  We investigate the use of correlated photon pair sources for the improved
quantum-level detection of a target in the presence of a noise background.
Photon pairs are generated by spontaneous four-wave mixing, one photon from
each pair (the herald) is measured locally while the other (the signal) is sent
to illuminate the target. Following diffuse reflection from the target, the
signal photons are detected by a receiver and non-classical timing correlations
between the signal and herald are measured in the presence of a configurable
background noise source. Quantum correlations from the photon pair source can
be used to provide an enhanced signal-to-noise ratio when compared to a
classical light source of the same intensity.
