Integration of quantum key distribution and high-throughput classical communications in field-deployed multi-core fibers

Qi Wu; Domenico Ribezzo; Giammarco Di Sciullo; Sebastiano Cocchi; Divya Ann Shaji; Lucas Alves Zischler; Ruben Luis; Paolo Serena; Chiara Lasagni; Alberto Bononi; Tetsuya Hayashi; Alessandro Gagliano; Paolo Martelli; Alberto Gatto; Paola Parolari; Pierpaolo Boffi; Davide Bacco; Alessandro Zavatta; Yixiao Zhu; Weisheng Hu; Zhaopeng Xu; Mark Shtaif; Andrea Marotta; Fabio Graziosi; Antonio Mecozzi; Cristian Antonelli

doi:10.1038/s41377-025-01982-z

Your Location：

Home >

Browse articles >

Integration of quantum key distribution and high-throughput classical communications in field-deployed multi-core fibers

Original Articles

- Integration of quantum key distribution and high-throughput classical communications in field-deployed multi-core fibers
- Light: Science & Applications Vol. 14, Issue 10, Pages: 2955-2970(2025)
- Affiliations：
  
  1.Department of Physical and Chemical Sciences, University of L'Aquila, L'Aquila 67100, Italy
  2.Photonics Research Institute, Department of Electrical and Electronic Engineering, The Hong Kong Polytechnic University, Hong Kong, China
  3.Department of Electronic Engineering, Shanghai Jiao Tong University, Shanghai 200240, China
  4.Department of Physics and Astronomy, University of Florence, Firenze 50019, Italy
  5.Photonic System Laboratory, NICT, Koganei, Tokyo 184-0015, Japan
  6.Department of Engineering and Architecture, Universitá degli Studi di Parma, Parma 43124, Italy
  7.CNIT National Laboratory of Advanced Optical Fibers for Photonics, L'Aquila 67100, Italy
  8.Sumitomo Electric Industries Ltd., Yokohama, Kanagawa 244-8588, Japan
  9.Department of Electronics, Information and Bioengineering, Politecnico di Milano, Milano 20133, Italy
  10.National Institute of Optics (CNR-INO), Firenze 50125, Italy
  11.Pengcheng Laboratory, Shenzhen 518055, China
  12.Department of Physical Electronics, Tel Aviv University, Tel Aviv 69978, Israel
- Author bio：
  
  Qi Wu (qi.wu@student.univaq.it)
  Cristian Antonelli (cristian.antonelli@univaq.it)
- Funds：
- DOI：10.1038/s41377-025-01982-z
  CLC：
- Received：04 April 2025，
  
  Revised：2025-07-15，
  
  Accepted：23 July 2025，
  
  Published Online：13 August 2025，
  
  Published：31 October 2025
- Accepted：
Scan QR Code
Wu, Q. et al. Integration of quantum key distribution and high-throughput classical communications in field-deployed multi-core fibers. Light: Science & Applications, 14, 2955-2970 (2025).
DOI：

Wu, Q. et al. Integration of quantum key distribution and high-throughput classical communications in field-deployed multi-core fibers. Light: Science & Applications, 14, 2955-2970 (2025). DOI： 10.1038/s41377-025-01982-z.

摘要

Abstract

Quantum key distribution (QKD) is a secure communication method for sharing symmetric cryptographic keys based on the principles of quantum physics. Its integration into the fiber-optic network infrastructure is important for ensuring privacy in optical communications. Multi-core fibers (MCFs)

the likely building blocks of future high-capacity optical networks

offer new opportunities for such integration. Here

we experimentally demonstrate

for the first time

the coexistence of discrete-variable QKD and high-throughput classical communication in the C-band over a field-deployed MCF with industry standard cladding diameter of 125 μm. Specifically

we demonstrate successful secure-key establishment in one core of a 25.2-km uncoupled-core MCF

while simultaneously loading the remaining three cores with full C-band counter-propagating classical traffic at an aggregate net rate of 110.8 Tb/s. By proposing and experimentally validating an improved analytical model for inter-core spontaneous Raman scattering noise

we find that this configuration is optimal for our deployed MCF link as it is immune to four-wave mixing

that becomes relevant when the quantum and classical signals are propagating in the same direction. Our findings make an important step forward in demonstrating the integration of QKD and classical transmission in uncoupled-core multi-core fibers for next-generation optical communication networks.

关键词

Keywords

references

Fröhlich, B. et al. A quantum access network. Nature 501 , 69–72 (2013)..

Lo, H. K., Ma, X. F. & Chen, K. Decoy state quantum key distribution. Phys. Rev. Lett. 94 , 230504 (2005)..

Hajomer, A. A. E. et al. Continuous-variable quantum passive optical network. Light 13 , 291 (2024)..

Hajomer, A. A. E. et al. Long-distance continuous-variable quantum key distribution over 100-km fiber with local local oscillator. Sci. Adv. 10 , eadi9474 (2024)..

Lo, H. K., Curty, M. & Tamaki, K. Secure quantum key distribution. Nat. Photonics 8 , 595–604 (2014)..

Lucamarini, M. et al. Overcoming the rate–distance limit of quantum key distribution without quantum repeaters. Nature 557 , 400–403 (2018)..

Preskill, J. Quantum computing in the NISQ era and beyond. Quantum 2 , 79 (2018)..

Peev, M. et al. The SECOQC quantum key distribution network in Vienna. New J. Phys. 11 , 075001 (2009)..

Wonfor, A. et al. High performance field trials of QKD over a metropolitan network. In Quantum Cryptography (QCrypt) (University of Cambridge, 2017) .

Sasaki, M. et al. Field test of quantum key distribution in the Tokyo QKD network. Opt. Express 19 , 10387–10409 (2011)..

Walenta, N. et al. Towards a North American QKD backbone with certifiable security. In Proc. 5th International Conference on Quantum Cryptography, pp. 1–3 (National Institute of Information and Communications Technology, 2015)..

Bacco, D. et al. Field trial of a finite-key quantum key distribution system in the metropolitan Florence area. In Proc. 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference , 1 (IEEE, 2019)..

Mao, Y. Q. et al. Integrating quantum key distribution with classical communications in backbone fiber network. Opt. Express 26 , 6010–6020 (2018)..

Sun, W. et al. Experimental integration of quantum key distribution and gigabit-capable passive optical network. J. Appl. Phys. 123 , 043105 (2018)..

Aguado, A. et al. The engineering of softwar e-defined quantum key distribution networks. IEEE Commun. Mag. 57 , 20–26 (2019)..

Tessinari, R. S. et al. Field trial of dynamic DV-QKD networking in the SDN-controlled fully-meshed optical metro network of the Bristol city 5GUK test network. In Proc . 45th European Conference on Optical Communication (ECOC 2019) 1–4 (IEEE, 2019)..

Kawahara, H., Medhipour, A. & Inoue, K. Effect of spontaneous Raman scattering on quantum channel wavelength-multiplexed with classical channel. Opt. Commun. 284 , 691–696 (2011)..

Eraerds, P. et al. Quantum key distribution and 1 Gbps data encryption over a single fibre. New J. Phys. 12 , 063027 (2010)..

Patel, K. A. et al. Coexistence of high-bit-rate quantum key distribution and data on optical fiber. Phys. Rev. X 2 , 041010 (2012)..

Chapuran, T. E. et al. Optical networking for quantum key distribution and quantum communications. New J. Phys. 11 , 105001 (2009)..

Dynes, J. F. et al. Ultra-high bandwidth quantum secured data transmission. Sci. Rep. 6 , 35149 (2016)..

da Silva, T. F. et al. Impact of Raman scattered noise from multiple telecom channels on fiber-optic quantum key distribution systems. J. Light. Technol. 32 , 2332–2339 (2014)..

Sun, Y. M. et al. Reduction of FWM noise in WDM-based QKD systems using interleaved and unequally spaced channels. Chin. Opt. Lett. 14 , 060602 (2016)..

Niu, J. N. et al. Optimized channel allocation scheme for jointly reducing four-wave mixing and Raman scattering in the DWDM-QKD system. Appl. Opt. 57 , 7987–7996 (2018)..

Wang, R. et al. End-to-end quantum secured inter-domain 5G service orchestration over dynamically switched flex-grid optical networks enabled by a q-roadm. J. Light. Technol. 38 , 139–149 (2020)..

Hajomer, A. A. E. et al. Coexistence of continuous-variable quantum key distribution and classical data over 120-km fiber. Preprint at https://arxiv.org/abs/2502.17388 https://arxiv.org/abs/2502.17388 (2025).

Puttnam, B. J., Rademacher, G. & Luís, R. S. Space-division multiplexing for optical fiber communications. Optica 8 , 1186–1203 (2021)..

Matsui, T., Pondillo, P. L. & Nakajima, K. Weakly coupled multicore fiber technology, deployment, and systems. Proc. IEEE 110 , 1772–1785 (2022)..

Wang, X. et al. Field trial of 7 × 89 λ × 256 Gb/s C-band classical/CVQKD co-existence transmission over 7-core fiber. In Proc . 2023 Asia Communications and Photonics Conference/2023 International Photonics and Optoelectronics Meetings (ACP/POEM) 1–4 (IEEE, 2023)..

Zahidy, M. et al. Practical high-dimensional quantum key distribution protocol over deployed multicore fiber. Nat. Commun. 15 , 1651 (2024)..

Kong, W. W. et al. Coexistence of quantum key distribution and optical communication with amplifiers over multicore fiber. Nanophotonics 12 , 1979–1994 (2023)..

Cai, C., Sun, Y. M. & Ji, Y. F. Intercore spontaneous Raman scattering impact on quantum key distribution in multicore fiber . New J. Phys. 22 , 083020 (2020)..

Lin, R. et al. Spontaneous Raman scattering effects in multicore fibers: impact on coexistence of quantum and classical channels. In Proc. 2019 Optical Fiber Communications Conference and Exhibition (OFC) 1–3 (IEEE, 2019)..

Kong, W. W. et al. Impact of classical modulation signals on quantum key distribution over multicore fiber. J. Light. Technol. 39 , 4341–4350 (2021)..

Dynes, J. F. et al. Quantum key distribution over multicore fiber. Opt. Express 24 , 8081–8087 (2016)..

Bacco, D. et al. Boosting the secret key rate in a shared quantum and classical fibre communication system. Commun. Phys. 2 , 140 (2019)..

Cai, C. et al. Experimental wavelength-space division multiplexing of quantum key distribution with classical optical communication over multicore fiber. Opt. Express 27 , 5125–5135 (2019)..

Hugues-Salas, E. et al. 11.2 Tb/s classical channel coexistence with DV-QKD over a 7-core multicore fiber. J. Light. Technol. 38 , 5064–5070 (2020)..

Eriksson, T. A. et al. Crosstalk impact on continuous variable quantum key distribution in multicore fiber transmission. IEEE Photonics Technol. Lett. 31 , 467–470 (2019)..

Geng, J. Q. et al. Integration in the C-band between quantum key distribution and the classical channel of 25 dbm launch power over multicore fiber media. Opt. Lett. 47 , 3111–3114 (2022)..

Lin, R. et al. Telecom compatibility validation of quantum key distribution co-existing with 112 Gbps/ λ /core data transmission in non-trench and trench-assistant multicore fibers. In Proc. 2018 European Conference on Optical Communication (ECOC) 1–3 (IEEE, 2018)..

van den Hout, M. et al. Reaching the pinnacle of high-capacity optical transmission using a standard cladding diameter coupled-core multi-core fiber. Nat. Commun. 16 , 3833 (2025)..

Hayashi, T. et al. Field-deployed multi-core fiber testbed. In Proc. 2019 24th OptoElectronics and Communications Conference (OECC) and 2019 International Conference on Photonics in Switching and Computing (PSC) 1–3 (IEEE, 2019)..

Wang, X. B. Beating the photon-number-splitting attack in practical quantum cryptography. Phys. Rev. Lett. 94 , 230503 (2005)..

Hwang, W. Y. Quantum key distribution with high loss: toward global secure communication. Phys. Rev. Lett. 91 , 057901 (2003)..

Ribezzo, D. et al. Deploying an inter-European quantum network. Adv. Quantum Technol. 6 , 2200061 (2023)..

Fung, C. H. F. & Lo, H. K. Security proof of a three-state quantum-key-distribution protocol without rotational symmetry. Phys. Rev. A 74 , 042342 (2006)..

Xie, W. X. et al. Higher key rate in asymmetric quantum-classical integrated measurement-device-independent quantum-key-distribution systems. Phys. Rev. Appl. 20 , 054042 (2023)..

Rusca, D. et al. Finite-key analysis for the 1-decoy state QKD protocol. Appl. Phys. Lett. 112 , 171104 (2018)..

Koshiba, M. et al. Multi-core fiber design and analysis: coupled-mode theory and coupled-power theory. Opt. Express 19 , B102–B111 (2011)..

Views

Downloads

CSCD

Alert me when the article has been cited

Submit

Tools

Publicity Resources

No data

Related Author

No data

Related Institution

No data

⁰