Liouvillian spectral control for fast charging of quantum batteries

TL;DR

This paper demonstrates that controlling the spectral gap of the Liouvillian operator in open quantum systems can significantly accelerate the charging process of quantum batteries, enabling faster energy storage.

Contribution

It introduces a method to enhance quantum battery charging speed by tuning the Liouvillian spectrum, especially near exceptional points, without requiring many-body effects.

Findings

Liouvillian spectral gap determines charging timescale.

Approaching an exceptional point increases spectral gap and speeds up charging.

Engineered reservoirs enable fast charging in a trapped ion quantum battery.

Abstract

Quantum batteries, which use quantum systems to store and deliver energy, are promising for next-generation energy storage. However, optimizing charging strategies and understanding the interplay between dissipation and quantum coherence remain open challenges. Here, we investigate steady-state charging in an open quantum battery and demonstrate that the charging timescale depends on the spectral gap of the Liouvillian operator governing dissipative dynamics. As a minimal example, we examine a three-level quantum battery realized in a single trapped ${}^{40}\mathrm{Ca}^{+}$ ion, where energy from an engineered thermal photon reservoir is coherently transferred to a long-lived metastable storage state. We find that long-term dynamics are confined to a low-dimensional manifold of slow Liouvillian modes, with their spectral structure determining the relaxation rate to the charged steady state. By adjusting experimentally accessible parameters, such as reservoir occupation and coherent coupling strength, the non-Hermitian Liouvillian spectrum can approach an exceptional point. This increases the spectral gap and accelerates the approach to steady state. As a result, this mechanism significantly enhances asymptotic charging power without relying on many-body collectivity or steady coherence. Our findings offer fundamental insights into open quantum thermodynamics and provide a path to efficient energy storage and fast-charging solutions in emerging quantum technologies.