Correlation Enhanced Autonomous Quantum Battery Charging via Structured Reservoirs

TL;DR

The paper addresses autonomous charging of a quantum battery coupled to a structured two-qubit reservoir, examining three interaction configurations to understand how coherence and correlations act as resources. It develops a theoretical framework with a local Markovian master equation and resonance-based interaction schemes, deriving bounds on extractable work via the free energy of coherence and correlation terms. The authors show that both global and local coherence, as well as total correlations, can enhance charging, and that the battery's stored energy decomposes into coherence and population contributions. They discuss two initial-state settings (incoherent and coherent) and provide numerical evidence in superconducting-qubit-relevant parameter regimes, highlighting autonomous operation without external work and offering guidance for experimental realization.

Abstract

In this work, we investigate the autonomous charging process of a quantum battery coupled to a structured reservoir composed of two qubits, each in thermal equilibrium with its own bosonic bath. Moreover, the reservoir interacts with a charger-battery architecture through three configurations: (I) direct coupling between reservoir qubits and battery, (II) collective coupling among the reservoir qubits, charger, and battery, while (III) reflects a collective coupling between the reservoir qubits and charger together with a local charger-battery interaction. However, by using incoherent and coherent initial states, we analyze the stored energy, ergotropy, and charging power of battery, where we derive the upper and lower bounds on the extractable work in terms of the free energy of coherence and correlations exchanged between subsystems. Our results show that global and local coherences, as well as total correlations act as quantum resources that enhance autonomous charging. Additionally, we demonstrate that the free energy stored in the quantum battery splits into contributions from coherence and correlations, providing numerical evidence that supports the derived ergotropy bounds. Importantly, this work highlights how structured reservoirs enable autonomous and resource-enhanced quantum battery operation.

Figures (4)

• Figure 1: Schematic representation of the three interaction scenarios between the structured reservoir qubits $S_{1}$ and $S_{2}$, charger $C$, and quantum battery $B$. (a) Scenario $I$: direct coupling between $S_{12}$ and $B$. (b) Scenario $II$: common coupling between $S_{12}-C-B$ system. (c) Scenario $III$: common coupling between $S_{12}-C$, together with a local interaction between $C-B$. Each reservoir qubit $S_{m}$ is in contact with its own bosonic thermal reservoir $R_{m}$$(m=1,2)$.
• Figure 2: Dynamics of ergotropy, energy, and charging power of the quantum battery versus time, namely $\frac{\mathcal{E}_B(t)}{\omega_{B}}$, $\frac{E_B(t)}{\omega_{B}}$, and $\frac{\mathcal{P}_B(t)}{\omega_{B}}$, respectively. Panels (a)--(c) correspond to scenarios ($I_a$, $II_a$, $III_a$), while panels (d)--(f) correspond to scenarios ($I_b$, $II_b$, $III_b$). Moreover, $g=0.03,\,0.05,\,0.07,$ and $0.09$ (in units of $\omega_{S_2}$) for red dotted, black dashed, blue dot--dashed and magenta solid curves, respectively.
• Figure 3: Dynamics of ergotropy of coherence as well as ergotropy of population of the quantum battery, respectively. Moreover, panels (a-c) correspond to scenarios ($I_a$, $II_a$, $III_a$), while panels (d-f) treat scenarios ($I_b$, $II_b$, $III_b$). However, we set $g=0.03,\,0.05,\,0.07,$ and $0.09$ (in units of $\omega_{S_2}$) for red, black, blue and magenta curves, respectively.
• Figure 4: Dynamics of ergotropy of coherence as well as ergotropy of population of the quantum battery, respectively. Moreover, panels (a-c) correspond to scenarios ($I_a$, $II_a$, $III_a$), while panels (d-f) treat scenarios ($I_b$, $II_b$, $III_b$). However, we set $g=0.03,\,0.05,\,0.07,$ and $0.09$ (in units of $\omega_{S_2}$) for red, black, blue and magenta curves, respectively.