Testing spectral filters as Gaussian quantum optical channels

TL;DR

This paper experimentally examines how spectral filtering affects the mode structure and correlations of multimode Gaussian quantum optical channels, revealing trade-offs between mode reduction and photon-number correlation preservation.

Contribution

It provides new insights into the impact of spectral filtering on mode characteristics and correlations in Gaussian quantum optical channels, with experimental validation.

Findings

Filtering reduces spectral modes but causes mode mismatch.

Filtering destroys perfect photon-number correlation.

Filtering influences the mode properties of heralded states.

Abstract

We experimentally investigate the mode characteristics of multimode radiation fields propagating through frequency dependent Gaussian channels. After manipulating the twin beams emitted from a conventional parametric down-conversion source via spectral filtering, we study the changes in their mode characteristics, utilizing the joint normalized correlation functions. While filtering reduces the number of spectral modes, it also leads to an apparent mode mismatch, which destroys the perfect photon-number correlation between the twin beams, and influences the mode properties of heralded states.