Vortices in spin-orbit-coupled Bose-Einstein condensates

Abstract

Realistic methods to create vortices in spin-orbit-coupled Bose-Einstein condensates are discussed. It is shown that, contrary to common intuition, rotation of the trap containing a spin-orbit condensate does not lead to an equilibrium state with static vortex structures, but gives rise instead to non-equilibrium behavior described by an intrinsically time-dependent Hamiltonian. We propose here the following alternative methods to induce thermodynamically stable static vortex configurations: (1) to rotate both the lasers and the anisotropic trap; and (2) to impose a synthetic Abelian field on top of synthetic spin-orbit interactions. Effective Hamiltonians for spin-orbit condensates under such perturbations are derived for most currently known realistic laser schemes that induce synthetic spin-orbit couplings. The Gross-Pitaevskii equation is solved for several experimentally relevant regimes. The new interesting effects include spatial separation of left-and right-moving spin-orbit condensates, the appearance of unusual vortex arrangements, and parity effects in vortex nucleation where the topological excitations are predicted to appear in pairs. All these phenomena are shown to be highly non-universal and depend strongly on a specific laser scheme and system parameters.

Spin-Orbit Coupled Quantum Gases

“…For SO coupled bosons, many questions remain open. Recently several works begin to address the questions about the superfluid critical velocity 42 , vortices in presence of external rotation 47,48,49 , the effects of dipolar interactions 50 , the collective modes 51 , superfluid to Mott insulator transition in a lattice 52 , the interplay between magnetic field and SO coupling 53 , and the dynamical effects nearby Dirac point due to SO coupling 54,55,56 . The research along this direction will definitely reveal more interesting physics and stimulate more interesting experiments.…”

Matter-Wave Bright Solitons in Spin-Orbit Coupled Bose-Einstein Condensates

“…Different studies have revealed the existence of a "stripe phase" (consisting of a linear combination of plane waves) [6] and phase transitions between it and states with a single plane wave or with zero momentum [7]. The existence of topological structures, such as vortices with [8] or without [9] rotation, Skyrmions [10] and Dirac monopoles [11], as well as self-trapped states (solitons) of an effective nonlinear Dirac equation (NLDE), was also illustrated [12]. While the above studies refer to BECs with repulsive interactions, to the best of our knowledge, SO-coupled BECs with attractive interactions have not been studied so far.…”

Drag force on a moving impurity in a spin-orbit-coupled Bose-Einstein condensate

“…In applications, the principal direction of the condensate (or equally the momentum of condensate wave function) can be controlled by applying an infinitesimal magnetic field or a shift of the wavelength of the vector light coupled with the hyperfine states of ultracold atoms [26,57]. The momenta of the excitations over the condensate due to the motion of the impurity at v/λ = 0.1 for the θ0 in (a).…”

“…It provides physicists with a new platform to study the effects of SOC in many-body systems. A plenty of researches have been done on the properties of the BEC with SOC, including the groundstate phase [14][15][16][17][18][19], fluctuations above the ground state [20][21][22][23], and spin-orbit coupled BECs with other coldatom techniques, such as dipole-dipole interactions, optical lattice and rotating trap [24][25][26][27][28].…”