Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networks

The scalability of quantum communication networks requires compact, fiber-integrated, easy-to-deploy, and efficient wavelength-division-multiplexed (WDM) sources for multi-user secure key distribution. Here, we demonstrate such a multi-channel source of polarization-entangled photon pairs in the low...

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Main Authors: Vikash Kumar Yadav, Vivek Venkataraman, Joyee Ghosh
Format: Article
Language:English
Published: AIP Publishing LLC 2025-03-01
Series:APL Quantum
Online Access:http://dx.doi.org/10.1063/5.0241324
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author Vikash Kumar Yadav
Vivek Venkataraman
Joyee Ghosh
author_facet Vikash Kumar Yadav
Vivek Venkataraman
Joyee Ghosh
author_sort Vikash Kumar Yadav
collection DOAJ
description The scalability of quantum communication networks requires compact, fiber-integrated, easy-to-deploy, and efficient wavelength-division-multiplexed (WDM) sources for multi-user secure key distribution. Here, we demonstrate such a multi-channel source of polarization-entangled photon pairs in the low-loss telecom C-band based on type-0 spontaneous parametric downconversion in a fiber-coupled Zn-indiffused MgO-doped periodically poled lithium-niobate (MgO:PPLN) ridge waveguide in the Sagnac configuration. The source can be easily tuned to generate the |Φ+⟩ or |Φ−⟩ Bell state in 14 channel pairs of the International Telecommunication Union dense WDM (100-GHz spacing) grid around 1550-nm with a raw fidelity of ≳89%, with a maximum value of ≳94%. The raw concurrence is ≳0.8 for both Bell states in all channel pairs, and the observed S-parameter (>2.56 ± 0.04 in all 14-channel pairs) shows a strong violation of CHSH-Bell’s inequality. The source’s suitability for long-distance entanglement transmission is also demonstrated by the successful transfer of entangled photons up to 100 km while maintaining fidelity >85% and quantum bit error rate <9%. The effect of polarization mode dispersion on entanglement distribution among remote users is also studied in detail. All these performance metrics are measured using conventional room-temperature semiconductor-based single-photon avalanche detectors, and these are the best reported with these detectors. Our highly flexible source can support up to ∼40 user pairs to communicate simultaneously, and it can be easily deployed into the current metro-area fiber-optic telecom infrastructure to form a complete WDM-based quantum communication network.
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spelling doaj-art-de76456111b74ebeb9d73fb3734ffdb92025-08-20T03:03:49ZengAIP Publishing LLCAPL Quantum2835-01032025-03-0121016102016102-1110.1063/5.0241324Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networksVikash Kumar Yadav0Vivek Venkataraman1Joyee Ghosh2Quantum Photonics Lab, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, IndiaQuantum Photonics Lab, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, IndiaQuantum Photonics Lab, Department of Physics, Indian Institute of Technology Delhi, New Delhi 110016, IndiaThe scalability of quantum communication networks requires compact, fiber-integrated, easy-to-deploy, and efficient wavelength-division-multiplexed (WDM) sources for multi-user secure key distribution. Here, we demonstrate such a multi-channel source of polarization-entangled photon pairs in the low-loss telecom C-band based on type-0 spontaneous parametric downconversion in a fiber-coupled Zn-indiffused MgO-doped periodically poled lithium-niobate (MgO:PPLN) ridge waveguide in the Sagnac configuration. The source can be easily tuned to generate the |Φ+⟩ or |Φ−⟩ Bell state in 14 channel pairs of the International Telecommunication Union dense WDM (100-GHz spacing) grid around 1550-nm with a raw fidelity of ≳89%, with a maximum value of ≳94%. The raw concurrence is ≳0.8 for both Bell states in all channel pairs, and the observed S-parameter (>2.56 ± 0.04 in all 14-channel pairs) shows a strong violation of CHSH-Bell’s inequality. The source’s suitability for long-distance entanglement transmission is also demonstrated by the successful transfer of entangled photons up to 100 km while maintaining fidelity >85% and quantum bit error rate <9%. The effect of polarization mode dispersion on entanglement distribution among remote users is also studied in detail. All these performance metrics are measured using conventional room-temperature semiconductor-based single-photon avalanche detectors, and these are the best reported with these detectors. Our highly flexible source can support up to ∼40 user pairs to communicate simultaneously, and it can be easily deployed into the current metro-area fiber-optic telecom infrastructure to form a complete WDM-based quantum communication network.http://dx.doi.org/10.1063/5.0241324
spellingShingle Vikash Kumar Yadav
Vivek Venkataraman
Joyee Ghosh
Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networks
APL Quantum
title Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networks
title_full Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networks
title_fullStr Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networks
title_full_unstemmed Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networks
title_short Telecom source of tunable polarization-entanglement distribution up to 100-km for multi-user QKD over metro-area fiber-optic networks
title_sort telecom source of tunable polarization entanglement distribution up to 100 km for multi user qkd over metro area fiber optic networks
url http://dx.doi.org/10.1063/5.0241324
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