Higher-order nonclassical effects in fluctuating-loss channels

TL;DR

This paper investigates how higher-order nonclassicality and entanglement evolve in atmospheric fluctuating-loss channels, revealing robustness of non-Gaussian entanglement and proposing detection schemes for quantum communication.

Contribution

It extends previous Gaussian-focused work to non-Gaussian and multimode fields, analyzing their behavior under atmospheric losses and proposing practical measurement methods.

Findings

Non-Gaussian entanglement is more robust against atmospheric loss than Gaussian entanglement.

The dependency of squeezing transfer on coherent displacement was discovered.

A detection scheme for moments after atmospheric propagation is proposed.

Abstract

We study the evolution of higher-order nonclassicality and entanglement criteria in atmospheric fluctuating-loss channels. By formulating input-output relations for the matrix of moments, we investigate the influence of such channels on the corresponding quantumness criteria. This generalization of our previous work on Gaussian entanglement [M. Bohmann et al., Phys. Rev. A 94, 010302(R) (2016)] not only exploits second-order-based scenarios, but it also provides a detailed investigation of nonclassicality and entanglement in non-Gaussian and multimode radiation fields undergoing a fluctuating attenuation. That is, various examples of criteria and states are studied in detail, unexpected effects, e.g., the dependency of the squeezing transfer on the coherent displacement, are discovered, and it is demonstrated that non-Gaussian entanglement can be more robust against atmospheric losses than Gaussian one. Additionally, we propose a detection scheme for measuring the considered moments after propagation through the atmosphere. Therefore, our results may help to develop, improve, and optimize non-Gaussian sources of quantum light for applications in free-space quantum communication.