Mapping and Measuring Large-scale Photonic Correlation with Single-photon Imaging

Quantum correlation and its measurement are essential in exploring fundamental quantum physics problems and developing quantum-enhanced technologies. A quantum correlation may be generated and manipulated in different spaces, which demands different measurement approaches corresponding to the position, time, frequency, and polarization of quantum particles. In addition, after early proof-of-principle demonstrations, it is of great demand to measure quantum correlation in a Hilbert space large enough for real quantum applications. When the number of modes goes up to several hundreds, the single-mode addressing becomes economically unfeasible, and the processing of correlation events with hardware also becomes extremely challenging. Here, we present a general and large-scale measurement approach of the Correlation on the Spatially Mapped Photon-Level Image. The quantum correlations in other spaces are mapped into the position space and are captured by a single-photon-sensitive imaging system. Synthetic methods are developed to suppress noises so that single-photon registrations can be faithfully identified in images. We eventually succeeded in retrieving all the correlations with a big-data technique from tens of millions of images.