Optimising the signal-to-noise ratio in measurement of photon pairs with detector arrays

TL;DR

This paper compares detector arrays for measuring photon pairs, showing EMCCD cameras provide superior signal-to-noise ratios for quantum correlation detection, with experimental validation of the model.

Contribution

It demonstrates that EMCCD cameras optimize the SNR in photon pair measurements, providing a quantitative model and experimental confirmation.

Findings

EMCCD cameras achieve higher SNR than ICCD cameras.

SNR scales with the square root of the number of coherence cells.

Experimental results confirm the theoretical model.

Abstract

To evidence multimode spatial entanglement of spontaneous down-conversion, detector arrays allow a full field measurement, without any a priori selection of the paired photons. We show by comparing results of the recent literature that electron-multiplying CCD (EMCCD) cameras allow, in the present state of technology, the detection of quantum correlations with the best signal-to-noise ratio (SNR), while intensified CCD (ICCD) cameras allow at best to identify pairs. The SNR appears to be proportional to the square root of the number of coherence cells in each image, or Schmidt number. Then, corrected estimates are derived for extended coherence cells and not very low and not space-stationary photon fluxes. Finally, experimental measurements of the SNR confirm our model.