Quantum battery of interacting spins with environmental noise

A quantum battery is a temporary energy-storage system. We construct a quantum battery model of an $N$-spin chain with nearest-neighbor hopping interaction and investigate the quantum battery's charging process. We obtain the maximum energy in the quantum battery charged by a coherent cavity driving field or a thermal heat bath. We confirm that for a finite-length spin chain, thermal charging results in a nonzero ergotropy, contradicting a previous result: An incoherent heat source cannot charge a single-spin quantum battery. The nearest-neighbor hopping interaction induces energy-band splitting, enhancing the energy storage and the ergotropy of the quantum battery. We find a critical point in the energy and ergotropy resulting from the ground-state quantum phase transition after which the energy significantly enhances. Finally, we also find that disorder increases the energy of the quantum battery.