Easy access to energy fluctuations in non-equilibrium quantum many-body systems

TL;DR

This paper introduces a method combining theory and experiment to measure energy fluctuations in non-equilibrium quantum many-body systems, using simple end-of-protocol measurements to recover transition probabilities and verify fluctuation theorems.

Contribution

It presents a novel approach to extract transition probabilities from local measurements in many-body quantum systems out-of-equilibrium.

Findings

Successful experimental verification of the detailed fluctuation theorem.

Recovery of transition probabilities using only local measurements.

Implementation demonstrated on a two-spin nuclear magnetic resonance system.

Abstract

We combine theoretical and experimental efforts to propose a method for studying energy fluctuations, in particular, to obtain the related bi-stochastic matrix of transition probabilities by means of simple measurements at the end of a protocol that drives a many-body quantum system out-of-equilibrium. This scheme is integrated with numerical optimizations in order to ensure a proper analysis of the experimental data, leading to physical probabilities. The method is experimentally evaluated employing a two interacting spin-1/2 system in a nuclear magnetic resonance setup. We show how to recover the transition probabilities using only local measures which enables an experimental verification of the detailed fluctuation theorem in a many-body system driven out-of-equilibrium.