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Berlin 2005 – scientific programme

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Q: Quantenoptik und Photonik

Q 2: Poster Quantengase

Q 2.8: Poster

Friday, March 4, 2005, 11:00–12:30, Poster HU

Macroscopic Quantum Tunneling — •O. Crasser1, R. Kleiner2, E. Goldobin3, K. Vogel1, R. Walser1, and W. P. Schleich11Abteilung für Quantenphysik, Universität Ulm, 89069 Ulm, Germany — 2Physikalisches Institut-Experimentalphysik II, Universität Tübingen, 72076 Tübingen, Germany — 3Oxxel GmbH, Technologiepark Universität, Bremen 28359, Germany

Tunneling in single particle physics is a well-studied phenomenon, as is the analogous effect that occurs in quantum fluids [1] and superconductivity [2]. However, the practical difficulty in theory arises from the transition from one quantized degree of freedom to having to deal with infinitely many. In this contribution, we are examining an excited state of a stationary BEC as described by the elementary Gross-Pitaevskii mean-field theory. By disregarding the inherent quantum fluctuations of the bosonic matter wave, this state would be preserved indefinitely. However, a more elaborate description leads to a macroscopic quantum tunneling towards the true ground state of the system. In the context of atomic Bose gases, this phenomenon was recently investigated experimentally in [1] and there are strong efforts to examine the behaviour of "classical" fluxons as well as semifluxons into the quantum regime as well.
[1] Y. Shin et al., Distillation of Bose-Einstein condensates in a double-well potential, Phys. Rev. Lett. 92, 150401 (2004) [2] W. Buckel and R. Kleiner, Superconductivity: Fundamentals and applications, Wiley-VCH, Berlin (2004)

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