The synthetic gauge field and exotic vortex phase with spin-orbital-angular-momentum coupling

Ultracold atoms endowed with tunable spin-orbital-angular-momentum coupling(SOAMC)represent a promising avenue for delving into exotic quantum phenomena. Building on recent experimental advancements, we propose the generation of synthetic gauge fields, and by including exotic vortex phases within spinor Bose-Einstein condensates, employing a combination of a running wave and Laguerre-Gaussian laser fields. We investigate the ground-state characteristics of the SOAMC condensate, revealing the emergence of exotic vortex states with controllable orbital angular momenta. It is shown that the interplay of the SOAMC and conventional spin-linear-momentum coupling induced by the running wave beam leads to the formation of a vortex state exhibiting a phase stripe hosting single multiply quantized singularity. The phase of the ground state will undergo the phase transition corresponding to the breaking of rotational symmetry while preserving the mirror symmetry. Importantly, the observed density distribution of the ground-state wavefunction, exhibiting broken rotational symmetry, can be well characterized by the synthetic magnetic field generated through light interaction with the dressed spin state. Our findings pave the way for further exploration into the rotational properties of stable exotic vortices with higher orbital angular momenta against splitting in the presence of synthetic gauge fields in ultracold quantum gases.

Cyclotron dynamics of a Bose—Einstein condensate in a quadruple-well potential with synthetic gauge fields

We investigate the cyclotron dynamics of Bose-Einstein condensate(BEC)in a quadruple-well potential with synthetic gauge fields.We use laser-assisted tunneling to generate large tunable effective magnetic fields for BEC.The mean position of BEC follows an orbit that simulated the cyclotron orbits of charged particles in a magnetic field.In the absence of atomic interaction,atom dynamics may exhibit periodic or quasi-periodic cyclotron orbits.In the presence of atomic interaction,the system may exhibit self-trapping,which depends on synthetic gauge fields and atomic interaction strength.In particular,the competition between synthetic gauge fields and atomic interaction leads to the generation of several discontinuous parameter windows for the transition to self-trapping,which is obviously different from that without synthetic gauge fields.