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 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
The chiral 2×2 charge order has been reported and confirmed in the kagome superconductor RbV_(3)Sb_(5),while its interplay with superconductivity remains elusive owing to its lowest superconducting transition tem...The chiral 2×2 charge order has been reported and confirmed in the kagome superconductor RbV_(3)Sb_(5),while its interplay with superconductivity remains elusive owing to its lowest superconducting transition temperature Tc of about 0.85K in the AV_(3)Sb_(5) family(A=K,Rb,Cs)that severely challenges electronic spectroscopic probes.Here,utilizing dilution-refrigerator-based scanning tunneling microscopy down to 30 mK,we observe chiral 2×2 pair density waves with residual Fermi arcs in RbV_(3)Sb_(5).We find a superconducting gap of 150 μeV with substantial residual in-gap states.The spatial distribution of this gap exhibits chiral 2×2 modulations,signaling a chiral pair density wave(PDW).Our quasi-particle interference imaging of the zero-energy residual states further reveals arc-like patterns.We discuss the relation of the gap modulations with the residual Fermi arcs under the space-momentum correspondence between PDW and Bogoliubov Fermi states.展开更多
In the quasi-free electron model,the Fermi surface spreads into a sphere in the Brillouin zone,i.e.,the Fermi sphere.The Fermi sphere exists widely in metal systems,no matter whether the crystal is in a body-center cu...In the quasi-free electron model,the Fermi surface spreads into a sphere in the Brillouin zone,i.e.,the Fermi sphere.The Fermi sphere exists widely in metal systems,no matter whether the crystal is in a body-center cubic,face-center cubic,or hexagonal close-packed lattice.Here,we report a class of compounds stabilized at high pressure with Rubik’s cubic Fermi surface.展开更多
This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems.We begin by examining the realization of non-Hermitian quantum sys...This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems.We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation,alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features.A pedagogical discussion is provided on the relationship between entanglement quantities and the correlation matrix in Hermitian systems.Building on this foundation,we focus on how entanglement concepts are extended to non-Hermitian systems from their Hermitian free-fermion counterparts,with a review of the general properties that emerge.Finally,we highlight various concrete studies,demonstrating that entanglement entropy remains a powerful diagnostic tool for characterizing non-Hermitian physics.The entanglement spectrum also reflects the topological characteristics of non-Hermitian topological systems,while unique non-Hermitian entanglement behaviors are also discussed.The review is concluded with several future directions.Through this review,we hope to provide a useful guide for researchers who are interested in entanglement in non-Hermitian quantum systems.展开更多
Strongly correlated electrons at the verge of quantum criticality give rise to unconventional phases of matter and behaviors,with the discovery of new quantum-critical materials driving synergistic experimental and th...Strongly correlated electrons at the verge of quantum criticality give rise to unconventional phases of matter and behaviors,with the discovery of new quantum-critical materials driving synergistic experimental and theoretical advances.In this paper,we report the structural and physical properties of a new quaternary Ce-based heavy fermion compound,Ce_(2)NiAl_(6)Si_(5),which was synthesized via the self-flux method.This compound forms a layered tetragonal structure(space group P4/nmm)with square nets of Ce atoms separated by Si-Al or Ni-Si-Ge layers.Specific heat measurements show a low-temperature Sommerfeld coefficient of 1.4 J/mol-Ce・K^(2)with reduced entropy,indicative of significant Kondo interactions.Below 0.6 K,an increase in resistivity and a deviation in magnetic susceptibility suggest the appearance of magnetic ordering or the development of dynamic magnetic correlations,which is further supported by a bulge in the specific heat around 0.4 K.The findings of this study suggest that Ce_(2)NiAl_(6)Si_(5)is a layered heavy fermion metal naturally located near a spin-density-wave quantum critical point.展开更多
Results of combined thermal and electrical transport measurements through the magnetic field-induced quantum critical point(QCP)in the heavy-fermion compound YbRh_(2)Si_(2) were revisited to explore the relationship b...Results of combined thermal and electrical transport measurements through the magnetic field-induced quantum critical point(QCP)in the heavy-fermion compound YbRh_(2)Si_(2) were revisited to explore the relationship between the strange-metal behavior observed in electrical and electronic thermal resistivities and the violation of the Wiedemann-Franz(WF)law in the zero-temperature limit.A new type of inelastic scattering center for the charge and heat carriers was detected,attributed to small-to-large Fermi surface fluctuations operating near the Kondo-destroying QCP.These fermionic quantum critical fluctuations are considered the primary driver of the strange-metal behavior and the violation of the WF law.展开更多
The locally noncentrosymmetric heavy fermion superconductor CeRh_(2)As_(2) has attracted considerable interests due to its rich superconducting phases,accompanied by possible quadrupole density wave and pronounced ant...The locally noncentrosymmetric heavy fermion superconductor CeRh_(2)As_(2) has attracted considerable interests due to its rich superconducting phases,accompanied by possible quadrupole density wave and pronounced antiferromagnetic excitations.To understand the underlying physics,here we report measurements from highresolution angle-resolved photoemission.Our results reveal fine splittings of the conduction bands related to the locally noncentrosymmetric structure,as well as a quasi-two-dimensional Fermi surface(FS)with strong 4f contributions.The FS shows signs of nesting with an in-plane vector q_(1)=(π/α,π/α),which is facilitated by the heavy bands nearˉ𝑋arising from the characteristic conduction-X hybridization.The FS nesting provides a natural explanation for the observed antiferromagnetic spin fluctuations at(π/α,π/α),which might be the driving force for its unconventional superconductivity.Our experimental results can be reasonably explained by density functional theory plus dynamical mean field theory calculations,which can capture the strong correlation effects.Our study not only provides spectroscopic signature of the key factors underlying the field-induced superconducting transition,but also uncovers the critical role of FS nesting and lattice Kondo effect in the underlying magnetic fluctuations.展开更多
We construct a three-dimensional topological superconductor Bogoliubov–de Gennes(BdG)Hamiltonian with the normal state being a three-dimensional topological insulator.By introducing inter-orbital spin-triplet pairing...We construct a three-dimensional topological superconductor Bogoliubov–de Gennes(BdG)Hamiltonian with the normal state being a three-dimensional topological insulator.By introducing inter-orbital spin-triplet pairings term△3,there are topological Majorana nodes in the bulk and they are connected by Majorana Fermi arcs on the surface,similar to the case of Weyl semimetal.Furthermore,by adding an inversion-breaking term to the normal state,momentum-independent pairing terms with different parities can coexist in the Bd G Hamiltonian,which creates more Majorana modes similar to Andreev bound states and a richer phase diagram.展开更多
We report on the optimal production of the Bose and Fermi mixtures with ^(87) Rb and ^(40)K in a crossed optical dipole trap(ODT).We measure the atomic number and lifetime of the mixtures in combination of the spin st...We report on the optimal production of the Bose and Fermi mixtures with ^(87) Rb and ^(40)K in a crossed optical dipole trap(ODT).We measure the atomic number and lifetime of the mixtures in combination of the spin state |F=9/2,m_(F)=9/2> of^(40)K and |1,1>of ^(87) Rb in the ODT,which is larger and longer compared with the combination of the spin state |9/2,9/2> of^(40)K and 12,2) of ^(87)Rb in the ODT.We observe the atomic numbers of ^(87)Rb and ^(40)K shown in each stage of the sympathetic cooling process while gradually reducing the depth of the optical trap.By optimizing the relative loading time of atomic mixtures in the MOT,we obtain the large atomic number of ^(40)K(~6 ×10^(6)) or the mixtures of atoms with an equal number(~1.6 × 10^(6)) at the end of evaporative cooling in the ODT.We experimentally investigate the evaporative cooling in an enlarged volume of the ODT via adding a third laser beam to the crossed ODT and found that more atoms(8 × 10^(6)) and higher degeneracy(T/T_(F)=0.25) of Fermi gases are obtained.The ultracold atomic gas mixtures pave the way to explore phenomena such as few-body collisions and the Bose-Fermi Hubbard model,as well as for creating ground-state molecules of ^(87)Rb^(40)K.展开更多
The Raman spectra in the C-H stretching region are of great importance for the study of the structure and dynamics of organic compounds.However,the Fermi resonance between the first overtone mode of C-H bending vibrat...The Raman spectra in the C-H stretching region are of great importance for the study of the structure and dynamics of organic compounds.However,the Fermi resonance between the first overtone mode of C-H bending vibration and C-H stretching vibration typically results in the disturbance of Raman bands in the C-H stretching region.In this context,a specific deuterated molecule with only one C-H bond was proposed,and it was found that the frequency of the first overtone mode of the C-H bending vibration was significantly different from the frequency of the C-H stretching vibration.Due to the significant discrepancy,Fermi resonance in the C-H stretching region was eliminated from the experimental and theoretical Raman spectra of deuterated leucine,deuterated benzoin,deuterated methanol,and deuterated ethanol.Hence then,the Raman spectra of these specific deuterated compounds in the C-H stretching region can be used to study the structure or the dynamics of the organic compounds.展开更多
Moirésuperlattices,a twisted functional structure crossing the periodic and nonperiodic potentials,have recently attracted great interest in multidisciplinary fields,including optics and ultracold atoms,because o...Moirésuperlattices,a twisted functional structure crossing the periodic and nonperiodic potentials,have recently attracted great interest in multidisciplinary fields,including optics and ultracold atoms,because of their unique band structures,physical properties,and potential implications.Driven by recent experiments on quantum phenomena of bosonic gases,the atomic Bose–Einstein condensates in moiréoptical lattices,by which other quantum gases such as ultracold fermionic atoms are trapped,could be readily achieved in ultracold atom laboratories,whereas the associated nonlinear localization mechanism remains unexploited.Here,we report the nonlinear localization theory of ultracold atomic Fermi gases in two-dimensional moiréoptical lattices.The linear Bloch-wave spectrum of such a twisted structure exhibits rich nontrivial flat bands,which are separated by different finite bandgaps wherein the existence,properties,and dynamics of localized superfluid Fermi gas structures of two types,gap solitons and gap vortices(topological modes)with vortex charge S¼1,are studied numerically.Our results demonstrate the wide stability regions and robustness of these localized structures,opening up a new avenue for studying soliton physics and moiréphysics in ultracold atoms beyond bosonic gases.展开更多
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 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 Key R&D Program of China(Grant Nos.2023YFA1407300,2023YFA1406500,2022YFA1403800,and 2023YFF0718403)the National Natural Science Foundation of China(Grant Nos.12374060,12274459,and 12074162)+2 种基金Guangdong Provincial Quantum Science Strategic Initiative(Grant No.GDZX2201001)the Beijing Natural Science Foundation(Grant No.Z200005)Guangdong Basic and Applied Basic Research Foundation(Grant No.2022B1515130005)。
文摘The chiral 2×2 charge order has been reported and confirmed in the kagome superconductor RbV_(3)Sb_(5),while its interplay with superconductivity remains elusive owing to its lowest superconducting transition temperature Tc of about 0.85K in the AV_(3)Sb_(5) family(A=K,Rb,Cs)that severely challenges electronic spectroscopic probes.Here,utilizing dilution-refrigerator-based scanning tunneling microscopy down to 30 mK,we observe chiral 2×2 pair density waves with residual Fermi arcs in RbV_(3)Sb_(5).We find a superconducting gap of 150 μeV with substantial residual in-gap states.The spatial distribution of this gap exhibits chiral 2×2 modulations,signaling a chiral pair density wave(PDW).Our quasi-particle interference imaging of the zero-energy residual states further reveals arc-like patterns.We discuss the relation of the gap modulations with the residual Fermi arcs under the space-momentum correspondence between PDW and Bogoliubov Fermi states.
基金supported by the Fundamental Research Funds for the Central Universities(Grant No.010-63243095)the National Science Foundation of China(Grant Nos.92263101 and 12174200)。
文摘In the quasi-free electron model,the Fermi surface spreads into a sphere in the Brillouin zone,i.e.,the Fermi sphere.The Fermi sphere exists widely in metal systems,no matter whether the crystal is in a body-center cubic,face-center cubic,or hexagonal close-packed lattice.Here,we report a class of compounds stabilized at high pressure with Rubik’s cubic Fermi surface.
基金National Natural Science Foundation of China(Grant No.12074438)The calculations reported were performed on resources provided by the Guangdong Provincial Key Laboratory of Magnetoelectric Physics and Devices(Grant No.2022B1212010008).
文摘This topical review article reports rapid progress on the generalization and application of entanglement in non-Hermitian free-fermion quantum systems.We begin by examining the realization of non-Hermitian quantum systems through the Lindblad master equation,alongside a review of typical non-Hermitian free-fermion systems that exhibit unique features.A pedagogical discussion is provided on the relationship between entanglement quantities and the correlation matrix in Hermitian systems.Building on this foundation,we focus on how entanglement concepts are extended to non-Hermitian systems from their Hermitian free-fermion counterparts,with a review of the general properties that emerge.Finally,we highlight various concrete studies,demonstrating that entanglement entropy remains a powerful diagnostic tool for characterizing non-Hermitian physics.The entanglement spectrum also reflects the topological characteristics of non-Hermitian topological systems,while unique non-Hermitian entanglement behaviors are also discussed.The review is concluded with several future directions.Through this review,we hope to provide a useful guide for researchers who are interested in entanglement in non-Hermitian quantum systems.
基金supported by the Pioneer and Leading Goose R&D Program of Zhejiang Province,China(Grant No.2022SDXHDX0005)the National Key R&D Program of China(Grant Nos.2022YFA1402200 and 2023YFA1406100)+2 种基金the Key R&D Program of Zhejiang Province,China(Grant No.2021C01002)the National Natural Science Foundation of China(Grant Nos.12034017,12274363,and 12350710785)the Fundamental Research Funds for the Central Universities(Grant No.226-2024-00068).
文摘Strongly correlated electrons at the verge of quantum criticality give rise to unconventional phases of matter and behaviors,with the discovery of new quantum-critical materials driving synergistic experimental and theoretical advances.In this paper,we report the structural and physical properties of a new quaternary Ce-based heavy fermion compound,Ce_(2)NiAl_(6)Si_(5),which was synthesized via the self-flux method.This compound forms a layered tetragonal structure(space group P4/nmm)with square nets of Ce atoms separated by Si-Al or Ni-Si-Ge layers.Specific heat measurements show a low-temperature Sommerfeld coefficient of 1.4 J/mol-Ce・K^(2)with reduced entropy,indicative of significant Kondo interactions.Below 0.6 K,an increase in resistivity and a deviation in magnetic susceptibility suggest the appearance of magnetic ordering or the development of dynamic magnetic correlations,which is further supported by a bulge in the specific heat around 0.4 K.The findings of this study suggest that Ce_(2)NiAl_(6)Si_(5)is a layered heavy fermion metal naturally located near a spin-density-wave quantum critical point.
文摘Results of combined thermal and electrical transport measurements through the magnetic field-induced quantum critical point(QCP)in the heavy-fermion compound YbRh_(2)Si_(2) were revisited to explore the relationship between the strange-metal behavior observed in electrical and electronic thermal resistivities and the violation of the Wiedemann-Franz(WF)law in the zero-temperature limit.A new type of inelastic scattering center for the charge and heat carriers was detected,attributed to small-to-large Fermi surface fluctuations operating near the Kondo-destroying QCP.These fermionic quantum critical fluctuations are considered the primary driver of the strange-metal behavior and the violation of the WF law.
基金supported by the National Key R&D Program of China(Grant Nos.2022YFA140220 and 2023YFA1406303)the State Key Project of Zhejiang Province(Grant No.LZ22A040007)+2 种基金the National Natural Science Foundation of China(Grant Nos.U23A20580,12174331,12204159,and 12274364)the Key R&D Program of Zhejiang Province,China(Grant No.2021C01002)the Bridging Grant(Grant No.BG11-072020)with China,Japan,South Korea and ASEAN region funded by the Swiss State Secretariat for Education,Research and Innovation。
文摘The locally noncentrosymmetric heavy fermion superconductor CeRh_(2)As_(2) has attracted considerable interests due to its rich superconducting phases,accompanied by possible quadrupole density wave and pronounced antiferromagnetic excitations.To understand the underlying physics,here we report measurements from highresolution angle-resolved photoemission.Our results reveal fine splittings of the conduction bands related to the locally noncentrosymmetric structure,as well as a quasi-two-dimensional Fermi surface(FS)with strong 4f contributions.The FS shows signs of nesting with an in-plane vector q_(1)=(π/α,π/α),which is facilitated by the heavy bands nearˉ𝑋arising from the characteristic conduction-X hybridization.The FS nesting provides a natural explanation for the observed antiferromagnetic spin fluctuations at(π/α,π/α),which might be the driving force for its unconventional superconductivity.Our experimental results can be reasonably explained by density functional theory plus dynamical mean field theory calculations,which can capture the strong correlation effects.Our study not only provides spectroscopic signature of the key factors underlying the field-induced superconducting transition,but also uncovers the critical role of FS nesting and lattice Kondo effect in the underlying magnetic fluctuations.
基金Project supported by the National Natural Science Foundation of China (Grant Nos.12174067 and 11804223)。
文摘We construct a three-dimensional topological superconductor Bogoliubov–de Gennes(BdG)Hamiltonian with the normal state being a three-dimensional topological insulator.By introducing inter-orbital spin-triplet pairings term△3,there are topological Majorana nodes in the bulk and they are connected by Majorana Fermi arcs on the surface,similar to the case of Weyl semimetal.Furthermore,by adding an inversion-breaking term to the normal state,momentum-independent pairing terms with different parities can coexist in the Bd G Hamiltonian,which creates more Majorana modes similar to Andreev bound states and a richer phase diagram.
基金supported by the Innovation Program for Quantum Science and Technology (Grant No. 2021ZD0302003)the National Natural Science Foundation of China (Grant Nos. 12034011, U23A6004, 12374245,12322409, 92065108, 11974224, and 12022406)+1 种基金the National Key Research and Development Program of China (Grant Nos. 2022YFA1404101 and 2021YFA1401700)the Fund for Shanxi 1331 Project Key Subjects Construction。
文摘We report on the optimal production of the Bose and Fermi mixtures with ^(87) Rb and ^(40)K in a crossed optical dipole trap(ODT).We measure the atomic number and lifetime of the mixtures in combination of the spin state |F=9/2,m_(F)=9/2> of^(40)K and |1,1>of ^(87) Rb in the ODT,which is larger and longer compared with the combination of the spin state |9/2,9/2> of^(40)K and 12,2) of ^(87)Rb in the ODT.We observe the atomic numbers of ^(87)Rb and ^(40)K shown in each stage of the sympathetic cooling process while gradually reducing the depth of the optical trap.By optimizing the relative loading time of atomic mixtures in the MOT,we obtain the large atomic number of ^(40)K(~6 ×10^(6)) or the mixtures of atoms with an equal number(~1.6 × 10^(6)) at the end of evaporative cooling in the ODT.We experimentally investigate the evaporative cooling in an enlarged volume of the ODT via adding a third laser beam to the crossed ODT and found that more atoms(8 × 10^(6)) and higher degeneracy(T/T_(F)=0.25) of Fermi gases are obtained.The ultracold atomic gas mixtures pave the way to explore phenomena such as few-body collisions and the Bose-Fermi Hubbard model,as well as for creating ground-state molecules of ^(87)Rb^(40)K.
基金supported by the Key Research Project of Shaanxi Provincial Science and Technology Department(2023-YBNY-158)the Xi'an Science and Technology Project(22NYYF016)+3 种基金the Natural Science Foundation of Shaanxi Province(2022JM-087)the Open Fund of the State Key Laboratory of Molecular Reaction Dynamics in DICP,CAS,(SKLMRDK202413)the Fundamental Research Funds for the Central Universities(QTZX23007)the 111 Project.
文摘The Raman spectra in the C-H stretching region are of great importance for the study of the structure and dynamics of organic compounds.However,the Fermi resonance between the first overtone mode of C-H bending vibration and C-H stretching vibration typically results in the disturbance of Raman bands in the C-H stretching region.In this context,a specific deuterated molecule with only one C-H bond was proposed,and it was found that the frequency of the first overtone mode of the C-H bending vibration was significantly different from the frequency of the C-H stretching vibration.Due to the significant discrepancy,Fermi resonance in the C-H stretching region was eliminated from the experimental and theoretical Raman spectra of deuterated leucine,deuterated benzoin,deuterated methanol,and deuterated ethanol.Hence then,the Raman spectra of these specific deuterated compounds in the C-H stretching region can be used to study the structure or the dynamics of the organic compounds.
基金supported by the National Natural Science Foundation of China(Grant No.12074423)the Young Scholar of Chinese Academy of Sciences in Western China(Grant No.XAB2021YN18)+2 种基金the Provincial Science Fund for Distinguished Young Scholars of Shaanxi(Grant No.2024JC-JCQN-11)the China Postdoctoral Science Foundation(Grant No.2023M733722)the Postdoctoral Fellowship Program of CPSF(Grant No.GZC20232947).
文摘Moirésuperlattices,a twisted functional structure crossing the periodic and nonperiodic potentials,have recently attracted great interest in multidisciplinary fields,including optics and ultracold atoms,because of their unique band structures,physical properties,and potential implications.Driven by recent experiments on quantum phenomena of bosonic gases,the atomic Bose–Einstein condensates in moiréoptical lattices,by which other quantum gases such as ultracold fermionic atoms are trapped,could be readily achieved in ultracold atom laboratories,whereas the associated nonlinear localization mechanism remains unexploited.Here,we report the nonlinear localization theory of ultracold atomic Fermi gases in two-dimensional moiréoptical lattices.The linear Bloch-wave spectrum of such a twisted structure exhibits rich nontrivial flat bands,which are separated by different finite bandgaps wherein the existence,properties,and dynamics of localized superfluid Fermi gas structures of two types,gap solitons and gap vortices(topological modes)with vortex charge S¼1,are studied numerically.Our results demonstrate the wide stability regions and robustness of these localized structures,opening up a new avenue for studying soliton physics and moiréphysics in ultracold atoms beyond bosonic gases.
