  In this work, we theoretically and experimentally demonstrate the possibility
to create an image of an opaque object using a few-photon thermal optical
field. We utilize the Quadrature-Noise Shadow Imaging (QSI) technique that
detects the changes in the quadrature-noise statistics of the probe beam after
its interaction with an object. We show that such thermal QSI scheme has an
advantage over the classical differential imaging when the effect of dark
counts is considered. At the same time, the easy availability of thermal
sources for any wavelength makes the method practical for broad range of
applications, not accessible with, e.g. quantum squeezed light. As a proof of
principle, we implement this scheme by two different light sources: a
pseudo-thermal beam generated by rotating ground glass (RGG) method and a
thermal beam generated by Four-Wave Mixing (FWM) method. The RGG method shows
simplicity and robustness of QSI scheme while the FWM method validates
theoretical signal-to-noise ratio predictions. Finally, we demonstrate
low-light imaging abilities with QSI by imaging a biological specimen on a CCD
camera, detecting as low as 0.03 photons on average per pixel per 1.7
microseconds exposure.
