Beyond coincidence: using all the data in Hong-Ou-Mandel interferometry

TL;DR

This paper enhances Hong-Ou-Mandel interferometry by incorporating detailed detector data, enabling more precise measurements of photon distinguishability and simultaneous parameter estimation, approaching quantum limits.

Contribution

It introduces a model that uses all available detector data in HOM experiments, improving precision and enabling calibration-free protocols.

Findings

Enhanced precision over traditional methods

Simultaneous estimation of time delay and calibration parameters

Approaching quantum Cramér-Rao bound

Abstract

The Hong-Ou-Mandel effect provides a mechanism to determine the distinguishability of a photon pair by measuring the bunching rates of two photons interfering at a beam splitter. Of particular interest is the distinguishability in time, which can be used to probe a time delay. Photon detectors themselves give some timing information, however--while that resolution may dwarf that of an interferometric technique--typical analyses reduce the interference to a binary event, neglecting temporal information in the detector. By modelling detectors with number and temporal resolution we demonstrate a greater precision than coincidence rates or temporal data alone afford. Moreover, the additional information can allow simultaneous estimation of a time delay alongside calibration parameters, opening up the possibility of calibration-free protocols and approaching the precision of the quantum Cram\'er-Rao bound.