Freiburg 2024 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 27: Phase Transitions

Q 27.6: Talk

Wednesday, March 13, 2024, 12:30–12:45, Aula

Low-energy modes in a trapped dipolar supersolid — •Paul Uerlings¹, Jens Hertkorn¹, Kevin Ng¹, Fiona Hellstern¹, Lucas Lavoine¹, Ralf Klemt¹, Tim Langen^1,2, and Tilman Pfau¹ — ¹5. Physikalisches Institut and Center for Integrated Quantum Science and Technology IQST, Universität Stuttgart — ²Atominstitut, TU Wien, Stadionallee 2; 1020 Vienna, Austria

A supersolid is a phase of matter that combines the crystal-like periodic density modulation of a solid with the frictionless flow of a superfluid, simultaneously breaking both the global U(1) gauge symmetry and the translational symmetry. Breaking these two symmetries gives rise to two types of collective modes, called the Nambu-Goldstone and amplitude Higgs mode. We theoretically and experimentally investigate the excitation spectrum of a trapped dipolar quantum gas across the Bose-Einstein condensate to supersolid phase transition. In order to experimentally observe these excitations, we prepare a ultracold quantum gas of ¹⁶²Dy in an optical dipole trap with variable geometry. We compare our experimental results to numerical simulations of the extended Gross-Pitaevskii equation and the Bogoliubov-de-Gennes equations. The observed low-energy modes reveal the existence of the two distinct amplitude Higgs and Nambu-Goldstone modes that emerge in our system at the phase transition point. Our findings extend earlier work on the obervation of the Nambu-Goldstone mode and theoretical predictions on the amplitude Higgs mode.

Keywords: supersolid; dysprosium; ultracold; dipolar; BEC