Volume 84, Number 2, October 2008
Article Number 20013
Number of page(s) 6
Section General
Published online 14 October 2008
EPL, 84 (2008) 20013
DOI: 10.1209/0295-5075/84/20013

Quantum direct communication with continuous variables

S. Pirandola1, S. L. Braunstein2, S. Mancini3 and S. Lloyd1, 4

1   MIT - Research Laboratory of Electronics - Cambridge MA 02139, USA
2   Computer Science, University of York - YO10 5DD York, UK, EU
3   CNISM and Dipartimento di Fisica, Università di Camerino - I-62032 Camerino, Italy, EU
4   MIT - Department of Mechanical Engineering - Cambridge MA 02139, USA

received 5 February 2008; accepted in final form 12 September 2008; published October 2008
published online 14 October 2008

We show how continuous-variable systems can allow the direct communication of messages with an acceptable degree of privacy. This is possible by combining a suitable phase-space encoding of the plain message with real-time checks of the quantum communication channel. The resulting protocol works properly when a small amount of noise affects the quantum channel. If this noise is non-tolerable, the protocol stops leaving a limited amount of information to a potential eavesdropper.

03.67.Dd - Quantum cryptography and communication security.
03.67.Hk - Quantum communication.
42.50.-p - Quantum optics.

© EPLA 2008