Higher-order topological quantum battery

arXiv:2611.07401v1 Announce Type: new Abstract: A quantum battery is a next-generation energy-storage device that exploits genuinely quantum properties such as superposition and coherence. We propose a second-order topological quantum battery coupled to a photonic crystal described by the breathing-Kagome model, where optical loss is present on all lattice sites while nonlinear gains are introduced selectively at the output sites. Under these realistic non-Hermitian conditions, the system exhibits a clear topological phase transition manifested in both the ergotropy and the charging power. Remarkably, perfect work extraction is realized in the topological phase, where the maximum value of the ergotropy is quantized and acts as a good topological-phase indicator.