The effect of scattering loss on connections between classical and quantum processes in second-order nonlinear waveguides

TL;DR

This paper explores how scattering loss affects the relationship between quantum and classical nonlinear optical processes in waveguides, revealing that certain classical measurements can accurately characterize quantum performance despite loss.

Contribution

It demonstrates a specific connection between SPDC and sum frequency generation in lossy waveguides, unlike with difference frequency generation, enhancing understanding of quantum-classical links.

Findings

SPDC and sum frequency generation are connected in lossy waveguides

The relationship does not hold for difference frequency generation

Classical measurements can characterize quantum performance under loss

Abstract

We show that a useful connection exists between spontaneous parametric downconversion (SPDC) and sum frequency generation in nonlinear optical waveguides with arbitrary scattering loss, while the same does not hold true for SPDC and difference frequency generation. This result deepens the relationship between quantum and classical second-order nonlinear optical processes in waveguides, and identifies the most accurate characterization of their quantum performance in the presence of loss based solely on classical measurements.