Coherence-Driven Quantum Battery Charging via Autonomous Thermal Machines: Energy Transfer, Memory Effects, and Ergotropy Enhancement

TL;DR

This work investigates coherence-driven charging of a quantum battery mediated by a two-qubit autonomous quantum thermal machine (QATM) coupled to two Markovian reservoirs at different temperatures. By applying a coherent drive to the charger and tuning the QATM–charger and charger–battery couplings, the study reveals that the QATM filters decoherence and generates non-Markovian memory via correlation backflow, while coherence driving substantially increases the battery’s ergotropy (by ~40%) and preserves the charger's energy to boost charging power. The analysis uses a structured bath description with a virtual temperature and a Born-Markov master equation featuring an on/off reservoir interaction to quantify information backflow and mutual information among subsystems. Coherence transfer and energy exchange between charger and battery are enhanced by non-Markovian dynamics, and strong charger–battery coupling further amplifies memory effects, leading to higher power and extractable work. The results are argued to be experimentally feasible in superconducting-qubit platforms, offering a pathway to more efficient quantum energy storage with controllable memory effects.

Abstract

In this work, we study a hybrid quantum system composed of a quantum battery and a coherence-driven charger interacting with a Quantum Autonomous Thermal Machine (QATM). The QATM, made of two qubits, each coupled to Markovian bosonic thermal reservoirs at different temperatures, acts as a structured environment that mediates energy and coherence between the charger and the battery. By applying a coherent driving field on the charger, we investigate the coherence injection effect on the dynamics, including non-Markovianity, power of charging, coherence storage, and ergotropy. We show that the QATM filters the decoherence induced by the thermal baths and induces non-Markovian memory effects due to correlation backflow. Our results demonstrate that coherence driving enhances the battery's ergotropy; coherence driving raises the maximum ergotropy by approximately 40% compared to the case without coherence driving, and the power of charging by preserving the internal energy of the charger.

Figures (8)

• Figure 1: Diagram of a QATM, namely $M_{12}=M_1\otimes M_2$ coupled to a quantum charger (C). The coherence driving is represented by a laser (F) which is coupled directly to (C), where $f$ is the field amplitude. Besides, (B) is the quantum battery coupled to the charger $C$, where $R_1$ and $R_2$ are the cold and hot bosonic reservoirs, respectively. Note that $g$ and $k$ are the coupling strengths between QATM-charger and battery-charger, respectively.
• Figure 2: Plots of the trace distance derivative over time $\sigma_{B}(t)$, $\sigma_{C}(t)$, and $\sigma_{M_{12}}(t)$ of the quantum battery (B), quantum charger (C), and the QATM $M_{12}$, respectively, where $g = 0.01\omega_{M_2}$, $0.03\omega_{M_2}$, $0.06\omega_{M_2}$, and $0.09\omega_{M_2}$ ('red, dotted line), (black, dashed line), (blue, dashed-dotted line), and (magenta, solid line), respectively. Figs (\ref{['NM_without_field']}) and (\ref{['NM_with_field']}) represent the cases of $f = 0$ and $f =0.1 \omega_{C}$. For $\sigma_{n}(t) > 0$ (yellow region), the subsystem $n = \{M_{12}, C, B\}$ loses information to its environment. If $\sigma_{n}(t) < 0$ (purple region), it gains information from the environment.
• Figure 3: Plots of the conventional mutual information over time, $I_{CB}(t)$ between the charger (C) and the battery (B), and $I_{M_{12}CB}(t)$ between the set of charger-battery (CB) and the QATM ($M_{12}$). For the line styles corresponding to $g = 0.01\omega_{M_2}$, $0.03\omega_{M_2}$, $0.06\omega_{M_2}$, and $0.09\omega_{M_2}$, we use the same convention as in Figure \ref{['NM']}. Figures (\ref{['MI_without_field']}) and (\ref{['MI_with_field']}) represent the cases of $f = 0$ and $f = 0.1\omega_{C}$, respectively.
• Figure 4: Plots of the normalized internal energies over time, $\frac{\Delta E_C(t)}{\omega_C}$, $\frac{\Delta E_B(t)}{\omega_B}$, and $\Delta E_{M_{12}}(t)$, of the quantum charger (C), quantum battery (B), and the QATM $M_{12}$, respectively. For the line styles corresponding to $g = 0.01\omega_{M_2}$, $0.03\omega_{M_2}$, $0.06\omega_{M_2}$, and $0.09\omega_{M_2}$, we use the same convention as in Figure \ref{['NM']}. Figure \ref{['En_witout_field']} represents the case of $f = 0$, while Figure \ref{['En_with_field']} represents the case of $f = 0.1\omega_{C}$.
• Figure 5: The density plot of the normalized power of charging for the quantum battery (B) over time and the coupling $g$, given by $\frac{\Delta P_{B}(t)}{\omega_{B}}$. Figure \ref{['po_witout_field']} represents the case of $f = 0$, while Figure \ref{['po_with_field']} represents the case of $f =0.1 \omega_{C}$. Here $g$ in unit of ($\omega_{M_2}/10$).