Measurement of Excitations in the Stripe Phase of a Spin-Orbit Coupled Bose-Einstein Condensate*

Recent experimental progress with quantum gases is providing new avenues for the study of exotic stripe phases and supersolid-like properties from a variety of different perspectives. In our lab, we generate a superfluid stripe phase by combining Raman induced spin-orbit coupling with an additional weak optical lattice. We study the excitation spectrum by applying Raman detuning quenches and observing the resulting spin polarization. We characterize the zero-momentum bandgap as a function of the optical lattice coupling strength and find good agreement between the experimental observations and numerical simulations. This work provides a direct experimental confirmation of the gapped pseudo-Goldstone spectrum and opens the door for further investigations into the excitation dynamics of a superfluid stripe phase.