We study the ground-state phases of spin–orbit coupled spin-2 Bose–Einstein condensates in a two-dimensional concentrically coupled annular trap with the attractive and repulsive spin-exchange interactions, respectively. For the system with the attractive spin-exchange interaction, the ground-state phase densities in the inner ring show the bright solitons along the azimuthal direction with the weak spin–orbit coupling strength and the vortex line along the radial direction with the strong spin–orbit coupling strength. For the system with the repulsive spin-exchange interaction, the necklace-like state is shown. The number of petals of the necklace-like state continuous growth as the spin–orbit coupling strength enhanced. The momentum distributions of the ground-state phases are also studied.
We study the ground-state phases of spin–orbit coupled spin-2 Bose–Einstein condensates in a two-dimensional concentrically coupled annular trap with the attractive and repulsive spin-exchange interactions, respectively. For the system with the attractive spin-exchange interaction, the ground-state phase densities in the inner ring show the bright solitons along the azimuthal direction with the weak spin–orbit coupling strength and the vortex line along the radial direction with the strong spin–orbit coupling strength. For the system with the repulsive spin-exchange interaction, the necklace-like state is shown. The number of petals of the necklace-like state continuous growth as the spin–orbit coupling strength enhanced. The momentum distributions of the ground-state phases are also studied.
We investigate the ground state of spin-orbit-coupled Bose-Einstein condensates confined in concentrically coupled annular traps within the full parameter space accounts for all the nonlinear two-body collisions and the spin-orbit coupling. We find that depending on the ratio between interaction parameters and the strength of spin-orbit coupling, this coupled system presents various ground-state phases. Moreover, phase transition between radial phase separation and azimuthal phase separation can be induced by varying the strength of spin-orbit coupling when the system is first in radial phase separation, while phase transition between phase coexistence and azimuthal phase separation can also be realized through spin-orbit coupling when the system is first in phase coexistence. Finally, the spin texture is studied and the results show that the meron-antimeron pair spontaneously appears as the ground state of this coupled system. We also give an experimental protocol to observe these phenomena in future experiments.
We investigate the ground states of spin-1 Bose–Einstein condensates (BECs) with spin–orbit coupling in a radially periodic potential by numerically solving the coupled Gross–Pitaevskii equations. In the radially periodic potential, we first demonstrate that spin–orbit-coupled antiferromagnetic BECs support a multiring petal phase. Polar–core vortex can be observed from phase profiles, which is manifested as circularly symmetric distribution. We further show that spin–orbit coupling can induce multiring soliton structure in ferromagnetic BECs. It is confirmed especially that the wave-function phase of the ring corresponding to uniform distribution satisfies the rotational symmetry, and the wave-function phase of the ring corresponding to partial splitting breaks the rotational symmetry. Adjusting the spin–orbit coupling strength can control the number of petal in antiferromagnetic BECs and the winding numbers of wave-function in ferromagnetic BECs. Finally, we discuss effects of spin-independent and spin-dependent interactions on the ground states.
The ground state structure of spin-orbit-coupled Bose-Einstein condensates in concentrical dual-ring potential well is studied,with changing of the spin-orbit-coupled,multiple ground state structures are appearing in the coupled system. If the spin-orbit-coupled is added increasingly only in one direction,inhomogeneous distribution of the azimuthal phase separation is appeared in the ground state density,however it is still the stating wave from the phase graph showing. The other spin-orbitcoupled strength is added increasingly in vertical direction until the same with the original direction,when the isotropy of spinorbit-coupled is shaped,homogeneous distribution of the azimuthal phase separation is appeared gradually in the ground state density. Investigation from phase diagram shows that a large number of vortexes in ground state system are generated by the function of isotropy spin-orbit-coupled.
We study trapped 2D spin-1 Bose–Einstein condensates with isotropic spin–orbit coupling and rotation, showing rich ground state phases and phase transition results from the nontrivial interplay among spin–orbit coupling, rotation and confinement. We show that for experimentally feasible parameters and only in the presence of spin–orbit coupling, a double-ring structure for the longitudinal magnetization of the system can be formed within the minima of inner and/or outer rings. Moreover, the rotation effectively enhances the effect of the spin–orbit coupling and controls the location of atoms between both rings. Our results provide a scenario of controlling different phases of a spin–orbit coupled condensate by varying the spin–orbit coupling strength and rotation frequency, instead of using the conventional approach of changing the s-wave scattering length.
We consider two-dimensional spinor F = 1 Bose–Einstein condensates in two types of radially-periodic potentials with spin–orbit coupling, i.e. , spin-independent and spin-dependent radially-periodic potentials. For the Bose–Einstein condensates in a spin-independent radially-periodic potential, the density of each component exhibits the periodic density modulation along the azimuthal direction, which realizes the necklacelike state in the ferromagnetic Bose–Einstein condensates. As the spin-exchange interaction increases, the necklacelike state gradually transition to the plane wave phase for the antiferromagnetic Bose–Einstein condensates with larger spin–orbit coupling. The competition of the spin-dependent radially-periodic potential, spin–orbit coupling, and spin-exchange interaction gives rise to the exotic ground-state phases when the Bose–Einstein condensates in a spin-dependent radially-periodic potential.
We investigate the ground-state phases and spin textures of spin–orbit-coupled dipolar pseudo-spin-1/2 Bose–Einstein condensates in a rotating two-dimensional toroidal potential. The combined effects of dipole–dipole interaction (DDI), spin–orbit coupling (SOC), rotation, and interatomic interactions on the ground-state structures and topological defects of the system are analyzed systematically. For fixed SOC strength and rotation frequency, we provide a set of phase diagrams as a function of the DDI strength and the ratio between inter- and intra-species interactions. The system can show rich quantum phases including a half-quantum vortex, symmetrical (asymmetrical) phase with quantum droplets (QDs), asymmetrical segregated phase with hidden vortices (ASH phase), annular condensates with giant vortices, triangular (square) vortex lattice with QDs, and criss-cross vortex string lattice, depending on the competition between DDI and contact interaction. For given DDI strength and rotation frequency, the increase of the SOC strength leads to a structural phase transition from an ASH phase to a tetragonal vortex lattice then to a pentagonal vortex lattice and finally to a vortex necklace, which is also demonstrated by the momentum distributions. Without rotation, the interplay of DDI and SOC may result in the formation of a unique trumpet-shaped Bloch domain wall. In addition, the rotation effect is discussed. Furthermore, the system supports exotic topological excitations, such as a half-skyrmion (meron) string, triangular skyrmion lattice, skyrmion–half-skyrmion lattice, skyrmion–meron cluster, skyrmion–meron layered necklace, skyrmion–giant-skyrmion necklace lattice, and half-skyrmion–half-antiskyrmion necklace.