Abstract We show that a micromaser is an excellent model of quantum battery. A highly excited, pure, and effectively steady state of the cavity mode, charged by coherent qubits, can be achieved, also in the ultrastrong coupling regime of field-matter interaction. Stability of these appealing features against loss of coherence of the qubits and the effect of counter-rotating terms in the interaction Hamiltonian are also discussed.
Abstract We show that a micromaser is an excellent model of quantum battery. A highly excited, pure, and effectively steady state of the cavity mode, charged by coherent qubits, can be achieved, also in the ultrastrong coupling regime of field-matter interaction. Stability of these appealing features against loss of coherence of the qubits and the effect of counter-rotating terms in the interaction Hamiltonian are also discussed.
We consider a micromaser model of a quantum battery, where the battery is a single mode of the electromagnetic field in a cavity, charged via repeated interactions with a stream of qubits, all prepared in the same non-equilibrium state, either incoherent or coherent, with the matter-field interaction modeled by the Jaynes-Cummings model. We show that the coherent protocol is superior to the incoherent one, in that an effective pure steady state is achieved for generic values of the model parameters. Finally, we supplement the above collision model with cavity losses, described by a Lindblad master equation. We show that battery performances, in terms of stored energy, charging power, and steady-state purity, are slightly degraded up to moderated dissipation rate. Our results show that micromasers are robust and reliable quantum batteries, thus making them a promising model for experimental implementations.
We investigate the open-system dynamics of a micromaser quantum battery in the ultrastrong-coupling (USC) regime. The battery consists of a quantized harmonic mode sequentially interacting, via the Rabi Hamiltonian, with a stream of qubits acting as chargers. USC enhances the charging speed but also induces unbounded energy growth and highly mixed cavity states. Dissipation suppresses this behavior, driving the system to a steady state with finite energy and ergotropy. Using optimal control theory, we show that the interplay between USC and dissipation enhances both charging performance and long-term stability against losses.
We theoretically investigate the role played by non-Markovianity in the charging of a quantum battery. We focus on the case of a Micromaser, where the energy is stored in a resonant cavity mode and memory effects are introduced and controlled by coupling this mode to a memory ancilla, described as a two-level system, that in turn sequentially interacts with a stream of two-level chargers through pairwise exchange interactions leading to a partial swap. Through numerical analysis, we show that non-Markovian memory effects act as a resource that enhances both the charging capacity and the stability of this device with respect to the Markovian counterpart. We conclude our study showing that the proposed scheme can be implemented in state-of-the-art solid-state platforms for circuit quantum electrodynamics.
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.
Nowadays, quantum batteries (QBs) have been designed to outperform their classical counterparts by leveraging quantum advantages. For instance, the charging power greatly benefits from the entanglement generation of a collective charging scheme (e.g., the Dicke QB), especially in the ultrastrong coupling (USC) regime or even larger. However, apart from the fragility of the QB under intrinsic decoherence effects, another critical drawback emerges inevitably. Specifically, the non-negligible counter-rotating (CR) term in the USC regime would induce coherence in the energy basis of QB, thus remarkably degrading the charging efficiency. To tackle these challenges, we propose a high-efficiency and noise-immune QB boosted by dynamical modulation. It is demonstrated that the time-varying modulation can effectively reduce the CR coupling, resulting in a notable improvement in charging efficiency. Particularly, for a judicious choice of modulation parameters that entirely eliminate the CR interaction, the Dicke QB can be charged optimally, resembling the behavior of the Tavis-Cummings QB. In the subsequent storage process, beyond the natural robustness to pure dephasing noise, our scenario is also highly resilient to the dissipation noise and thus can achieve perfect energy storage by effective bath engineering. While feasible with current experimental platforms, our proposal offers a solid foundation for the implementation of a powerful QB and may drastically promote the development of energy storage and delivery techniques in the future.
The microscopically pumped maser, or micromaser is a cavity QED experiment intended to be a physical realisation of the Jaynes-Cummings model of a single two-level atom interacting with a single mode electromagnetic field. This is the simplest model that describes the interaction between light and matter, yet it predicts behaviour unexpected from semiclassical models, such as the revival of Rabi oscillations of an atom interacting with an initially coherent field and non-monotonic linewidth as a function of pumping. The micromaser at the University of Leeds consists of a high quality superconducting microwave cavity designed to be resonant with the transition between two specific Rydberg states of rubidium. These two states behave like an ideal two level atom, and couple strongly to the cavity field due to a large dipole moment. These Rydberg atoms are passed through the cavity in a rarified beam such that in most instances when there is an atom in the cavity, there will only be one, closely approximating the Jaynes-Cummings model. I present experimental work on the build phase of the micromaser. Specifically I routed all of the wiring and microwave lines in the cryostat that contains the micromaser, and designed mounts for various components. I also designed several testing methods for probing high quality microwave cavity resonances and quality factors which are presented. Using the Jaynes-Cummings model as a prototype, I demonstrate how extensions to the model can be used to construct universal quantum logic gates that operate on photonic qubits in a multi-mode cavity. This could be realised in a micromaser with a multi-mode cavity. Conversely, I demonstrate that by using atoms as qubits, detuned cavities can be used to generate entangled resources such as the Greenberger-Horne-Zeilinger state, the W state, and graph states of atoms. I show that single qubit rotations on Rydberg atom qubits have already been experimentally demonstrated so that in combination these entangled resources are useful for quantum metrology, quantum computation and even tests of quantum gravity.