One of the most fundamental tasks in quantum thermodynamics is extracting energy from one system and subsequently storing this energy in an appropriate battery. Both of these steps, work extraction and charging, can be viewed as cyclic Hamiltonian processes acting on individual quantum systems. Interestingly, so-called passive states exist, whose energy cannot be lowered by unitary operations, but it is safe to assume that the energy of any not fully charged battery may be increased unitarily. However, unitaries raising the average energy by the same amount may differ in qualities such as their precision, fluctuations, and charging power. Moreover, some unitaries may be extremely difficult to realize in practice. It is hence of crucial importance to understand the qualities that can be expected from practically implementable transformations. Here, we consider the limitations on charging batteries when restricting to the feasibly realizable family of Gaussian unitaries. We derive optimal protocols for general unitary operations as well as for the restriction to easier implementable Gaussian unitaries. We find that practical Gaussian battery charging, while performing significantly less well than is possible in principle, still offers asymptotically vanishing relative charge variances and fluctuations.
Charging efficiency bursts in a quantum battery with cyclic indefinite causal order
National Cheng Kung University（国立成功大学）；Center for Quantum Frontiers of Research and Technology, NCKU（国立成功大学量子前沿科技研究中心）；University of Rochester（罗切斯特大学）；National Center for Theoretical Sciences（国家理论科学中心）
Enhancing the charging performance of an atomic quantum battery
School of Science, Xi’an University of Posts and Telecommunications（西安邮电大学理学院）；Institute of Physics, Chinese Academy of Sciences（中国科学院物理研究所）；School of Physical Sciences, University of Chinese Academy of Sciences（中国科学院大学物理科学学院）；Beijing Academy of Quantum Information Sciences（北京量子信息科学研究院）
Charging of a Quantum Battery by a Two-Photon Quantum Pulse
Institute for Physical Research, Armenian National Academy of Sciences（亚美尼亚国家科学院物理研究所）；Basic Sciences Group, Golpayegan College of Engineering, Isfahan University of Technology（伊斯法罕理工大学戈尔佩根工程学院基础科学组）
Comment on "Fluctuations in Extractable Work Bound the Charging Power of Quantum Batteries"
在García-Pintos等人的一篇文章中[Rev. Lett. 125，040601（2020）]研究了量子电池的充电功率与“自由能算子”的波动之间的联系，该自由能算子的期望值表征了电池的最大可提取功。闭系统分析的结果表明，对于一般的充电过程，电池将有一个非零的充电功率当且仅当电池的状态是不是一个本征态的自由能算子。本文指出了分析中的几个错误，并得出了充电功率的正确界。因此，闭系统动力学的结果一般是不正确的。
Correlation Enhanced Autonomous Quantum Battery Charging via Structured Reservoirs
Abdelmalek Essaadi University（阿卜杜勒马利克·埃萨迪大学）；Mohammed VI Polytechnic University (UM6P)（穆罕默德六世polytechnic大学）；University of Santiago de Compostela（圣地亚哥-德孔波斯特拉大学）；Koç University（库奇大学）；TÜBİTAK Research Institute for Fundamental Sciences（土耳其科学与技术研究基金会基础科学研究所）
Spectral and Impedance Matching for Multi-excitation Charging of an Interacting Quantum Battery via an Anharmonic Mediator
Ramakrishna Mission Vivekananda Educational and Research Institute（拉马克里希纳使命维韦卡南达教育与研究机构）；TCG CREST；Academy of Scientific and Innovative Research (AcSIR)（科学与创新研究学院）
Non-Markovian Charging of a Micromaser Quantum Battery
Università di Genova（热那亚大学）；CNR-SPIN（意大利国家研究委员会自旋物理研究所）；Università degli Studi dell’Insubria（因苏布里亚大学）；Istituto Nazionale di Fisica Nucleare, Sezione di Milano（意大利国家核物理研究所，米兰分部）
Collective dynamics versus entanglement in quantum battery performance
Bar-Ilan University（巴伊兰大学）；Indian Institute of Technology (Banaras Hindu University)（印度理工学院（贝拿勒斯印度教大学））；Harish-Chandra Research Institute, A CI of Homi Bhabha National Institute（哈里什-钱德拉研究所，霍米·巴巴国立学院）
Coherence-Enhanced Quantum Battery Charging with Ergotropy Stabilization
Texas A&M University（德克萨斯农工大学）；Okinawa Institute of Science and Technology Graduate University（冲绳科学技术大学院大学）；Baylor University（贝勒大学）；Princeton University（普林斯顿大学）
Bound-state-mediated remote charging of a quantum battery
School of Science, Xi’an University of Posts and Telecommunications（西安邮电大学理学院）；School of Physics and Information Technology, Shaanxi Normal University（陕西师范大学物理学与信息技术学院）
