This study demonstrates a solid-state quantum battery in which metastable states enable stable and long-lived energy storage. The authors further show that the stored energy can be controllably extracted for coherent microwave emission at room temperature.
Recently proposed metastability-induced quantum batteries have shown particular promise for coherent microwave generation. However, achieving high-power coherent microwave generation in quantum batteries remains fundamentally challenging due to quantum correlations, aging, and self-discharging processes. For the cavity-quantum-electrodynamics (CQED)-based quantum batteries, a further trade-off arises between strong spin-photon coupling for energy storage and sufficient output coupling for power delivery. To overcome these constraints, we introduce dissipation engineering as a dynamic control strategy that temporally separates energy storage and release. By suppressing emission during charging and rapidly enhancing the output coupling during discharging, we realize nanosecond microwave bursts with watt-level peak power. By optimizing three dissipation schemes, we improve work extraction efficiency of the quantum battery by over two orders of magnitude and achieve high power compression factors outperforming the state-of-the-art techniques, establishing dissipation engineering as a pathway toward room-temperature, high-power coherent microwave sources.
In the process of charging a quantum battery, quantum jumps play a detrimental role because they induce transitions from higher to lower energy levels, leading to energy dissipation. This be- havior directly opposes the fundamental objective of the charging protocol, which is to increase the population of higher-energy states and store usable energy in the system. Furthermore, decoherence introduced by randomness of quantum jumps leads to a mixed state, thereby reducing the amount of energy that can be extracted from the charged quantum battery. Here, we propose a quantum battery comprising an ensemble of three-level atoms in the Λ configuration to store energy in the metastable state over a long time. We demonstrate that, when spontaneous atomic transitions are restricted to occur solely from the excited state to a metastable state, with decay to the ground state completely suppressed, quantum jumps acquire a constructive character. Under these con- ditions, they drive the quantum battery to a fully charged state, render the entire stored energy extractable, and shorten the duration of the second stage of the charging protocol.
In the process of charging a quantum battery, quantum jumps play a detrimental role because they induce transitions from higher to lower energy levels, leading to energy dissipation. This behavior directly opposes the fundamental objective of the charging protocol, which is to increase the population of higher-energy states and store usable energy in the system. Furthermore, decoherence introduced by randomness of quantum jumps leads to a mixed state, thereby reducing the amount of energy that can be extracted from the charged quantum battery. Here, we propose a quantum battery comprising an ensemble of three-level atoms in the Λ configuration to store energy in the metastable state over a long time. We demonstrate that, when spontaneous atomic transitions are restricted to occur solely from the excited state to a metastable state, with decay to the ground state completely suppressed, quantum jumps acquire a constructive character. Under these conditions, they drive the quantum battery to a fully charged state, render the entire stored energy extractable, and shorten the duration of the second stage of the charging protocol.
Quantum batteries promise revolutionary advantages for energy storage but are fundamentally crippled by environmental decoherence, which induces self-discharge and rapid "aging." Here, we crack this critical bottleneck by exploiting the decoherence-suppression mechanism: the formation of system-environment bound states. We consider a charger-battery system embedded in a three-dimensional anisotropic photonic crystal bath and derive exact non-Markovian dynamics. Strikingly, we reveal a tunable phase diagram where modulating the atomic eigenfrequency and coupling strength switches the system between zero, one, and two bound states. In the presence of two bound states, the battery energy evolves into a persistent periodic oscillation, enabling lossless energy storage and on-demand extraction indefinitely, effectively realizing an aging-free quantum battery. Conversely, the absence of bound states leads to complete energy decay. We also demonstrate that even during self-discharge, a single bound state can stabilize extractable energy. This work establishes bound-state formation as a powerful and feasible strategy for combating decoherence, offering a clear blueprint for designing durable solid-state quantum batteries in non-Markovian photonic platforms.
Batteries are fundamental components of nowadays technologies and play a crucial role in our daily lives. Varying greatly in size and capacity, they are devices capable of storing energy, supplied from an external system, and releasing it in a controlled manner to a user system. Despite the impressive technological improvements over the past two centuries, the batteries we currently use still rely on the electrochemical principles exploited by A. Volta at the end of the 18th century. However, the constant miniaturization of electronic devices calls for the realization of increasingly smaller batteries, down to sizes comparable to those of molecules and atoms. At these scales, quantum effects must be taken into account. It is therefore necessary to reconsider energy manipulation within the framework of quantum thermodynamics, a research field that aims to extend the laws of classical thermodynamics and non-equilibrium statistical physics to systems where quantum effects become significant. In this context, the possibility to properly characterize the energetics of miniaturized thermal machines represented a major boost for the development of quantum technologies devoted to energy storage and manipulation. This Thesis explores solid-state quantum batteries, bridging theoretical models with experimental simulations. Key contributions include the simulation of few-level QBs on IBM quantum hardware, demonstrating the viability of superconducting circuits for energy tasks. The work introduces a cyclic QB model where quantum correlations enable efficiencies exceeding 50%, and examines a harmonic oscillator battery where non-Markovian dynamics facilitate ultra-fast charging. Finally, a novel implementation based on Graphene Josephson Junctions is proposed to realize a Dicke quantum battery. These results highlight the potential of quantum technologies for the future of miniaturized energy storage.
Quantum batteries have recently emerged as promising candidates for microscopic energy-storage technologies exploiting uniquely quantum mechanical effects. In this work, we introduce the concept of a quantum capacitor, a coherence-based quantum energy-storage device exhibiting reversible and ultrafast charging-discharging dynamics. Unlike conventional quantum batteries, which primarily focus on extractable work, the proposed quantum capacitor operates through reactive energy accumulation mediated by coherent quantum polarization. We formulate a theoretical framework based on a driven two-level system and define a dynamical quantum capacitance associated with the response of stored energy to coherent external driving. The charging power, reversible energy exchange, and the effects of environmental decoherence are investigated analytically within the Lindblad formalism. We extend the proposal to interacting many-body systems and show that collective coherence and interactions can enhance the effective quantum capacitance and charging power, potentially leading to cooperative energy-storage advantages beyond the single-qubit regime.