Quantum Battery Stores More Energy with Heat Applied

Researchers investigate a novel approach to quantum battery design, exploring energy storage and release within an open system utilising two ultrastrongly coupled oscillators. Yu-qiang Liu and Zunlue Zhu, both from the School of Physics at Henan Normal University, alongside Yi-jia Yang and Zheng Liu from the School of Physics, Dalian University of Technology, detail this work in collaboration with Bao-qing Guo of the Quantum Information Research Center, Shangrao Normal University, Ting-ting Ma, Wuming Liu from the Beijing National Laboratory for Condensed Matter Physics and the Institute of Physics, Chinese Academy of Sciences, and Xingdong Zhao and Chang-shui Yu from Henan Normal University. Their findings demonstrate significantly enhanced charging energy and ergotropy, a measure of useful work, within the ultrastrong coupling regime and across a wider temperature range, achieved through a unique combination of beam-splitter and parametric amplification couplings.

This research advances understanding of open bosonic battery operation and potentially unlocks improved energy storage capabilities in quantum technologies. Quantum power storage just entered a new era of efficiency. Harnessing the ultrastrong coupling between light and matter allows for markedly improved energy transfer and storage. This development promises batteries that can charge faster and operate effectively across a wider range of temperatures. Scientists are increasingly focused on the efficient storage and transfer of energy at the quantum scale. Recent investigations centre on quantum batteries, devices designed to use quantum mechanical phenomena for improved energy management. Researchers have detailed a new approach to quantum battery design, utilising ultrastrongly coupled bosonic systems to both store and release energy. Their work demonstrates a pathway to enhanced charging capabilities and sustained energy levels, potentially overcoming limitations found in conventional battery models. Achieving stable energy flow remains a significant challenge in quantum battery development, as current designs often suffer from energy backflow, hindering efficient charging processes. To address this, the team proposed an open quantum battery constructed from two coupled oscillators, where one oscillator acts as a charger and interacts with a heat reservoir. By operating within the ultrastrong coupling regime, where the interaction between light and matter becomes exceptionally strong, they observed a marked improvement in both charging energy and ergotropy, a measure of the useful work obtainable from the battery. The benefits extend beyond simple energy storage. Initial conditions, specifically employing a two-mode squeezed ground state, allow for unidirectional energy flow, preventing detrimental backflow seen in other designs. Analyses reveal that the steady-state stored energy and ergotropy increase with both temperature and coupling strength. Unlike systems relying solely on beam-splitter interactions or two-mode squeezing, this design achieves non-zero ergotropy, indicating a more effective energy storage mechanism. The inclusion of a squared electromagnetic vector potential term proves vital in preventing phase transitions and maintaining high ergotropy even in the deep-strong coupling regime. At these coupling strengths, the battery exhibits enhanced performance, suggesting a new avenue for optimising quantum energy storage. By carefully controlling the system’s parameters, the researchers have not only improved energy storage but also gained a deeper understanding of the underlying principles governing open bosonic quantum batteries. Ergotropy enhancement via combined interactions and vector potential stabilisation Stored energy within the proposed open quantum battery demonstrably increases with both temperature and coupling strength. At larger temperatures, the steady-state stored energy exhibits enhancement, alongside a corresponding increase in ergotropy. Calculations reveal that a purely beam-splitter or two-mode squeezing interaction results in zero ergotropy, indicating these interactions alone are insufficient for effective energy storage. The enhanced stored energy and ergotropy originate from the combined effects of beam-splitter and parametric amplification, squeezing couplings. Once the system is initialised in a two-mode squeezed ground state, unidirectional energy flow is achieved, preventing backflow between the battery and charger during the charging process. The presence of the squared electromagnetic vector potential term proves vital in preventing a phase transition, achieving significant charging energy and high ergotropy even within the deep-strong coupling regime. At coupling strengths exceeding the bare frequency of the bosonic mode, the system maintains stable charging characteristics. The study shows that the battery’s performance is not diminished by strong coupling, but rather benefits from it. Analysis of average populations, which characterise the battery’s energy and ergotropy, reveals that the ultrastrong coupling regime presents distinct characteristics compared to weak coupling scenarios. By controlling the initial state and charging energy, ergotropy can be effectively enhanced, enabling stable charging. The charger mode, coupled to an independent heat reservoir, plays a key role in facilitating this process. At temperatures exceeding zero, the steady-state stored energy and ergotropy are both amplified by stronger coupling strengths. Increasing the coupling strength between the charger and battery modes directly correlates with a higher capacity for energy storage. Ergotropy is a important metric for assessing the battery’s ability to perform useful work. Ultrastrong coupling and non-classical states for enhanced energy storage and ergotropy A two-mode ultrastrongly coupled bosonic system served as the core of this work, designed to store and release energy as an open battery. This system incorporates one mode functioning as a charger, directly coupled to a separate, independent heat reservoir, allowing for investigation of energy storage capabilities under varying thermal conditions and coupling strengths. The system’s initial state was carefully controlled using a two-mode squeezed ground state, a non-classical state of light that ensures unidirectional energy flow within the battery. Researchers utilised beam-splitter and parametric amplification couplings, deliberately combining these to maximise both stored energy and ergotropy. A purely beam-splitter or two-mode squeezing interaction alone proved insufficient, yielding zero ergotropy, highlighting the importance of their combined effect. The inclusion of a squared electromagnetic vector potential term became essential, preventing undesirable effects and enabling substantial charging energy and high ergotropy even in the deep-strong coupling regime. Previous studies, such as those by Kockum et al (2017) and Langford et al (2017), have explored ultrastrong coupling regimes using superconducting circuits, but this work extends those approaches by focusing on the specific dynamics of an open battery system. By carefully selecting these techniques, the research aimed to gain a deeper understanding of the fundamental operating principles governing open bosonic batteries. Ultrastrong coupling unlocks efficient energy storage in open quantum systems Scientists are increasingly focused on the challenge of energy storage, yet conventional approaches are nearing their theoretical limits.

This research presents a departure, exploring battery designs rooted in the peculiar behaviours of quantum systems, specifically ‘open’ batteries that exchange energy with their surroundings in a controlled manner. Building a quantum battery that outperforms its classical counterparts has remained elusive, hampered by the delicate nature of quantum states and their susceptibility to environmental noise. Investigations into ultrastrongly coupled bosonic systems reveal a pathway to enhanced energy storage and release. Manipulating the fundamental interactions between energy modes can unlock greater efficiency, even at higher temperatures where quantum effects are typically diminished. The ability to direct energy flow, to charge the battery unidirectionally, is a significant step towards practical devices. Translating these findings into tangible technologies is not without hurdles. The experimental realisation of ultrastrong coupling requires precise control over electromagnetic fields and materials, a feat that remains difficult to achieve consistently. This system’s performance relies on a specific combination of interactions, limiting the flexibility of design. The models examined outperform alternatives only within a narrow set of conditions. Once these engineering challenges are addressed, the implications extend beyond small-scale devices. Improved quantum batteries could underpin more efficient energy harvesting from ambient sources, or provide stable power for sensitive quantum sensors. Beyond batteries, the principles of manipulating energy flow in coupled systems could find applications in areas like quantum computing and materials science, prompting further research into the interaction between quantum mechanics and thermodynamics. 👉 More information 🗞 Dissipative Quantum Battery in the Ultrastrong Coupling Regime Between Two Oscillators 🧠 ArXiv: https://arxiv.org/abs/2602.15235 Tags: