Extractable work, the role of correlations, and asymptotic freedom in quantum batteries

TL;DR

This paper studies quantum batteries made of two-level systems charged by an optical mode, analyzing how correlations affect extractable energy and showing that coherence can mitigate this effect, with correlations vanishing as system size grows.

Contribution

It demonstrates the impact of correlations on extractable energy in quantum batteries and shows how coherence preparation mitigates this, proving asymptotic freedom of correlations.

Findings

Correlations reduce the fraction of extractable energy.

Coherent optical states mitigate correlation effects.

Correlations vanish as the number of systems approaches infinity.

Abstract

We investigate a quantum battery made of N two-level systems, which is charged by an optical mode via an energy-conserving interaction. We quantify the fraction E(N) of energy stored in the B battery that can be extracted in order to perform thermodynamic work. We first demonstrate that E(N) is highly reduced by the presence of correlations between the charger and the battery or B between the two-level systems composing the battery. We then show that the correlation-induced suppression of extractable energy, however, can be mitigated by preparing the charger in a coherent optical state. We conclude by proving that the charger-battery system is asymptotically free of such locking correlations in the N \to \infty limit.