Collective dynamics versus entanglement in quantum battery performance

Abstract

Identifying the origin of enhanced charging performance in many-body quantum batteries remains a central challenge in quantum thermodynamics. It is unclear whether improvements in stored energy and instantaneous charging power stem from genuinely quantum correlations, such as entanglement, or from coherent collective dynamics, in which energy is transferred through the battery by many particles acting together in a coordinated, phase-preserving manner. Here, we address this question by comparing the time evolution of energy and a hierarchy of entanglement measures probing bipartite, tripartite, and multipartite correlations. Across diverse battery charger configurations, the instantaneous power peaks early, before significant entanglement develops, indicating that peak charging is dominated by coherent collective transport. Further analysis of k-local interactions under fair constraints shows that only fully collective schemes (k = N ) engage all particles, aligning entanglement growth with energy storage and yielding a genuine enhancement. Partially extended interactions leave many particles inactive and fail to improve performance. Our analysis indicates that the charging advantage arises not from entanglement alone, but from correlations that coherently involve the entire system.