Characterization of space-momentum entangled photon with a time resolving CMOS SPAD array

TL;DR

This paper demonstrates the use of a time-resolving CMOS SPAD array to characterize space-momentum entangled photon pairs, enabling direct extraction of spatial correlations and verification of entanglement through EPR inequality violation.

Contribution

The study introduces a specialized sensor capable of high-precision time-tagging at the pixel level for quantum imaging applications, specifically for characterizing entangled photons.

Findings

Successful characterization of entangled photon pairs

Violation of EPR-type inequality confirming entanglement

High temporal and spatial resolution in photon detection

Abstract

Single photon avalanche diode arrays can provide both the spatial and temporal information of each detected photon. We present here the characterization of entangled light with a sensor specifically designed for quantum imaging applications. The sensors is time-tagging each detection events at the pixel level with sub-nanosecond accuracy, within frames of 50 ns. The spatial correlations between any number of detections in a defined temporal window can thus be directly extracted from the data. We show the ability of the sensor to characterize space-momentum entangled photon pairs emitted by spontaneous parametric downconversion. Their entanglement is demonstrated by violating an EPR-type inequality.