Second Order Virial Expansion for an Atomic Gas in Harmonic Waveguides
Résumé
We study the virial expansion for a quantum gas in a 1D or a 2D atomic waveguide. We use a two-channel Hamiltonian which takes into account the coherent coupling between atoms and molecules near a possible Feshbach resonance. We focus on the second order virial coefficient by using a diagrammatic approach. We derive the phase-shift in a multimode regime of the waveguide and deduce a Beth-Uhlenbeck formula taking into account the presence of the molecules and of the external trap.