Cavity magnomechanical framework for a high-efficiency quantum battery

TL;DR

This work models a hybrid cavity magnomechanical system as a quantum battery charged by two identical two-level atoms, analyzed under the rotating-wave approximation with a Lindblad-type dissipation description. The authors derive an effective interaction Hamiltonian coupling the cavity, magnons, and phonons, then track coherence, stored energy, and ergotropy in the single-excitation subspace. They show that strong, resonant coupling and balanced interactions maximize both stored energy and extractable work, while detuning and decoherence erode coherence and reduce performance, with ergotropy decaying faster than total energy due to loss of quantum coherence. The results offer a design roadmap for high-efficiency quantum energy storage in hybrid magnonic platforms and highlight the central role of coherence preservation in practical QB operation.

Abstract

We theoretically investigate a quantum battery architecture where two identical two-level atoms are charged by a cavity-magnomechanical system, which includes a microwave cavity, a magnon mode hosted in a YIG sphere, and phonon mode due to the deformation of the YIG sphere. The charging process relies on coherent energy exchange, where the atoms couple to the cavity, which in turn, it interacts with the magnon mode via a beam-splitter mechanism. By deriving the system Hamiltonian under the rotating-wave approximation and employing a Lindblad master equation to rigorously model dissipation, we analyze the complete dynamical evolution of the battery. Our study demonstrates that strong, resonant light-matter interactions are crucial for enhancing the key performance metrics: charging efficiency, stored energy, and ergotropy (extractable work). We systematically investigate the deleterious effects of detuning and decoherence, and critically, we uncover a non-trivial interplay between the system's coupling strengths. This reveals optimal operating regimes where constructive interference maximizes performance, while excessive coupling in specific channels can degrade it. Ultimately, our findings provide a quantitative framework for engineering high-efficiency quantum batteries in hybrid magnonic platforms, offering a design roadmap for future experimental realizations.

Figures (7)

• Figure 1: Schematic of a hybrid cavity magnomechanical quantum battery where two identical two-level atoms (frequency $\omega_q$) are coupled to the microwave cavity mode. Energy transfer and storage are mediated by cavity--magnon coupling $g_a$, phonon--magnon coupling $g_b$, and atom--cavity interaction $\lambda$, with respective decay rates $\kappa_{a,b,m}$ and $\gamma$.
• Figure 2: Coherence dynamics $C(t)$ of the charger as a function of time $t$. (a) $\delta_i = 1$ for $i = 1, 2, 3$, $g_a = g_b = 1$, $\kappa_a = \kappa_b = \kappa_m = \gamma = 0$, with varying $\lambda$. (b) $\delta_2 = \delta_3 = 1$, $g_a = g_b = 1$, $\kappa_a = \kappa_b = \kappa_m = \gamma = 0$, with varying $\delta_1$. (c) $\delta_1 = \delta_3 = 1$, $g_a = g_b = 1$, $\kappa_a = \kappa_b = \kappa_m = \gamma = 0$, with varying $\delta_2$. (d) $\delta_1 = \delta_2 = 1$, $g_a = g_b = 1$, $\kappa_a = \kappa_b = \kappa_m = \gamma = 0$, with varying $\delta_3$. (e) $\delta_i = 1$ for $i = 1, 2, 3$, $g_b = 1$, $\kappa_a = \kappa_b = \kappa_m = \gamma = 0$, with varying $g_a$. (f) $\delta_i = 1$ for $i = 1, 2, 3$, $g_a = 1$, $\kappa_a = \kappa_b = \kappa_m = \gamma = 0$, with varying $g_b$. (g) $\delta_i = 1$ for $i = 1, 2, 3$, $g_a = g_b = 1$, $\kappa_a = \kappa_b = \kappa_m = 0$, with varying $\gamma$. (h) $\delta_i = 1$ for $i = 1, 2, 3$, $g_a = g_b = 1$, with varying $\kappa_a, \kappa_b, \kappa_m$.
• Figure 3: Energy dynamics $E(t)$ as a function of time $t$ for the same parameters as given in Figure \ref{['f1']}
• Figure 4: Ergotropy dynamics $\epsilon(t)$ as a function of time $t$ for the same parameters as shown in Figure \ref{['f1']}
• Figure 5: Contour plots of the maximum ergotropy as functions of the coupling parameters. We set $\delta_i = 1$ for $i = 1,2,3$, and $\kappa_a = \kappa_b = \kappa_m = \gamma = 0$. (a) $g_a$ versus $g_b$ with $\lambda = 1$. (b) $g_a$ versus $\lambda$ with $g_b = 1$. (c) $\lambda$ versus $g_b$ with $g_a = 1$.