Measuring high-order photon-number correlations in multimode pulsed quantum states

TL;DR

This paper presents a novel experimental method using hybrid photodetectors to measure high-order photon correlations in multimode quantum states, enabling detailed characterization and nonclassicality assessment.

Contribution

It introduces a self-consistent detection scheme for high-order correlations that estimates key parameters directly from data, improving quantum state characterization.

Findings

Good agreement with theoretical predictions

Effective nonclassicality criterion based on high-order correlations

Reliable estimation of quantum efficiency, modes, and energy

Abstract

We implement a direct detection scheme based on hybrid photodetectors to experimentally investigate high-order correlations for detected photons by means of quantities that can be experimentally accessed. We show their usefulness in fully characterizing a multimode twin-beam state in comparison with classical states and, in particular, we introduce a nonclassicality criterion based on a simple linear combination of high-order correlation functions. Our scheme is self-consistent, allowing the estimation of all the involved parameters (quantum efficiency, number of modes and average energy) directly from the same experimental data. Results are in very good agreement with theory, thus suggesting the exploitation of our scheme for reliable state characterization in quantum technology.