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Fermi level tuning in Sn_(1-x)Pb_(x)Te/Pb heterostructure via changing interface roughness

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Science China(Physics,Mechanics & Astronomy) 2024年第8期67卷 118-125页

作者： Tengteng Liu Zhaoxia Yi Bangjin Xie Weiyan Zheng Dandan Guan Shiyong Wang Hao Zheng Canhua Liu Hao Yang Yaoyi Li Jinfeng Jia Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education) Tsung-Dao Lee InstituteSchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Shanghai Research Center for Quantum Sciences Shanghai 201315China Hefei National Laboratory Hefei 230088China

Superconducting SnTe-type topological crystalline insulators(TCIs)are predicted to host multiple Majorana zero modes(MZMs)which can coexist in a single *** level(FL)close to the Dirac points of topological surface states is helpful for detecting ***,the TCI SnTe is a heavily p-type semiconductor which is very difficult to modify to n-type via doping or *** this work,we fabricate the atomically flat Sn_(1-x)Pb_(x)Te/Pb heterostructure by molecular beam epitaxy,and make the p-type Sn_(1-x)Pb_(x)Te become n-type through changing the interface *** scanning tunnelling microscope,we find the Dirac points of Sn_(1-x)Pb_(x)Te/Pb heterostructure are always above the FL due to the Fermi level pinning(FLP)induced by topological surface states at atomically flat *** increasing the interface roughness,the FLP effect is suppressed and then the Dirac points of p-type Sn_(1-x)Pb_(x)Te can be tuned very close to or even below the *** work provides a new method for tuning the FL of SnTe-type TCI which has potential application in novel topological superconductor device.

关键词： topological crystalline insulator superconductor heterostructure Fermi level pinning interface roughness

New signature of low mass Z'in J/ψdecays

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Chinese Physics C 2024年第8期48卷 1-5页

作者： Chao-Qiang Geng Chia-Wei Liu Jiabao Zhang School of Fundamental Physics and Mathematical Sciences Hangzhou Institute for Advanced StudyUCASHangzhou 310024China tsung-dao lee institute&School of Physics and Astronomy Shanghai Jiao Tong UniversityShanghai 200240China institute of Theoretical Physics University of Chinese Academy of SciencesBeijing 100190China

We explored a new approach to search for a low-mass Z′particle through J/ψdecays by identifying its existence through parity-violating phenomena in the isospin-violating final states ofΛΣ¯^(0)and the corresponding charge conjugated states ofΛΣ¯^(0).Our investigation centered on a generation-independent and leptophobic Z′with mass below 10 *** the present experimental conditions at Beijing Spectrometer III(BESIII)and the anticipated opportunities at the Super Tau Charm Factory(STCF),we conducted Monte-Carlo simulations to predict possible events at both ***,we foresee a substantial enhancement in the precision of the lower limit estimation ofαNP as well as a reduction in statistical uncertainty with upcoming STCF ***,it is essential to highlight that a null result in the measurement ofαNP would impose stringent constraints,requiring the Z′−q−q couplings to be in the order of 10^(−2).

关键词： Z′ parity violation J/ψ

Optical modification of nonlinear crystals for quasi-parametric chirped-pulse amplification

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Fundamental Research 2024年第1期4卷 43-50页

作者： Qian Lin Jingui Ma Zhe Yin Peng Yuan Jing Wang Guoqiang Xie Liejia Qian Key Laboratory for Laser Plasmas(MOE) Collaborative Innovation Center of IFSASchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China tsung-dao lee institute Shanghai Jiao Tong UniversityShanghai 200240China

Quasi-parametric chirped-pulse amplification(QPCPA),which features a theoretical peak power much higher than those obtained with Ti:sapphire laser or optical parametric chirped-pulse amplification,is promising for future ultra-intense *** doped rare-earth ion used for idler dissipation is critical for effective QPCPA,but is usually not compatible with traditional *** far,only one dissipative crystal of Sm^(3+)-doped yttrium calcium oxyborate has been grown and *** we introduce optical means to modify traditional crystals for QPCPA *** theoretically demonstrate two dissipation schemes by idler frequency doubling and sum-frequency generation with an additional *** contrast to absorption dissipation,the proposed nonlinear dissipations ensure not only high signal efficiency but also high small-signal *** demonstrated ability to optically modify crystals will facilitate the wide application of QPCPA.

关键词： Quasi-parametric amplifier Second-harmonic generation Sum-frequency generation Back conversion Idler dissipation

Nearly degenerate ground states of a checkerboard antiferromagnet and their bosonic interpretation

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 84-89页

作者： Haiyuan Zou Fan Yang Wei Ku Key Laboratory of Polar Materials and Devices(MOE) School of Physics and Electronic ScienceEast China Normal UniversityShanghai 200241China Department of Physics Beijing Institute of TechnologyBeijing 100081China tsung-dao lee institute Shanghai 200240China Key Laboratory of Artificial Structures and Quantum Control(Ministry of Education) Shanghai 200240China Shanghai Branch Hefei National LaboratoryShanghai 201315China

The spin-1/2 model system with antiferromagnetic(AF) couplings on a J1-J2checkerboard lattice, known as the planar pyrochlore model, is strongly frustrated and associated with a two-to-one dimensional crossover. Using the Projected Entangled Simplex States tensor network ansatz, we identify a large number of nearly degenerate states in the frustrated region(J_(1)

关键词： tensor networks frustrated magnetism dimensional crossover degenerate states

Fermi level tuning in SnPbTe/Pb heterostructure via changing interface roughness

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Science China(Physics,Mechanics & Astronomy) 2024年

作者： Tengteng Liu Zhaoxia Yi Bangjin Xie Weiyan Zheng Dandan Guan Shiyong Wang Hao Zheng Canhua Liu Hao Yang Yaoyi Li Jinfeng Jia Key Laboratory of Artificial Structures and Quantum Control (Ministry of Education) Tsung-Dao Lee InstituteSchool of Physics and AstronomyShanghai Jiao Tong University Shanghai Research Center for Quantum Sciences Hefei National Laboratory

Superconducting SnTe-type topological crystalline insulators （TCIs） are predicted to host multiple Majorana zero modes（MZMs） which can coexist in a single vortex. Fermi level （FL） close to the Dirac points of topological surface states is helpful for detecting MZMs. However, the TCI SnTe is a heavily p-type semiconductor which is very difficult to modify to n-type via doping or alloying. In this work, we fabricate the atomically flat Sn1-xPbxTe/Pb heterostructure by molecular beam epitaxy, and make the p-type Sn1-xPbxTe become n-type through changing the interface roughness. Using scanning tunnelling microscope, we find the Dirac points of Sn1-xPbxTe/Pb heterostructure are always above the FL due to the Fermi level pinning （FLP） induced by topological surface states at atomically flat interface. After increasing the interface roughness, the FLP effect is suppressed and then the Dirac points of p-type Sn1-xPbxTe can be tuned very close to or even below the FL. Our work provides a new method for tuning the FL of SnTe-type TCI which has potential application in novel topological superconductor device.

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(DarkAI)Mapping the large-scale density field of dark matter using artificial intelligence

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Science China(Physics,Mechanics & Astronomy) 2024年第1期67卷 143-159页

作者： Zitong Wang Feng Shi Xiaohu Yang Qingyang Li Yanming Liu Xiaoping Li School of Aerospace Science and Technology Xidian UniversityXi’an 710126China Department of Astronomy School of Physics and Astronomyand Shanghai Key Laboratory for Particle Physics and CosmologyShanghai Jiao Tong UniversityShanghai 200240China tsung-dao lee institute and Key Laboratory for Particle Physics Astrophysics and CosmologyMinistry of EducationShanghai Jiao Tong UniversityShanghai 200240China institute for Astronomy University of EdinburghRoyal ObservatoryEdinburgh EH93HJUnited Kingdom

Herein,we present a deep-learning technique for reconstructing the dark-matter density field from the redshift-space distribution of dark-matter *** built a UNet-architecture neural network and trained it using the COmoving Lagrangian Acceleration fast simulation,which is an approximation of the N-body simulation with 5123 particles in a box size of 500 h^(-1)***,we tested the resulting UNet model not only with training-like test samples but also with standard N-body simulations,such as the Jiutian simulation with 61443particles in a box size of 1000 h^(-1)Mpc and the ELUCID simulation,which has a different *** real-space dark-matter density fields in the three simulations can be reconstructed reliably with only a small reduction of the cross-correlation power spectrum at 1%and 10%levels at k=0.1 and 0.3 h Mpc-1,*** reconstruction clearly helps to correct for redshift-space distortions and is unaffected by the different cosmologies between the training(Planck2018)and test samples(WMAP5).Furthermore,we tested the application of the UNet-reconstructed density field to obtain the velocity&tidal field and found that this approach provides better results compared with the traditional approach based on the linear bias model,showing a 12.2%improvement in the correlation slope and a 21.1%reduction in the scatter between the predicted and true ***,our method is highly efficient and has excellent extrapolation reliability beyond the training *** provides an ideal solution for determining the three-dimensional underlying density field from the plentiful galaxy survey data.

关键词： dark matter large-scale structure cosmology

Féeton(B-L gauge boson)dark matter for the 511-keV gamma-ray excess and the prediction of low-energy neutrino flux

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Chinese Physics C 2024年第8期48卷 76-82页

作者： Jie Sheng Yu Cheng Weikang Lin Tsutomu T.Yanagida tsung-dao lee institute&School of Physics and Astronomy Shanghai Jiao Tong UniversityChina Key Laboratory for Particle Astrophysics and Cosmology(MOE)&Shanghai Key Laboratory for Particle Physics and Cosmology Shanghai Jiao Tong UniversityShanghai 200240China South-Western institute For Astronomy Research Yunnan UniversityKunming 650500China Kavli IPMU(WPI) UTIASUniversity of TokyoKashiwa277-8583Japan

The féeton is the gauge boson of the U(1)_(B−L) gauge *** the gauge coupling constant is extremely small,the féeton becomes a candidate for dark *** show that its decay to a pair of an electron and a positron explains the observed Galactic 511-keV gamma-ray excess in a consistent *** féeton dark matter decays mainly into pairs neutrino and *** low-energy experiments with improved directional capability will enable capturing these neutrino *** seesaw-motivated parameter space predicts a relatively short féeton lifetime that is comparable to the current cosmological constraint.

关键词： feeton 511-keV gamma-ray excess low-energy neutrino

A comparative lattice analysis of SU(2)dark glueballs

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Chinese Physics C 2024年第8期48卷 113-126页

作者： Min-Huan Chu Jun-Hui Lai Wei Wang Jialu Zhang Qianteng Zhu INPAC Key Laboratory for Particle Astrophysics and Cosmology(MOE)Shanghai Key Laboratory for Particle Physics and CosmologySchool of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 200240China Yang Yuanqing Scientific Computering Center Tsung-Dao Lee InstituteShanghai Jiao Tong UniversityShanghai 200240China Southern Center for Nuclear-Science Theory(SCNT) Institute of Modern PhysicsChinese Academy of SciencesHuizhou 516000China

We study the mass and scattering cross section of SU(2)glueballs as dark matter candidates using lattice *** employ both naive and improved SU(2)gauge actions in 3+1 dimensions with severalβvalues,and we adopt both the traditional Monte Carlo method and flow-based model based on machine learning techniques to generate lattice *** mass of a dark scalar glueball with J^(PC)=0^(++)and the Nambu-Bethe-Salpeter wave function are *** a coupling constant ofβ=2.2 as an illustration,we compare the dark glueball mass calculated from the configurations generated from the two *** consistent results can be achieved,the two methods demonstrate distinct *** the Runge-Kutta method,we extract the glueball interaction potential and two-body scattering cross *** the observational constraints,we obtain the lower bound of the mass of scalar glueballs as candidates of dark matter.

关键词： lattice QCD dark matter machine learning

Surface doping manipulation of the insulating ground states in Ta_(2)Pd_(3)Te_(5) and Ta_(2)Ni_(3)Te_(5)

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Chinese Physics B 2024年第6期33卷 88-93页

作者：江北姚静宇闫大禹郭照芃屈歌星邓修同黄耀波丁洪石友国王志俊钱天 Beijing National Laboratory for Condensed Matter Physics and institute of Physics Chinese Academy of SciencesBeijing 100190China University of Chinese Academy of Sciences Beijing 100049China Songshan Lake Materials Laboratory Dongguan 523808China Shanghai Synchrotron Radiation Facility Shanghai Advanced Research InstituteChinese Academy of SciencesShanghai 201204China tsung-dao lee institute New Cornerstone Science Laboratoryand School of Physics and AstronomyShanghai Jiao Tong UniversityShanghai 201210China Hefei National Laboratory Hefei 230088China

Manipulating emergent quantum phenomena is a key issue for understanding the underlying physics and contributing to possible *** we study the evolution of insulating ground states of Ta_(2)Pu_(3)Te_(5) and Ta_(2)Ni_(3)Te_(5) under in-situ surface potassium deposition via angle-resolved photoemission *** results confirm the excitonic insulator character of Ta_(2)d_(3)Te_(5).Upon surface doping,the size of its global gap decreases *** a deposition time of more than 7 min,the potassium atoms induce a metal-insulator phase transition and make the system recover to a normal *** contrast,our results show that the isostructural compound Ta_(2)Ni_(3)Te_(5) is a conventional *** size of its global gap decreases upon surface doping,but persists positive throughout the doping *** results not only confirm the excitonic origin of the band gap in Ta_(2)Pd_(3)Te_(5),but also offer an effective method for designing functional quantum devices in the future.

关键词： excitonic insulator metal–insulator phase transition surface doping angle-resolved photoemission spectroscopy