Optimal propagation distance for maximal biphoton entanglement through the weakly turbulent atmosphere

Fuente: arXiv
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Autori principali: Niu, Luchang, Iqbal, Saleem, Xu, Yang, Boyd, Robert W.
Natura: Preprint
Pubblicazione: 2025
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author Niu, Luchang
Iqbal, Saleem
Xu, Yang
Boyd, Robert W.
author_facet Niu, Luchang
Iqbal, Saleem
Xu, Yang
Boyd, Robert W.
contents Understanding the influence of atmospheric turbulence on the propagation of entangled biphoton states is essential for free-space quantum communication protocols. Using the extended Huygens-Fresnel principle and the Kolmogorov turbulence model, we derive an analytical expression for the combined density operator of the signal and idler fields generated via SPDC, following propagation through separate turbulent channels. By expressing this density operator in the continuous position basis, we show how the spatial correlations between signal and idler persist through turbulence despite the loss of state purity, as they transition from being quantum to classical in nature. We further identify a finite range of propagation distances over which the angle-OAM entanglement is maximized, which provides valuable insights for designing free-space quantum communication links operating over several kilometers through the turbulent atmosphere.
format Preprint
id arxiv_https___arxiv_org_abs_2511_10755
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Optimal propagation distance for maximal biphoton entanglement through the weakly turbulent atmosphere
Niu, Luchang
Iqbal, Saleem
Xu, Yang
Boyd, Robert W.
Quantum Physics
Understanding the influence of atmospheric turbulence on the propagation of entangled biphoton states is essential for free-space quantum communication protocols. Using the extended Huygens-Fresnel principle and the Kolmogorov turbulence model, we derive an analytical expression for the combined density operator of the signal and idler fields generated via SPDC, following propagation through separate turbulent channels. By expressing this density operator in the continuous position basis, we show how the spatial correlations between signal and idler persist through turbulence despite the loss of state purity, as they transition from being quantum to classical in nature. We further identify a finite range of propagation distances over which the angle-OAM entanglement is maximized, which provides valuable insights for designing free-space quantum communication links operating over several kilometers through the turbulent atmosphere.
title Optimal propagation distance for maximal biphoton entanglement through the weakly turbulent atmosphere
topic Quantum Physics
url https://arxiv.org/abs/2511.10755