Bereiche | Tage | Auswahl | Suche | Aktualisierungen | Downloads | Hilfe
Q: Fachverband Quantenoptik und Photonik
Q 33: Quantum Gases
Q 33.1: Vortrag
Mittwoch, 16. März 2022, 14:00–14:15, Q-H10
First and Second Sound in a compressible 3D Bose fluid — •Timon A. Hilker1,2, Lena H. Dogra1, Christoph Eigen1, Jake A. P. Glidden1, Robert P. Smith3, and Zoran Hadzibabic1 — 1University of Cambridge — 2Max Planck Institute of Quantum Optics — 3University of Oxford
One of the hallmarks of superfluidity is the existence of two distinct sound modes with the same wavelength. In the incompressible-liquid regime, this phenomenon has been extensively studied with superfluid Helium.
In this talk, I will present our observation and characterization of first and second sound in a compressible 3D ultracold Bose gas. Using a magnetic field gradient, we excite center-of-mass oscillations of a homogeneous K-39 Bose gas in a box trap revealing two distinct resonances. We find quantitative agreement with the hydrodynamic description of Landau’s two-fluid model, both for the sound speeds and for the mode structure in terms of in-phase/out-of-phase oscillations dominated by the thermal/BEC atoms for the first/second sound. In addition, we study the full crossover from the hydrodynamic to the collisionless regime above Tc and find a decreasing speed of sound with increasing damping.