Bulletin of the American Physical Society
APS March Meeting 2015
Volume 60, Number 1
Monday–Friday, March 2–6, 2015; San Antonio, Texas
Session F45: Focus Session: Systems far from Equilibrium I |
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Sponsoring Units: GSNP Chair: Uwe Tauber, Virginia Polytechnic Institute and State University Room: 216AB |
Tuesday, March 3, 2015 8:00AM - 8:36AM |
F45.00001: Thermodynamics with information flow: Applications to Maxwell demons and biochemical sensing Invited Speaker: Jordan Horowitz Information is often perceived as an immaterial entity. However, since the birth of statistical physics, it has been argued, based on thought experiments by the likes of Maxwell, that there are physical thermodynamic implications to information manipulation. In this talk, I will discuss a unified framework for the information transfers between continuously interacting systems, describing how information generated in an auxiliary system can be utilized by another as a fuel for an otherwise impossible process. Indeed, while the joint system satisfies the second law, the entropy balance of each system is modified by an information term related to the mutual information between the pair of systems. I will then show how this result incorporates the traditional analysis of Maxwell's demon. In addition, I will use this framework to analyze the thermodynamics and energetics of biological sensory adaptation, employing the biochemical sensing network of E. Coli chemotaxis as a representative example. [Preview Abstract] |
Tuesday, March 3, 2015 8:36AM - 8:48AM |
F45.00002: Efficiency and Large Deviations in Time-Asymmetric Stochastic Heat Engines Todd Gingrich, Grant Rotskoff, Suriyanarayanan Vaikuntanathan, Phillip Geissler In a stochastic heat engine driven by a cyclic non-equilibrium protocol, fluctuations in work and heat give rise to a fluctuating efficiency. Using computer simulations and tools from large deviation theory, we have examined these fluctuations in detail for a model two-state engine. We find in general that the form of efficiency probability distributions is similar to those described by Verley et al. [2014 Nat Comm, 5 4721], in particular featuring a local minimum in the long-time limit. In contrast to the time-symmetric engine protocols studied previously, however, this minimum need not occur at the value characteristic of a reversible Carnot engine. Furthermore, while the local minimum may reside at the global minimum of a large deviation rate function, it does not generally correspond to the least likely efficiency measured over finite time. [Preview Abstract] |
Tuesday, March 3, 2015 8:48AM - 9:00AM |
F45.00003: High-Precision Tests of Stochastic Thermodynamics in a Feedback Trap Mom\v cilo Gavrilov, Yonggun Jun, John Bechhoefer Feedback traps can trap and manipulate small particles and molecules in solution. They have been applied to the measurement of physical and chemical properties of particles and to explore fundamental questions in the non-equilibrium statistical mechanics of small systems. Feedback traps allow one to choose an arbitrary virtual potential, do any time-dependent transformation of the potential, and measure various thermodynamic quantities such as stochastic work, heat, or entropy. In feedback-trap experiments, the dynamics of a trapped object is determined by the imposed potential but is also affected by drifts due to electrochemical reactions and by temperature variations in the electronic amplifier. Although such drifts are small for measurements on the order of seconds, they dominate on time scales of minutes or slower. In this talk, we present a recursive algorithm that allows real-time estimations of drifts and other particle properties. These estimates let us do a real-time calibration of the feedback trap. Having eliminated systematic errors, we were able to show that erasing a one-bit memory requires at least $kT$ ln 2 of work, in accordance with Landauer's principle. [Preview Abstract] |
Tuesday, March 3, 2015 9:00AM - 9:12AM |
F45.00004: On the heat flux and entropy produced by thermal fluctuations Sergio Ciliberto, Alberto Imparato We study both experimentally and theoretically the statistical properties of the energy exchanged between two electrical conductors, kept at different temperature by two different heat reservoirs, and coupled by the electric thermal noise. Such a system is ruled by the same equations as two Brownian particles kept at different temperatures and coupled by an elastic force. We measure the heat flowing between the two reservoirs, the thermodynamic work done by one part of the system on the other, and we show that these quantities exhibit a long time fluctuation theorem. Furthermore, we evaluate the fluctuating entropy, which satisfies a conservation law. These experimental results are fully justified by the theoretically analysis. Our results give more insight into the energy transfer in the famous Feymann ratchet widely studied theoretically but never in an experiment. Starting from this example we also discuss the experimental results of the heat transfer between two Brownian particle kept at different temperature [Preview Abstract] |
Tuesday, March 3, 2015 9:12AM - 9:24AM |
F45.00005: The thermodynamic geometry of the Ising model Grant Rotskoff, Gavin Crooks Biological machines have evolved to produce useful work in a finite time by operating out-of-equilibrium, but we do not know how evolution has guided the design of these machines: Are there generic design principles that direct motors towards higher efficiency? To answer this question, one must first calculate a finite-time efficiency, which poses a significant challenge---tools of equilibrium statistical mechanics fail to describe the relationship between a protocol and the efficiency of a machine subject to that protocol. Using a geometric framework, I will describe a procedure for predicting the protocol that minimizes the dissipated work during an irreversible process. My talk will focus on optimal control of the 2D Ising model; this example will provide strategies for employing geometric thermodynamics to models that cannot be solved analytically. [Preview Abstract] |
Tuesday, March 3, 2015 9:24AM - 9:36AM |
F45.00006: Thermodynamic metric of nonequilibrium steady states Dibyendu Mandal, Christopher Jarzynski Within the linear response regime, minimally dissipative~transitions~between~equilibrium states are given by the geodesics of a thermodynamic metric in~parameter~space. We~derive an analogous~geometric structure for transitions~between nonequilibrium steady~states, after a suitable renormalization of heat. With a novel expansion formula for the governing master equation, we propose an~exact~expression~for the metric.~As in~the equilibrium scenario, the components of the metric are given by the time-integrals of correlation functions in nonequilibrium steady states. [Preview Abstract] |
Tuesday, March 3, 2015 9:36AM - 9:48AM |
F45.00007: Work fluctuations for a colloidal particle in a time-varying optical trap in analogy with gas in expansion and compression Hyuk Kyu Pak, Dongyun Lee, Chulan Kwon The fluctuation theorem provides a rigorous statistical rule for thermally fluctuating quantities such as work, heat, and entropy production in nonequilibrium thermodynamic processes. However, testing the theorem needs small systems where the fluctuations are more observable. Therefore, there are great difficulties in the experimental measurements. In this work, we investigate the motion of a colloidal particle trapped in a harmonic potential with time-varying stiffness. Here, we estimate the work done on the particle during compression and expansion by measuring its particle position in the first time. The resultant probability distributions of the work in both processes satisfy very well the Jarzynski equality and the Crooks fluctuation theorem. Because this isothermal expansion and compression process in a soft wall qualitatively mimics that in a rigid wall, it offers valuable tool for extracting work from micromechanical heat engines. [Preview Abstract] |
Tuesday, March 3, 2015 9:48AM - 10:00AM |
F45.00008: Engineering Maxwell's Demon Zhiyue Lu, Dibyendu Mandal, Christopher Jarzynski We describe a hypothetical machine, with moving, mechanical components, that acts as an autonomous Maxwell's demon. The machine operates in two useful modes. It can act as an {\it information engine} by rectifying the thermal motions of surrounding gas particles to lift a mass against gravity, while writing information to a stream of bits. Alternatively, it can act as an {\it eraser}, harnessing the energy of a falling mass to erase information from a stream of bits. We solve for the phase diagram and compute the efficiency of our model, both analytically and numerically. Our model provides a simple example of a mechanical machine that is driven by the information entropy of a stream of bits, rather than a difference in temperatures or chemical potentials. [Preview Abstract] |
Tuesday, March 3, 2015 10:00AM - 10:12AM |
F45.00009: Work Relations from Doi-Peliti Field Theory Andrew Baish, Benjamin Vollmayr-Lee We develop a field-theoretic description of non-equilibrium work relations, using Doi-Peliti field theory. We consider classical particles on a lattice, with pair interactions and a local potential, coupled to a thermal bath. Work protocols are imposed by varying the local potential, which drives the system out of equilibrium. In this framework, work relations appear simply as the result of a gauge-like transformation. [Preview Abstract] |
Tuesday, March 3, 2015 10:12AM - 10:24AM |
F45.00010: Experimental test of Generalized Flutuation Dissipation Theorems during a tranient Sergio Ciliberto, Isaac Theurkauff, Artyom Petrosyan In recent years the study of the Fluctuation Dissipation Theorem (FDT) in out of equilibrium system have received a lot of attention both theoretically and experimentally. Several Generalized FDT (GFDT) have been proposed but many theoretical results concern the steady state regimes and only a few the transient regimes. We report here an experiment in which two formulations of GFDT have been tested during the relaxation dynamics of a liquid crystal quenched near the critical point of Fr\'eedericksz transition, which is similar to a second order phase transition and it presents a critical slowing down. Thus the relaxation dynamics after the quench is sufficiently slow to perform several measurements. During the relaxation, the equilibrium FDT is strongly violated and this allows us to test the two GFDT. One is based on a transient fluctuation theorem and the time dependent distribution function. The other is a generalization of the Hatano-Sasa relations for transient state and has the very clear interpretation that the violation of the equilibrium FDT is related to the heat fluxes. The advantages and draw back of the two GFDT are discussed from an experimental point of view. [Preview Abstract] |
Tuesday, March 3, 2015 10:24AM - 10:36AM |
F45.00011: Nonequilibrium equalities in absolutely irreversible processes Yuto Murashita, Ken Funo, Masahito Ueda Nonequilibrium equalities have attracted considerable attention in the context of statistical mechanics and information thermodynamics. Integral nonequilibrium equalities reveal an ensemble property of the entropy production $\sigma$ as $\langle e^{-\sigma} \rangle = 1$. Although nonequilibrium equalities apply to rather general nonequilibrium situations, they break down in absolutely irreversible processes, where the forward-path probability vanishes and the entropy production diverges. We identify the mathematical origins of this inapplicability as the singularity of probability measure. As a result, we generalize conventional integral nonequilibrium equalities to absolutely irreversible processes as $\langle e^{-\sigma} \rangle = 1-\lambda_{\rm S}$, where $\lambda_{\rm S}$ is the probability of the singular part defined based on Lebesgue's decomposition theorem. The acquired equality contains two physical quantities related to irreversibility: $\sigma$ characterizing ordinary irreversibility and $\lambda_{\rm S}$ describing absolute irreversibility. An inequality derived from the obtained equality demonstrates the absolute irreversibility leads to the fundamental lower bound on the entropy production. We demonstrate the validity of the obtained equality for a simple model. [Preview Abstract] |
Tuesday, March 3, 2015 10:36AM - 10:48AM |
F45.00012: Work Relations Connecting Nonequilibrium Steady States Without Detailed Balance Ying Tang, Ruoshi Yuan, Ping Ao Bridging equilibrium and nonequilibrium statistical physics attracts sustained interest. Hallmarks of nonequilibrium systems include a breakdown of detailed balance, and an absence of a priori potential function corresponding to the Boltzmann-Gibbs distribution, without which classical equilibrium thermodynamical quantities could not be defined. Here, we construct dynamically the potential function through decomposing the system into a dissipative part and a conservative part. We then develop a nonequilibrium theory by defining thermodynamical quantities based on the potential function. We elucidate this procedure explicitly in a class of time-dependent linear diffusive systems without mathematical ambiguity. We also obtain the exact work distribution, and generalized work relations for the calculation of free energy difference between nonequilibrium steady states. Our results demonstrate that concepts for equilibrium can be naturally extended to nonequilibrium steady state, which provides a platform to study thermodynamics of systems without detailed balance. [Preview Abstract] |
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