Spin-vortex nucleation in a Bose-Einstein condensate by a spin-dependent rotating trap

A method to produce a spin-dependent rotating potential using near-resonant circularly polarized laser beams is proposed. It is shown that half-quantum vortices are nucleated in a spinor Bose-Einstein condensate (BEC) with an antiferromagnetic interaction. In contrast to the vortex nucleation in a scalar BEC, the spin-vortex nucleation occurs at a low rotation frequency ($\simeq 0.1{\omega }_{\perp }$ with ${\omega }_{\perp }$ being the radial trap frequency) in a short nucleation time $\simeq 50\mathrm{ms}$ without dissipation. A method for nondestructive measurement of half-quantum vortices is discussed.

Figure 1

Transition strengths with circularly polarized laser beams for the (a) $D_1$ and (b) $D_2$ lines. (c) Subtraction of the transition strengths in (b) from those in (a) for the case of $\hslash {\omega }_0=(E_{D_1}+E_{D_2})∕2$.

Figure 2

(Color) Time evolution of the density and phase profiles of the $m=\pm 1$ components and the total density profile for the potential given in Eqs. (12, 13, 14, 15) with $\Omega =0.13{\omega }_{\perp }$. The $m=1$ component is affected by the rotating potential. The $m=0$ component is negligibly small. The field of view of each panel is $38.2\times 38.2\mu \mathrm{m}$. The unit of the density is $N∕a_{\mathrm{ho}}^2$ with $a_{\mathrm{ho}}={[\hslash ∕\left(M{\omega }_{\perp }\right)]}^{1∕2}$.

Figure 3

(Color) Time evolution of the orbital angular momentum $L_1$ in the $m=1$ component for $\Omega =0.05{\omega }_{\perp }$, $0.13{\omega }_{\perp }$, and $0.5{\omega }_{\perp }$. The insets show the density and phase profiles at $50\mathrm{ms}$ for $\Omega =0.13{\omega }_{\perp }$ and at $20\mathrm{ms}$ for $\Omega =0.05{\omega }_{\perp }$.