Characterizing Performance and Optimal Charging Strategies in a Three-Spin XXZ Quantum Battery

Quantum batteries are emerging as a promising platform for nanoscale energy storage, where quantum correlations and coherence can be harnessed to enhance efficiency and enable fast charging. In this presentation, I will discuss a minimal model consisting of a three-spin XXZ chain operating under open boundary conditions. We examine how the ground-state configuration—ferromagnetic versus antiferromagnetic, determined by the anisotropy parameter—affects the charging dynamics. Two charging mechanisms are investigated: static charging with a constant external field and harmonic charging with a periodically oscillating field. Our results show that static charging is optimal for ferromagnetic initial states, enabling complete population inversion and maximal stored energy, while harmonic driving proves advantageous for antiferromagnetic initial states by sustaining coherence and facilitating faster charging. By comparing stored energy, charging power, and coherence as figures of merit, we demonstrate how anisotropy and the choice of protocol jointly determine performance. These insights highlight strategies for tailoring charging schemes to initial conditions, offering guidelines for the design of efficient quantum energy storage devices.