Adiabatic Phase Diagram of an Ultracold Atomic Fermi Gas with a Feshbach Resonance

Abstract

We determine the adiabatic phase diagram of a resonantly-coupled system of Fermi atoms and Bose molecules confined in a harmonic trap by using the local density approximation. The adiabatic phase diagram shows the fermionic condensate fraction composed of condensed molecules and Cooper paired atoms. The key idea of our work is conservation of entropy through the adiabatic process, extending the study of Williams et al. [New J. Phys. 6 (2004) 123] for an ideal gas mixture to include the resonant interaction in a mean-field theory. We also calculate the molecular conversion efficiency as a function of initial temperature. Our work helps to understand recent experiments on the BCS–BEC crossover, in terms of the initial temperature measured before a sweep of the magnetic field.