Quantum microscopy based on Hong-Ou-Mandel interference

Hong-Ou-Mandel (HOM) interference-the bunching of indistinguishable photons at a beamsplitter-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 photon flux as small as seven photon pairs per frame. Using a single-photon avalanche diode camera, we measure both bunched and anti-bunched photon-pair distributions at the output of an HOM interferometer, which are combined to provide a lower-noise image of the sample. This approach demonstrates the possibility of HOM microscopy as a tool for the label-free imaging of transparent samples in the very low photon regime. Hong-Ou-Mandel interference enables depth-resolved quantum imaging at very low light levels.

Automated summary

In this study, a full-field, scan-free quantum imaging technique exploiting Hong-Ou-Mandel interference is developed to reconstruct the surface depth profile of transparent samples. The ability to retrieve images with micrometre-scale depth features is demonstrated even with a low photon flux.