Band inversion induced by spin–orbit coupling in topological semimetals typically generates light charge carriers with high Fermi velocities,which are highly desirable for low-dissipation and coherent quantum transpo...Band inversion induced by spin–orbit coupling in topological semimetals typically generates light charge carriers with high Fermi velocities,which are highly desirable for low-dissipation and coherent quantum transport in topological devices.The presence of these carriers in real materials strongly depends on the Fermi-level position.2M-WSe_(2),with its topological and van der Waals nature,serves as an ideal platform for studying quantum transport in two-dimensional systems,despite the fact that interlayer coupling suppresses the formation of light carriers.In this study,we solvothermally intercalate 1,3-diaminopropane molecules into the interlayer space of 2M-WSe_(2);these molecules effectively adapt to the electronic structure by eliminating interlayer coupling.Simultaneously,slight electron doping via charge transfer results in a small Fermi pocket with an extremely light effective mass,0.04–0.06 me,as revealed by quantum oscillation measurements.This study demonstrates that molecular intercalation is an effective approach for engineering van der Waals topological materials to achieve specific quantum transport properties.展开更多
This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the i...This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the increase of light amplitude;(Ⅳ)Formalism for light-induced anomalous Hall effects.展开更多
The doped quantum spin liquid on the kagome lattice provides a fascinating platform to explore exotic quantum states,such as the reported holon Wigner crystal at low doping.By extending the doping range toδ=0.027–0....The doped quantum spin liquid on the kagome lattice provides a fascinating platform to explore exotic quantum states,such as the reported holon Wigner crystal at low doping.By extending the doping range toδ=0.027–0.36,we studied the kagome-lattice t-J model using state-of-the-art density matrix renormalization group calculations.On the L_(y)=3 cylinder(Ly is the number of unit cells along the circumferential direction),we established a quantum phase diagram with an increasing doping level.In addition to the charge density wave states at lower doping levels,we found an emergent Fermi-liquid-like phase by melting the holon Wigner crystal at δ≈0.15,which is characterized by the suppression of charge density oscillation and power-law decay of various correlation functions.For a wider L_(y)=4 cylinder,the bond-dimension extrapolated correlation functions also support such a Fermi-liquid-like state,suggesting its stability with increasing system size.In a narrow doping range near δ=1/3 for the L_(y)=3 cylinder,we find a state with an exponential decay of the single-particle correlation,but the other correlation functions preserve the features in the Fermi-liquid-like phase,which may be a precursor of a superconducting state.Nevertheless,this peculiar state nearδ=1/3 disappears for the L_(y)=4 cylinder,implying a possible lattice-size dependence.Our results reveal quantum melting from a holon Wigner crystal to a Fermi-liquid-like state with increasing hole density and suggest a doping regime to explore superconductivity in future studies.展开更多
The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced qu...The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced quantum electrodynamics.We used the perturbative renormalization group method to study the low-energy behavior of the system and found that it flows to a fixed point of the non-Fermi liquid composed of relativistic pseudospin-1/2 Dirac fermions in the deep infrared limit.At the fixed point,the fermion Green function exhibits a finite anomalous dimension,and the residue of the quasiparticle pole vanishes in a power-law fashion.Our research provides new theoretical perspectives for understanding the origin of spin-1/2 fermions in the standard model.展开更多
We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay betwe...We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay between non-Hermiticity and birefringence leads to distinct behaviors in two and three dimensions, where the system exhibits different fixed points and scaling properties due to dimension-dependent charge renormalization effects. In two dimensions, where the electronic charge remains unrenormalized, the system flows in the deep infrared limit from non-Hermitian birefringent spin-3/2fermions to two copies of non-Hermitian spin-1/2 Dirac fermions, demonstrating a crossover of relativistic liquid and nonrelativistic liquid. In three dimensions, dynamic screening of electromagnetic interactions modifies the logarithmic growth of Fermi velocity, leading to richer quantum corrections while maintaining similar suppression of birefringence in the infrared limit. Our findings provide theoretical insights into the emergence of Lorentz symmetry in non-Hermitian systems,laying theoretical foundations for studying low-energy behavior in other non-Hermitian models.展开更多
We demonstrate a reinforcement learning(RL)-based control framework for optimizing evaporative cooling in the preparation of strongly interacting degenerate Fermi gases of 6Li.Using a Soft Actor-Critic(SAC)algorithm,t...We demonstrate a reinforcement learning(RL)-based control framework for optimizing evaporative cooling in the preparation of strongly interacting degenerate Fermi gases of 6Li.Using a Soft Actor-Critic(SAC)algorithm,the system autonomously explores a high-dimensional parameter space to learn optimal cooling trajectories.Compared to conventional exponential ramps,our method achieves up to 130%improvement in atomic density within 0.5 second,revealing non-trivial control strategies that balance fast evaporation and thermalization.While our current optimization focuses on the evaporation stage,future integration of other cooling stages,such as gray molasses cooling,could further extend RL to the full preparation pipeline.Our result highlights the promise of RL as a general tool for closed-loop quantum control and automated calibration in complex atomic physics experiments.展开更多
We investigate distinct non-Hermitian skin effects(NHSEs)in real and Fock spaces induced by the interplay between the Hilbert space fragmentation and multiple non-Hermitian pumping channels.Using an extended Hatano–N...We investigate distinct non-Hermitian skin effects(NHSEs)in real and Fock spaces induced by the interplay between the Hilbert space fragmentation and multiple non-Hermitian pumping channels.Using an extended Hatano–Nelson model with next-nearest neighbor hopping and strong interaction as an example,we found that two fermions loaded in the lattice exhibit different real-space NHSE depending on the Hilbert space fragments to which they belong.Moreover,in the high-energy sector resulting from fragmentation,the two-particle-bound states form a one-dimensional lattice in Fock space,producing a Fock-space NHSE.At half-filling,richer patterns of Fock-space skin-like localization emerge for the different fragmented energy sectors and subsectors while realspace NHSE is suppressed by many-body effects.This study extends our understanding of the interplay between NHSE and Hilbert space fragmentation and provides detailed insights into their manifestation in interacting non-Hermitian systems.展开更多
本文通过将给定的单层周期量子图与具有循环群作用的正三边形做笛卡尔积构造了一类“三层”量子图,其中正三边形被称为连接图,得到“三层”量子图的函数空间分解和算子分解,证明了其Fermi面可约,并将结论推广到连接图为具有循环群作用的...本文通过将给定的单层周期量子图与具有循环群作用的正三边形做笛卡尔积构造了一类“三层”量子图,其中正三边形被称为连接图,得到“三层”量子图的函数空间分解和算子分解,证明了其Fermi面可约,并将结论推广到连接图为具有循环群作用的正n边形情况。 This paper constructs a class of"three-layer" quantum graphs by taking the Cartesian product of a given single-layer periodic quantum graph with an equilateral triangle (referred to as the connecting graph) endowed with a cyclic group action. The function space decomposition and operator decomposition of the resulting"three-layer" quantum graphs are derived. It is proven that their Fermi surfaces are reducible. Furthermore, the conclusions are generalized to the case where the connecting graph is a regular n-gon with a cyclic group action.展开更多
We investigate the topological phase marked by the Thouless–Kohmoto–Nightingale–Nijs（TKNN） number and the phase transitions driven by the next nearest neighbor（NNN） hopping in noncentrosymmetric cold Fermi gase...We investigate the topological phase marked by the Thouless–Kohmoto–Nightingale–Nijs（TKNN） number and the phase transitions driven by the next nearest neighbor（NNN） hopping in noncentrosymmetric cold Fermi gases, both spinsinglet pairing and spin-triplet pairing are considered. There exists a critical t＇c for the NNN hopping, at which the quantum phase transition occurs, and the system changes from an Abelian（non-Abelian） phase to a non-Abelian（Abelian） one. By numerically diagonalizing the Hamiltonian in the real space, the energy spectra with edge states for different topological phases and the Majorana zero modes are discussed. Although the spin-triplet pairing does not contribute to the gap closing and the phase diagram, it induces gapless states in the presence of a magnetic field, and the TKNN number in this region is still zero.展开更多
We demonstrate that dual dark magnetic-optical-traps(MOTs)have great importance in the two-species^(87)Rb and^(40)K mixture compared with dual bright MOTs.The dark MOT has a little improvement in the trapping of singl...We demonstrate that dual dark magnetic-optical-traps(MOTs)have great importance in the two-species^(87)Rb and^(40)K mixture compared with dual bright MOTs.The dark MOT has a little improvement in the trapping of single-species^(87)Rb or^(40)K gases compared with bright MOT.For the case of loading two-species^(87)Rb and^(40)K simultaneously,the improvement of^(40)K in the dual dark MOTs is mainly from the reduction of light-assisted collision losses.The dual dark MOTs employ a pair of conical lenses to produce the hollow beam for repump laser with high efficiency.The number and density of^(87)Rb and^(40)K atoms after evaporative cooling in the hybrid magnetic trap with dark MOT loading are compared with those in bright MOT.The atoms with large number and high density make it easier to realize the quantum degenerate of Bose-Fermi mixture.展开更多
基金supported by the National Key Research and Development Program of China (Grant No.2023YFA1406301)the National Natural Science Foundation of China (Grant Nos.52250308 and 52525205)。
文摘Band inversion induced by spin–orbit coupling in topological semimetals typically generates light charge carriers with high Fermi velocities,which are highly desirable for low-dissipation and coherent quantum transport in topological devices.The presence of these carriers in real materials strongly depends on the Fermi-level position.2M-WSe_(2),with its topological and van der Waals nature,serves as an ideal platform for studying quantum transport in two-dimensional systems,despite the fact that interlayer coupling suppresses the formation of light carriers.In this study,we solvothermally intercalate 1,3-diaminopropane molecules into the interlayer space of 2M-WSe_(2);these molecules effectively adapt to the electronic structure by eliminating interlayer coupling.Simultaneously,slight electron doping via charge transfer results in a small Fermi pocket with an extremely light effective mass,0.04–0.06 me,as revealed by quantum oscillation measurements.This study demonstrates that molecular intercalation is an effective approach for engineering van der Waals topological materials to achieve specific quantum transport properties.
文摘This supplemental material contains three sections:(Ⅰ)Derivation of the Floquet lattice Hamiltonian;(Ⅱ)Surface states of the Floquet lattice Hamiltonian;(Ⅲ)Evolution of Floquet Weyl points and Fermi arcs with the increase of light amplitude;(Ⅳ)Formalism for light-induced anomalous Hall effects.
基金supported by the National Natural Science Foundation of China (Grant Nos.12274014 and 12534009)the Guangdong Provincial Quantum Science Strategic Initiative (Grant No.GDZX2501006)+4 种基金the Special Project in Key Areas for Universities in Guangdong Province (Grant No.2023ZDZX3054)the Dongguan Key Laboratory of Artificial Intelligence Design for Advanced Materialssupported by the U.S.Department of Energy,Office of Basic Energy Sciences (Grant No.DE-FG02-06ER46305) for DMRG studies on unconventional superconductivitysupported by the SongShan Lake HPC Center (SSL-HPC) at Great Bay University (X.Y.J.and S.S.G.)supported in part by the US National Science Foundation (Grant No.DMR-2406524) (D.N.S.)。
文摘The doped quantum spin liquid on the kagome lattice provides a fascinating platform to explore exotic quantum states,such as the reported holon Wigner crystal at low doping.By extending the doping range toδ=0.027–0.36,we studied the kagome-lattice t-J model using state-of-the-art density matrix renormalization group calculations.On the L_(y)=3 cylinder(Ly is the number of unit cells along the circumferential direction),we established a quantum phase diagram with an increasing doping level.In addition to the charge density wave states at lower doping levels,we found an emergent Fermi-liquid-like phase by melting the holon Wigner crystal at δ≈0.15,which is characterized by the suppression of charge density oscillation and power-law decay of various correlation functions.For a wider L_(y)=4 cylinder,the bond-dimension extrapolated correlation functions also support such a Fermi-liquid-like state,suggesting its stability with increasing system size.In a narrow doping range near δ=1/3 for the L_(y)=3 cylinder,we find a state with an exponential decay of the single-particle correlation,but the other correlation functions preserve the features in the Fermi-liquid-like phase,which may be a precursor of a superconducting state.Nevertheless,this peculiar state nearδ=1/3 disappears for the L_(y)=4 cylinder,implying a possible lattice-size dependence.Our results reveal quantum melting from a holon Wigner crystal to a Fermi-liquid-like state with increasing hole density and suggest a doping regime to explore superconductivity in future studies.
基金supported by the National Key Research and Development Program of China(Grant Nos.2021YFA1400900,2021YFA0718300,and 2021YFA1400243)the National Natural Science Foundation of China(Grant Nos.61835013,12174461,and 12234012)Space Application System of China Manned Space Program.
文摘The system consisting of(2+1)-dimensional quasirelativistic birefringent Dirac fermions with Coulomb interactions and retarded current–current interactions is described by a quantum field theory similar to reduced quantum electrodynamics.We used the perturbative renormalization group method to study the low-energy behavior of the system and found that it flows to a fixed point of the non-Fermi liquid composed of relativistic pseudospin-1/2 Dirac fermions in the deep infrared limit.At the fixed point,the fermion Green function exhibits a finite anomalous dimension,and the residue of the quasiparticle pole vanishes in a power-law fashion.Our research provides new theoretical perspectives for understanding the origin of spin-1/2 fermions in the standard model.
基金Project supported by the National Key Research and Development Program of China (Grants Nos. 2021YFA1400900,2021YFA0718300, and 2021YFA1400243)the National Natural Science Foundation of China (Grant Nos. 61835013,12174461, and 12234012)the Fund from the Space Application System of China Manned Space Program。
文摘We investigate the behavior of non-Hermitian birefringent Dirac fermions by examining their interaction with electromagnetic fields through renormalization group analysis. Our research reveals that the interplay between non-Hermiticity and birefringence leads to distinct behaviors in two and three dimensions, where the system exhibits different fixed points and scaling properties due to dimension-dependent charge renormalization effects. In two dimensions, where the electronic charge remains unrenormalized, the system flows in the deep infrared limit from non-Hermitian birefringent spin-3/2fermions to two copies of non-Hermitian spin-1/2 Dirac fermions, demonstrating a crossover of relativistic liquid and nonrelativistic liquid. In three dimensions, dynamic screening of electromagnetic interactions modifies the logarithmic growth of Fermi velocity, leading to richer quantum corrections while maintaining similar suppression of birefringence in the infrared limit. Our findings provide theoretical insights into the emergence of Lorentz symmetry in non-Hermitian systems,laying theoretical foundations for studying low-energy behavior in other non-Hermitian models.
基金supported by the Innovation Program for Quantum Science and Technology of China(Grant No.2024ZD0300100)the National Basic Research Program of China(Grant No.2021YFA1400900)+1 种基金Shanghai Municipal Science and Technology(Grant Nos.25TQ003,2019SHZDZX01,and 24DP2600100)the National Natural Science Foundation of China(Grant No.12304555).
文摘We demonstrate a reinforcement learning(RL)-based control framework for optimizing evaporative cooling in the preparation of strongly interacting degenerate Fermi gases of 6Li.Using a Soft Actor-Critic(SAC)algorithm,the system autonomously explores a high-dimensional parameter space to learn optimal cooling trajectories.Compared to conventional exponential ramps,our method achieves up to 130%improvement in atomic density within 0.5 second,revealing non-trivial control strategies that balance fast evaporation and thermalization.While our current optimization focuses on the evaporation stage,future integration of other cooling stages,such as gray molasses cooling,could further extend RL to the full preparation pipeline.Our result highlights the promise of RL as a general tool for closed-loop quantum control and automated calibration in complex atomic physics experiments.
基金supported by the National Natural Science Foundation of China(Grant No.12474159)the Fundamental Research Funds for the Central University,Sun Yat-sen University(Grant No.24qnpy119)the China Postdoctoral Science Foundation(Grant No.2024T171067)。
文摘We investigate distinct non-Hermitian skin effects(NHSEs)in real and Fock spaces induced by the interplay between the Hilbert space fragmentation and multiple non-Hermitian pumping channels.Using an extended Hatano–Nelson model with next-nearest neighbor hopping and strong interaction as an example,we found that two fermions loaded in the lattice exhibit different real-space NHSE depending on the Hilbert space fragments to which they belong.Moreover,in the high-energy sector resulting from fragmentation,the two-particle-bound states form a one-dimensional lattice in Fock space,producing a Fock-space NHSE.At half-filling,richer patterns of Fock-space skin-like localization emerge for the different fragmented energy sectors and subsectors while realspace NHSE is suppressed by many-body effects.This study extends our understanding of the interplay between NHSE and Hilbert space fragmentation and provides detailed insights into their manifestation in interacting non-Hermitian systems.
文摘本文通过将给定的单层周期量子图与具有循环群作用的正三边形做笛卡尔积构造了一类“三层”量子图,其中正三边形被称为连接图,得到“三层”量子图的函数空间分解和算子分解,证明了其Fermi面可约,并将结论推广到连接图为具有循环群作用的正n边形情况。 This paper constructs a class of"three-layer" quantum graphs by taking the Cartesian product of a given single-layer periodic quantum graph with an equilateral triangle (referred to as the connecting graph) endowed with a cyclic group action. The function space decomposition and operator decomposition of the resulting"three-layer" quantum graphs are derived. It is proven that their Fermi surfaces are reducible. Furthermore, the conclusions are generalized to the case where the connecting graph is a regular n-gon with a cyclic group action.
基金supported by the National Natural Science Foundation of China(Grant No.11304281)the Natural Science Foundation of Zhejiang Province,China(Grant No.LY13D060002)
文摘We investigate the topological phase marked by the Thouless–Kohmoto–Nightingale–Nijs（TKNN） number and the phase transitions driven by the next nearest neighbor（NNN） hopping in noncentrosymmetric cold Fermi gases, both spinsinglet pairing and spin-triplet pairing are considered. There exists a critical t＇c for the NNN hopping, at which the quantum phase transition occurs, and the system changes from an Abelian（non-Abelian） phase to a non-Abelian（Abelian） one. By numerically diagonalizing the Hamiltonian in the real space, the energy spectra with edge states for different topological phases and the Majorana zero modes are discussed. Although the spin-triplet pairing does not contribute to the gap closing and the phase diagram, it induces gapless states in the presence of a magnetic field, and the TKNN number in this region is still zero.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.12034011,92065108,11974224,12022406,and 12004229)the National Key Research and Development Program of China(Grant No.2018YFA0307601)+1 种基金the Fund for Shanxi 1331 Project Key Subjects Constructionthe Program of Youth Sanjin Scholar。
文摘We demonstrate that dual dark magnetic-optical-traps(MOTs)have great importance in the two-species^(87)Rb and^(40)K mixture compared with dual bright MOTs.The dark MOT has a little improvement in the trapping of single-species^(87)Rb or^(40)K gases compared with bright MOT.For the case of loading two-species^(87)Rb and^(40)K simultaneously,the improvement of^(40)K in the dual dark MOTs is mainly from the reduction of light-assisted collision losses.The dual dark MOTs employ a pair of conical lenses to produce the hollow beam for repump laser with high efficiency.The number and density of^(87)Rb and^(40)K atoms after evaporative cooling in the hybrid magnetic trap with dark MOT loading are compared with those in bright MOT.The atoms with large number and high density make it easier to realize the quantum degenerate of Bose-Fermi mixture.
