Topological Excitations In Spin-1 BEC With Novel Artificial Gauge Fields

With the development of experimental technology in the past two decades,cold atom physics has become a broad and active research field.In the ultra-cold state,all atoms have exactly the same physical properties.It has good coherence and is highly controllable due to its odd characteristics,developing greatly in theory and experiment.The realization of spin-orbit coupling in Bose-Einstein condensate(BEC)makes the interaction between atoms richer and provides an ideal platform for the study of novel macro-physical phenomena.Other new coupling methods proposed recently,such as spin tensor-momentum coupling,etc.,provide conditions for us to explore new quantum phases and novel topological excitations.This paper mainly studies the structure,evolution and novelty properties of solitons in spin-1 BEC with spin-tensor-momentum coupling,and the three-dimensional topological excitation in spin-1 BEC with spin-orbit coupling.The main work is divided into two parts:(1)1D topological excitation in spin-1 BEC with spin-tensor-momentum couplingWe systematically study the bright soliton in antiferromagnetic spin-1 BEC with spin tensor-momentum coupling(4i?xFx2).By numerically solving the Gross-Pitaevskii(GP)equation in spin-1 BEC with spin-tensor coupling,we obtain the ground state solution of the soliton.Different from the solutions discussed before,there are not only real part solutions,but also imaginary part solutions.Then we compare and analyze the properties of solitons with spin-tensor coupling and conventional spin-orbit coupling.Taking the steady state after imaginary-time evolution as the initial state,we carry out real-time evolution and find that the soliton show periodic spontaneous motion.Finally,we analyze the physical mechanism behind this phenomenon.(2)3D topological excitation in spin-1 BEC with spin-orbit couplingWe numerically solve the coupled 3D Gross-Pitaevskii equation with spin-orbit coupling to present the density distribution,phase diagram and stable spin structure texture of solitons,and find that the topological excitation has a certain degree of breaking in z direction,which is caused by the symmetry of the antiferromagnetic phase order parameters.In an ideal state,a two-component Bose-Einstein condensate with spin-orbit coupling can produce an perfect knot structure.The structure produced in spin-1 BEC is different from that in two-component BEC.Our work has realized the knotlike structure and studied its properties and the underlying physical mechanism in detail.The realization of the knotlike structure enriches the research field of three-dimensional spin-orbit coupling in spin BECs,which provides a feasible experimental scheme for people to realize this type of topological structure.