Quantum Imaging and Sensing

Research Topics

Hong-Ou-Mandel Interference for Quantum Imaging

In this research line, we develop quantum imaging techniques based on Hong–Ou–Mandel (HOM) interference of single photons for high-sensitivity characterization of materials. By controlling and measuring the degree of indistinguishability between entangled photon pairs in a HOM interferometer, we encode sample properties into changes in the visibility and depth of the HOM interference dip. In particular, we use narrowband polarization-entangled single-photon sources that generate a broad HOM dip, making the coincidence rate predominantly sensitive to polarization-induced distinguishability. This enables precise, label-free imaging of birefringent samples, allowing us to map local fast-axis orientation and phase retardance with nanometer-scale retardance precision and sub-degree angular resolution while operating at average powers of only a few hundred femtowatts.

Quantum Imaging with Undetected Photons

In this research line, we investigate quantum imaging with undetected photons (IUP) to enable hyperspectral imaging in the infrared using only visible-light detectors. Using SU(1,1) nonlinear interferometers, idler photons in the IR interact with the sample while only their signal partners are detected. The information imprinted on the undetected IR photons is recovered through interference of the visible beam, giving access to absorption and phase contrast at otherwise hard-to-detect wavelengths in a compact, scalable platform. We are also developing robust quantum imaging with undetected photons, combining wavefront control and data-driven analysis to enable practical hyperspectral sensing and classification of complex materials.