System versus charger in performance optimization of quantum batteries

Abstract

Quantum batteries have emerged as promising devices that work within the quantum regime and provide energy storage and power delivery. In this work, we explore the interplay between the battery and charger Hamiltonians, focusing on controlling and minimizing the batterys intrinsic influence during the charging process. To this end, we introduce a tunable parameter that allows partial suppression of the batterys contribution, enabling a systematic study of its role in energy transfer. We examine several charging configurations: a non-interacting qubit battery driven by an interacting many-body charger, an interacting qubit battery energized by a non-interacting charger, and setups in which both the battery and the charger are interacting qubit chains. In all cases, the inclusion of a controllable counteraction, or anti-effect of the battery Hamiltonian, allows us to modulate the batterys internal dynamics during charging. Our results demonstrate a significant enhancement in both stored energy and charging power when the batterys influence is suppressed, emphasizing the critical role of the charger in optimizing performance. Notably, we find that incorporating the batterys countereffect consistently improves storage characteristics across all configurations, suggesting a novel avenue for designing highly efficient quantum batteries.

Figures (7)

• Figure 1: Illustration of an all-to-all interaction among spins, where every spin is coupled to all the others simultaneously. Such a configuration highlights the collective nature of spin dynamics compared to local or nearest-neighbor interactions.
• Figure 2: Non-interacting battery charged by an ATA interacting Ising spin system. (a) Stored energy $\Delta E$ and (b) charging power $P$ as functions of time $t$ for different values of the countereffect strength $\lambda$, with system size fixed at $N = 10$. (c$_1$) and (c$_2$) show the time evolution of the stored energy $\Delta E$ for systems with odd and even numbers of spins $N$, respectively, with the countereffect strength fixed at $\lambda = 1$. (d) Charging power $P$ as a function of time $t$ for different system sizes $N$. All simulations are performed with interaction strength $J = 1$, external field $h = 1$, and periodic boundary conditions.
• Figure 3: (a) Maximum stored energy and (b) maximum power as functions of the battery’s countereffect strength $\lambda$ for a non-interacting battery charged by four types of chargers: Ising ATA, Ising NN, XY ATA, and XY NN, with system size $N = 10$. (c) Maximum stored energy and (d) maximum power as functions of system size $N$ for the same four charger types, with the countereffect strength fixed at $\lambda = 1$. The parameters are $J = 1$, $h = 1$, and $\gamma = 0.5$.
• Figure 4: (a) Stored energy $\Delta E$ and (b) charging power $P$ as functions of time $t$ for a battery described by a NN Ising Hamiltonian with a non-interacting charger. (c) Stored energy $\Delta E$ and (d) charging power $P$ for a battery described by a NN XY Hamiltonian with the same non-interacting charger. The system parameters are $N = 12$, $J = 1$, $h = 1$, and $\gamma = 0.5$, with periodic boundary conditions.
• Figure 5: Storage energy $\Delta E$ and power $P$ of the NN Ising spin system as a quantum battery, with non-interacting spins as the charger, shown as a function of time for different interaction strengths $J$ (fixing $\lambda=0$). The inset shows the maximum storage energy and power as $J$ is varied. The maximum power scales approximately logarithmically with interaction strengh , following $P_{\rm max} \approx 17.91 \log_{10}(J) + 16.86$.