  We demonstrate coupling of light resonant to transition between two excited
states of rubidium and long-lived ground-state atomic coherence. In our
proof-of-principle experiment a non-linear process of four-wave mixing is used
to achieve light emission proportional to independently prepared ground-state
atomic coherence. Strong correlations between stimulated Raman scattering light
heralding generation of ground-state coherence and the four-wave mixing signal
are measured and shown to survive the storage period, which is promising in
terms of quantum memory applications. The process is characterized as a
function of laser detunings.
