We investigate a one-dimensional two-component system in an optical lattice of attractive interactions under a spin- dependent external potential. Based on the density-matrix renormalization group methods, we obtain i...We investigate a one-dimensional two-component system in an optical lattice of attractive interactions under a spin- dependent external potential. Based on the density-matrix renormalization group methods, we obtain its phase diagram as a function of the external potential imbalance and the strength of the attractive interaction through the analysis on the density profiles and the momentum pair correlation functions. We find that there are three different phases in the system, a coexisted fully polarized and Fulde-Ferrell-Larkin-Ovchinnikov （FFLO） phase, a normal polarized phase, and a Bardeen- Cooper-Schrieffer （BCS） phase. Different from the systems of spin-independent external potential, where the FFLO phase is normally favored by the attractive interactions, in the present situation, the FFLO phases are easily destroyed by the attractive interactions, leading to the normal polarized or the BCS phase.展开更多
We study the possibility of stabilizing a Fulde-Ferrell-Larkin-Ovchinnikov(FFLO)state in an equally populated two-component Fermi gas trapped in a moving two-dimensional optical lattice.For a system with nearly half f...We study the possibility of stabilizing a Fulde-Ferrell-Larkin-Ovchinnikov(FFLO)state in an equally populated two-component Fermi gas trapped in a moving two-dimensional optical lattice.For a system with nearly half filling,we find that a finite pairing momentum perpendicular to the moving direction can be spontaneously induced for a proper choice of lattice velocity.As a result,the total pairing momentum is tilted towards the nesting vector to take advantage of the significant enhancement of the density of states.展开更多
The influence of the off-resonant circularly polarized light on the Josephson current in the time-reversal broken superconducting Weyl semimetal junctions is investigated by using the Bogoliubov–de Gennes equation an...The influence of the off-resonant circularly polarized light on the Josephson current in the time-reversal broken superconducting Weyl semimetal junctions is investigated by using the Bogoliubov–de Gennes equation and the transfer matrix approach.Both the zero momentum BCS pairing states and the finite momentum Fulde–Ferrell–Larkin–Ovchinnikov(FFLO)pairing states are considered for the Weyl superconductors.When a circularly polarized light is applied,it is shown that the current phase relation remains unchanged for the BCS pairing with the increasing of incident radiation intensity A_(0).For FFLO pairing,the Josephson current exhibits the 0–πtransition and periodic oscillation as a function of A_(0).The dependence of free energy and critical current on A_(0) are also investigated.展开更多
Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carri...Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carries over to the superconducting state,which receives a geometric contribution to the superfluid weight.In this paper,we show that this contribution could become negative under certain appropriate circumstances.This may facilitate the stabilization of Cooper pairings with real space phase modulation,i.e.,the pair density wave order,as we demonstrate through two-orbital model Bogoliubov de-Gennes mean-field calculations.The quantum geometric effect therefore constitutes an intrinsic mechanism for the formation of such a novel phase of matter in the absence of external magnetic field.展开更多
We study numerically the phase diagram for s and d-wave fermionic superftuidity/superconductivity with spin-dependent band- width imbalance on a two-dimensional square-lattice. We also investigate the spontaneous spac...We study numerically the phase diagram for s and d-wave fermionic superftuidity/superconductivity with spin-dependent band- width imbalance on a two-dimensional square-lattice. We also investigate the spontaneous space symmetry breaking states at low temperatures by solving the Bogoliubov-de Gennes equations. It is found that, the spatial configuration of the order parameter, both the uni-directional Fulde-Ferrell-Larkin-Ovchinnikov （FFLO） states and the two-dimensional FFLO state may show up in the presence of finite spin-dependent bandwidth imbalance. Moreover, we calculate the spectra of local density of states, and the experimental proposals of observing such FFLO states are therefore suggested.展开更多
基金supported by the National Natural Science Foundation of China(Grant Nos.11374266 and 11174253)the Program for New Century Excellent Talents in University,China
文摘We investigate a one-dimensional two-component system in an optical lattice of attractive interactions under a spin- dependent external potential. Based on the density-matrix renormalization group methods, we obtain its phase diagram as a function of the external potential imbalance and the strength of the attractive interaction through the analysis on the density profiles and the momentum pair correlation functions. We find that there are three different phases in the system, a coexisted fully polarized and Fulde-Ferrell-Larkin-Ovchinnikov （FFLO） phase, a normal polarized phase, and a Bardeen- Cooper-Schrieffer （BCS） phase. Different from the systems of spin-independent external potential, where the FFLO phase is normally favored by the attractive interactions, in the present situation, the FFLO phases are easily destroyed by the attractive interactions, leading to the normal polarized or the BCS phase.
基金supported by the Beijing Natural Science Foundation,China(Grant No.Z180013)the National Natural Science Foundation of China(Grant Nos.11522436,11774425,and 12074428)+1 种基金the National Key R&D Program of China(Grant No.2018YFA0306501)the Research Funds of Renmin University of China(Grant Nos.16XNLQ03 and 18XNLQ15)。
文摘We study the possibility of stabilizing a Fulde-Ferrell-Larkin-Ovchinnikov(FFLO)state in an equally populated two-component Fermi gas trapped in a moving two-dimensional optical lattice.For a system with nearly half filling,we find that a finite pairing momentum perpendicular to the moving direction can be spontaneously induced for a proper choice of lattice velocity.As a result,the total pairing momentum is tilted towards the nesting vector to take advantage of the significant enhancement of the density of states.
基金the National Key Research and Development Program of China(Grant No.2017YFA0303203)the National Natural Science Foundation of China(Grant No.11474149)。
文摘The influence of the off-resonant circularly polarized light on the Josephson current in the time-reversal broken superconducting Weyl semimetal junctions is investigated by using the Bogoliubov–de Gennes equation and the transfer matrix approach.Both the zero momentum BCS pairing states and the finite momentum Fulde–Ferrell–Larkin–Ovchinnikov(FFLO)pairing states are considered for the Weyl superconductors.When a circularly polarized light is applied,it is shown that the current phase relation remains unchanged for the BCS pairing with the increasing of incident radiation intensity A_(0).For FFLO pairing,the Josephson current exhibits the 0–πtransition and periodic oscillation as a function of A_(0).The dependence of free energy and critical current on A_(0) are also investigated.
基金supported by the National Natural Science Foundation of China(Grant No.11904155)the Guangdong Provincial Key Laboratory(Grant No.2019B121203002)+1 种基金the Guangdong Science and Technology Department(Grant No.2022A1515011948)the Shenzhen Science and Technology Program(Grant No.KQTD20200820113010023)。
文摘Bloch electrons in multiorbital systems carry quantum geometric information characteristic of their wavevector-dependent interorbital mixing.The geometric nature impacts electromagnetic responses,and this effect carries over to the superconducting state,which receives a geometric contribution to the superfluid weight.In this paper,we show that this contribution could become negative under certain appropriate circumstances.This may facilitate the stabilization of Cooper pairings with real space phase modulation,i.e.,the pair density wave order,as we demonstrate through two-orbital model Bogoliubov de-Gennes mean-field calculations.The quantum geometric effect therefore constitutes an intrinsic mechanism for the formation of such a novel phase of matter in the absence of external magnetic field.
基金supported by the National Key Basic Research Program of China(Grant No.2012CB921604)the National Natural Science Foundation of China(Grant Nos.11274069 and 11474064)
文摘We study numerically the phase diagram for s and d-wave fermionic superftuidity/superconductivity with spin-dependent band- width imbalance on a two-dimensional square-lattice. We also investigate the spontaneous space symmetry breaking states at low temperatures by solving the Bogoliubov-de Gennes equations. It is found that, the spatial configuration of the order parameter, both the uni-directional Fulde-Ferrell-Larkin-Ovchinnikov （FFLO） states and the two-dimensional FFLO state may show up in the presence of finite spin-dependent bandwidth imbalance. Moreover, we calculate the spectra of local density of states, and the experimental proposals of observing such FFLO states are therefore suggested.
