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A: Fachverband Atomphysik
A 28: Poster Session - Atomic Physics IV
A 28.12: Poster
Thursday, March 12, 2020, 16:00–18:00, Empore Lichthof
Sound in a Homogeneous Bose Gas - The Two Fluid Model and Nonlinear Damping — •Timon Hilker1, Christoph Eigen1, Jinyi Zhang1, Lena Dogra1, Jake Glidden1,2, Robert Smith1,2, Nir Navon1,3, and Zoran Hadzibabic1 — 1Cavendish Laboratory, University of Cambridge, UK — 2Clarendon Laboratory, University of Oxford, UK — 3Department of Physics, Yale University, New Haven, CT USA
The existence of two distinct sound velocities is one of the hallmarks of superfluids. In a compressible quantum gas both modes couple to density, which allows us to observe, for the first time, both sound velocities in a moderately interacting ultracold Bose gas. Using a magnetic field gradient, we excite centre-of-mass oscillations of a homogeneous K-39 Bose gas in a three-dimensional box trap, revealing two distinct resonant oscillations as described by Landau's two-fluid model. We study the speed, the damping and the microscopic structure of both modes for various interaction strengths and temperatures. At zero temperature, all standard damping vanishes for the lowest BEC mode giving us the unique opportunity to investigate purely nonlinear damping due to collisional coupling to higher modes.