Quantum speed-up in collisional battery charging

TL;DR

This paper demonstrates that quantum coherence in collisional models enables faster and more efficient charging of quantum batteries, surpassing classical strategies by exploiting quantum interference effects.

Contribution

It introduces a collision model showing quantum coherence leads to a quantum speed-up in battery charging, outperforming incoherent methods.

Findings

Quantum coherence enhances charging speed.

Coherent protocols outperform incoherent strategies.

Faster energy distribution spreading due to quantum effects.

Abstract

We present a collision model for the charging of a quantum battery by identical nonequilibrium qubit units. When the units are prepared in a mixture of energy eigenstates, the energy gain in the battery can be described by a classical random walk, where both average energy and variance grow linearly with time. Conversely, when the qubits contain quantum coherence, interference effects buildup in the battery and lead to a faster spreading of the energy distribution, reminiscent of a quantum random walk. This can be exploited for faster and more efficient charging of a battery initialized in the ground state. Specifically, we show that coherent protocols can yield higher charging power than any possible incoherent strategy, demonstrating a quantum speed-up at the level of a single battery. Finally, we characterize the amount of extractable work from the battery through the notion of ergotropy.