We propose and demonstrate a single-photon sensitive technique for optical vibrometry. It uses high speed photon counting to sample the modulated backscattering from a vibrating target. Designed for remote vibration sensing with ultralow photon flux, we show that this technique can detect small displacements down to 110 nm and resolve vibration frequencies from DC up to several kilohertz, with less than 0.01 detected photons per pulse. This single-photon sensitive optical vibrometry may find important applications in acousto-optic sensing and imaging, especially in photon-starved environments.

We are investigating a method for identifying materials from a distance, even when they are obscured, using a technique called Quantum Parametric Mode Sorting and single photons detection. By scanning a segment of the material, we are able to capture data on the relationships between the peak count of photons reflected at each position and the location of that reflection. This information allows us to measure the relative reflectance of the material and the texture of its surface, which enables us to achieve a material recognition accuracy of 99%, even maintaining 89.17% when materials are obscured by a lossy and multi-scattering obscurant that causes up to 15.2 round-trip optical depth.

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We explore an active illumination approach to remote material recognition, based on quantum parametric mode sorting and single-photon detection. By measuring a photon’s time of flight at picosecond resolution, 97.8% recognition is demonstrated by illuminating only a single point on the materials. Thanks to the exceptional detection sensitivity and noise rejection, a high recognition accuracy of 96.1% is achieved even when the materials are occluded by a lossy and multiscattering obscurant.