Imaging and certifying high-dimensional entanglement with a single-photon avalanche diode camera

TLDR

Spatial correlations between photon pairs are essential for quantum imaging, yet conventional measurement with scanning detectors or CCD cameras is slow, requiring hours of acquisition due to limited frame rates. We aim to measure the spatial joint probability distribution of a bi‑photon state from spontaneous parametric down‑conversion using a high‑frame‑rate single‑photon avalanche diode camera. The camera records 10^7 frames, providing rapid statistics for the joint distribution. The data violate an Einstein–Podolsky–Rosen criterion by 227 σ, confirming spatial entanglement, and certify an entanglement dimensionality of 48 within 140 s, illustrating the SPAD camera’s capability for rapid entanglement characterization and paving the way for real‑time quantum imaging and information processing.

Abstract

Abstract Spatial correlations between two photons are the key resource in realising many quantum imaging schemes. Measurement of the bi-photon correlation map is typically performed using single-point scanning detectors or single-photon cameras based on charged coupled device (CCD) technology. However, both approaches are limited in speed due to the slow scanning and the low frame rate of CCD-based cameras, resulting in data acquisition times on the order of many hours. Here, we employ a high frame rate, single-photon avalanche diode (SPAD) camera, to measure the spatial joint probability distribution of a bi-photon state produced by spontaneous parametric down-conversion, with statistics taken over 10 7 frames. Through violation of an Einstein–Podolsky–Rosen criterion by 227 sigmas, we confirm the presence of spatial entanglement between our photon pairs. Furthermore, we certify, in just 140 s, an entanglement dimensionality of 48. Our work demonstrates the potential of SPAD cameras in the rapid characterisation of photonic entanglement, leading the way towards real-time quantum imaging and quantum information processing.