Vortex nucleations in spinor Bose condensates under synthetic azimuthal gauge potentials

We demonstrate the experimental observation of vortex nucleations in spinor Bose-Einstein Condensates under radially-localized synthetic gauge potentials. Such gauge potentials are azimuthal and created by light-induced spin-orbital-angular-momentum coupling, generating circulating azimuthal velocity fields. A sufficiently large azimuthal velocity peaked near the condensate center results in a dynamically unstable localized excitation that initiates vortex nucleations. This excitation appears as a spontaneously-formed vortex-antivortex pair near the cloud center. Following the initially developed instability, the dynamics is governed by the asymmetry and dissipation, where the atomic orbital angular momentum evolves and can reach the value of the ground state. Our experimental results agrees reasonably with time-dependent Gross-Pitaevskii equation (GPE) simulations.