Formation of a Bose condensate of stable molecules via a Feshbach resonance

We propose and analyze an approach to convert an atomic condensate into a c ondensate of diatomic molecules in the rovibrational ground state. The proc ess consists of a stimulated Raman transition dramatically enhanced by a ti me-dependent magnetic field that sweeps over a field-induced Feshbach reson ance. For a condensate of Na atoms a judicious choice of Feshbach resonance enhances the Raman transition probability by seven orders of magnitude. A conversion efficiency of 3% can be realized by a field varying over a reson ance at B = 853 G in the direction of increasing field strength. With the o pposite direction an efficiency of 23% is realized. (C) 2001 Academie des s ciences/Editions scientifiques et medicales Elsevier SAS.