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DY: Fachverband Dynamik und Statistische Physik

DY 11: Superfluidity and Bose-Einstein condensation

DY 11.1: Hauptvortrag

Dienstag, 27. März 2007, 09:30–10:00, H2

A single Josephson junction for atomic Bose-Einstein condensates: Dynamics and finite temperature effects — •Markus Oberthaler — Kirchhoff Institut für Physik, University of Heidelberg, Im Neuneheimer Feld 227, 69120 Heidelberg

The recent realization of a single weak link for an atomic Bose-Einstein condensate in an optical double-well potential allows for the first time the observation of Josephson oscillations directly on the level of populations on either side of the junction. Furthermore it opens up the way to fully characterize the tunneling dynamics since not only the dynamics of the population difference can be measured but even the time evolution of the relative phase is detectable. How the residual interaction of the atoms can lead to a new dynamical regime, which is characterized by an inhibition of tunneling, will be discussed in detail.

The good experimental control of the atomic system also allows for a quantitative study of thermally induced fluctuations of the relative phase between the weakly linked condensates. These fluctuations even persist in the ultra low temperature limit and thus can be employed for the realization of a new type of thermometer for atomic Bose-Einstein condensates. Our recent results on the measurement of the heat capacity of a quantum gas at ultra low temperatures using this new noise-thermometer will be presented.