Observation of the dynamics of stripe patterns of a spin-orbit-coupled supersolid

With their characteristic simultaneous breaking of the phase and translational symmetry, supersolids are an exotic phase of matter that have sparked much debate over their features and the validity of different platforms. Here, we report on the first in-situ observation of the density modulation of supersolid stripes in a spin-orbit-coupled Bose-Einstein condensate. We use a mixture of two spin states of 41K, coupled with a two-photon Raman transition, and prepare the system in the so-called supersolid stripe phase. By magnifying the density pattern using a matter-wave lensing technique, we can resolve the stripe spacing and observe its dependence on the Raman coupling strength. This observation disproves the common misconception that the density modulation is determined exclusively by the wavelength of the Raman coupling laser. Further evidence of the flexibility of the stripe pattern is obtained when exciting its compression mode and observing the spacing of the stripes oscillate. Finally, we have exploited the softening of this mode to reveal the supersolid-to-plane-wave phase transition. Moreover, thanks to the Feshbach resonances of 41K, we can tune the different interaction parameters of the system and modify the transition point. Experimentally, we find an excellent agreement with theoretical predictions in all configurations, demonstrating that spin-orbit-coupled condensates offer a competitive platform to study novel properties of supersolidity.