Erlangen 2018 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 9: Cold atoms II - interactions (joint session A/Q)

Q 9.1: Talk

Monday, March 5, 2018, 10:30–10:45, K 2.019

Dimensional Crossover for the Beyond-Mean-Field Corrections in the Weakly Interacting Bose Gas — •Tobias Ilg, Jan Kumlin, and Hans Peter Büchler — Institute for Theoretical Physics III, University of Stuttgart, 70569 Stuttgart, Germany

We investigate the beyond-mean-field corrections in a confined weakly interacting Bose gas at zero temperature. The system is elongated along one direction and tightly confined along the transverse directions. The confined gas can exhibit three-dimensional as well as quasi-one-dimensional behavior. We use the field-theoretic approach of Hugenholtz and Pines to include beyond-mean-field corrections. The field-theoretic treatment allows us to connect the three-dimensional regime to the quasi-one-dimensional regime and to describe a dimensional crossover of the system. We show that the inclusion of the beyond-mean-field terms leads to a correction of the coupling constant in the quasi-one-dimensional regime due to the presence of the confinement. Thus, the confinement-induced shift of the ground state energy appears naturally in our approach.