Positive Operator-Valued Measure reconstruction of a beam-splitter tree based photon-number-resolving detector

TL;DR

This paper demonstrates the reconstruction of a photon-number-resolving detector using a beam-splitter tree and advanced electronics to accurately identify photon numbers up to four, improving detector performance at high count rates.

Contribution

It introduces a method to reconstruct POVMs of a complex beam-splitter tree detector with smart counting to mitigate dead time effects.

Findings

Successfully reconstructed the POVM of the detector

Achieved accurate photon number resolution up to four photons

Implemented dead time compensation for high count rate operation

Abstract

Here we present a reconstruction of the Positive Operator-Value Measurement of a photon-number-resolving detector comprised of three 50:50 beamsplitters in a tree configuration, terminated with four single-photon avalanche detectors. The four detectors' outputs are processed by an electronic board that discriminates detected photon number states from 0 to 4 and implements a "smart counting" routine to compensate for dead time issues at high count rates.