Spin-Orbit Coupling And Rotation Induced Novel Excitations In Spinor F=2 Bose-Einstein Condensate

The spin-orbit coupling has become a frontier topic in quantum physics,condensed matter physics and material science area.Ultracold atom system has offered a great platform for investigating spin-orbit coupling.The nontrivial quantum states induced by spin-orbit coupling have offered thearetial guidance to the new material simulation and the material design.The article mainly focuses on skyrmion exciation,domain wall and other excitations.The spinor F=2 ferromagnetic phase and cyclic phase Bose-Einstein condensates are used to investigate topological phase transition,domain wall and other novel topological quantum states.Some novel results are described as follows:First,the article studies the influence of spin-orbit coupling on the topological phase transition in the ferromagnetic spinor F = 2 Bose-Einstein condensate system.Results have shown that the spin particle flow caused by the spin-orbit coupling can induce a regular particle flow in the opposite direction.The canonical angular momentum and the degree of phase separation can be used as "probes" to describe the first or second order phase transition.By adjusting the strength of the spin-orbit coupling,many different topological excitations,including phase-separated states,Anderson-Toulouse vortices,and dipole-vortex lattices can be obtained.In addition,when the spin-orbit coupling is strong,two mutually perpendicular vortex chains appear in the system.Unlike atomic spin singlet-pairing interactions,spin-exchange interactions can affect topological phase transitions.This work unveils the topological phase transition law of the system.Moreover,it offers a good opportunity to understand the physical properties of the high spin system and provides thearetial guidances.Secondly,the article studies the evolution of domain wall structure in the ferromagnetic spinor F=2 Bose-Einstein condensate system.In rotating Bose-Einstein condensate,Raman laser can be used to generate Rashba-Dresselhaus spin-orbit coupling and Rabi coupling.In order to induce the domain wall structure,both spin-orbit coupling and rotation are essential.The results reveal that the velocity field of the domain wall is significantly different from the velocity field excited by the traditional skyrmion.Using domain wall width,relative particle number,degree of phase separation,root mean square radius,and angular momentum(including regular angular momentum and spin angular momentum)as "probes",the evolution of the domain wall under the action of rotation and spin-orbit coupling are studied.On the other hand,when the Rabi coupling strength exceeds a certain critical value,the domain wall structure can be destroyed.Surprisingly,under the action of Gaussian noise,the domain wall structure can exist stably for a long time,which also provides a favorable opportunity for experimental detection of this topological excitation.Finally,the article studies a novel quantum state in spinor F = 2 Bose-Einstein condensate.When the rotation rate is very slow and the atomic spin-exchange interaction is weak,the vortex nucleus cannot be observed in the cyclic phase.However,the stronger atomic spin-exchange interaction can induce the vortex-bright soliton structure.In this topology,mass solitons are distributed in the vortex core.By analyzing the velocity fields of different components,it can be obtained that the velocity field in the vortex-bright soliton structure rotates in a counterclockwise direction.In addition,by enhancing the atomic density-density interaction,more vortex-bright soliton structures are excited and distributed in axial symmetry.It is worth noting that all vortex-bright soliton structures rotate in the counterclockwise direction,which is completely different from the vortex-antivortex pair.Afterwards,by adjusting the atomic density-density interaction and rotation rate in numerical calculations,we find that when the angular momentum shows a "jump",a topological phase change occurs.This work has thoroughly studied nontrivial topological excitations and provided a new direction for manipulating topological phase transitions in high-spin systems.