Hyperentanglement-enabled Quantum Privacy Amplification for Classical-Quantum Coexistence in Fiber Networks
Abstract
Integrating quantum communication into existing fiber infrastructures requires coexisting with high-power classical traffic, which generates noise in the quantum channel. Spontaneous Raman Scattering (SpRS) is the dominant noise source, generating a broadband photon background that degrades quantum states and, in Quantum Key Distribution (QKD), can entirely suppress secure key generation. In this work, we implement single-copy entanglement distillation utilizing energy-time and frequency hyperentanglement, and we exploit it to perform Quantum Privacy Amplification (QPA) directly at a physical layer. Strict frequency anti-correlations of spontaneous parametric down-conversion are used to selectively discard uncorrelated Raman photons while preserving genuine entangled pairs, suppressing accidental coincidences by a factor 1/N, where N is the number of frequency channel pairs. Using passive borosilicate-glass photonic integrated circuits and standard DWDM demultiplexers over a 20~km single-mode fiber testbed, we demonstrate a 4~dB improvement in tolerance to classical laser launch power PC when QPA is performed, extending the secure key threshold from PC=−13.3 dBm to PC=−9.3 dBm. The result shows that off-the-shelf telecom components can be repurposed as physical-layer quantum privacy amplifiers.
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BibTeX
@misc{ribezzo2026hyperentanglementenabled,
title = {{Hyperentanglement-enabled Quantum Privacy Amplification for Classical-Quantum Coexistence in Fiber Networks}},
author = {Domenico Ribezzo and Giulia Guarda and Alessandro Zavatta and Davide Bacco},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38645},
eprint = {2610.38645},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38645},
}
RIS
TY - UNPB
TI - Hyperentanglement-enabled Quantum Privacy Amplification for Classical-Quantum Coexistence in Fiber Networks
AU - Domenico Ribezzo
AU - Giulia Guarda
AU - Alessandro Zavatta
AU - Davide Bacco
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38645
UR - https://arxiv.org/abs/2610.38645
AB - Integrating quantum communication into existing fiber infrastructures requires coexisting with high-power classical traffic, which generates noise in the quantum channel. Spontaneous Raman Scattering (SpRS) is the dominant noise source, generating a broadband photon background that degrades quantum states and, in Quantum Key Distribution (QKD), can entirely suppress secure key generation. In this work, we implement single-copy entanglement distillation utilizing energy-time and frequency hyperentanglement, and we exploit it to perform Quantum Privacy Amplification (QPA) directly at a physical layer. Strict frequency anti-correlations of spontaneous parametric down-conversion are used to selectively discard uncorrelated Raman photons while preserving genuine entangled pairs, suppressing accidental coincidences by a factor 1/N, where N is the number of frequency channel pairs. Using passive borosilicate-glass photonic integrated circuits and standard DWDM demultiplexers over a 20~km single-mode fiber testbed, we demonstrate a 4~dB improvement in tolerance to classical laser launch power P_C when QPA is performed, extending the secure key threshold from P_C=−13.3 dBm to P_C=−9.3 dBm. The result shows that off-the-shelf telecom components can be repurposed as physical-layer quantum privacy amplifiers.
ER -