Abstract

We have observed a stimulated Raman resonance between free and bound molecular states of atoms in a Bose-condensed gas. In our experiment, we first produce a Bose-condensed cloud containing about 5 × 10^{5 87}Rb 5²S_1/2(f = 1, m_f = −1) atoms in a magnetic “TOP” trap, with a typical condensate fraction of about 20%. We then illuminate the atoms with a τ = 10 ms duration pulse of light from two laser beams 1 and 2 of frequency v, and v₂, and intensities I₁ = 120 W/cm² and I₂ = 2.2 W/cm², respectively, as shown in Fig. 1. The frequency v₁ is fixed on the peak of the photoassociation transition which couples free pair states |f〉 of the atoms to an electronically excited ^8/Rb₂ bound level $|e〉=|0_{\text{g}}^{-}\left(v=1,\text{ J}=0\right)〉$. The frequency difference Δ = v₂ − v₁ is established by an acousto-optical modulator. The light pulse induces strong losses of atoms from the cloud, due to spontaneous emission from level |e〉 back to hot atoms. We measure the fraction of atoms N(τ)/N₀ remaining after the 10 ms pulse with laser-induced fluorescence. A typical plot of this signal as a function of Δ is shown in Fig. 2.

© 1999 Optical Society of America