Spin-Orbit Coupled Quantum Gases

Abstract

In this review we will discuss the experimental and theoretical progresses in studying spin-orbit coupled degenerate atomic gases during the last two years. We shall first review a series of pioneering experiments in generating synthetic gauge potentials and spin-orbit coupling in atomic gases by engineering atom-light interaction. Realization of spin-orbit coupled quantum gases opens a new avenue in cold atom physics, and also brings out a lot of new physical problems. In particular, the interplay between spin-orbit coupling and inter-atomic interaction leads to many intriguing phenomena. Here, by reviewing recent theoretical studies of both interacting bosons and fermions with isotropic Rashba spinorbit coupling, the key message delivered here is that spin-orbit coupling can enhance the interaction effects, and make the interaction effects much more dramatic even in the weakly interacting regime.

A stripe phase with supersolid properties in spin–orbit-coupled Bose–Einstein condensates

“…With ultracold atoms, idealized Hamiltonians can be experimentally realized and studied. Starting from superfluid Bose-Einstein condensates (BECs), several forms of supersolid have been predicted by adding interactions in the form of dipolar interactions 12,13 , Rydberg interactions 14 , superradiant Rayleigh scattering 15 , nearest-neighbour interaction in lattices 16 and spin-orbit interactions [5][6][7][8] . Several of these proposals lead to solidity along a single spatial direction maintaining their gaseous or liquid-like properties along the other directions i .…”

Harmonically trapped two-atom systems: Interplay of short-ranges-wave interaction and spin-orbit coupling

“…For q rel > 0 (q rel ≪ 1), the interplay leads to an increase of the energy. Interestingly, for q rel ≈ 0.4 (or a aa ≈ 2a ho ), D (4) q rel vanishes. For yet larger q rel , D (4) q rel becomes negative.…”

“…Arrows in panels (a) and (b) show the "allowed paths" that contribute to the energy shift ∆E (2) 0,0,±1/2 . Arrows in panels (c) and (d) show the "allowed paths" that contribute to the energy shift ∆E (4) 0,0,±1/2 . E nρ,m l ,ms with the same E (0) nρ,m l and |m j | are degenerate.…”

“…Squares in Fig. 9 show the coefficient D (4) q rel as a function of q rel . When the s-wave scattering length is negative (q rel < 0), the interplay between the spin-orbit coupling term and the s-wave interaction lowers the energy.…”

“…A variety of intriguing phenomena such as non-equilibrium dynamics [9,10], the spin-orbit coupling assisted formation of molecules [7], and the engineering of band structures [11] have been investigated. At the mean-field level, spin-orbit coupled gases exhibit rich phase diagrams [4,[12][13][14][15][16][17][18]. Effects beyond mean-field theory [19][20][21][22], associated with the renormalization of interactions, are enhanced by the spin-orbit coupling, especially in the pure Rashba case, and can qualitatively change the mean-field results.…”