Time  Speaker  Title  Resources  

13:30 to 15:30  David Lacoste (ESPCI, Paris, France)  Session Chair  
13:31 to 14:10  J. M. R. Parrondo (Universidad Complutense de Madrid, Spain) 
The Irreversibility Problem Revisited: Objectivity and Gaint Fluctuations Boltzmann’s explanation of irreversibility is based on the concept of macrostates and the definition of entropy as the logarithm of the volume in phase space of the region of microstates compatible with a given macrostate. The explanation, however, lacks an objective (i.e. non arbitrary) definition of macrostates and of the crossover between micro and macroscales. Here we show that this problem can be solved by reformulating Boltzmann’s explanation in terms of observables relaxing from giant fluctuations. We show that the irreversible behavior of an observable is a fully objective property and has nothing to do with its micro or macroscopic nature. In fact, we will show a situation where a system exhibits irreversibility at the microscale and reversibility at the macroscale. In the second part of the talk, we propose a mechanism for creating giant fluctuations of an observable (hence, irreversibility) based on metastable states induced by symmetry breaking. 

14:10 to 14:50  R. Marathe (Indian Institute of Technology, Delhi, India) 
Simple models of Active Brownian Heat engines (Passive) Brownian heat engines are popular systems where a single microscopic particle is confined with the help of an optical trap and cycled through a time dependent protocol and kept in contact with two heat baths of different temperatures alternately, to mimic the macroscopic engine cycles like Carnot or Stirling. Due to the minute size of the system the fluctuations dominate. Recently it has been observed that presence of so called Active entities like Bacteria or Janus particles in the heat bath may drastically alter the thermodynamic properties, especially the efficiency of the engine, when compared with their passive counterparts. These are termed as Active Brownian Heat engines. I will discuss a few simple models of active heat engines that we have developed recently. I will also discuss a few general results that allow us to map such active, nonequilibrium system to an effective equilibrium system in the quasistatic limit of the cycle time. Ref: 1) https://iopscience.iop.org/article/10.1088/17425468/aae84a/meta 

14:50 to 15:30  S. Sabhapandit (RRI, Bangalore, India) 
Entropy production for partially observed systems The probability distribution of the total entropy production in the non equilibrium steady state follows a symmetry relation called the fluctuation theorem. When a certain part of the system is masked or hidden, it is difficult to infer the exact estimate of the total entropy production. Entropy produced from the observed part of the system shows significant deviation from the steadystate fluctuation theorem. This deviation occurs due to the interaction between the observed and the masked part of the system. A naive guess would be that the deviation from the steady state fluctuation theorem may disappear in the limit of small interaction between both parts of the system. 

17:09 to 17:50  J M R Parrondo (Universidad de Madrid, Spain)  Session Chair  
17:10 to 17:50  E. Barkai (BarIlan University, Israel) 
NonNormalized BoltzmannGibbs Statistics Fermi pointed out that the Hydrogen atom in a thermal setting is unstable, as the canonical partition function of this simple system diverges. We show how a nonnormalised Boltzmann Gibbs measure can still yield statistical averages and thermodynamic properties of physical observables, exploiting a model of Langevin dynamics of a Brownian particle in an asymptotically flat potential [1]. The ergodic theory of such systems is known in mathematics as infinite (nonnormalisable) ergodic theory, time permitting we will discuss these isssues in the context of a gas of laser cooled atoms [2]. References: [1] E. Aghion, D. A. Kessler, and E. Barkai From Nonnormalizable BoltzmannGibbs statistics to infiniteergodic theory Phys. Rev. Lett. 122, 010601 (2019). [2] E. Barkai, G. Radons, and T. Akimoto Transitions in the ergodicity of subrecoillasercooled gases Phys. Rev. Lett. 127, 140605 (2021). 
Time  Speaker  Title  Resources  

13:30 to 15:30  Sanjib Sabhapandit (RRI, Bengaluru, India)  Session Chair  
13:31 to 14:10  S. Pigolotti (Okinawa Institute of Science and Technology, Japan) 
Dynamics of bacterial replisomes and stochastic resetting Replisomes are multiprotein complexes that replicate genomes with remarkable speed and accuracy. Despite their importance, their dynamics is poorly characterized, especially in vivo. We introduce a theory to infer the stochastic dynamics of replisomes from the DNA abundance observed in a growing bacterial population. We show, in particular, how this dynamics can be mapped into a twodimensional stochastic process subject to stochastic resetting. To apply our theory, we present experiments with E.coli bacteria growing at different temperatures. Our theory reveals that replisome speed presents regular oscillations along the genome and is characterized by a small diffusion constant. We conclude with a discussion of the possible causes and consequences of this finding, and possible extensions of our theory. Reference: https://www.biorxiv.org/content/10.1101/2021.10.15.464478v1


14:10 to 14:50  M. Cates (University of Cambridge, Cambridgeshire, UK) 
Large deviations of the entropy production in active matter The entropy production, defined either microscopically or informatically at coarsegrained scale, is a key measure of irreversibility in active systems. This talk will address the large deviations of the entropy production: in a given system what is the probability of this being much larger or smaller than usual for a prolonged period, and what is the likeliest way for this to happen? Studying the full probability distribution for entropy production in this way reveals various nonequilibrium phase transitions, including some into symmetrybroken phases that are absent for dynamically typical states. These transitions point to design principles for active matter. Such studies are typically numerical, but for one wellchosen model (an active lattice gas) the nonequilibrium phase diagram can be calculated in its entirety, revealing unforeseen complexity. 

14:50 to 15:30  E. Roldan (Abdus Salam International Centre for Theoretical Physics (ICTP), Italy) 
Active Fluctuations in Bullfrogs Sacculus TBA 

16:30 to 18:30  Michael Cates (University of Cambridge, UK)  Session Chair  
16:31 to 17:10  T. Sagawa (University of Tokyo, Japan) 
Quantum Fluctuation Theorem with Continuous Measurement and Feedback While the fluctuation theorem in classical systems has been thoroughly generalized under various feedback control setups, the role of continuous measurement and feedback in the quantum regime has not yet been elucidated, despite its significance in quantum control. In this work, we derive the generalized fluctuation theorem with continuous measurement and feedback, by newly introducing the operationally meaningful quantum information, which we call quantumclassicaltransfer (QCtransfer) entropy. QCtransfer entropy can be naturally interpreted as the quantum counterpart of transfer entropy that is commonly used in classical time series analysis. We also verify our theoretical results by numerical simulation and propose an experimentnumerics hybrid verification method. Our work reveals a fundamental connection between quantum thermodynamics and quantum information, which can be experimentally tested with artificial quantum systems such as circuit quantum electrodynamics. 

17:10 to 17:50  S. Krishnamurthy (Stockholm University, Sweden) 
Finite and shorttime properties of current fluctuations in nonequilibrium systems Longtime results for current fluctuations are often obtained within the framework of large deviation theory. Finitetime results are harder to get however due to the prevalence of transient effects and correlations. In this talk, I will mention some of the known results for finite and short time current fluctuations, including some of our own. 

17:50 to 18:30  A. C. Barato (University of Houston (UH), Houston, USA) 
Cost of precise biochemical oscillations and second law for active heat engines I will then talk about two of our recent results. First, for biochemical oscillations, such as circadian rhythms, in stochastic systems, we have conjectured the universal minimal free energy cost of coherent oscillations. Second, active cyclic heat engines are heat engines with a working substance is in the presence of hidden dissipative degrees of freedom such as bacteria. In this case, the external bath is an active medium (or active matter). We have derived a generic second law for active heat engines, which has been a challenge since active heat engines have been introduced in an experiment in 2016. Study materials:

Time  Speaker  Title  Resources  

13:30 to 15:30  Abhishek Dhar (ICTS, Bengaluru, India)  Session Chair  
13:31 to 14:10  S. Still (University of Hawaii, Mānoa, USA)  Partially Observable Information Engines  
14:10 to 15:30    Session in memory of Prof. A. M. Jayannavar 