Broadband Telecom Entanglement from an All-Fiber Type-0 Sagnac Source
Abstract
We demonstrate a compact, practical all-fiber source of non-degenerate telecom-band polarization-entangled photon pairs assembled from off-the-shelf components. The compact fiber-integrated architecture is designed to be affordable, straightforward to assemble and align, and compatible with existing optical-fiber infrastructure. Photon pairs are generated through type-0 spontaneous parametric down-conversion in a pigtailed periodically poled lithium-niobate waveguide embedded in a Sagnac interferometer. At 0.5 mW pump power, quantum-state tomography yields a Bell-state fidelity FΦ-=0.850, purity P=0.836, and concurrence C=0.782. A separate CHSH measurement gives S=2.3301±0.0075. The measured Bell-state fidelity is sufficient for the reconstructed polarization state to support qubit teleportation above the classical fidelity limit under ideal protocol operations. Analysis of the density matrix shows that approximately 96.7% of the population remains in the desired |HH⟩-|VV⟩ subspace, with a normalized coherence of approximately 0.86. A residual relative-phase offset indicates that local phase compensation could increase the Bell-state fidelity to approximately 0.8865. We further characterize the brightness--quality trade-off and obtain a corrected pair-rate slope of (0.918±0.040) Mcps mW−1. The broadband emission and fiber interfaces offer a route to multiuser entanglement distribution through off-the-shelf multichannel wavelength-division multiplexers with passbands matched to the signal and idler wavelengths.
Related
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BibTeX
@misc{cestelli2026broadband,
title = {{Broadband Telecom Entanglement from an All-Fiber Type-0 Sagnac Source}},
author = {Alessandro Cestelli and Spyridon Grountas and Scott Mc Haffie and Jun Gao and Val Zwiller and Ali Elshaari},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.08025},
eprint = {2610.08025},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.08025},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Broadband Telecom Entanglement from an All-Fiber Type-0 Sagnac Source
AU - Alessandro Cestelli
AU - Spyridon Grountas
AU - Scott Mc Haffie
AU - Jun Gao
AU - Val Zwiller
AU - Ali Elshaari
PY - 2026
DA - 2026/10/06
PB - arXiv
DO - 10.48550/arxiv.2610.08025
UR - https://arxiv.org/abs/2610.08025
AB - We demonstrate a compact, practical all-fiber source of non-degenerate telecom-band polarization-entangled photon pairs assembled from off-the-shelf components. The compact fiber-integrated architecture is designed to be affordable, straightforward to assemble and align, and compatible with existing optical-fiber infrastructure. Photon pairs are generated through type-0 spontaneous parametric down-conversion in a pigtailed periodically poled lithium-niobate waveguide embedded in a Sagnac interferometer. At 0.5 mW pump power, quantum-state tomography yields a Bell-state fidelity F_Φ^-=0.850, purity P=0.836, and concurrence C=0.782. A separate CHSH measurement gives S=2.3301±0.0075. The measured Bell-state fidelity is sufficient for the reconstructed polarization state to support qubit teleportation above the classical fidelity limit under ideal protocol operations. Analysis of the density matrix shows that approximately 96.7% of the population remains in the desired |HH⟩-|VV⟩ subspace, with a normalized coherence of approximately 0.86. A residual relative-phase offset indicates that local phase compensation could increase the Bell-state fidelity to approximately 0.8865. We further characterize the brightness--quality trade-off and obtain a corrected pair-rate slope of (0.918±0.040) Mcps mW^−1. The broadband emission and fiber interfaces offer a route to multiuser entanglement distribution through off-the-shelf multichannel wavelength-division multiplexers with passbands matched to the signal and idler wavelengths.
ER -