AAPPS Bulletin

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

AAPPS bulletin

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

Abstract Polaron, a typical quasi-particle that describes a single impurity dressed with surrounding environment, serves as an ideal platform for bridging few- and many-body physics. In particular, different few-body correlations can compete with each other and lead to many intriguing phenomena. In this work, we review the recent progresses made in understanding few-body correlation effects in attractive Fermi polarons of ultracold gases. By adopting a unified variational ansatz that incorporates different few-body correlations in a single framework, we will discuss their competing effects in Fermi polarons when the impurity and majority fermions have the same or different masses. For the equal-mass case, we review the nature of polaron-molecule transition that is driven by two-body correlations, and especially highlight the finite momentum character and huge degeneracy of molecule states. For the mass-imbalanced case, we focus on the smooth crossover between polaron and various dressed clusters that originate from high-order correlations. These competing few-body correlations reviewed in Fermi polarons suggest a variety of exotic new phases in the corresponding many-body system of Fermi-Fermi mixtures.

Ruijin Liu

Xiaoling Cui

Competing few-body correlations in ultracold Fermi polarons

超冷费米极化子中的竞争少体关联

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

The development of active optical clock

主动光学时钟的发展

Abstract We present a microscopic many-body calculation of the nonlinear two-dimensional coherent spectroscopy (2DCS) of trion-polaritons and exciton-polaritons in charge-tunable transition-metal-dichalcogenides monolayers placed in an optical microcavity. The charge tunability leads to an electron gas with nonzero density that brings brightness to the trion — a polaron quasiparticle formed by an exciton with a nonzero residue bounded to the electron gas. As a result, a trion-polariton is created under strong light-matter coupling, as observed in the recent experiment by Sidler et al. [Nat. Phys. 13, 255 (2017)]. We analyze in detail the structure of trion-polaritons, by solving an extended Chevy ansatz for the trion quasiparticle wave-function. We confirm that the effective light-matter coupling for trion-polaritons is determined by the residue of the trion quasiparticle. The solution of the full many-body polaron states within Chevy ansatz enables us to microscopically calculate the nonlinear 2DCS spectrum of both trion-polaritons and exciton-polaritons. We predict the existence of three kinds of off-diagonal cross-peaks in the 2DCS spectrum, as an indication of the coherence among the different branches of trion-polaritons and exciton-polaritons. Due to the sensitivity of 2DCS spectrum to quasiparticle interactions, our work provides a good starting point to explore the strong nonlinearity exhibited by trion-polaritons in some recent exciton-polariton experiments.

Hui Hu

Jia Wang

Riley Lalor

Xia-Ji Liu

Two-dimensional coherent spectroscopy of trion-polaritons and exciton-polaritons in atomically thin transition metal dichalcogenides

二维相干光谱学在原子级薄层过渡金属二硫化物中的激子极化子和激子-极化子

Abstract NASICON (Na $$_{1+x}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow> <mml:mn>1</mml:mn> <mml:mo>+</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> <mml:mrow/> </mml:mmultiscripts> </mml:math> Zr $$_2$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mn>2</mml:mn> <mml:mrow/> </mml:mmultiscripts> </mml:math> Si $$_x$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mi>x</mml:mi> <mml:mrow/> </mml:mmultiscripts> </mml:math> P $$_{3-x}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mrow> <mml:mn>3</mml:mn> <mml:mo>-</mml:mo> <mml:mi>x</mml:mi> </mml:mrow> <mml:mrow/> </mml:mmultiscripts> </mml:math> O $$_{12}$$ <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mmultiscripts> <mml:mrow/> <mml:mn>12</mml:mn> <mml:mrow/> </mml:mmultiscripts> </mml:math> ) is a well-established solid-state electrolyte, renowned for its high ionic conductivity and excellent chemical stability, rendering it a promising candidate for solid-state batteries. However, the intricate influence of ion doping on their performance has been a central focus of research, with existing studies often lacking comprehensive evaluation methods. This study introduces a deep-learning-based approach to efficiently evaluate ion-doped NASICON materials. We developed a convolutional neural network (CNN) model capable of predicting the performance of various ion-doped NASICON compounds by leveraging extensive datasets from prior experimental investigation. The model demonstrated high accuracy and efficiency in predicting ionic conductivity and electrochemical properties. Key findings include the successful synthesis and validation of three NASICON materials predicted by the model, with experimental results closely matching the model’s predictions. This research not only enhances the understanding of ion-doping effects in NASICON materials but also establishes a robust framework for material design and practical applications. It bridges the gap between theoretical predictions and experimental validations. Graphical Abstract

Zirui Zhao

Xiaoke Wang

Si Wu

Pengfei Zhou

Qian Zhao

Guanping Xu

Kaitong Sun

Hai-Feng Li

Deep learning-driven evaluation and prediction of ion-doped NASICON materials for enhanced solid-state battery performance

深度学习驱动的掺杂离子NASICON材料评估与预测，以提升固态电池性能

Abstract In September 2022, Yemilab, a new underground laboratory, was finally completed in Jeongseon, Gangwon Province, South Korea. Situated at a depth of 1000 m, it boasts an exclusive experimental area of 3000 m 2 . Currently, preparations are in progress for the AMoRE-II experiment, which aims to investigate neutrinoless double beta decay, as well as for the COSINE-100 upgrade (COSINE-100U), a direct dark matter detection experiment. Both experiments are scheduled to commence in the second quarter of 2024 at Yemilab. Furthermore, the facility encompasses a cylindrical pit, approximately 6300 m 3 in volume, designed to serve as a multipurpose laboratory. This laboratory will facilitate next-generation experiments focusing on neutrinos, dark matter, and related areas of research. This article presents a detailed overview of Yemilab’s construction, infrastructure, and its pivotal physics programs.

Yeongduk Kim

Hyun Su Lee

Yemilab, a new underground laboratory in Korea

韩国新建地下实验室Yemilab

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

涉及主题	physics
出版信息	出版商: Springer，出版周期: ，期刊类型: journal，开源期刊: 是
基本数据	创刊年份: 2021，原创研究文献占比: ，自引率:， Gold OA占比:
期刊费用	$2090详情
平均审稿周期	11 weeks

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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

Competing few-body correlations in ultracold Fermi polarons

The development of active optical clock

Two-dimensional coherent spectroscopy of trion-polaritons and exciton-polaritons in atomically thin transition metal dichalcogenides

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

Competing few-body correlations in ultracold Fermi polarons

Deep learning-driven evaluation and prediction of ion-doped NASICON materials for enhanced solid-state battery performance

Yemilab, a new underground laboratory in Korea