Topological Excitation Of Rotating Spin-orbit-coupled Dipolar Spin-1 BECs

Recently,the experimental realization of artificial spin-orbit coupling(SOC)in both Bose-Einstein condensates(BEC s)and quantum degenerate Fermi gases provides us an ideal platform to study exotic quantum phenomena and novel states of matter.So far,a lot of experimental and theoretical studies of spin-orbit-coupled Bose gases have been focused on the quantum phases of pseudo-spin-1/2 BECs with SOC.Most recently,spin-orbit-coupled spin-1 BECs of Rb atoms have been realized experimentally which opens another window for the exploration of peculiar physical properties of spin-1 BECs generally unaccessible in pseudo-spin-1/2 BECs and electronic materials due to the competition among the spin-exchange interaction,SOC and the other parameters.On the other hand,quantum gases with magnetic dipole-dipole interaction(DDI),especially the BECs with DDI,have also drawn much attention both experimentally and theoretically in recent years.Relevant studies on spinor BECs with DDI have shown that the interplay between the short-range spin-exchange interaction and the long-range anisotropic DDI can lead to rich topological defects,spin textures and spin dynamics.Therefore it is of particular interest to investigate the combined effects of SOC and DDI on spinor BECs,and this idea has recently attracted extensive attention.However,the existing studies of the BECs with SOC and DDI refer to the nonrotating case.Considering that one of the most striking hallmarks of a superfluid is its response to rotation,we study the combined effects of rotation,SOC and DDI on the ground-state structure and spin texture of a dipolar spin-1 BEC with SOC confined in a rotating harmonic plus quartic trap(anharmonic trap).The main contents of this dissertation are as follows:Firstly,we have investigated the topological defects and spin structures of spin-1 BECs with Rashba SOC and DDI in a rotating harmonic plus quartic trap.The combined effects of SOC,DDI and rotation on the ground-state phases of the system have been analyzed.Our results showed that for fixed rotation frequency structural phase transitions can be achieved by adjusting the magnitudes of the SOC and DDI.A ground-state phase diagram was given as a function of the SOC and DDI strengths.It is shown that the system can exhibit rich quantum phases including vortex string phase with isolated density peaks(DPs),triangular(square)vortex lattice phase with DPs,checkerboard phase,and stripe phase with hidden vortices and antivortices.For given SOC and DDI strengths,the system can display pentagonal vortex lattice with DPs,vortex necklace with DPs,and exotic topological structure composed of multi-layer visible vortex necklaces,a hidden giant vortex and hidden vortex necklaces,depending on the rotation frequency.In addition,the system sustains fascinating novel spin textures and skyrmion excitations,such as an antiskyrmion pair,antiskyrmionhalf-antiskyrmion(antiskyrmion-antimeron)cluster,skyrmion-anti skyrmion lattice,skyrmion-anti skyrmion cluster,skyrmion-antiskyrmion-meron-antimeron lattice,double-layer half-antiskyrmion necklaces,and composite giant-antiskyrmion-antimeron necklaces.Secondly,we have systematically studied the ground-state properties and topological structures of rotating spin-1 ferromagnetic BECs with SU(3)SOC and DDI in a anharmonic trap.The effects of SU(3)SOC,DDI and rotation on the ground-state properties and spin textures of the system have been analyzed in detail.It is shown that when the rotation frequency is small the SU(3)SOC and DDI have significant influence on the ground-state structure of the system.For fixed DDI strength,with the increase of SU(3)SOC strength the vortex number increases and the vortices form vortex chains such that the system forms multi-layer nested triangular vortex lattices.For the case of fixed SU(3)SOC,as the DDI strength increases,stripe phases or similar stripe phases are gradually created in the system.When the rotation frequency is large,the rotation effect is dominant among many important factors that determine the ground-state structure of the system.It is found that with the number of vortices in each component increases gradually with the increase of rotation frequency and the three components tend to be mixed,where the central region in each component is occupied by a complex topological structure consist of a hidden vortex(hidden giant vortex)plus hidden vortex necklaces(or pure hidden vortex necklaces).Furthermore,the system can exhibit rich and exotic spin textures and skyrmion excitations including antiskyrmion lattice,antiskyrmion-half-antiskyrmion(antiskyrmion-antimeron)cluster,giant antiskyrmions-half-antiskyrmion cluster,and giant antiskyrmions-antiskyrmions-half-antiskyrmion cluster.