesis has been proposed. We investigate the method in the test case of gas mixtures where analytic results from kinetic theory, as well as experiments, are available. We discuss extension of the method to liquid electrolytes. |
Wednesday, March 16, 2022 1:42PM - 1:54PM |
N08.00012: Nanoelectromechanical rotary current rectifier Christopher W Wächtler, Alan Celestino, Alexander Croy, Alexander Eisfeld Nanoelectromechanical systems (NEMS) are devices integrating electrical and mechanical functionality on the nanoscale. Because of individual electron tunneling, such systems can show rich self-induced, highly non-linear dynamics. We show theoretically that rotor shuttles, fundamental NEMS without intrinsic frequencies, are able to rectify an oscillatory bias voltage over a wide range of external parameters in a highly controlled manner, even if subject to the stochastic nature of electron tunneling and thermal noise. Supplemented by a simple analytic model, we identify dif- ferent operational modes of charge rectification. Intriguingly, the direction of the current depends sensitively on the external parameters. |
Wednesday, March 16, 2022 1:54PM - 2:06PM |
N08.00013: Tunneling percolation staircase in nanoparticle composite systems Shiva Pokhrel, Zhi-Feng Huang, Boris Nadgorny Electrical conduction in composite systems consisting of conducting fillers embedded in insulating matrix is defined by two mechanisms, an electron current flow via a direct contact between metallic particles/clusters (classical percolation) and the flow through tunnel barriers separating metallic particles/clusters (tunneling percolation). Classical percolation obeys scaling law with universal critical exponents while tunneling percolation obeys scaling law with a non-universal critical exponent for system conductivity. In this work, we investigated tunneling percolation in CrO2 (half-metal) and Cr2O3 (insulator) experimentally. Composite samples with different volume fractions were prepared and the four-wire electrical transport measurements were performed. We observed tunneling staircase at low volume fractions of CrO2 due to conduction through interphase regions. We also studied tunneling percolation staircase in CrO2 and CrO2 particles with a Cr2O3 shell, and investigated the conductivity property at various temperatures. |
Wednesday, March 16, 2022 2:06PM - 2:18PM |
N08.00014: Inferences from transition statistics of partial information Pedro E Harunari, Annwesha Dutta, Édgar Roldán, Matteo Polettini The rapidly growing field of Stochastic Thermodynamics relies on the mathematics of Markov processes to assess Statistical Physics concepts outside of thermal equilibrium, it thrives under the full knowledge of the microscopic dynamics via master or Fokker-Planck equations. However, in most realistic settings, part of the information is hidden, what in fact distinguishes Statistical Mechanics from Thermodynamics is that for the latter only macroscopic phenomena are available. |
Wednesday, March 16, 2022 2:18PM - 2:30PM |
N08.00015: BEYOND BELL'S LAW: MODEL-FREE TRANSITION RATE ESTIMATION FROM NONEQUILIBRIUM TRAJECTORIES Benjamin Kuznets-Speck, David T Limmer Nonequilibrium systems regulate the rate at which they transition from one long-lived functional state to another by channeling chemical and mechanical energy from external forces and noisy environments. Here we discuss a concrete tradeoff, imposed by statistical physics, between the extent to which such transitions can be sped-up and the work required to do so [1]. We use a model cooperatively (un)folding protein to illustrate how such a guiding principle can be put to use inferring transition rates from nonequilibrium force spectroscopy experiments and molecular simulation. Our general, model independent framework reduces to Bell’s phenomenological rate law in the appropriate limit, and goes beyond it, allowing for arbitrary time-dependent driving forces without the assumption of quasi-equilibrium. Finally, we show how this dissipative rate bound can be used as a variational principle to iteratively design optimal forcing protocols to minimize artifacts from experimental apparatus, and better recapitulate unbiased transition paths from steered molecular dynamics [2]. |
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