Uncovering Quantum Correlations with Time-Multiplexed Click Detection

TL;DR

This paper demonstrates a time-multiplexed click detection method to reveal quantum correlations in multimode light fields, enabling robust characterization of quantum states for quantum communication applications.

Contribution

It introduces a novel detection scheme that uncovers nonclassical correlations in multimode light without requiring data postprocessing or low-intensity approximations.

Findings

Successfully detected nonclassical correlations in multimode light

Method works with relatively high photon numbers and experimental imperfections

Provides a reliable way to characterize quantum-correlated light fields

Abstract

We report on the implementation of a time-multiplexed click detection scheme to probe quantum correlations between different spatial optical modes. We demonstrate that such measurement setups can uncover nonclassical correlations in multimode light fields even if the single mode reductions are purely classical. The nonclassical character of correlated photon pairs, generated by a parametric down-conversion, is immediately measurable employing the theory of click counting instead of low-intensity approximations with photoelectric detection models. The analysis is based on second- and higher-order moments, which are directly retrieved from the measured click statistics, for relatively high mean photon numbers. No data postprocessing is required to demonstrate the effects of interest with high significance, despite low efficiencies and experimental imperfections. Our approach shows that such novel detection schemes are a reliable and robust way to characterize quantum-correlated light fields for practical applications in quantum communications.