Work extraction from a quantum battery charged through an array of coupled cavities

TL;DR

This paper explores how to optimize work extraction from a quantum battery charged via a coupled cavity array, showing that engineered interactions and initial states can enhance performance even at large scales.

Contribution

It introduces methods to maintain nonzero ergotropy in quantum batteries charged through coupled cavities by engineering initial states and coupling profiles.

Findings

Ergotropy decreases with line length but can be preserved through initial state engineering.

Entangled initial states improve work extraction in the charging line.

Spatially engineered coupling profiles restore high ergotropy values.

Abstract

We investigate the problem of work extraction from a cavity-based quantum battery that is remotely charged via a transmission line composed of an array of coupled single-mode cavities. For uniform coupling along the line, we show that the ergotropy of the battery, evaluated at the point of maximum power transfer, decreases with the length of the charging line and vanishes beyond a critical size. By carefully engineering the initial state of the charger, nonzero ergotropy can still be harvested even beyond this critical length. We further examine scenarios in which the charging line is initialized in an entangled state, as well as configurations with nonuniform, parabolically varying coupling strengths. In the latter case, we demonstrate that high ergotropy values can be restored, highlighting the potential of spatially engineered interactions to enhance quantum battery performance.