Hannover 2016 – scientific programme
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A: Fachverband Atomphysik
A 23: Ultra-cold atoms, ions and BEC I (with Q)
A 23.2: Talk
Wednesday, March 2, 2016, 11:15–11:30, f107
Probing superfluidity of Bose-Einstein condensates via laser stirring — •Vijay Pal Singh1,2, Wolf Weimer2, Kai Morgener2, Jonas Siegl2, Klaus Hueck2, Niclas Luick2, Henning Moritz2, and Ludwig Mathey1,2 — 1Zentrum für Optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany — 2Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
We investigate the superfluid behavior of a Bose-Einstein condensate of 6Li molecules. In the experiment by Weimer et al., Phys. Rev. Lett. 114, 095301 (2015) a condensate is stirred by a weak, red-detuned laser beam along a circular path around the trap center. The rate of induced heating increases steeply above a velocity vc, which we define as the critical velocity. Below this velocity, the moving beam creates almost no heating. In this paper [1], we demonstrate a quantitative understanding of the critical velocity. Using both numerical and analytical methods, we identify the non-zero temperature, the circular motion of the stirrer, and the density profile of the cloud as key factors influencing the magnitude of vc. A direct comparison to the experimental data shows excellent agreement.
[1] V. P. Singh, W. Weimer, K. Morgener, J. Siegl, K. Hueck, N. Luick, H. Moritz, and L. Mathey, arXiv: 1509.02168.