https://doi.org/10.1140/epjqt/s40507-024-00260-y
Research
Experimental demonstration of quantum encryption in phase space with displacement operator in coherent optical communications
1
Department of Electrical and Computer Engineering, McGill University, Montreal, QC, Canada
2
Synopsys Inc., Ottawa, ON, Canada
3
Quantropi Inc., Ottawa, ON, Canada
a
mostafa.khalil2@mail.mcgill.ca
c
david.plant@mcgill.ca
d
lawrence.chen@mcgill.ca
e
randy.kuang@quantropi.com
Received:
7
March
2024
Accepted:
22
July
2024
Published online:
31
July
2024
We provide experimental validation of quantum encryption in phase space using displacement operators in coherent states (DOCS) in a conventional coherent optical communication system. The proposed encryption technique is based on displacing the information symbols in the phase space using random phases and amplitudes to achieve encryption randomly and provide security at the physical layer. We also introduce a dual polarization encryption approach where we use two different and random DOCS to encrypt the X and Y polarizations separately. The experimental results show that only authorized users can decrypt the signal correctly, and any mismatch in the displacement operator coefficients, amplitudes, or phases will lead to a bit error ratio (BER) of approximately 50%. We also compare the performance of the system with and without encryption over 80 km of standard-single mode fiber (SSMF) transmission to assess the added penalty of such encryption. The achieved net bit rates are 224, 448, and 560 Gb/s for QPSK, 16QAM, and 32QAM modulation formats, respectively. The experimental results showcase the efficacy of the DOCS encryption technique in resisting various decryption attempts, demonstrating its effectiveness in ensuring the security and confidentiality of transmitted data in a real-world transmission scenario.
Key words: Displacement operator / Encryption in phase space / Coherent optical communications / Key distribution / Data confidentiality
© The Author(s) 2024
Open Access This article is licensed under a Creative Commons Attribution 4.0 International License, which permits use, sharing, adaptation, distribution and reproduction in any medium or format, as long as you give appropriate credit to the original author(s) and the source, provide a link to the Creative Commons licence, and indicate if changes were made. The images or other third party material in this article are included in the article’s Creative Commons licence, unless indicated otherwise in a credit line to the material. If material is not included in the article’s Creative Commons licence and your intended use is not permitted by statutory regulation or exceeds the permitted use, you will need to obtain permission directly from the copyright holder. To view a copy of this licence, visit http://creativecommons.org/licenses/by/4.0/.
