AAPPS Bulletin

Abstract The atomic clocks, whether operating at optical or microwave region, can be divided into two categories according to their working mode, namely the passive clocks and active clocks. The passive clocks, whose standard frequency is locked to an ultra-narrow atomic spectral line, such as laser cooled Cs beam or lattice trapped Sr atoms, depend on the spontaneous emission line. On the contrary, the active clocks, in which the atoms are used as the gain medium, are based on the stimulated emission radiation, their spectrum can be directly used as the frequency standard. Up to now, the active hydrogen maser has been the most stable microwave atomic clocks. Also, the Sr superradiant active atomic clock is prospects for a millihertz-linewidth laser. Moreover, the optical clocks are expected to surpass the performance of microwave clocks both in stability and uncertainty, since their higher working frequency. The active optical clock has the potential to improve the stability of the best clocks by 2 orders of magnitude. In this work, we introduce the development of active optical clocks, and their types is classified according to the energy-level structure of atoms for stimulated radiation.

Jia Zhang

Tiantian Shi

Jianxiang Miao

Jingbiao Chen

AAPPS bulletin

The development of active optical clock

主动光学时钟的发展

Abstract Comprehensive neutron diagnostics have been developed and used to study magnetic confinement fusion plasmas. The neutron emission spectrometer is one of the most powerful tools for understanding fusion plasma physics. Neutron spectroscopy was originally developed to measure the fuel ion temperature in thermal plasmas. With the advent of fast ion heating, the role of neutron spectroscopy has evolved to deepen the understanding of fast ion confinement. Since neutrons are primarily produced by the fusion reaction between the bulk ion and the fast ion, the neutron energy carries information about the fast ion energy. The details of neutron emission spectrometers, i.e., time-of-flight spectrometer, magnetic proton recoil spectrometer, and compact neutron emission spectrometer, as well as representative results of neutron spectrometry in Large Helical Device are reviewed.

Siriyaporn Sangaroon

Kunihiro Ogawa

Mitsutaka Isobe

Neutron emission spectrometer in magnetic confinement fusion

磁约束聚变中的中子发射谱仪

Abstract Quantum clock synchronization (QCS) can measure out the high-precision clock difference among distant users, which breaks through the standard quantum limit by employing the properties of quantum entanglement. Currently, the wavelength division multiplexed QCS network has been demonstrated with a spontaneous parametric down-conversion entangled photon source. In this paper, we propose a more efficient QCS network scheme with the wavelength multicasting entangled photon source, which can decrease at least 25% of wavelength channel consumption under the identical network scale. Afterwards, a four node QCS network is demonstrated, where the wavelength multicasting entangled photon source is utilized with dual-pumped four-wave mixing silicon chip. The experimental results show that the measured time deviation is 3.4 ps with an average time of 640 s via the multiple fiber links of more than 10 km.

Jiaao Li

Hui Han

Xiaopeng Huang

Bangying Tang

Kai Guo

Jinquan Huang

Siyu Xiong

Wanrong Yu

Zhaojian Zhang

Junbo Yang

Bo Liu

Huan Chen

Zhenkun Lu

Wavelength multicasting quantum clock synchronization network

波长多播量子时钟同步网络

Abstract To satisfy the needs of modern intelligent society for power supplies with long-endurance ability, Li-rich Mn-based layered oxides (LRMOs) are receiving much attention because of their ultrahigh capacity. However, their real-world implementation is hindered by the serious voltage decay, which results in a continuous decrease in energy density. The understanding on voltage decay still remains a mystery due to the complicated hybrid cationic-anionic redox and the serious surface-interface reactions in LRMOs. Moreover, some of the mechanisms are occasionally contradictory, indicating that the origin of voltage decay is still unclear. As a result, none of the innovative strategies proposed on the basis of mechanisms has effectively alleviated the problem of voltage decay, and voltage decay becomes a long-term distress of LRMOs. Therefore, it is particularly crucial to sort out the mutual relation of various mechanisms, which helps to go back to the source of voltage decay. In this review, we summarize the current mechanisms of voltage decay as structural evolution and oxygen chemistry, and attempt to trace the origin of voltage decay for LRMOs. In addition, we discuss how current researches address the issue with generalized guidance in designing appropriate strategies based on mechanisms.

Huixian Xie

Jiacheng Xiao

Hongyi Chen

Boyang Zhang

Kwun Nam Hui

Shanqing Zhang

Chenyu Liu

Dong Luo

Zhan Lin

Fundamental understanding of voltage decay in Li-rich Mn-based layered oxides cathode materials

富锂锰基层状氧化物正极材料电压衰减的基本理解

Abstract We present a theoretical review of the recent progress in non-equilibrium BCS (Bardeen-Cooper-Schrieffer)-BEC (Bose-Einstein condensation) crossover physics. As a paradigmatic example, we consider a strongly interacting driven-dissipative two-component Fermi gas where the non-equilibrium steady state is tuned by adjusting the chemical potential difference between two reservoirs that are coupled with the system. As a powerful theoretical tool to deal with this system, we employ the Schwinger-Keldysh Green’s function technique. We systematically evaluate the superfluid transition, as well as the single-particle properties, in the non-equilibrium BCS-BEC crossover region, by adjusting the chemical potential difference between the reservoirs and the strength of an s -wave pairing interaction associated with a Feshbach resonance. In the weak-coupling BCS side, the chemical potential difference is shown to imprint a two-step structure on the particle momentum distribution, leading to an anomalous enhancement of pseudogap, as well as the emergence of exotic Fulde-Ferrell-Larkin-Ovchinnikov-type superfluid instability. Since various non-equilibrium situations have recently been realized in ultracold Fermi gases, the theoretical understanding of non-equilibrium BCS-BEC crossover physics would become increasingly important in this research field.

Taira Kawamura

Yoji Ohashi

Non-equilibrium BCS-BEC crossover and unconventional FFLO superfluid in a strongly interacting driven-dissipative Fermi gas

强相互作用驱动耗散费米气体中的非平衡BCS-BEC跨越与非常规FFLO超流态

Ruyi Song

Rundong Zhao

Publisher Correction: Density functional theory study of two-dimensional hybrid organic-inorganic perovskites: frontier level alignment and chirality-induced spin splitting

出版者更正：二维杂化有机-无机钙钛矿的密度泛函理论研究：前沿能级对齐与手性诱导的自旋分裂

ISSN	0218-2203, 2309-4710
h-index	13

Publication Information	Publisher: Springer，Publishing cycle: ，Journal Type: journal，Open Access Journals: Yes
Basic data	Year of publication: 2021，Proportion of original research papers: ，Self Citation Rate:， Gold OA Rate:
Journal Fees	$2090Details
Average review cycle	11 weeks

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The development of active optical clock

Neutron emission spectrometer in magnetic confinement fusion

Wavelength multicasting quantum clock synchronization network

Fundamental understanding of voltage decay in Li-rich Mn-based layered oxides cathode materials

Non-equilibrium BCS-BEC crossover and unconventional FFLO superfluid in a strongly interacting driven-dissipative Fermi gas

Neutron emission spectrometer in magnetic confinement fusion

Fundamental understanding of voltage decay in Li-rich Mn-based layered oxides cathode materials

Wavelength multicasting quantum clock synchronization network

Non-equilibrium BCS-BEC crossover and unconventional FFLO superfluid in a strongly interacting driven-dissipative Fermi gas

Publisher Correction: Density functional theory study of two-dimensional hybrid organic-inorganic perovskites: frontier level alignment and chirality-induced spin splitting