Quantum key distribution with phase-encoded coherent states: Asymptotic security analysis in thermal-loss channels

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We consider discrete-alphabet encoding schemes for coherent-state quantum key distribution. The sender encodes the letters of a finite-size alphabet into coherent states whose amplitudes are symmetrically distributed on a circle centered in the origin of the phase space. We study the asymptotic performance of this phase-encoded coherent-state protocol in direct and reverse reconciliation assuming both loss and thermal noise in the communication channel. In particular, we show that using just four phase-shifted coherent states is sufficient for generating secret key rates of the order of $4 \times 10^{-3}$ bits per channel use at about 15 dB loss in the presence of realistic excess noise.
Original languageEnglish
Article number012340
Pages (from-to)1-8
Number of pages8
JournalPhys. Rev. A
Publication statusPublished - 31 Jul 2018

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©2018 American Physical Society. This is an author-produced version of the published paper. Uploaded in accordance with the publisher’s self-archiving policy. Further copying may not be permitted; contact the publisher for details.

REVTeX. 8 pages. 7 figures


  • quant-ph
  • physics.optics

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