Number-state reconstruction with a single SPAD

Abstract

Single-photon avalanche detectors (SPADs) are used ubiquitously in optical and quantum science, but they are not photon-number-resolving detectors. Despite this, in this work we present preliminary results that show that a single SPAD can still be used to perform number-state reconstruction. Through detector characterization and use of maximum-likelihood analysis, we perform number-state reconstruction with a single SPAD and obtain good agreement with independently measured distributions for both Poissonian and anti-bunched light. Our method works well for photon rates up to roughly one input photon per dead time as well as pulse lengths and correlation times of at least a few dead times, fitting many of today's quantum optics experiments.