Ancilla-assisted measurement of quantum work

TL;DR

This paper reviews methods using external auxiliary detectors to measure quantum work distributions, unifying different schemes and exploring the effects of quantum coherences, with discussions on physical implementations.

Contribution

It introduces a unified framework for quantum work measurement schemes and analyzes their ability to assess work fluctuations and quantum coherences.

Findings

Unified framework for work measurement schemes

Protocols yielding complementary information on quantum work

Discussion of physical implementations and experimental realizations

Abstract

We review the use of an external auxiliary detector for measuring the full distribution of the work performed on or extracted from a quantum system during a unitary thermodynamic process. We first illustrate two paradigmatic schemes that allow one to measure the work distribution: a Ramsey technique to measure the characteristic function and a positive operator valued measure (POVM) scheme to directly measure the work probability distribution. Then, we show that these two ideas can be understood in a unified framework for assessing work fluctuations through a generic quantum detector and describe two protocols that are able to yield complementary information. This allows us also to highlight how quantum work is affected by the presence of coherences in the system's initial state. Finally, we describe physical implementations and experimental realisations of the first two schemes.