Extracting Photon-Number Information from Superconducting Nanowire Single-Photon Detectors Traces via Mean-Derivative Projection

TL;DR

This paper presents a new method combining PCA and a novel readout technique to interpret and benchmark photon-number resolution in SNSPDs, enabling real-time, scalable photon counting with moderate hardware requirements.

Contribution

It introduces a systematic framework using principal component analysis and a new confidence metric to interpret and compare SNSPD photon-number resolving capabilities.

Findings

Photon number information is contained in a single principal component.

The proposed method achieves photon-number resolution with moderate hardware specs.

The approach enables real-time, scalable photon counting in SNSPDs.

Abstract

Photon-number resolved detection with superconducting nanowire single-photon detectors (SNSPDs) attracts increasing interest, but lacks a systematic framework for interpreting and benchmarking this capability. In this work, we combine principal component analysis (PCA) with a new readout technique to explore the photon-number resolving capabilities of SNSPDs and find that the information of the photon number is contained in a single principal component which approximates the time derivative of the average response trace. We introduce a new confidence metric based on the Bhattacharyya coefficient to quantify the photon-number-resolving capabilities of a detector system and show that this metric can be used to compare different systems. Our analysis and interpretation of the principal components imply that photon-number resolution in SNSPDs can be achieved with moderate hardware requirements in terms of both sample rate (5 GSample/sec) and analog bandwidth (3 GHz) and could be implemented in an FPGA, giving a highly scalable solution for real-time photon counting.