Modulator vulnerability in continuous-variable quantum key distribution

Nitin Jain, Ivan Derkach, Hou Man Chin, Radim Filip, Ulrik L. Andersen, Vladyslav C. Usenko, Tobias Gehring

Research output: Chapter in Book/Report/Conference proceedingArticle in proceedingsResearchpeer-review


Encoding of key bits in the quadratures of the electromagnetic light field is an essential part of any continuous-variable quantum key distribution system. However, flaws of practical implementation can make such systems susceptible to leakage of secret information. We verify a side channel presence in an optical in-phase and quadrature modulator which is caused by limited suppression of a quantum information-carrying sideband. We investigate various strategies an unauthorized third party can exploit the vulnerability in a proof-of-concept experiment and theoretically assess the modulation leakage effect on a security of the Gaussian coherent-state continuous-variable quantum key distribution protocol and show that the leakage reduces the range of conditions which support secure key generation. Without the control of sideband modulation in practical in-phase and quadrature modulator-based systems the security can be compromised.

Original languageEnglish
Title of host publicationEmerging Imaging and Sensing Technologies for Security and Defence VII
Number of pages5
Publication date2022
Article number122740R
ISBN (Electronic)9781510655515
Publication statusPublished - 2022
EventSPIE Sensors + Imaging 2022 - Berlin, Germany
Duration: 5 Sept 20228 Sept 2022
Conference number: 8


ConferenceSPIE Sensors + Imaging 2022
SeriesProceedings of SPIE - The International Society for Optical Engineering


  • Coherent states
  • Continuous-Variable Quantum Key Disribution
  • Heterodyne detection
  • IQ modulator
  • Side channels


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