Although entanglement is considered as a crucial resource for quantum information processing, it is still unknown whether the presence of quantum entanglement in the working medium can enhance the charging performance of a quantum battery (QB). Here, we address this problem by considering a QB with working medium consisted of an entangled coupled-cavity array. We show that the optimal charging performance of the QB is achieved in the two-cavity case when cavities are initially in a maximum entangled state without cavity couplings. We then extend our discussion to multicavity case. It is demonstrated that the charging power of the QB under an entangled coupled-cavity array can be further enhanced by increasing the number of cavities. Our findings reveal the advantage of an entangled working medium in enhancing the charging performance of a QB, and therefore, contribute to the experimental realization of quantum batteries with excellent performance.
Although entanglement is considered as a crucial resource for quantum information processing, it is still unknown whether the presence of quantum entanglement in the working medium can enhance the charging performance of a quantum battery (QB). Here, we address this problem by considering a QB with working medium consisted of an entangled coupled-cavity array. We show that the optimal charging performance of the QB is achieved in the two-cavity case when cavities are initially in a maximum entangled state without cavity couplings. We then extend our discussion to multicavity case. It is demonstrated that the charging power of the QB under an entangled coupled-cavity array can be further enhanced by increasing the number of cavities. Our findings reveal the advantage of an entangled working medium in enhancing the charging performance of a QB, and therefore, contribute to the experimental realization of quantum batteries with excellent performance.
In the process of using quantum resources to improve the performance of quantum battery devices, device performance is highly restricted by decoherence due to the influence of the external environment. In particular, the fact that such devices are subject to complex environmental influences in real scenarios should be taken into account. Here, we investigate the performance (i.e., the internal energy, charging power, and ergotropy) of a quantum battery in a double-layer environment, where the first-layer environment is a single-mode cavity and the second-layer environment is a single reservoir. We are surprised to find that the memory effect of the reservoir does not affect the charging performance of a quantum battery; in sharp contrast, the reduction in the coupling between the quantum battery and the first-layer environment can improve the charging performance of a quantum battery. We then extend our discussion to the case where the second-layer environment consists of multiple reservoirs, each consisting of a single-mode cavity dissipated to the Markovian reservoir. It is shown that the charging performance of the quantum battery can be enhanced by increasing the number of cavities in the second-layer environment and the coupling strength between the first-layer environment and the second-layer environment. Our results may be helpful for realizing optimal charging performance of quantum batteries in a complex environment.
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.
Quantum battery (QB) is an application of quantum thermodynamics which uses quantum effects to store and transfer energy, overcoming the limitations of classical batteries and potentially improving the QB's performance. However, due to the interaction with the external environment, it leads to decoherence and thus reduces both the lifetime and the charging efficiency of QB. Here, we propose suppressing the environmental dissipation in the energy-storage process of the QB by exploiting both the electromagnetically-induced-transparency (EIT) effect and bound states. By constructing a hybrid system composed of a four-level atom and a coupled-cavity array, two bound states are formed in the system when the energy of the QB is in the energy band of the cavity array. Environmental dissipation is significantly inhibited due to the bound state and EIT effects, which extends the lifetime of the QB. We show that the charging efficiency of the QB is optimal when the energy of the QB is in resonance with the cavity. In addition, there is an optimal coupling strength between the two adjacent cavities, which helps to improve the performance of the QB. Our research has achieved the realization of long-term energy storage while improving the charging efficiency of QB, which has practical implications for the realization of QB.
Abstract In the realm of quantum batteries (QBs), model construction and performance optimization are central tasks which can be addressed by exploiting machine learning algorithms. Here, we propose a cavity-Heisenberg spin chain QB model with spin- j ( j = 1 / 2 , 1 , 3 / 2 ) and investigate the charging performance under both closed and open quantum cases, considering spin–spin interactions, ambient temperature, and cavity dissipation. By employing a reinforcement learning (RL) algorithm to modulate the cavity-battery coupling, we further optimize the QB performance, enhancing the charging capability of the spin chain. It is shown that the charging energy and the power of the QB are significantly improved with the spin size. In particular, the use of a RL algorithm in case of large spin ( j = 3 / 2 ) in presence of cavity losses allows for more stability in the optimization of the cavity-spin coupling strength, which in perspective makes an experimental realization more feasible. We analyze the optimization mechanism and find an intrinsic relationship between cavity-spin entanglement and charging performance: while in the closed-system scenario the charging energy increases together with the cavity-spin entanglement, in the open-system scenario the increase of the charging energy can be accompanied by a decrease of entanglement. Our results provide a possible scheme for design and optimization of QBs.
Quantum information theorems state that it is possible to exploit collective quantum resources to greatly enhance the charging power of quantum batteries (QBs) made of many identical elementary units. We here present and solve a model of a QB that can be engineered in solid-state architectures. It consists of N two-level systems coupled to a single photonic mode in a cavity. We contrast this collective model ("Dicke QB"), whereby entanglement is genuinely created by the common photonic mode, to the one in which each two-level system is coupled to its own separate cavity mode ("Rabi QB"). By employing exact diagonalization, we demonstrate the emergence of a quantum advantage in the charging power of Dicke QBs, which scales like sqrt[N] for N≫1.
The advent of quantum batteries (QBs) has coincided with the accelerated progress in quantum science and technology. Here, we propose a novel double-cavity QB design, wherein the maximum charging power can be enhanced to N2.5 times or even higher, up to N3 times, through the manipulation of atomic distribution, which surpasses the upper limit of N2 reported in previous study. The advantage of this manipulation is pronounced with an increasing number of atoms in the QB. A significant atom number discrepancy between the two cavities results in the simultaneous optimization of charging power and battery capacity, thereby enhancing charging efficiency without compromising energy storage capacity. Additionally, by modulating the number of atoms within each cavity, the QB is theoretically capable of transitioning between ``fast charging'' and ``slow charging'' modes. Notably, in an open system environment, the superiority of the QB is even more pronounced, with negligible energy loss at the final steady state relative to the maximum energy storage of an isolated system.