QOSST: A Highly-Modular Open Source Platform for Experimental Continuous-Variable Quantum Key Distribution

Yoann Piétri; Matteo Schiavon; Valentina Marulanda Acosta; Baptiste Gouraud; Luis Trigo Vidarte; Philippe Grangier; Amine Rhouni; Eleni Diamanti

doi:10.22331/q-2024-12-23-1575

QOSST: A Highly-Modular Open Source Platform for Experimental Continuous-Variable Quantum Key Distribution

Yoann Piétri¹, Matteo Schiavon¹, Valentina Marulanda Acosta^1,2, Baptiste Gouraud³, Luis Trigo Vidarte⁴, Philippe Grangier⁵, Amine Rhouni¹, and Eleni Diamanti¹

¹Sorbonne Université, CNRS, LIP6, F-75005 Paris, France
²DOTA, ONERA, Université Paris Saclay, F-92322 Châtillon, France
³Exail, F-25000, Besançon
⁴ICFO - Institut de Ciènces Fotòniques, The Barcelona Institute of Science and Technology, Castelldefels (Barcelona) 08860, Spain
⁵Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127, Palaiseau, France

Published:	2024-12-23, volume 8, page 1575
Eprint:	arXiv:2404.18637v4
Doi:	https://doi.org/10.22331/q-2024-12-23-1575
Citation:	Quantum 8, 1575 (2024).

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Abstract

Quantum Key Distribution (QKD) enables secret key exchange between two remote parties with information-theoretic security rooted in the laws of quantum physics. Encoding key information in continuous variables (CV), such as the values of quadrature components of coherent states of light, brings implementations much closer to standard optical communication systems, but this comes at the price of significant complexity in the digital signal processing techniques required for operation at low signal-to-noise ratios. In this work, we wish to lower the barriers to entry for CV-QKD experiments associated to this difficulty by providing a highly modular, open source software that is in principle hardware agnostic and can be used in multiple configurations. We benchmarked this software, called QOSST, using an experimental setup with a locally generated local oscillator, frequency multiplexed pilots and RF-heterodyne detection, and obtained state-of-the-art secret key rates of the order of Mbit/s over metropolitan distances at the asymptotic limit. We hope that QOSST can be used to stimulate further experimental advances in CV-QKD and be improved and extended by the community to achieve high performance in a wide variety of configurations.

Featured image: Logo of the Quantum Open Software for Secure Transmissions (QOSST) software

Popular summary

The use of the principles of Quantum Mechanics to distribute a cryptographic key between two users, in order to reach information-theoretic security, usually known as Quantum Key Distribution (QKD), is one of the most mature applications of Quantum Information. Among the different protocols, encoding the information on the quadratures of coherent states in Continuous-Variable QKD (CV-QKD) is a very practical method, allowing the usage of standard telecom, room-temperature, components. In the past years, the complexity of CV-QKD systems from the optical and hardware setup to digital processing, and reaching for high repetition rates. Here we present the first open source software for experimental CV-QKD, performing the different digital signal processing algorithms, along with hardware control, classical communications, parameter estimation and secret key rate computation. Along with the proper optical setup, the software allows for key exchange at metropolitan distances.

► BibTeX data

@article{Pietri2024qossthighlymodular,
  doi = {10.22331/q-2024-12-23-1575},
  url = {https://doi.org/10.22331/q-2024-12-23-1575},
  title = {{QOSST}: {A} {H}ighly-{M}odular {O}pen {S}ource {P}latform for {E}xperimental {C}ontinuous-{V}ariable {Q}uantum {K}ey {D}istribution},
  author = {Pi{\'{e}}tri, Yoann and Schiavon, Matteo and Marulanda Acosta, Valentina and Gouraud, Baptiste and Trigo Vidarte, Luis and Grangier, Philippe and Rhouni, Amine and Diamanti, Eleni},
  journal = {{Quantum}},
  issn = {2521-327X},
  publisher = {{Verein zur F{\"{o}}rderung des Open Access Publizierens in den Quantenwissenschaften}},
  volume = {8},
  pages = {1575},
  month = dec,
  year = {2024}
}

► References

[1] S. Pirandola, U. L. Andersen, L. Banchi, M. Berta, D. Bunandar, R. Colbeck, D. Englund, T. Gehring, C. Lupo, C. Ottaviani, J. L. Pereira, M. Razavi, J. Shamsul Shaari, M. Tomamichel, V. C. Usenko, G. Vallone, P. Villoresi, and P. Wallden. ``Advances in quantum cryptography''. Advances in Optics and Photonics 12, 1012 (2020).
https://doi.org/10.1364/aop.361502

[2] C. H. Bennett and G. Brassard. ``Quantum cryptography: Public-key distribution and coin tossing''. In IEEE Press, editor, Proceedings of IEEE International Conference on Computers, Systems and Signal Processing. (1984).

[3] M. Lucamarini, Z. L. Yuan, J. F. Dynes, and A. J. Shields. ``Overcoming the rate–distance limit of quantum key distribution without quantum repeaters''. Nature 557, 400–403 (2018).
https://doi.org/10.1038/s41586-018-0066-6

[4] Frédéric Grosshans and Philippe Grangier. ``Continuous variable quantum cryptography using coherent states''. Physical Review Letters 88 (2002).
https://doi.org/10.1103/physrevlett.88.057902

[5] Ezra Ip, Alan Pak Tao Lau, Daniel J. F. Barros, and Joseph M. Kahn. ``Coherent detection in optical fiber systems''. Opt. Express 16, 753–791 (2008).
https://doi.org/10.1364/OE.16.000753

[6] M. D. Eisaman, J. Fan, A. Migdall, and S. V. Polyakov. ``Invited review article: Single-photon sources and detectors''. Review of Scientific Instruments 82 (2011).
https://doi.org/10.1063/1.3610677

[7] Qiang Liu, Yinming Huang, Yongqiang Du, Zhengeng Zhao, Minming Geng, Zhenrong Zhang, and Kejin Wei. ``Advances in chip-based quantum key distribution''. Entropy 24, 1334 (2022).
https://doi.org/10.3390/e24101334

[8] Yichen Zhang, Ziyang Chen, Stefano Pirandola, Xiangyu Wang, Chao Zhou, Binjie Chu, Yijia Zhao, Bingjie Xu, Song Yu, and Hong Guo. ``Long-distance continuous-variable quantum key distribution over 202.81 km of fiber''. Physical Review Letters 125 (2020).
https://doi.org/10.1103/physrevlett.125.010502

[9] Yan Pan, Heng Wang, Yun Shao, Yaodi Pi, Yang Li, Bin Liu, Wei Huang, and Bingjie Xu. ``Experimental demonstration of high-rate discrete-modulated continuous-variable quantum key distribution system''. Optics Letters 47, 3307 (2022).
https://doi.org/10.1364/ol.456978

[10] Francois Roumestan, Amirhossein Ghazisaeidi, Jeremie Renaudier, Luis Trigo Vidarte, Anthony Leverrier, Eleni Diamanti, and Philippe Grangier. ``Shaped constellation continuous variable quantum key distribution: Concepts, methods and experimental validation''. Journal of Lightwave TechnologyPages 1–8 (2024).
https://doi.org/10.1109/JLT.2024.3391168

[11] J. Aldama, S. Sarmiento, S. Etcheverry, I. López Grande, L. Trigo Vidarte, L. Castelvero, A. Hinojosa, T. Beckerwerth, Y. Piétri, A. Rhouni, E. Diamanti, and V. Pruneri. ``Inp-based cv-qkd pic transmitter''. In Optical Fiber Communication Conference (OFC) 2023. Page M1I.3. Optica Publishing Group (2023).
https://doi.org/10.1364/OFC.2023.M1I.3

[12] Yoann Piétri, Luis Trigo Vidarte, Matteo Schiavon, Laurent Vivien, Philippe Grangier, Amine Rhouni, and Eleni Diamanti. ``Experimental demonstration of continuous-variable quantum key distribution with a silicon photonics integrated receiver''. Optica Quantum 2, 428–437 (2024).
https://doi.org/10.1364/OPTICAQ.534699

[13] Adnan A. E. Hajomer, Cédric Bruynsteen, Ivan Derkach, Nitin Jain, Axl Bomhals, Sarah Bastiaens, Ulrik L. Andersen, Xin Yin, and Tobias Gehring. ``Continuous-variable quantum key distribution at 10 gbaud using an integrated photonic-electronic receiver''. Optica 11, 1197–1204 (2024).
https://doi.org/10.1364/OPTICA.530080

[14] Aurélie Denys, Peter Brown, and Anthony Leverrier. ``Explicit asymptotic secret key rate of continuous-variable quantum key distribution with an arbitrary modulation''. Quantum 5, 540 (2021).
https://doi.org/10.22331/q-2021-09-13-540

[15] John G. Proakis. ``Digital communications 5th edition''. McGraw Hill. (2007).

[16] R. Heimiller. ``Phase shift pulse codes with good periodic correlation properties''. IEEE Transactions on Information Theory 7, 254–257 (1961).
https://doi.org/10.1109/tit.1961.1057655

[17] D. Chu. ``Polyphase codes with good periodic correlation properties (corresp.)''. IEEE Transactions on Information Theory 18, 531–532 (1972).
https://doi.org/10.1109/tit.1972.1054840

[18] Hans-Jurgen Zepernick and Adolf Finger. ``Pseudo random signal processing''. Wiley-Blackwell. Hoboken, NJ (2005).
https://doi.org/10.1002/9780470866597

[19] Igor Devetak and Andreas Winter. ``Distillation of secret key and entanglement from quantum states''. Proceedings of the Royal Society A: Mathematical, Physical and Engineering Sciences 461, 207–235 (2005).
https://doi.org/10.1098/rspa.2004.1372

[20] Anthony Leverrier, Frédéric Grosshans, and Philippe Grangier. ``Finite-size analysis of a continuous-variable quantum key distribution''. Physical Review A 81 (2010).
https://doi.org/10.1103/physreva.81.062343

[21] Xiangyu Wang, Yichen Zhang, Song Yu, and Hong Guo. ``High speed error correction for continuous-variable quantum key distribution with multi-edge type ldpc code''. Scientific Reports 8 (2018).
https://doi.org/10.1038/s41598-018-28703-4

[22] Kadir Gümüş, Tobias A. Eriksson, Masahiro Takeoka, Mikio Fujiwara, Masahide Sasaki, Laurent Schmalen, and Alex Alvarado. ``A novel error correction protocol for continuous variable quantum key distribution''. Scientific Reports 11 (2021).
https://doi.org/10.1038/s41598-021-90055-3

[23] Enjian Bai, Xue-qin Jiang, and Yun Wu. ``Memory-saving and high-speed privacy amplification algorithm using lfsr-based hash function for key generation''. Electronics 11, 377 (2022).
https://doi.org/10.3390/electronics11030377

[24] Pierre-Alain Fouque, Jeffrey Hoffstein, Paul Kirchner, Vadim Lyubashevsky, Thomas Pornin, Thomas Prest, Thomas Ricosset, Gregor Seiler, William Whyte, Zhenfei Zhang. ``Falcon'' (2020). https://falcon-sign.info/.
https://falcon-sign.info/

[25] Thomas Prest. ``Falcon, Python Implementation'' (2020). https://github.com/tprest/falcon.py.
https://github.com/tprest/falcon.py

[26] The Python implementation was slightly modified to separate the public and private keys.https://github.com/nanoy42/falcon.
https://github.com/nanoy42/falcon

[27] NIST. ``Pqc standardization process: Announcing four candidates to be standardized, plus fourth round candidates'' (2022). https://csrc.nist.gov/news/2022/pqc-candidates-to-be-standardized-and-round-4.
https://csrc.nist.gov/news/2022/pqc-candidates-to-be-standardized-and-round-4

[28] Python Software Foundation. ``Python''. https://www.python.org/.
https://www.python.org/

[29] Tom Preston-Werner. ``Tom's obvious minimal language (toml)''. https://toml.io/en/.
https://toml.io/en/

[30] Brett Cannon, Nathaniel Smith, Donald Stufft. ``PEP 518 - Specifying Minimum Build System Requirements for Python Projects'' (2016). https://peps.python.org/pep-0518/#file-formats.
https://peps.python.org/pep-0518/#file-formats

[31] Taneli Hukkinen, Shantanu Jain. ``PEP 680 - tomllib: Support for Parsing TOML in the Standard Library'' (2022). https://peps.python.org/pep-0680/.
https://peps.python.org/pep-0680/

[32] Nathaniel J. Smith. ``Comparison of configuration file languages'' (2016). https://gist.github.com/njsmith/78f68204c5d969f8c8bc645ef77d4a8f.
https://gist.github.com/njsmith/78f68204c5d969f8c8bc645ef77d4a8f

[33] Charles R. Harris, K. Jarrod Millman, Stéfan J. van der Walt, Ralf Gommers, Pauli Virtanen, David Cournapeau, Eric Wieser, Julian Taylor, Sebastian Berg, Nathaniel J. Smith, Robert Kern, Matti Picus, Stephan Hoyer, Marten H. van Kerkwijk, Matthew Brett, Allan Haldane, Jaime Fernández del Río, Mark Wiebe, Pearu Peterson, Pierre Gérard-Marchant, Kevin Sheppard, Tyler Reddy, Warren Weckesser, Hameer Abbasi, Christoph Gohlke, and Travis E. Oliphant. ``Array programming with NumPy''. Nature 585, 357–362 (2020).
https://doi.org/10.1038/s41586-020-2649-2

[34] Kazuro Kikuchi. ``Fundamentals of coherent optical fiber communications''. Journal of Lightwave Technology 34, 157–179 (2016).
https://doi.org/10.1109/JLT.2015.2463719

[35] Paul Jouguet, Sébastien Kunz-Jacques, and Anthony Leverrier. ``Long-distance continuous-variable quantum key distribution with a gaussian modulation''. Physical Review A 84 (2011).
https://doi.org/10.1103/physreva.84.062317

[36] Anthony Leverrier. ``Theoretical study of continuous-variable quantum key distribution''. Theses. Télécom ParisTech. (2009). url: https://pastel.hal.science/tel-00451021.
https://pastel.hal.science/tel-00451021

[37] Jérôme Lodewyck, Matthieu Bloch, Raúl García-Patrón, Simon Fossier, Evgueni Karpov, Eleni Diamanti, Thierry Debuisschert, Nicolas J. Cerf, Rosa Tualle-Brouri, Steven W. McLaughlin, and Philippe Grangier. ``Quantum key distribution over 25km with an all-fiber continuous-variable system''. Physical Review A 76 (2007).
https://doi.org/10.1103/physreva.76.042305

[38] S Fossier, E Diamanti, T Debuisschert, R Tualle-Brouri, and P Grangier. ``Improvement of continuous-variable quantum key distribution systems by using optical preamplifiers''. Journal of Physics B: Atomic, Molecular and Optical Physics 42, 114014 (2009).
https://doi.org/10.1088/0953-4075/42/11/114014

[39] Yaodi Pi, Heng Wang, Yan Pan, Yun Shao, Yang Li, Jie Yang, Yichen Zhang, Wei Huang, and Bingjie Xu. ``Sub-mbps key-rate continuous-variable quantum key distribution with local local oscillator over 100-km fiber''. Optics Letters 48, 1766 (2023).
https://doi.org/10.1364/ol.485913

[40] Alexander Franzen. ``gwoptics components library'' (2012). http://www.gwoptics.org/ComponentLibrary/.
http://www.gwoptics.org/ComponentLibrary/

Cited by

[1] Haiyan Dai, Bozhi Wei, Ao Liu, Lanjian Chen, Chun Zhou, Yaping Li, Chen Dong, and Zhenrong Zhang, "Comprehensive noise model impact for classical signals and CV-QKD coexistence in multi-core fiber", Optics Express 34 13, 24199 (2026).

[2] Seyed Saman Mahjour and Fernando M. Araújo-Moreira, "Laser Linewidth Effects in Continuous-Variable QKD: Simulation-Based Analysis and Optimization Guidelines for Defense-Grade Secure System", Photonics 13 5, 432 (2026).

[3] Carlos Pascual-García, Stefan Bäuml, Mateus Araújo, Rotem Liss, and Antonio Acín, "Improved finite-size key rates for discrete-modulated continuous-variable quantum key distribution under coherent attacks", Physical Review A 111 2, 022610 (2025).

[4] Thomas Pousset, Maxime Federico, Romain Alléaume, and Nicolas Fabre, "Kramers-Kronig detection in the quantum regime", Physical Review Research 7 4, 043287 (2025).

[5] Vladyslav C. Usenko, Antonio Acín, Romain Alléaume, Ulrik L. Andersen, Eleni Diamanti, Tobias Gehring, Adnan A. E. Hajomer, Florian Kanitschar, Christoph Pacher, Stefano Pirandola, and Valerio Pruneri, "Continuous-variable quantum communication", Reviews of Modern Physics 98 1, 015003 (2026).

[6] Erdem Eray Cil and Laurent Schmalen, "An Open-Source Library for Information Reconciliation in Continuous-Variable QKD", arXiv:2408.00569, (2024).

[7] J. Aldama, S. Sarmiento, L. Trigo Vidarte, S. Etcheverry, I. López Grande, L. Castelvero, A. Hinojosa, T. Beckerwerth, Y. Piétri, A. Rhouni, E. Diamanti, and V. Pruneri, "Integrated InP-based transmitter for continuous-variable quantum key distribution", Optics Express 33 4, 8139 (2025).

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