Energy transfer from pump to probe in a resonant medium is accompanied
by the addition of spontaneous noise of the medium. A scheme is prese
nted where this energy transfer can be made noise free i.e., a coheren
t signal is transformed into a coherent signal with larger intensity.
The scheme uses a LAMBDA-system with injected coherence between two gr
ound levels - this coherence leads to the transfer of energy from the
pump to the probe beam.