Quantum Speed-Up in Collisional Battery Charging

We present a collision model for the charging of quantum battery by identical nonequilibrium qubit units. When units are prepared in mixture energy eigenstates, gain can be described classical random walk, where both average and variance grow linearly with time. Conversely, when qubits contain coherence, interference effects buildup lead to faster spreading distribution, reminiscent walk. This exploited more efficient initialized ground state. Specifically, we show that coherent protocols yield higher power than any possible incoherent strategy, demonstrating speed-up at level single battery. Finally, characterize amount extractable work from through notion ergotropy.