Collective Quantum Battery vs Parallel Charging: A Comparative Simulation Study of the Dicke Model

Quantum batteries aim to exploit collective and coherent quantum effects to enhance energy storage and charging performance. In this context, the Dicke model provides a paradigmatic platform in which an ensemble of two-level systems interacts collectively with a single cavity mode, potentially enabling superlinear scaling of the charging power. Here, we present a controlled numerical comparison between a collective Dicke quantum battery and a parallel, non-collective benchmark composed of independent two-level systems charged by separate cavity modes. By simulating the open-system dynamics using Lindblad master equations, we analyze the stored energy, optimal charging time, and average charging power as functions of the system size. We identify a clear crossover from superlinear to linear scaling of the charging power controlled by dissipation: collective advantages persist only when coherent light--matter coupling dominates over losses, approximately when $g \gtrsim \kappa + \gamma$. These results delineate the operational regimes in which collective quantum batteries can outperform non-collective architectures and clarify the limitations imposed by environmental decoherence.