High-speed imaging of spatiotemporal correlations in Hong-Ou-Mandel interference

TL;DR

This paper demonstrates high-speed measurement of two-photon interference across thousands of spatial modes using a time tagging camera, enhancing quantum technology capabilities.

Contribution

It introduces a novel high-speed imaging technique for spatiotemporal correlations in Hong-Ou-Mandel interference, enabling practical utilization of high-dimensional entangled photon modes.

Findings

Observed 64% bi-photon interference visibility

Achieved measurement of up to 2000 spatial modes

Demonstrated rapid data acquisition within seconds

Abstract

The Hong-Ou-Mandel interference effect lies at the heart of many emerging quantum technologies whose performance can be significantly enhanced with increasing numbers of entangled modes one could measure and thus utilize. Photon pairs generated through the process of spontaneous parametric down conversion are known to be entangled in a vast number of modes in the various degrees of freedom (DOF) the photons possess such as time, energy, and momentum, etc. Due to limitations in detection technology and techniques, often only one such DOFs can be effectively measured at a time, resulting in much lost potential. Here, we experimentally demonstrate, with the aid of a time tagging camera, high speed measurement and characterization of two-photon interference. {With a data acquisition time of only a few seconds, we observe a bi-photon interference and coalescence visibility of $\sim64\%$ with potentially up to $\sim2\times10^3$ spatial modes}. These results open up a route for practical applications of using the high dimensionality of spatiotemporal DOF in two-photon interference, and in particular, for quantum sensing and communication.