Rotating Atomic Quantum Gases with Light-Induced Azimuthal Gauge Potentials and the Observation of the Hess-Fairbank Effect

Abstract

We demonstrate synthetic azimuthal gauge potentials for Bose-Einstein condensates from engineering atom-light couplings. The gauge potential is created by adiabatically loading the condensate into the lowest energy Raman-dressed state, achieving a coreless vortex state. The azimuthal gauge potentials act as effective rotations and are tunable by the Raman coupling and detuning. We characterize the spin textures of the dressed states, in agreements with the theory. The lowest energy dressed state is stable with a 4.5-s half-atom-number-fraction lifetime. In addition, we exploit the azimuthal gauge potential to demonstrate the Hess-Fairbank effect, the analogue of Meissner effect in superconductors. The atoms in the absolute ground state has a zero quasi-angular momentum and transits into a polar-core vortex when the synthetic magnetic flux is tuned to exceed a critical value. Our demonstration serves as a paradigm to create topological excitations by tailoring atomlight interactions where both types of SO(3) vortices in the | F | = 1 manifold, coreless vortices and polar-core vortices, are created in our experiment. The gauge field in the stationary Hamiltonian opens a path to investigating rotation properties of atomic superfluids under thermal equilibrium.

Non-Abelian geometric potentials and spin-orbit coupling for periodically driven systems

“…On the other hand, the term L xFx + L yFy = L +F− + L −F+ represents transitions between different spin and OAM projection states described by the raising / lowering operators L ± = L x ± iL y andF ± =F x ± iF y . Therefore the present SOC has some similarities to the coupling between the spin and OAM induced by Raman laser beams carrying optical vortices [76][77][78][79][80][81][82][83][84][85][86][87]. Yet, unlike the Raman case now the coupling between the spin and OAM is described by all three OAM projections L x , L y and L z as long as α ⊥ = 0 and α z = 0, so the coupling is truly three dimensional.…”

Angular stripe phase in spin-orbital-angular-momentum coupled Bose condensates

“…For this reason, phase III was previously referred to as the stripe phase [16,17]. The SOAMC was most recently engineered in spin-1 [20,21] and spin-1/2 87 Rb Bose gases [22]. Different from the theoretical proposals [15][16][17][18][19], LG laser beams with a tune-out wavelength λ = 790.02 nm were used to eliminate the unnecessary diagonal Stark shift [20][21][22].…”

“…In this paper we investigate ground-state phases and lowlying collective modes of a harmonically trapped pancakelike SOAMC Bose gas for realistic parameters using 87 Rb and 41 K atoms, by developing a self-consistent Gross-Pitaevskii theory within the Bogoliubov approximation and a variational theory at zero temperature. The former theory concentrates on the case with definite angular momentum (i.e., phases I and II), which possesses axial symmetry, and has been intensively studied theoretically [15][16][17][18][19] and experimentally [20][21][22]. We consider the low-lying collective excitations such as the dipole and breathing modes in these quantum phases and investigate the Rabi-frequency dependence of the mode frequencies (Fig.…”

Universal relations for spin-orbit-coupled Fermi gases in two and three dimensions

“…In the past decade, the realizations of the spin-orbit (SO) coupling in ultracold neutral atoms have sparked a great deal of interest [37][38][39][40][41][42][43][44]. It provides an ideal platform on which to study novel quantum phenomena resulted from SO coupling in a highly controllable and tunable way, such as topological insulators and superconductors [6,7], and (spin) Hall effect [45][46][47].…”