Thermodynamics of quantum information scrambling

TL;DR

This paper introduces a thermodynamic approach to measure quantum information scrambling via out-of-time-order correlators (OTOCs), linking quantum chaos to non-equilibrium thermodynamics and providing a versatile experimental method.

Contribution

It presents a novel thermodynamic measurement scheme for OTOCs that is broadly applicable and offers a clear interpretation of quantum scrambling through thermodynamic fluctuations.

Findings

The scheme can measure OTOCs more broadly than existing methods.

Numerical simulations on a spin chain illustrate differences between integrable and ergodic systems.

Connections to recent experimental efforts are discussed.

Abstract

Scrambling of quantum information can be conveniently quantified by so called out-of-time-order-correlators (OTOCs), whose measurements presents a formidable experimental challenge. Here we report on a method for the measurement of OTOCs based on the so-called two-point measurements scheme developed in the field of non-equilibrium quantum thermodynamics. The scheme is of broader applicability than methods employed in current experiments and also provides a clear-cut interpretation of quantum information scrambling in terms of non-equilibrium fluctuations of thermodynamic quantities such as work. Furthermore, we provide a numerical example on a spin chain which highlights the utility of our thermodynamic approach when understanding the differences between integrable and ergodic behavior. We also discuss connections to some recent experiments.