Nonequilibrium entropy production for open quantum systems

We consider open quantum systems weakly coupled to a heat reservoir and driven by arbitrary time-dependent parameters. We derive exact microscopic expressions for the nonequilibrium entropy production and entropy production rate, valid arbitrarily far from equilibrium. By using the two-point energy measurement statistics for system and reservoir, we further obtain a quantum generalization of the integrated fluctuation theorem put forward by Seifert [PRL 95, 040602 (2005)].Comment: 4 pages, 1 figur

Holevo's bound from a general quantum fluctuation theorem

We give a novel derivation of Holevo's bound using an important result from nonequilibrium statistical physics, the fluctuation theorem. To do so we develop a general formalism of quantum fluctuation theorems for two-time measurements, which explicitly accounts for the back action of quantum measurements as well as possibly non-unitary time evolution. For a specific choice of observables this fluctuation theorem yields a measurement-dependent correction to the Holevo bound, leading to a tighter inequality. We conclude by analyzing equality conditions for the improved bound.Comment: 5 page

The second law and beyond in microscopic quantum setups

The Clausius inequality (CI) is one of the most versatile forms of the second law. Although it was originally conceived for macroscopic steam engines, it is also applicable to quantum single particle machines. Moreover, the CI is the main connecting thread between classical microscopic thermodynamics and nanoscopic quantum thermodynamics. In this chapter, we study three different approaches for obtaining the CI. Each approach shows different aspects of the CI. The goals of this chapter are: (i) To show the exact assumptions made in various derivations of the CI. (ii) To elucidate the structure of the second law and its origin. (iii) To discuss the possibilities each approach offers for finding additional second-law like inequalities. (iv) To pose challenges related to the second law in nanoscopic setups. In particular, we introduce and briefly discuss the notions of exotic heat machines (X machines), and "lazy demons".Comment: As a chapter of: F. Binder, L. A. Correa, C. Gogolin, J. Anders, and G. Adesso (eds.), "Thermodynamics in the quantum regime - Recent Progress and Outlook", (Springer International Publishing). v1 does not include references to other book chapter

Do the more flexible individuals rely more on causal cognition? Observation versus intervention in causal inference in great-tailed grackles

Behavioral flexibility, the ability to change behavior when circumstances change based on learning from previous experience, is thought to play an important role in a species’ ability to successfully adapt to new environments and expand its geographic range. However, it is possible that causal cognition, the ability to understand relationships beyond their statistical covariations, could play a significant role in rapid range expansions by allowing one to learn faster by making better predictions about outcomes and by exerting more control over events. We aim to determine whether great-tailed grackles (Quiscalus mexicanus), a species that is rapidly expanding its geographic range, use causal inference and whether this ability relates to their behavioral flexibility (flexibility measured in these individuals by Logan et al. 2019: reversal learning of a color discrimination and solution switching on a puzzle box). We found that grackles showed no evidence of making causal inferences when given the opportunity to intervene on observed events using a touchscreen apparatus, and that performance on the causal cognition task did not correlate with behavioral flexibility measures. This could indicate that causal cognition is not implicated as a key factor involved in a rapid geographic range expansion, though we suggest further exploration of this hypothesis using larger sample sizes and multiple test paradigms before considering this a robust conclusion

Shortcuts in Stochastic Systems and Control of Biophysical Processes

The biochemical reaction networks that regulate living systems are all stochastic to varying degrees. The resulting randomness affects biological outcomes at multiple scales, from the functional states of single proteins in a cell to the evolutionary trajectory of whole populations. Controlling how the distribution of these outcomes changes over time-via external interventions like time-varying concentrations of chemical species-is a complex challenge. In this work, we show how counterdiabatic (CD) driving, first developed to control quantum systems, provides a versatile tool for steering biological processes. We develop a practical graph-theoretic framework for CD driving in discrete-state continuous-time Markov networks. Though CD driving is limited to target trajectories that are instantaneous stationary states, we show how to generalize the approach to allow for nonstationary targets and local control-where only a subset of system states is targeted. The latter is particularly useful for biological implementations where there may be only a small number of available external control knobs, insufficient for global control. We derive simple graphical criteria for when local versus global control is possible. Finally, we illustrate the formalism with global control of a genetic regulatory switch and local control in chaperone-assisted protein folding. The derived control protocols in the chaperone system closely resemble natural control strategies seen in experimental measurements of heat shock response in yeast and E. coli

Are the more flexible great-tailed grackles also better at behavioral inhibition? (In principle acceptance by PCI Ecology of the version on 6 Mar 2019)

Behavioral flexibility should theoretically be positively related to behavioral inhibition (hereafter referred to as inhibition) because one should need to inhibit a previously learned behavior to change their behavior when the task changes (the flexibility component;). However, several investigations show no or mixed support of this hypothesis, which challenges the assumption that inhibition is involved in making flexible decisions. We aimed to test the hypothesis that behavioral flexibility (measured as reversal learning and solution switching on a multi-access box by Logan et al. 2019) is associated with inhibition by measuring both variables in the same individuals and three inhibition tests (a go/no go task on a touchscreen, a detour task, and a delay of gratification experiment). We set out to measure grackle inhibition to determine whether those individuals that are more flexible are also better at inhibition. Because touchscreen experiments had never been conducted in this species, we additionally validated that a touchscreen setup is functional for wild-caught grackles who learned to use the touchscreen and completed the go/no go inhibition task on it. Results showed that only performance on the go/no go inhibition task correlated with the two flexibility measures: positively with the number of trials to reverse a preference in the reversal learning experiment, and negatively with the average latency to attempt a new option on the multi-access box. That is, individuals who were faster to update their behavior in the reversal experiment were also faster to reach criterion in the go/no go task, but took more time to attempt a new option in the multi-access box experiment. Performance on the detour inhibition task did not correlate with either measure of flexibility, suggesting that detour performance and the flexibility experiments may measure separate traits. We were not able to run the delay of gratification experiment because the grackles never habituated to the apparatuses. Performance on the go/no go and detour inhibition tests did not correlate with each other, indicating that they did not measure the same trait. We conclude that behavioral flexibility is associated with certain types of inhibition, but not others, in great-tailed grackles

Quantum fluctuation theorems in the strong damping limit

We consider a driven quantum particle in the strong friction regime described by the quantum Smoluchowski equation. We derive Crooks and Jarzynski type relations for the reduced quantum system by properly generalizing the entropy production to take into account the non-Gibbsian character of the equilibrium distribution. In the case of a nonequilibrium steady state, we obtain a quantum version of the Hatano-Sasa relation. We, further, propose an experiment with driven Josephson junctions that would allow to investigate nonequilibrium entropy fluctuations in overdamped quantum systems.Comment: 6 pages, 2 figures, with simplified derivation and examples adde

Hierarchical Equations of Motion Approach to Quantum Thermodynamics

We present a theoretical framework to investigate quantum thermodynamic processes under non-Markovian system-bath interactions on the basis of the hierarchical equations of motion (HEOM) approach, which is convenient to carry out numerically "exact" calculations. This formalism is valuable because it can be used to treat not only strong system-bath coupling but also system-bath correlation or entanglement, which will be essential to characterize the heat transport between the system and quantum heat baths. Using this formalism, we demonstrated an importance of the thermodynamic effect from the tri-partite correlations (TPC) for a two-level heat transfer model and a three-level autonomous heat engine model under the conditions that the conventional quantum master equation approaches are failed. Our numerical calculations show that TPC contributions, which distinguish the heat current from the energy current, have to be take into account to satisfy the thermodynamic laws.Comment: 9 pages, 4 figures. As a chapter of: F. Binder, L. A. Correa, C. Gogolin, J. Anders, and G. Adesso (eds.), "Thermodynamics in the quantum regime - Recent Progress and Outlook", (Springer International Publishing