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Unveiling a Novel Insulator-to-Metal Transition in La_(N)iO_(4+δ):Challenging High-Temperature Superconductivity Claimed for Single-Layer Lanthanum Nickelates

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Chinese physics Letters 2024年第9期41卷 93-106页

作者： Yunqi Ji Xiaohan Wang Xiaohe Li Wenting Tang Xinyang Li Xin Wang Fangfei Li Liang Li Qiang Zhou Synergetic extreme condition User Facility State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin UniversityChangchun 130012China

La_(2)NiO_(4)has a similar structure to La_(2)CuO_(4)and was proposed as a high-temperature superconductor based on magnetic-moment measurements decades ***,with the exception for electrical resistance drop behavior of about 4 orders of magnitude that is claimed to originate from the superconductivity ever observed in Sr-doped La_(N)iO_(4),most electrical data reported to date in La_(N)iO_(4)system exhibit a trivial insulating ground ***,we definitively identify the similar electrical resistance drop behavior of more than 3 orders of magnitude in La_(2)NiO_(4+δ).However,our extensive investigations reveal that this phenomenon is a novel insulatorto-metal transition,distinct from ***,compared to the weak magnetic-field effects,pressure can significantly suppress the transition and transform from the metallic to an insulating ground state,accompanied by an isostructural phase *** work not only elucidates the fundamental properties of the metallic conducting ground state in La_(N)iO_(4)+δ,but also critically challenges the notion of superconductivity in single-layer lanthanum nickelates.

关键词： resistance electrical metallic

Ultrafast investigation of room temperature valley polarization in“optical bilayer”WS_(2)

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Science China(Technological Sciences) 2024年第1期67卷 91-97页

作者： ZHAO LeYi WANG Hai LIU TianYu LI FangFei ZHOU Qiang WANG HaiYu Synergetic extreme condition High-Pressure Science Center State Key Laboratory of Superhard MaterialsCollege of PhysicsJilin UniversityChangchun 130012China State Key laboratory of Integrated Optoelectronics College of Electronic Science and EngineeringJilin UniversityChangchun 130012China

Monolayer transition metal dichalcogenides(TMDCs)have become a promising platform in valleytronics due to possessing the regulatable valley degrees of ***,as a result of the rapid intervalley scattering,it is difficult to measure the PL valley polarization of monolayer TMDCs at room temperature,which limits their application in valleytronics ***,we report a room temperature photoluminescence(PL)valley polarization up to 3.73%in an“optical bilayer”WS_(2)formed by transferring monolayer WS_(2)onto flat Ag ***,in the transient absorption(TA)measurements,a remarkably long valley depolarization lifetime is ***,we demonstrate the valley properties of such“optical bilayer”WS_(2)resemble actual bilayer WS_(2),in which the robust valley polarization can be attributed to the phonons depletion effect and the blocked interlayer hopping *** peculiar valley features in“optical bilayer”WS_(2)provide a particularly simple method to enhance valley control at room temperature.

关键词： valleytronics optical bilayer transient absorption tungsten disulfide

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Unveiling a Novel Insulator-to-Metal Transition in La2NiO4+δ:Challenging High-Temperature Superconductivity Claimed for Single-Layer Lanthanum Nickelates

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Chinese physics Letters 2024年第9期 73-78页

作者：吉云奇王晓晗李晓赫唐雯婷李新阳王鑫李芳菲李亮周强 Synergetic extreme condition User Facility State Key Laboratory of Superhard MaterialsCollege of Physics Jilin University

La2NiO4has a similar structure to La2CuO4and was proposed as a high-temperature superconductor based on magnetic-moment measurements decades ago. Nevertheless, with the exception for electrical resistance drop behavior of about 4 orders of magnitude that is claimed to originate from the superconductivity ever observed in Sr-doped La2NiO4, most electrical data reported to date in La2NiO4system exhibit a trivial insulating ground state.

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Pressure generation under deformation in a large-volume press

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Chinese physics B 2024年第09期 626-630页

作者：王赛赛赵鑫宇胡阔丰丙涛侯旭远张羿鸣刘书成尚宇琛刘兆东姚明光刘冰冰 State Key laboratory of Superhard Materials Synergetic Extreme Condition User Facility College of PhysicsJilin University College of Earth Sciences Jilin University

Deformation can change the transition pathway of materials under high pressure, thus significantly affects physical and chemical properties of matters. However, accurate pressure calibration under deformation is challenging and thereby causes relatively large pressure uncertainties in deformation experiments, resulting in the synthesis of complex multiphase materials. Here, pressure generations of three types of deformation assemblies were well calibrated in a Walker-type largevolume press（LVP） by electrical resistance measurements combined with finite element simulations（FESs）. Hard Al2O3or diamond pistons in shear and uniaxial deformation assemblies significantly increase the efficiency of pressure generation compared with the conventional quasi-hydrostatic assembly. The uniaxial deformation assembly using flat diamond pistons possesses the highest efficiency in these deformation assemblies. This finding is further confirmed by stress distribution analysis based on FESs. With this deformation assembly, we found shear can effectively promote the transformation of C60into diamond under high pressure and realized the synthesis of phase-pure diamond at relatively moderate pressure and temperature conditions. The present developed techniques will help improve pressure efficiencies in LVP and explore the new physical and chemical properties of materials under deformation in both science and technology.

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Coupling ideality of standing-wave supermode microresonators

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Photonics Research 2024年第08期12卷 1610-1618页

作者： MIN WANG YUECHEN LEI ZHI-GANG HU CHENGHAO LAO YUANLEI WANG XIN ZHOU JINCHENG LI QI-FAN YANG BEI-BEI LI Beijing National laboratory for Condensed Matter physics Institute of PhysicsChinese Academy of Sciences University of Chinese Academy of Sciences State Key laboratory for Mesoscopic physics and Frontiers Science Center for Nano-optoelectronics School of PhysicsPeking University School of physics Beihang University Collaborative Innovation Center of extreme Optics Shanxi University Songshan Lake Materials laboratory

Standing-wave supermode microresonators that are created through the strong coupling between counter-propagating modes have emerged as versatile platforms for sensing and nonlinear optics. For example, these microresonators have shown potential in nanoparticle sizing and counting, as well as enhancing the single-photon optomechanical coupling rate of stimulated Brillouin scattering. However, it has been observed that the relation between the mode linewidth and on-resonance transmission of the split supermodes differs obviously from that of the non-split modes. This behavior is typically quantified by the coupling ideality(I), which remains inadequately explored for the standing-wave supermodes. In this study, we theoretically and experimentally investigate the coupling ideality of standing-wave supermodes in a commonly employed configuration involving a Si O2microresonator side-coupled to a tapered fiber. Our findings demonstrate that, even with a single-mode tapered fiber, the coupling ideality of the standing-wave supermodes is limited to 0.5, due to the strong backscattering-induced energy loss into the counter-propagating direction, resulting in an additional equivalent parasitic loss. While achieving a coupling ideality of 0.5 presents challenges for reaching over-coupled regimes,it offers a convenient approach for adjusting the total linewidth of the modes while maintaining critically-coupled conditions.

关键词： Optical filters Rayleigh scattering Single mode fibers Stimulated Brillouin scattering Tapered fibers Waveguide modes

A virtual thermometer for ultrahigh-temperature-pressure experiments in a large-volume press

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Matter and Radiation at extremes 2024年第4期9卷 98-110页

作者： Bingtao Feng Longjian Xie Xuyuan Hou Shucheng Liu Luyao Chen Xinyu Zhao Chenyi Li Qiang Zhou Kuo Hu Zhaodong Liu Bingbing Liu State Key laboratory of Superhard Materials Synergetic Extreme Condition User FacilityCollege of PhysicsJilin UniversityChangchun 130012China Department of Earth Sciences University College LondonLondon WC1E 6BSUnited Kingdom Earth and Planetary laboratory Carnegie Institute for ScienceWashingtonDistrict of Columbia 20015USA College of Earth Sciences Jilin UniversityChangchun 130012China

Ultrahigh-temperature-pressure experiments are crucial for understanding the physical and chemical properties of *** recent development of boron-doped diamond(BDD)heaters has made such melting experiments possible in large-volume ***,estimates of temperatures above 2600 K and of the temperature distributions inside BDD heaters are not well constrained,owing to the lack of a suitable ***,we establish a three-dimensional finite element model as a virtual thermometer to estimate the temperature and temperature field above 2600 *** advantage of this virtual thermometer over those proposed in previous studies is that it considers both alternating and direct current heating modes,the actual sizes of cell assemblies after compression,the effects of the electrode,thermocouple and anvil,and the heat dissipation by the pressure-transmitting *** virtual thermometer reproduces the power-temperature relationships of ultrahigh-temperature-pressure experiments below 2600 K at press loads of 2.8-7.9 MN(~19 to 28 GPa)within experimental *** temperatures above 2600 K predicted by our virtual thermometer are within the uncertainty of those extrapolated from power-temperature relationships below 2600 ***,our model shows that the temperature distribution inside a BDD heater(19-26 K/mm along the radial direction and<83 K/mm along the longitudinal direction)is more homogeneous than those inside conventional heaters such as graphite or LaCrO_(3) heaters(100-200 K/mm).Our study thus provides a reliable virtual thermometer for ultrahigh-temperature experiments using BDD heaters in Earth and material sciences.

关键词： virtual ultrahigh sizes

Deep-learning-empowered synthetic dimension dynamics: morphing of light into topological modes

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Advanced Photonics 2024年第2期6卷 61-68页

作者： Shiqi Xia Sihong Lei Daohong Song Luigi Di Lauro Imtiaz Alamgir Liqin Tang Jingjun Xu Roberto Morandotti Hrvoje Buljan Zhigang Chen Nankai University TEDA Institute of Applied Physics School of Physics The MOE Key Laboratory of Weak-Light Nonlinear Photonics Shanxi University Collaborative Innovation Center of Extreme Optics INRS-EMT University of Zagreb Department of PhysicsFaculty of Science

Synthetic dimensions(SDs) opened the door for exploring previously inaccessible phenomena in high-dimensional space. However, construction of synthetic lattices with desired coupling properties is a challenging and unintuitive task. Here, we use deep learning artificial neural networks(ANNs) to construct lattices in real space with a predesigned spectrum of mode eigenvalues, and thus to validly design the dynamics in synthetic mode dimensions. By employing judiciously chosen perturbations(wiggling of waveguides at desired frequencies), we show resonant mode coupling and tailored dynamics in SDs. Two distinct examples are illustrated: one features uniform synthetic mode coupling, and the other showcases the edge defects that allow for tailored light transport and confinement. Furthermore, we demonstrate morphing of light into a topologically protected edge mode with modified Su–Schrieffer–Heeger photonic lattices. Such an ANN-assisted construction of SDs may advance toward “utopian networks,” opening new avenues for fundamental research beyond geometric limitations as well as for applications in mode lasing,optical switching, and communication technologies.

关键词： synthetic dimensions deep learning mode manipulation topological mode morphing photonic lattices

Twin-Capture Rydberg State Excitation Enhanced with Few-Cycle Laser Pulses

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Chinese physics Letters 2024年第1期41卷 6-10页

作者：赵晶刘金磊王小伟赵增秀 Department of physics National University of Defense TechnologyChangsha 410073China Hunan Key laboratory of extreme Matter and Applications National University of Defense TechnologyChangsha 410073China

Quantum excitation is usually regarded as a transient process occurring instantaneously,leaving the underlying physics shrouded in *** research shows that Rydberg-state excitation with ultrashort laser pulses can be investigated and manipulated with state-of-the-art few-cycle *** theoretically find that the efficiency of Rydberg state excitation can be enhanced with a short laser pulse and modulated by varying the laser *** also uncover new facets of the excitation dynamics,including the launching of an electron wave packet through strong-field ionization,the re-entry of the electron into the atomic potential and the crucial step where the electron makes a U-turn,resulting in twin captures into Rydberg *** tuning the laser intensity,we show that the excitation of the Rydberg state can be coherently controlled on a sub-optical-cycle *** work paves the way toward ultrafast control and coherent manipulation of Rydberg states,thus benefiting Rydberg-state-based quantum technology.

关键词： Rydberg excitation coherent

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Programmable silicon-photonic quantum simulator based on a linear combination of unitaries

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Photonics Research 2024年第8期12卷 1760-1767页

作者： YUE YU YULIN CHI CHONGHAO ZHAI JIESHAN HUANG QIHUANG GONG JIANWEI WANG State Key laboratory for Mesoscopic physics School of Physics Peking University Frontiers Science Center for Nano-optoelectronics & Collaborative Innovation Center of Quantum Matter Peking University Collaborative Innovation Center of extreme Optics Shanxi University Yangtze Delta Institute of Optoelectronics Peking University Hefei National laboratory

Simulating the dynamic evolution of physical and molecular systems in a quantum computer is of fundamental interest in many applications. The implementation of dynamics simulation requires efficient quantum algorithms. The Lie-Trotter-Suzuki approximation algorithm, also known as the Trotterization, is basic in Hamiltonian dynamics simulation. A multi-product algorithm that is a linear combination of multiple Trotterizations has been proposed to improve the approximation accuracy. However, implementing such multiproduct Trotterization in quantum computers remains challenging due to the requirements of highly controllable and precise quantum entangling operations with high success probability. Here, we report a programmable integrated-photonic quantum simulator based on a linear combination of unitaries, which can be tailored for implementing the linearly combined multiple Trotterizations, and on the simulator we benchmark quantum simulation of Hamiltonian dynamics. We modify the multi-product algorithm by integrating it with oblivious amplitude amplification to simultaneously reach high simulation precision and high success probability. The quantum simulator is devised and fabricated on a large-scale silicon-photonic quantum chip, which allows the initialization, manipulation, and measurement of arbitrary four-qubit states and linearly combined unitary gates. As an example, the quantum simulator is reprogrammed to emulate the dynamics of an electron spin and nuclear spin coupled system. This work promises the practical dynamics simulations of real-world physical and molecular systems in future large-scale quantum computers. ? 2024 Chinese Laser Press

关键词： Numerical simulation Quantum computation Quantum simulator Quantum technology Signal processing Silicon photonics