Toward photon-efficient key distribution over optical channels

Yuval Kochman, Ligong Wang, Gregory W. Wornell

Research output: Contribution to journalArticlepeer-review

11 Scopus citations


This paper considers the distribution of a secret key over an optical (bosonic) channel in the regime of high photon efficiency, i.e., when the number of secret key bits generated per detected photon is high. While, in principle, the photon efficiency is unbounded, there is an inherent tradeoff between this efficiency and the key generation rate (with respect to the channel bandwidth). We derive asymptotic expressions for the optimal generation rates in the photon-efficient limit, and propose schemes that approach these limits up to certain approximations. The schemes are practical, in the sense that they use coherent or temporally entangled optical states and direct photodetection, all of which are reasonably easy to realize in practice, in conjunction with off-the-shelf classical codes.

Original languageAmerican English
Article number6835214
Pages (from-to)4958-4972
Number of pages15
JournalIEEE Transactions on Information Theory
Issue number8
StatePublished - Aug 2014


  • Information-theoretic security
  • key distribution
  • optical communication
  • wiretap channel


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