A Hubbard-Holstein dimer functions as a correlation-driven quantum battery, with ergotropy robustly stored, under some conditions, even in the presence of dissipation. We find that, although optimal work extraction can in principle recover all the stored energy, it requires unrealistically fine-tuned couplings. By contrast, a physically realizable protocol based on spectral matching between the battery and the load achieves substantial, albeit suboptimal, energy extraction. Our results identify a mechanism for quantum energy storage, provide a realistic route to work extraction that is amenable to machine-learning-based theoretical exploration, and suggest that quantum batteries may not be universally deployable: the microscopic mechanism responsible for storing energy can constrain the classes of systems able to efficiently extract it.
A Hubbard-Holstein dimer functions as a correlation-driven quantum battery, with ergotropy robustly stored, under some conditions, even in the presence of dissipation. We find that, although optimal work extraction can in principle recover all the stored energy, it requires unrealistically fine-tuned couplings. By contrast, a physically realizable protocol based on spectral matching between the battery and the load achieves substantial, albeit suboptimal, energy extraction. Our results identify a mechanism for quantum energy storage, provide a realistic route to work extraction that is amenable to machine-learning-based theoretical exploration, and suggest that quantum batteries may not be universally deployable: the microscopic mechanism responsible for storing energy can constrain the classes of systems able to efficiently extract it.
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.
As a quantum thermodynamic device that utilizes quantum systems for energy storage and delivery, the quantum battery (QB) is expected to offer revolutionary advantages in terms of increasing the charging power and the extractable work by using quantum resources. However, the ubiquitous decoherence in the microscopic world inevitably forces the QB to spontaneously lose its stored energy. This is called the self-discharging of the QB and severely limits its realization. We propose a QB scheme based on the nitrogen-vacancy center in diamond, where the electronic spin serves as the QB. Inspired by our finding that the coherent ergotropy decays more slowly than the incoherent ergotropy, we reveal a mechanism to enhance the inherent robustness of the QB to the self-discharging by improving the ratio of coherent ergotropy to total ergotropy. The unique hyperfine interaction between the electron and the native ^{14}N nucleus in our scheme allows one to coherently optimize this ratio. Mitigating the self-discharging and optimizing the extractable work simultaneously, our results pave the way for the practical realization of the QB.
A quantum system which can store energy, and from which one can extract useful work, is known as a quantum battery. Such a device raises interesting issues surrounding how quantum physics can provide certain advantages in the charging, energy storage, or discharging of the quantum battery as compared to their classical equivalents. However, the pernicious effect of dissipation degrades the performance of any realistic battery. Here, we show how one can circumvent this problem of energy loss by proposing a quantum battery model which benefits from quantum squeezing. Namely, charging the battery quadratically with a short temporal pulse induces a hyperbolic enhancement in the stored energy, such that the dissipation present becomes essentially negligible in comparison. Furthermore, we show that when the driving is strong enough, the useful work which can be extracted from the quantum battery, that is the ergotropy, is exactly equal to the stored energy. These impressive properties imply a highly efficient quantum energetic device with abundant amounts of ergotropy. Our theoretical results suggest a possible route to realizing high-performance quantum batteries, which could be realized in a variety of platforms exploiting quantum continuous variables. Published by the American Physical Society 2024
Abstract Quantum batteries are miniature energy storage devices and play a very important role in quantum thermodynamics. In recent years, quantum batteries have been extensively studied, but limited in theoretical level. Here we report the experimental realization of a quantum battery based on superconducting qutrit. Our model explores dark and bright states to achieve stable and powerful charging processes, respectively. Our scheme makes use of the quantum adiabatic brachistochrone, which allows us to speed up the battery ergotropy injection. Due to the inherent interaction of the system with its surrounding, the battery exhibits a self-discharge, which is shown to be described by a supercapacitor-like self-discharging mechanism. Our results paves the way for proposals of new superconducting circuits able to store extractable work for further usage.
Charging a quantum battery through a pumped charger can lock a substantial part of its stored energy inside the bipartite correlations that grow between the constituent cells, and this \emph{correlation ergotropy}, being the energy that no local single-cell operation can reach and that only collective operations can recover, is the object of the present study. Following the charging trajectory of two coupled three-level cells, we find that the correlation ergotropy closely tracks the logarithmic negativity, which shows that the locked energy is carried by genuine bipartite entanglement rather than by coherent collective dynamics alone, and that an equal-strength coherent non-entangling drive produces no such locking at all. For a pure two-cell battery we establish an exact, basis-independent closed form in which the locked energy depends only on the sorted eigenvalues of the reduced cell and the cell energy levels, revealing that the locked fraction rises from zero at the separable corners of the Schmidt simplex to unity at the symmetric maximally entangled state and remains invariant under local unitaries. Decoherence and dephasing, which destroy the correlations, do \emph{not} release this energy but erase it, so extraction must be collective and must take place while the correlations persist, while cold damping leaves the effect intact and thermal occupation suppresses it. These results give a resource-theoretic reading of correlations in quantum batteries, sharpen the line between genuine entanglement and coherent collective dynamics, and point to experimentally accessible conditions for correlated-charge and collective-extraction protocols.
This study examines the steady state characteristics of work extraction in a two cell and three cell quantum battery interacting with multiple thermal reservoirs. Employing the quantum master equation framework within the Born-Markov approximation, we explore the non equilibrium dynamics governing energy storage and extraction in the system. Our analysis focuses on the influence of thermal gradients across the reservoirs and the impact of inter cell coupling strength on the battery performance. The findings demonstrate that an increase in the middle reservoir temperature substantially enhances the extractable work, underscoring the pivotal role of thermal bath amplification in optimizing energy storage efficiency. Furthermore, we uncover a non trivial relationship between ergotropy and the coupling strength among the quantum cells, revealing the existence of an optimal coupling regime that maximizes energy extraction. Beyond this threshold, excessive coupling induces energy localization, thereby diminishing the system efficiency. These insights provide a theoretical foundation for the strategic design of high performance quantum batteries by harnessing thermal gradients and interaction driven control mechanisms.