You are cordially invited to the SCL seminar of the Center for the Study of Complex Systems, which will be held on Thursday, 5 June 2025 at 14:00 in the "Zvonko Mariić" lecture hall of the Institute of Physics Belgrade. The talk entitled

Sound in Dipolar Supersolids

will be given by Dr. Marija Šindik (SCL, Institute of Physics Belgrade). The abstract of the talk:

Supersolid is an intriguing state of matter characterized by the spontaneous and simultaneous breaking of phase and continuous translational symmetry, resulting in the non-intuitive coexistence of superfluid and crystalline features. This phase has recently been realized experimentally in dipolar Bose-Einstein condensates. In one-dimensional ring-trap geometries, superolids exhibit two Goldstone modes, which can be excited by the sudden removal of a weak periodic perturbation. In this talk we will present a numerical investigation of the resulting collective oscillations using the extended Gross-Pitaevskii theory and extract the corresponding sound velocities. Comparing these with predictions from supersolid hydrodynamic theory will enable us to identify the superfluid fraction -  a key parameter characterizing the supersolid phase. In the presence of persistent currents, the excitation spectrum is modified by a Doppler effect, resulting in a doubling of the sound velocities. We will demonstrate that the Doppler shifts differ for the two modes, with analytical predictions from hydrodynamics showing good agreement with Gross-Pitaevskii simulations.