We theoretically investigate a three-dimensional Fermi gas with Rashba spin-orbit coupling in the presence of both out-of-plane and in-plane Zeeman fields. We show that, driven by a sufficiently large Zeeman field, ei...We theoretically investigate a three-dimensional Fermi gas with Rashba spin-orbit coupling in the presence of both out-of-plane and in-plane Zeeman fields. We show that, driven by a sufficiently large Zeeman field, either out-of-plane or in-plane, the superfluid phase of this system exhibits a number of interesting features, including inhomogeneous Fulde- Ferrell pairing, gapped or gapless topological order, and exotic quasi-particle excitations known as Weyl fermions that have linear energy dispersions in momentum space （i.e., massless Dirac fermions）. The topological superfluid phase can have either four or two topologically protected Weyl nodes. We present the phase diagrams at both zero and finite temperatures and discuss the possibility of their observation in an atomic Fermi gas with synthetic spin-orbit coupling. In this context, topological superfluid phase with an imperfect Rashba spin-orbit coupling is also studied.展开更多
The spin-orbit coupled lattice system under Zeeman fields provides an ideal platform to realize exotic pairing states. Notable examples range from the topological superfluid/superconducting （tSC） state, which is gap...The spin-orbit coupled lattice system under Zeeman fields provides an ideal platform to realize exotic pairing states. Notable examples range from the topological superfluid/superconducting （tSC） state, which is gapped in the bulk but metallic at the edge, to the Fulde-Ferrell （FF） state （having a phase-modulated order parameter with a uniform amplitude） and the Larkin-Ovchinnikov （LO） state （having a spatially varying order parameter amplitude）. Here, we show that the topological FF state with Chern number （C = -1） （tFF1） and topological LO state with C = 2 （tLO2） can be stabilized in Rashba spin-orbit coupled lattice systems in the presence of both in-plane and out-of-plane Zeeman fields. Besides the inhomogeneous tSC states, in the presence of a weak in-plane Zeeman field, two topological BCS phases may emerge with C = -1 （tBCS1） far from half fining and C = 2 （tBCS2） near half filling. We show intriguing effects such as different spatial profiles of order parameters for FF and LO states, the topological evolution among inhomogeneous tSC states, and different non-trivial Chern numbers for the tFF1 and tLO1,2 states, which are peculiar to the lattice system. Global phase diagrams for various topological phases are presented for both half-rifling and doped cases. The edge states as well as local density of states spectra are calculated for tSC states in a 2D strip.展开更多
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
This study investigated episodic memory in prodromal HD. Three groups were compared (N = 70): mutation carriers with less than 12.5 years to disease onset (n = 16), mutation carriers with 12.5 or more years to disease...This study investigated episodic memory in prodromal HD. Three groups were compared (N = 70): mutation carriers with less than 12.5 years to disease onset (n = 16), mutation carriers with 12.5 or more years to disease onset (n = 16), and noncarriers (n = 38). Episodic memory was assessed using the Fuld Object Memory Evaluation, which included multimodal presentation and selective reminding, and the Claeson-Dahl Learning Test which included verbal repeated presentation and recall trials. Both carrier groups demonstrated deficient episodic memory compared to noncarriers. The results suggest deficient episodic memory in prodromal HD, and that inconsistent retrieval contributes to these deficits. Multimodal presentation attenuates the deficits.展开更多
基金supported by the ARC Discovery Projects(Grant Nos.FT140100003,FT130100815,DP140103231,and DP140100637)the National Basic Research Program of China(Grant No.2011CB921502)+1 种基金the US National Science Foundationthe Welch Foundation(Grant No.C-1669)
文摘We theoretically investigate a three-dimensional Fermi gas with Rashba spin-orbit coupling in the presence of both out-of-plane and in-plane Zeeman fields. We show that, driven by a sufficiently large Zeeman field, either out-of-plane or in-plane, the superfluid phase of this system exhibits a number of interesting features, including inhomogeneous Fulde- Ferrell pairing, gapped or gapless topological order, and exotic quasi-particle excitations known as Weyl fermions that have linear energy dispersions in momentum space （i.e., massless Dirac fermions）. The topological superfluid phase can have either four or two topologically protected Weyl nodes. We present the phase diagrams at both zero and finite temperatures and discuss the possibility of their observation in an atomic Fermi gas with synthetic spin-orbit coupling. In this context, topological superfluid phase with an imperfect Rashba spin-orbit coupling is also studied.
基金We thank Y. S. Wu, R. B. Tao, T. K. Lee, and A. Varlamov for fruitful discussions. This work was supported by the State Key Programs of Chiaa （Grant Nos. 2017YFA0304204, and 2016YFA0300504） and the National Nat- ural Science Foundation of China （Grant Nos. 11625416 and 11474064）.
文摘The spin-orbit coupled lattice system under Zeeman fields provides an ideal platform to realize exotic pairing states. Notable examples range from the topological superfluid/superconducting （tSC） state, which is gapped in the bulk but metallic at the edge, to the Fulde-Ferrell （FF） state （having a phase-modulated order parameter with a uniform amplitude） and the Larkin-Ovchinnikov （LO） state （having a spatially varying order parameter amplitude）. Here, we show that the topological FF state with Chern number （C = -1） （tFF1） and topological LO state with C = 2 （tLO2） can be stabilized in Rashba spin-orbit coupled lattice systems in the presence of both in-plane and out-of-plane Zeeman fields. Besides the inhomogeneous tSC states, in the presence of a weak in-plane Zeeman field, two topological BCS phases may emerge with C = -1 （tBCS1） far from half fining and C = 2 （tBCS2） near half filling. We show intriguing effects such as different spatial profiles of order parameters for FF and LO states, the topological evolution among inhomogeneous tSC states, and different non-trivial Chern numbers for the tFF1 and tLO1,2 states, which are peculiar to the lattice system. Global phase diagrams for various topological phases are presented for both half-rifling and doped cases. The edge states as well as local density of states spectra are calculated for tSC states in a 2D strip.
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Department of Clinical Genetics, Karolinska University Hospital
文摘This study investigated episodic memory in prodromal HD. Three groups were compared (N = 70): mutation carriers with less than 12.5 years to disease onset (n = 16), mutation carriers with 12.5 or more years to disease onset (n = 16), and noncarriers (n = 38). Episodic memory was assessed using the Fuld Object Memory Evaluation, which included multimodal presentation and selective reminding, and the Claeson-Dahl Learning Test which included verbal repeated presentation and recall trials. Both carrier groups demonstrated deficient episodic memory compared to noncarriers. The results suggest deficient episodic memory in prodromal HD, and that inconsistent retrieval contributes to these deficits. Multimodal presentation attenuates the deficits.
