Vortices in spin-orbit-coupled Bose-Einstein condensates

TL;DR

This paper explores methods to create stable vortices in spin-orbit-coupled Bose-Einstein condensates, revealing that traditional rotation does not produce equilibrium vortices and proposing alternative techniques involving laser and field manipulations.

Contribution

It introduces new methods to induce stable vortex configurations in spin-orbit BECs and derives effective Hamiltonians for various laser schemes, expanding understanding of vortex behavior.

Findings

Rotation of the trap does not produce static vortices in spin-orbit BECs.

Alternative methods can generate thermodynamically stable vortices.

Vortex arrangements and parity effects depend on laser schemes and system parameters.

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.