Bragg spectroscopy of spin-orbit coupled BEC

Scott B. Papp, Juan Miguel Rey Pino, Robert J. Wild +3 more

Raphael Lopes, Christoph Eigen, A. N. Baker +3 more

Andika Putra, Francisco Salces-Carcoba, Yuchen Yue +2 more

M. A. Khamehchi, Yongping Zhang, Chris Hamner +2 more

We measure the collective excitation spectrum of a spin-orbit-coupled Bose-Einstein condensate using Bragg spectroscopy. The spin-orbit coupling is generated by Raman dressing of atomic hyperfine states. When the Raman detuning is reduced, mode softening at a finite momentum is revealed, which provides insight into a supersolid-like phase transition. We find that for the parameters of our system, this softening stops at a finite excitation gap and is symmetric under a sign change of the Raman detuning. Finally, using a moving barrier that is swept through the BEC, we also show the effect of the collective excitation on the fluid dynamics.

Inderpreet Kaur, Sankalpa Ghosh

Abstract We compute the Bogoliubov–de Gennes excitation spectrum in a trapped two-component spin-orbit-coupled (SOC) Bose–Einstein condensate (BEC) in quasi-two-dimensions as a function of linear and angular momentum and analyze them. The excitation spectrum exhibits a minima-like feature at finite momentum for the immiscible SOC-BEC configuration, which implies dynamical instability. We augment these results by computing the dynamic structure factor in the density and pseudo-spin sector, and discuss its interesting features that can be experimentally measured through Bragg spectroscopy of such ultracold condensates.

Robert Niffenegger, Chunlei Qu, Abraham J. Olson +2 more