Hannover 2010 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 31: Quantum Gases: Interaction Effects II

Q 31.3: Talk

Wednesday, March 10, 2010, 14:30–14:45, E 001

Macroscopic quantum tunnelling and bounce solutions of Bose-Einstein condensates with attractive interactions — •Rolf Häfner, Holger Cartarius, Jörg Main, and Günter Wunner — 1. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart

Solutions of the Gross-Pitaevskii equation for Bose-Einstein condensates with 1/r interaction reveal the existence of a metastable ground state, which can decay in the collapse of the wave function. The decay rate can be calculated from the bounce trajectory in imaginary time. Using a variational approach with a Gaussian wave function, it is possible to introduce canonical variables and to find the bounce trajectory by solving Hamilton’s equations of motion in an inverted potential.

Generalizing the variational approach by the use of a wave function built from a superposition of Gaussians leads to non-canonical equations of motion for the Gaussian parameters which allow us to investigate the imaginary-time dynamics of the condensate. We show how bounce solutions in these coordinates can be found which are the prerequisite for the calculation of the decay rate of the metastable ground state.