Non-equilibrium thermodynamics in a single-molecule quantum system

TL;DR

This paper develops a non-equilibrium thermodynamic analysis method for nanoscale quantum systems, enabling entropy measurement far from equilibrium, applicable to various single-electron devices, and demonstrates its use on a single-molecule device.

Contribution

It introduces a stochastic thermodynamics-based entropy measurement protocol for non-equilibrium conditions in single-electron devices, expanding beyond previous equilibrium-restricted methods.

Findings

Successfully measures entropy differences in a single-molecule device.

Applies the method to a two-site Hubbard model system.

Identifies selection rules governing electron transfers.

Abstract

Thermodynamic probes can be used to deduce microscopic internal dynamics of nanoscale quantum systems. Several direct entropy measurement protocols based on charge transport measurements have been proposed and experimentally applied to single-electron devices. To date, these methods have relied on (quasi-)equilibrium conditions between the nanoscale quantum system and its environment, which constitutes only a small subset of the experimental conditions available. In this paper, we establish a thermodynamic analysis method based on stochastic thermodynamics, that is valid far from equilibrium conditions, is applicable to a broad range of single-electron devices and allows us to find the difference in entropy between the charge states of the nanodevice, as well as a characteristic of any selection rules governing electron transfers. We apply this non-equilibrium entropy measurement protocol to a single-molecule device in which the internal dynamics can be described by a two-site Hubbard model.