Photon-number-resolving segmented detectors based on single-photon avalanche-photodiodes

TL;DR

This paper explores a novel segmented waveguide detector design using SPADs side-coupled to a waveguide, aiming to improve photon-number resolution by minimizing photon loss and analyzing detector performance.

Contribution

It introduces a new SPAD segmented waveguide detector design with side-coupling, reducing photon loss and enabling better photon-number resolution analysis.

Findings

The proposed detector design effectively reduces photon loss.

Performance characterized by POVM purity depends on SPAD number, loss, and dark counts.

The design shows promise for improved quantum photodetection.

Abstract

We investigate the feasibility and performance of photon-number-resolved photodetection employing single-photon avalanche photodiodes (SPADs) with low dark counts. While the main idea, to split $n$ photons into $m$ detection modes with no more than one photon per mode, is not new, we investigate here a important variant of this situation where SPADs are side-coupled to the same waveguide rather than terminally coupled to a propagation tree. This prevents the nonideal SPAD quantum efficiency from contributing to photon loss. We propose a concrete SPAD segmented waveguide detector based on vertical directional coupler design, and characterize its performance by evaluating the purities of positive-operator-valued measurements (POVMs) in terms of SPAD number $m$, photon loss, and dark counts.