Abstract A quantum battery (QB) model composed of two atoms is studied, where the charger and battery elements are coupled to a multimode vacuum field that serves as the mediator for energy transfer. Different figures of merit such as ergotropy, charging time, and charging efficiency are analyzed, putting emphasis on the role of various control parameters on the charging performance. It is found that there is a range of angle between the transition dipole moments and interatomic axis in which the QB can be charged, and the optimal performance is achieved when the dipole moments are parallel to the interatomic axis. The charging performance also improves with the decrease of the interatomic distance. Besides, the ergotropy charged on the QB can be enhanced by enhancing the initial charger ergotropy and it is beneficial to charge the QB starting from its ground state.
Abstract A quantum battery (QB) model composed of two atoms is studied, where the charger and battery elements are coupled to a multimode vacuum field that serves as the mediator for energy transfer. Different figures of merit such as ergotropy, charging time, and charging efficiency are analyzed, putting emphasis on the role of various control parameters on the charging performance. It is found that there is a range of angle between the transition dipole moments and interatomic axis in which the QB can be charged, and the optimal performance is achieved when the dipole moments are parallel to the interatomic axis. The charging performance also improves with the decrease of the interatomic distance. Besides, the ergotropy charged on the QB can be enhanced by enhancing the initial charger ergotropy and it is beneficial to charge the QB starting from its ground state.
We explore the wireless charging of a quantum battery (QB) via n charging units, whose coupling is mediated by a common bosonic reservoir. We consider the general scenarios in which the charger energy is not maximal and the QB has residual ergotropy initially. It is found that the charging performance improves with the increase of the coupling strength. In the strong coupling regime, the charging time is insensitive to the charger energy, the number of charging units, and the residual ergotropy in the QB, while the ergotropy charged on the QB strongly depends on the charger energy and ergotropy, and the residual ergotropy in the QB does not help to enhance its performance. Moreover, the multiple charging units help to enhance the charging performance in the weak and moderate coupling regimes, while they are less efficient in the strong coupling regime.
Abstract A two‐mode micromaser quantum battery (QB) is investigated, where a quantized cavity field is charged by a stream of V‐type three‐level atoms. Within an open quantum systems framework, stored energy, ergotropy, charging power, and fluctuations are analyzed under different coherence conditions of the atomic charger. It is first showed that coherence between the two degenerate excited states of the charger enhances both the average stored energy and the amount of extractable work. Using the concept of global ergotropy, it is further demonstrated that correlations between the two cavity modes enable work extraction beyond the local contributions. Furthermore, it is shown that, among the different coherence configurations, ground–excited state coherence emerges as the most effective, simultaneously enhancing energy storage, extractable work, and stability. Finally, by applying a geometric power bound based on Fisher information and energy variance, it is showed that coherent charging protocols approach the ultimate charging limit more closely than incoherent ones. These findings establish atomic coherence and intermode correlations as valuable thermodynamic resources and highlight the two‐mode micromaser as a minimal yet versatile platform for multimode quantum batteries.
Abstract Quantum batteries (QBs) have been proposed as devices that exploit the advantage of quantum resources, such as coherence and entanglement, to improve charging performance. In this study, we theoretically investigate a QB model based on two coupled double quantum dots (TDQDs) implemented on the well-established AlGaAs/GaAs platform for quantum nanodevice fabrication. Using ergotropy and power as key performance indicators, we examine how various system parameters affect the energy performance of the QB. Our study begins with an analysis of quantum resources in the QB’s initial state, followed by an examination of how control parameters that influence these resources impact the modeling and performance of the battery. Our results demonstrate that increasing the energy offset improves ergotropy and power but reduces quantum correlations. Conversely, increasing tunneling couplings leads to a non-monotonic variation in the maximum ergotropy, which peaks at a certain point before decreasing, closely following the behavior of quantum entanglement despite continued growth in quantum coherence. This highlights the feasibility of efficient energy storage in quantum dots (QDs) for use in quantum batteries (QBs). It also emphasizes that coherence alone is insufficient for optimal performance and that other quantum correlations are necessary and must be carefully considered to fully exploit the potential of quantum resources.
ABSTRACT We investigate a quantum battery within an open quantum system, in which a harmonic oscillator acts as the charger and two‐level atoms serve as battery cells. This model accounts for the dissipative effects arising from the coupling between both the charger and battery cells with the environment. By analyzing the time evolution of the battery energy, charging power, ergotropy, and logarithmic negativity, we systematically examine the influence of the number of battery cells and environmental dissipation on battery performance. Our results show that increasing significantly enhances the charging power, exhibiting a collective enhancement effect. Both the atomic number and environmental dissipation strongly affect the ergotropy per atom, but their influences are distinct.
Abstract Reservoir engineering has been widely used in various quantum technologies. Based on a cavity-QED (quantum electrodynamics) model, we propose a potentially practical scheme using squeezed-vacuum reservoir engineering to optimize the performance of a quantum battery (QB) located inside a cavity driven by a broadband squeezed laser, which acts as a squeezed-vacuum reservoir. Using the reduced master equation of the QB obtained via the adiabatic elimination method, we focus on the QB’s charging dynamics under tunable squeezed reservoirs governed by parametrically controlled squeezing parameters, which dictate the efficiency of energy transfer and the extractable work (ergotropy) of the QB. We show that increasing the squeezing strength improves the charging rate and enables rapid energy transfer, whereas the steady-state energy of the QB saturates at specific values of the squeezing parameter. Notably, the ergotropy of the QB reaches its maximum at a critical squeezing strength and does not scale monotonically with the squeezing strength. This nonmonotonic behavior underscores the existence of optimal parameter regimes, through which the performance of the QB can be significantly enhanced.
The performance of open quantum batteries (QBs) is severely limited by decoherence due to the interaction with the surrounding environment. So, protecting the charging processes against decoherence is of great importance for realizing QBs. In this work we address this issue by developing a charging process of a qubit-based open QB composed of a qubit-battery and a qubit-charger, where each qubit moves inside an independent cavity reservoir. Our results show that, in both the Markovian and non-Markovian dynamics, the charging characteristics, including the charging energy, efficiency and ergotropy, regularly increase with increasing the speed of charger and battery qubits. Interestingly, when the charger and battery move with higher velocities, the initial energy of the charger is completely transferred to the battery in the Markovian dynamics. In this situation, it is possible to extract the total stored energy as work for a long time. Our findings show that open moving-qubit systems are robust and reliable QBs, thus making them a promising candidate for experimental implementations.