Hamburg 2009 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 41: Quantengase: Dipolare Gase

Q 41.5: Talk

Thursday, March 5, 2009, 11:30–11:45, Audi-A

Macroscopic excitations and quantum tunnelling of Bose-Einstein condensates with long-range interactions — Torsten Schwidder, •Holger Cartarius, Jörg Main, and Günter Wunner — 1. Institut für Theoretische Physik, Universität Stuttgart, 70550 Stuttgart

Macroscopic excitations and quantum tunnelling are discussed for Bose-Einstein condensates with both an attractive 1/r and a dipolar interaction. A time-dependent variational approach to the nonlinear Gross-Pitaevskii equation leads to classical Hamiltonians in canonical form which are quantized by diagonalization in a complete Sturmian-type basis set and using the method of complex dilatation. The real and imaginary parts of the resonance energies provide the macroscopic quantum excitations and decay rates of the condensate, respectively. The results are compared with excitations obtained by a harmonic approximation to the potential and tunnelling rates derived using the “bounce trajectory.” Significant differences between the semiclassical and exact quantum results are observed in particular for the decay rates.