Trade-off relations and enhancement protocol of quantum battery capacities in multipartite systems

TL;DR

This paper explores the fundamental trade-off relations of quantum battery capacities in multipartite systems, introduces an enhancement protocol using incoherent operations, and validates these concepts through numerical examples and theoretical analysis.

Contribution

It establishes capacity trade-off relations for two- and three-qubit systems and proposes a protocol for capacity enhancement via incoherent unitaries, advancing quantum battery theory.

Findings

Capacity sum is governed by total system capacity across various Hamiltonians.

A protocol for capacity enhancement using incoherent unitaries is validated numerically.

Minimum time for capacity enhancement via a single incoherent operation is determined.

Abstract

First, we investigate the trade-off relations of quantum battery capacities in two-qubit system. We find that the sum of subsystem battery capacity is governed by the total system capacity, with this trade-off relation persisting for a class of Hamiltonians, including Ising, XX, XXZ and XXX models. Then building on this relation, we define residual battery capacity for general quantum states and establish coherent/incoherent components of subsystem battery capacity. Furthermore, we introduce the protocol to guide the selection of appropriate incoherent unitary operations for enhancing subsystem battery capacity in specific scenarios, along with a sufficient condition for achieving subsystem capacity gain through unitary operation. Numerical examples validate the feasibility of the incoherent operation protocol. Additionally, for the three-qubit system, we also established a set of theories and results parallel to those for two-qubit case. Finally, we determine the minimum time required to enhance subsystem battery capacity via a single incoherent operation in our protocol. Our findings contribute to the development of quantum battery theory and quantum energy storage systems.