Volume 79, Number 4, August 2007
Article Number 40001
Number of page(s) 5
Section General
Published online 18 July 2007
EPL, 79 (2007) 40001
DOI: 10.1209/0295-5075/79/40001

Improved practical decoy state method in quantum key distribution with parametric down-conversion source

Q. Wang1, X.-B. Wang2, G. Björk1 and A. Karlsson1

1  Department of Microelectronics and Information Technology, The Royal Institute of Technology, KTH, Electrum 229 - SE-164 40 Kista, Sweden
2  Department of Physics, Tsinghua University - Beijing 100084, China

received 11 March 2007; accepted in final form 25 June 2007; published August 2007
published online 18 July 2007

In this paper, a new decoy state scheme for quantum key distribution with parametric down-conversion source is proposed. We use both three-intensity decoy states and their triggered and nontriggered components to estimate the fraction of single-photon counts and the quantum bit-error rate of single-photon pulses, and then deduce a more accurate value of the key generation rate. The final key rate over transmission distance is simulated, which shows that we can obtain a higher key rate than that of the existing methods, including our own earlier work.

03.67.Dd - Quantum cryptography.
42.65.Lm - Parametric down conversion and production of entangled photons.
03.67.Hk - Quantum communication.

© Europhysics Letters Association 2007