Spin exchange-induced spin-orbit coupling in a superfluid mixture

Mubarak Alqahtani, Maxim Dzero

Li Chen, Chuanzhou Zhu, Yunbo Zhang +1 more

We investigate the ground-state properties of a dual-species spin-1/2 Bose-Einstein condensate. One of the species is subjected to a pair of Raman laser beams that induces spin-orbit (SO) coupling, whereas the other species is not coupled to the Raman laser. In certain limits, analytical results can be obtained. It is clearly shown that, through the interspecies spin-exchange interaction, the second species also exhibits SO coupling. This mixture system displays a very rich phase diagram, with many of the phases not present in an SO-coupled single-species condensate. Our work provides a way of creating SO coupling in atomic quantum gases, and opens up an avenue of research in SO-coupled superfluid mixtures. From a practical point of view, the spin-exchange-induced SO coupling may overcome the heating issue for certain atomic species when subjected to Raman beams.

Chuanzhou Zhu, Li Chen, Hui Hu +2 more

We investigate the ground-state properties of a mixture of spin-1/2 Bose-Einstein condensate and spin-1/2 Fermi superfluid. In our system, bosons are subjected to a pair of Raman laser beams that induces spin-orbit coupling, while fermions are not coupled to the Raman laser. We show that the fermions can acquire an effective spin-orbit coupling from the spin-exchange interaction between bosons and fermions. In the regime where the boson number is more than the fermion number, we study the topological phase transition of the Fermi superfluid by monitoring the close and re-open of the energy gap, the Berry phase, and the superfluid order parameter, where the back-action to the Bose condensate is also taken into consideration. Our work provides a new way of achieve topological Fermi superfluid … The American Physical Society (APS) is a non-profit membership organization working to advance the knowledge of physics.

Chuanzhou Zhu, Li Chen, Hui Hu +2 more

Chuanzhou Zhu, Li Chen, Hui Hu +2 more

We consider a mixture of spin-1/2 bosons and fermions, where only the bosons are subjected to the spin-orbit coupling induced by Raman beams. The fermions, although not directly coupled to the Raman lasers, acquire an effective spin-orbit coupling through the spin-exchange interaction between the two species. Our calculation shows that this is a promising way of obtaining spin-orbit coupled Fermi gas without Raman-induced heating, where the long-sought topological Fermi superfluids and topological bands can be realized. Conversely, we find that the presence of fermions not only provides a new way to create the supersolid stripe phase of the bosons, but more strikingly it can also greatly increase the spatial period of the bosonic density stripes, and hence makes this phase directly observable in the experiment. This system provides a new and practical platform to explore the physics of spin-orbit coupling, which possesses a dynamic nature through the interaction between the two species.

Ryan Price, Daniel Campbell, Andika Putra +2 more