Stable and charge-switchable quantum batteries

TL;DR

This paper introduces a scalable quantum battery design utilizing an energy current observable, enabling indefinite energy retention and stable discharge through eigenstate trapping and adiabatic evolution.

Contribution

It proposes a novel energy current operator-based framework for quantum batteries, enabling control over energy retention and stable discharge mechanisms.

Findings

Energy current operator effectively describes energy transfer in quantum batteries.

Eigenstate trapping allows indefinite energy retention.

Adiabatic evolution achieves asymptotically stable discharge.

Abstract

A fully operational loss-free quantum battery requires an inherent control over the energy transfer process, with the ability of keeping the energy retained with no leakage. Moreover, it also requires a stable discharge mechanism, which entails that no energy revivals occur as the device starts its energy distribution. Here, we provide a scalable solution for both requirements. To this aim, we propose a general design for a quantum battery based on an {\it{energy current}} (EC) observable quantifying the energy transfer rate to a consumption hub. More specifically, we introduce an instantaneous EC operator describing the energy transfer process driven by an arbitrary interaction Hamiltonian. The EC observable is shown to be the root for two main applications: (i) a trapping energy mechanism based on a common eigenstate between the EC operator and the interaction Hamiltonian, in which the battery can indefinitely retain its energy even if it is coupled to the consumption hub; (ii) an asymptotically stable discharge mechanism, which is achieved through an adiabatic evolution eventually yielding vanishing EC. These two independent but complementary applications are illustrated in quantum spin chains, where the trapping energy control is realized through Bell pairwise entanglement and the stability arises as a general consequence of the adiabatic spin dynamics.