  The introduction of quantum methods in spectroscopy can provide enhanced
performance and technical advantages in the management of noise. We investigate
the application of quantum illumination in a pump and probe experiment. Thermal
lensing in a suspension of gold nanorods is explored using a classical beam as
the pump and the emission from parametric downconversion as the probe. We
obtain an insightful description of the behaviour of the suspension under
pumping with a method known to provide good noise rejection. Our findings are a
further step towards investigating effects of quantum light in complex
plasmonic media.
