According to the"no-node"theorem,the many-body ground state wavefunctions of conventional Bose–Einstein condensations(BEC)are positive-definite,thus time-reversal symmetry cannot be spontaneously broken.We ...According to the"no-node"theorem,the many-body ground state wavefunctions of conventional Bose–Einstein condensations(BEC)are positive-definite,thus time-reversal symmetry cannot be spontaneously broken.We find that multi-component bosons with spin-orbit coupling provide an unconventional type of BECs beyond this paradigm.We focus on a subtle case of isotropic Rashba spin-orbit coupling and the spin-independent interaction.In the limit of the weak confining potential,the condensate wavefunctions are frustrated at the Hartree–Fock level due to the degeneracy of the Rashba ring.Quantum zero-point energy selects the spin-spiral type condensate through the"order-from-disorder"mechanism.In a strong harmonic confining trap,the condensate spontaneously generates a half-quantum vortex combined with the skyrmion type of spin texture.In both cases,time-reversal symmetry is spontaneously broken.These phenomena can be realized in both cold atom systems with artificial spin-orbit couplings generated from atom-laser interactions and exciton condensates in semi-conductor systems.展开更多
The thermodynamic properties of the bilayer ruthenate compound Sr3Ru2O7 at very low temperatures are inves- tigated by using a tight-binding model yielding the realistic band structure combined with the on-site intera...The thermodynamic properties of the bilayer ruthenate compound Sr3Ru2O7 at very low temperatures are inves- tigated by using a tight-binding model yielding the realistic band structure combined with the on-site interactions treated at the mean-field level. We find that both the total density of states at the Fermi energy and the entropy exhibit a sudden increase near the critical magnetic field for the nematic phase, echoing the experimental find- ings. A new mechanism to explain the anisotropic transport properties is proposed based on scatterings at the anisotropic domain boundaries. Our results suggest that extra cares are necessary to isolate the contributions due to the quantum criticality from the band structure singularity in Sr3Ru2O7.展开更多
In recent years,topological physics has become one of the major topics in condensed matter research.Various quantum topological phases are experimentally discovered and theoretically explored,including quantum Hall st...In recent years,topological physics has become one of the major topics in condensed matter research.Various quantum topological phases are experimentally discovered and theoretically explored,including quantum Hall states[1–3]and topological insulators[4,5].The fractional quantum Hall(FQH)states are among the most celebrated examples,which attract a great deal of attention due to the interplay between correlation and topology.Topological orders exhibited in FQH systems are characterized by long-range quantum entanglements,emergent gauge fields,and fractional statistics[1–3].Nevertheless,experimental realizations of novel topological orders in quantum materials remain an open challenge.展开更多
基金by US NSF-DMR 1105945 and AFOSR-YIP program.X.F.Z.acknowledges the support of CUSF,,SRFD(20103402120031)and the China Postdoctoral Science.
文摘According to the"no-node"theorem,the many-body ground state wavefunctions of conventional Bose–Einstein condensations(BEC)are positive-definite,thus time-reversal symmetry cannot be spontaneously broken.We find that multi-component bosons with spin-orbit coupling provide an unconventional type of BECs beyond this paradigm.We focus on a subtle case of isotropic Rashba spin-orbit coupling and the spin-independent interaction.In the limit of the weak confining potential,the condensate wavefunctions are frustrated at the Hartree–Fock level due to the degeneracy of the Rashba ring.Quantum zero-point energy selects the spin-spiral type condensate through the"order-from-disorder"mechanism.In a strong harmonic confining trap,the condensate spontaneously generates a half-quantum vortex combined with the skyrmion type of spin texture.In both cases,time-reversal symmetry is spontaneously broken.These phenomena can be realized in both cold atom systems with artificial spin-orbit couplings generated from atom-laser interactions and exciton condensates in semi-conductor systems.
基金Supported by the NSF DMR-1410375 and AFOSR FA9550-14-1-0168the President's Research Catalyst Award(No CA-15-327861) from the University of California Office of the Presidentthe CAS/SAFEA International Partnership Program for Creative Research Teams
文摘The thermodynamic properties of the bilayer ruthenate compound Sr3Ru2O7 at very low temperatures are inves- tigated by using a tight-binding model yielding the realistic band structure combined with the on-site interactions treated at the mean-field level. We find that both the total density of states at the Fermi energy and the entropy exhibit a sudden increase near the critical magnetic field for the nematic phase, echoing the experimental find- ings. A new mechanism to explain the anisotropic transport properties is proposed based on scatterings at the anisotropic domain boundaries. Our results suggest that extra cares are necessary to isolate the contributions due to the quantum criticality from the band structure singularity in Sr3Ru2O7.
基金supported by the National Natural Science Foundation of China(12234016 and 12174317)supported by the New Cornerstone Science Foundation。
文摘In recent years,topological physics has become one of the major topics in condensed matter research.Various quantum topological phases are experimentally discovered and theoretically explored,including quantum Hall states[1–3]and topological insulators[4,5].The fractional quantum Hall(FQH)states are among the most celebrated examples,which attract a great deal of attention due to the interplay between correlation and topology.Topological orders exhibited in FQH systems are characterized by long-range quantum entanglements,emergent gauge fields,and fractional statistics[1–3].Nevertheless,experimental realizations of novel topological orders in quantum materials remain an open challenge.
