Hong-Ou-Mandel (HOM) interference, the bunching of indistinguishable photons at a beam splitter, is a staple of quantum optics and lies at the heart of many quantum sensing approaches and recent optical quantum computers. Here, we report a full-field, scan-free, quantum imaging technique that exploits HOM interference to reconstruct the surface depth profile of transparent samples. We demonstrate the ability to retrieve images with micrometre-scale depth features with a photon flux as small as 7 photon pairs per frame. Using a single photon avalanche diode camera we measure both the bunched and anti-bunched photon-pair distributions at the HOM interferometer output which are combined to provide a lower-noise image of the sample. This approach demonstrates the possibility of HOM microscopy as a tool for label-free imaging of transparent samples in the very low photon regime.
@article{arxiv.2108.05346,
title = {Quantum microscopy based on Hong-Ou-Mandel interference},
author = {Bienvenu Ndagano and Hugo Defienne and Dominic Branford and Yash D. Shah and Ashley Lyons and Niclas Westerberg and Erik M. Gauger and Daniele Faccio},
journal= {arXiv preprint arXiv:2108.05346},
year = {2022}
}