This paper discusses the evolving dynamics of a quantum battery (QB) model consisting of two qubits interacting with a cavity field via multi-photon transitions. Employing the Lindblad master equation to account for dissipative effects, we investigated energy charging, charging power, ergotropy, and energy fluctuations to ascertain optimal conditions for efficient energy storage and extraction. Our results elucidate that lower photon numbers and moderate coherent state result in higher energy peaks and more stable storage. The charging power underscores the significance of maximizing initial energy transfer rates while mitigating rapid power decay. Ergotropy, representing the maximum extractable energy, is highly sensitive to dissipation rates, with elevated photon numbers enhancing charging efficiency but reducing stability. Energy fluctuation reveals that systems with higher photon numbers exhibit greater instability, emphasizing the necessity for controlling dissipation to preserve energy stability.
This paper discusses the evolving dynamics of a quantum battery (QB) model consisting of two qubits interacting with a cavity field via multi-photon transitions. Employing the Lindblad master equation to account for dissipative effects, we investigated energy charging, charging power, ergotropy, and energy fluctuations to ascertain optimal conditions for efficient energy storage and extraction. Our results elucidate that lower photon numbers and moderate coherent state result in higher energy peaks and more stable storage. The charging power underscores the significance of maximizing initial energy transfer rates while mitigating rapid power decay. Ergotropy, representing the maximum extractable energy, is highly sensitive to dissipation rates, with elevated photon numbers enhancing charging efficiency but reducing stability. Energy fluctuation reveals that systems with higher photon numbers exhibit greater instability, emphasizing the necessity for controlling dissipation to preserve energy stability.
Abstract Quantum batteries harness quantum coherence and entanglement to achieve efficient energy storage beyond classical limits. This study presents a comparative analysis of series and parallel charging protocols, evaluating their impact on charging efficiency, stability, and dissipation. Using the Lindblad master equation, we investigate the effects of multi-photon interactions, cavity decay, atomic relaxation, and thermal fluctuations on the evolution of key physical quantities, including stored energy, ergotropy, and entropy of the charger. Our findings reveal that parallel charging exhibits superior stability, reduced entropy fluctuations, and higher ergotropy, while series charging suffers from increased dissipation and oscillatory instabilities. These insights contribute to the development of high-performance quantum energy storage systems for advanced quantum technologies.
Abstract We investigate a three-level quantum battery (QB) coupled to a two-mode cavity, focusing on V-type, Ξ-type and Λ-type atomic configurations. Three-level QBs exhibit enhanced complexity in their characteristic properties compared to two-level QBs, arising fundamentally from their distinctive energy level configurations. By investigating three distinct classes of initial cavity states—Fock states, coherent states, and squeezed states—we demonstrate that adjusting the ratio of photon numbers at distinct frequencies enhances both the maximum stored energy and ergotropy, while simultaneously reducing the time to reach maximum stored energy. Moreover, while the cavity-environment interaction inevitably induces persistent energy dissipation, strategic manipulation of frequency-dependent photon decay rates enables optimization of three critical performance metrics: the maximum stored energy, maximum ergotropy, and charging power at the initialization stage.
With intensive studies of quantum thermodynamics, quantum batteries (QBs) have been proposed to store and transfer energy via quantum effects. Despite many theoretical models, decoherence remains a severe challenge and practical platforms are still rare. Here, we propose a QB based on the coherent Ising machine, in which the signal field acts as the core energy-storage unit. To clarify the role of quantum coherence in resisting dissipation, we decompose the ergotropy, i.e., the maximum extractable work from the QB, into its coherent and incoherent components. We find that the coherent part decays at a rate roughly half that of the incoherent part, exhibiting much stronger robustness against decoherence. More importantly, the coherent ergotropy and the average charging power reach their respective maxima at essentially the same moment, which defines the optimal instant to switch off the pump field. Finally, by coupling the QB to a two-level system as the load, we demonstrate an efficient energy discharge process of the proposed QB. Our work establishes a realistic and immediately-implementable QB architecture on a mature optical platform, laying a foundation for experimental exploration of quantum energy storage.
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.
Quantum batteries are quantum systems that potentially serve as fuel for other quantum devices by receiving and supplying energy. In this work, we propose a theoretical scheme to enhance ergotropy and charging power of quantum Battery in the system under consideration through squeezed light. Moreover, The system comprises a coherently driven charger cavity, a strongly dissipative auxiliary cavity acting as a mediator, and an energy--storage battery cavity. Quantum nonreciprocity and directional energy flow are established via destructive quantum interference between the direct coupling path and the loss--engineered indirect path. A degenerate optical parametric amplifier integrated into the charger cavity acts as an active, phase--sensitive energy source that injects two--photon quantum excitations and anomalous correlations. Using a strictly open--quantum--system framework derived directly from the Lindblad master equation, we obtain the full expectation--value dynamics and stationary states. We show that active parametric driving drastically increases the stored energy and peak charging power while maintaining nonreciprocal energy trapping in the battery. We achieve a multi-order-of-magnitude boost in the battery's stored energy, charging power, and ergotropy. We also analyze the effects of pure dephasing on the charging power, ergotropy, and extractable work quality.. Although two--photon pumping introduces photon--number fluctuations that slightly lower the fractional ergotropy ratio WB/EB, the absolute extractable work remains substantially elevated compared to unassisted configurations.
We consider a quantum battery that is based on a two-level system coupled with a cavity radiation by means of a two-photon interaction. Various figures of merit, such as stored energy, average charging power, energy fluctuations, and extractable work are investigated, considering, as possible initial conditions for the cavity, a Fock state, a coherent state, and a squeezed state. We show that the first state leads to better performances for the battery. However, a coherent state with the same average number of photons, even if it is affected by stronger fluctuations in the stored energy, results in quite interesting performance, in particular since it allows for almost completely extracting the stored energy as usable work at short enough times.