A Two-Atom Picture of Coherent Atom-Molecule Quantum Beats

Abstract

A simple two-atom model is shown to describe a Bose-Einstein condensate of alkali atoms subjected to external magnetic field ramps near a Feshbach resonance. The implications uncovered for two atoms in a trap can be applied at least approximately to a many-atom condensate. A connection to observations is accomplished by scaling the trap frequency to achieve a density comparable to that of the experiments, which yields the fraction of atom pairs in the gas that become molecules. A sudden approximation is used to model the external magnetic field ramps in the vicinity of a two-body Feshbach resonance. The results of this model are compared with recent experimental observations of Donley et al. [1].

16 pages, 5 figures; Submitted to the New. J. Phys. Focus Issue on Quantum Gases; Revision: changed the formula for the scaled frequency and the numerical results in Sec. 5, Replaced figures 2-5