Düsseldorf 2007 – scientific programme

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Q: Fachverband Quantenoptik und Photonik

Q 64: Poster Quantengase

Q 64.24: Poster

Thursday, March 22, 2007, 16:30–18:30, Poster C

Quantum fluctuations in the time-dependent BCS-BEC crossover — •Bernhard M. Breid and James R. Anglin — Technische Universität Kaiserslautern, Fachbereich Physik, D-67653 Kaiserslautern

We present current work on a path integral approach to the time-dependent BCS-BEC crossover. In order to describe the creation of a molecular BEC out of cold fermionic atoms by a slow Feshbach sweep, we treat the molecules by means of a coherent state path integral formalism. Within the path integral, the molecules can be seen as a classical background field for the fermions. However, the dynamics of the fermionic atoms is calculated using multiple timescale analysis, assuming that the Feshbach sweep is adiabatically slow and that the resonance is narrow compared to the Fermi energy. By solving the fermionic part of the time evolution first, a coherent state path integral for the molecular part remains. Using this as a starting point, we want to analyze the behaviour of the correlation length and the quantum fluctuations in the frame of an adiabatic dynamics. To reach this goal we start with the analytically solveable toy model of just two fermions forming one boson which we treat by the formalism described above. We expect that we can then generalize this method to the many-body problem.