Long distance quantum illumination and ranging using polarization entangled photon pairs in a lossy environment

Fuente: arXiv
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Autores principales: Matta, Sujai, Asokan, Soumya, Chakraborti, Sanchari, Joshi, Mayank, Dalal, Rahul, Chandrashekar, C. M.
Formato: Preprint
Publicado: 2026
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author Matta, Sujai
Asokan, Soumya
Chakraborti, Sanchari
Joshi, Mayank
Dalal, Rahul
Chandrashekar, C. M.
author_facet Matta, Sujai
Asokan, Soumya
Chakraborti, Sanchari
Joshi, Mayank
Dalal, Rahul
Chandrashekar, C. M.
contents Using polarization entangled photon pairs, we demonstrate a robust scheme for quantum illumination and ranging in a lossy environment. Entangled photon pairs are generated in a Sagnac interferometer configuration, yielding high-visibility two-photon polarization entanglement with a measured CHSH parameter of $S =2.802\pm0.002$. One of the photons from the entangled pair is retained as idler and the other one is directed into either of the two paths, namely reference and probe, of which probe is sent toward a distant object through a lossy free-space channel, and the reflected photons are collected after round-trip free-space propagation over distances approaching $1$ km. Remarkably, strong correlations are observed with CHSH values $S >2.6$ even when only a few tens of probe photons are returned, confirming the robustness of polarization entanglement under long-distance free-space propagation. This work reports the robustness of encoding photons in different basis before it is sent towards the object and recovery of polarization entanglement even after a kilometer-scale scattering from the objects, establishing a practical foundation for scalable quantum-assisted object detection and ranging.
format Preprint
id arxiv_https___arxiv_org_abs_2602_08947
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Long distance quantum illumination and ranging using polarization entangled photon pairs in a lossy environment
Matta, Sujai
Asokan, Soumya
Chakraborti, Sanchari
Joshi, Mayank
Dalal, Rahul
Chandrashekar, C. M.
Quantum Physics
Using polarization entangled photon pairs, we demonstrate a robust scheme for quantum illumination and ranging in a lossy environment. Entangled photon pairs are generated in a Sagnac interferometer configuration, yielding high-visibility two-photon polarization entanglement with a measured CHSH parameter of $S =2.802\pm0.002$. One of the photons from the entangled pair is retained as idler and the other one is directed into either of the two paths, namely reference and probe, of which probe is sent toward a distant object through a lossy free-space channel, and the reflected photons are collected after round-trip free-space propagation over distances approaching $1$ km. Remarkably, strong correlations are observed with CHSH values $S >2.6$ even when only a few tens of probe photons are returned, confirming the robustness of polarization entanglement under long-distance free-space propagation. This work reports the robustness of encoding photons in different basis before it is sent towards the object and recovery of polarization entanglement even after a kilometer-scale scattering from the objects, establishing a practical foundation for scalable quantum-assisted object detection and ranging.
title Long distance quantum illumination and ranging using polarization entangled photon pairs in a lossy environment
topic Quantum Physics
url https://arxiv.org/abs/2602.08947