---
_id: '62860'
abstract:
- lang: eng
text: "\r\n The Quantum Internet, a network of quantum-enabled
infrastructure, represents the next frontier in telecommunications, promising
capabilities that cannot be attained by classical counterparts. A crucial step
in realizing such large-scale quantum networks is the integration of entanglement
distribution within existing telecommunication infrastructure. Here, we demonstrate
a real-world scalable quantum networking testbed deployed within Deutsche Telekom’s
metropolitan fibers in Berlin. Using commercially available quantum devices and
standard add-drop multiplexing hardware, we distributed polarization-entangled
photon pairs over dynamically selectable looped fiber paths ranging from 10 m
to 60 km and showed entanglement distribution over up to approximately 100 km.
Quantum signals, transmitted at 1324 nm (O-band), coexist with conventional bidirectional
C-band traffic without dedicated fibers or infrastructure changes. Active stabilization
of the polarization enables robust long-term performance, achieving entanglement
Bell-state fidelity bounds between 85% and 99% and Clauser–Horne–Shimony–Holt
parameter\r\n S\r\n -values
between 2.36 and 2.74 during continuous multiday operation. By achieving a high-fidelity
entanglement distribution with less than 1.5% downtime, we confirm the feasibility
of hybrid quantum-classical networks under real-world conditions at the metropolitan
scale. These results establish deployment benchmarks and provide a practical roadmap
for telecom operators to integrate quantum capabilities.\r\n "
article_number: '1072'
author:
- first_name: Matheus
full_name: Sena, Matheus
last_name: Sena
- first_name: Mael
full_name: Flament, Mael
last_name: Flament
- first_name: Shane
full_name: Andrewski, Shane
last_name: Andrewski
- first_name: Ioannis
full_name: Caltzidis, Ioannis
last_name: Caltzidis
- first_name: Niccolò
full_name: Bigagli, Niccolò
last_name: Bigagli
- first_name: Thomas
full_name: Rieser, Thomas
last_name: Rieser
- first_name: Gabriel
full_name: Bello Portmann, Gabriel
last_name: Bello Portmann
- first_name: Rourke
full_name: Sekelsky, Rourke
last_name: Sekelsky
- first_name: Ralf-Peter
full_name: Braun, Ralf-Peter
last_name: Braun
- first_name: Alexander N.
full_name: Craddock, Alexander N.
last_name: Craddock
- first_name: Maximilian
full_name: Schulz, Maximilian
last_name: Schulz
- first_name: Klaus
full_name: Jöns, Klaus
id: '85353'
last_name: Jöns
- first_name: Michaela
full_name: Ritter, Michaela
last_name: Ritter
- first_name: Marc
full_name: Geitz, Marc
last_name: Geitz
- first_name: Oliver
full_name: Holschke, Oliver
last_name: Holschke
- first_name: Mehdi
full_name: Namazi, Mehdi
last_name: Namazi
citation:
ama: Sena M, Flament M, Andrewski S, et al. High-fidelity quantum entanglement distribution
in metropolitan fiber networks with co-propagating classical traffic. Journal
of Optical Communications and Networking. 2025;17(12). doi:10.1364/jocn.575396
apa: Sena, M., Flament, M., Andrewski, S., Caltzidis, I., Bigagli, N., Rieser, T.,
Bello Portmann, G., Sekelsky, R., Braun, R.-P., Craddock, A. N., Schulz, M., Jöns,
K., Ritter, M., Geitz, M., Holschke, O., & Namazi, M. (2025). High-fidelity
quantum entanglement distribution in metropolitan fiber networks with co-propagating
classical traffic. Journal of Optical Communications and Networking, 17(12),
Article 1072. https://doi.org/10.1364/jocn.575396
bibtex: '@article{Sena_Flament_Andrewski_Caltzidis_Bigagli_Rieser_Bello Portmann_Sekelsky_Braun_Craddock_et
al._2025, title={High-fidelity quantum entanglement distribution in metropolitan
fiber networks with co-propagating classical traffic}, volume={17}, DOI={10.1364/jocn.575396},
number={121072}, journal={Journal of Optical Communications and Networking}, publisher={Optica
Publishing Group}, author={Sena, Matheus and Flament, Mael and Andrewski, Shane
and Caltzidis, Ioannis and Bigagli, Niccolò and Rieser, Thomas and Bello Portmann,
Gabriel and Sekelsky, Rourke and Braun, Ralf-Peter and Craddock, Alexander N.
and et al.}, year={2025} }'
chicago: Sena, Matheus, Mael Flament, Shane Andrewski, Ioannis Caltzidis, Niccolò
Bigagli, Thomas Rieser, Gabriel Bello Portmann, et al. “High-Fidelity Quantum
Entanglement Distribution in Metropolitan Fiber Networks with Co-Propagating Classical
Traffic.” Journal of Optical Communications and Networking 17, no. 12 (2025).
https://doi.org/10.1364/jocn.575396.
ieee: 'M. Sena et al., “High-fidelity quantum entanglement distribution in
metropolitan fiber networks with co-propagating classical traffic,” Journal
of Optical Communications and Networking, vol. 17, no. 12, Art. no. 1072,
2025, doi: 10.1364/jocn.575396.'
mla: Sena, Matheus, et al. “High-Fidelity Quantum Entanglement Distribution in Metropolitan
Fiber Networks with Co-Propagating Classical Traffic.” Journal of Optical Communications
and Networking, vol. 17, no. 12, 1072, Optica Publishing Group, 2025, doi:10.1364/jocn.575396.
short: M. Sena, M. Flament, S. Andrewski, I. Caltzidis, N. Bigagli, T. Rieser, G.
Bello Portmann, R. Sekelsky, R.-P. Braun, A.N. Craddock, M. Schulz, K. Jöns, M.
Ritter, M. Geitz, O. Holschke, M. Namazi, Journal of Optical Communications and
Networking 17 (2025).
date_created: 2025-12-04T12:20:01Z
date_updated: 2025-12-04T13:37:02Z
department:
- _id: '623'
- _id: '15'
doi: 10.1364/jocn.575396
intvolume: ' 17'
issue: '12'
language:
- iso: eng
publication: Journal of Optical Communications and Networking
publication_identifier:
issn:
- 1943-0620
- 1943-0639
publication_status: published
publisher: Optica Publishing Group
status: public
title: High-fidelity quantum entanglement distribution in metropolitan fiber networks
with co-propagating classical traffic
type: journal_article
user_id: '85353'
volume: 17
year: '2025'
...