Quantum cryptography in free space with coherent-state light

Geraldo A. Barbosa*, Eric Corndorf, Prem Kumar, Horace P. Yuen

*Corresponding author for this work

Research output: Contribution to journalConference articlepeer-review

4 Scopus citations


In this paper, we present a proof-of-concept experimental demonstration of the secret key quantum cryptographic scheme. A tabletop communication link was set up in the free-space channel using ordinary lasers as transmitters, which emit coherent states of light, and quantum-limited direct detection was employed in the receivers. In the secret key scheme, one needs a supply of M possible quantum states that are uniformly distributed over some random variable. In the free-space case, we used polarization angle as the variable determining the state. In the proof-of-concept demonstration, we aimed towards sending data messages encrypted with a short secret key from the transmitter to the receiver. The messages could be successfully deciphered by the receiver by its knowledge of the secret key. However, when the secret key was taken away, in order to mimic an eavesdropper, the messages could not be deciphered.

Original languageEnglish (US)
Pages (from-to)409-420
Number of pages12
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - 2002
EventFree-Space Laser Communication and Laser Imaging II - Seattle, WA, United States
Duration: Jul 9 2002Jul 11 2002

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


Dive into the research topics of 'Quantum cryptography in free space with coherent-state light'. Together they form a unique fingerprint.

Cite this