Vortex nucleations in spinor Bose-Einstein condensates under radially-localized synthetic magnetic fields

We report the first experimental observation of vortex nucleations in light-dressed spinor Bose-Einstein condensates under radially-localized synthetic magnetic fields. The light-induced spin-orbital-angular-momentum coupling creates azimuthal gauge potentials $\vec{A}$ for the lowest-energy spinor branch dressed eigenstate. The observation of the atomic wave function in the lowest-energy dressed eigenstate reveals that vortices nucleate from the cloud center of a vortex-free state with canonical momentum $\vec{p} = 0$. This is because a large circulating azimuthal velocity field ∝ $\vec{p}-\vec{A}$ at the condensate center results in a dynamically unstable localized excitation that initiates vortex nucleations. We study the effects of cylindrical asymmetry and dissipation on vortex nucleations, and our observation has reasonable agreement with the time-dependent Gross-Pitaevskii simulations.