We propose a decoy-state method to increase key generation rate of frequency-coded (FC) implementation of B92 quantum key distribution (QKD) protocol. Direct application of decoy-state method to FC-QKD results in a security loophole. We overcome this loophole by optimizing the ratio of decoy-to-signal carrier photon number to unity. Simulation results for a single-channel FC-QKD show 16 kbits of raw key length at a transmission distance of 70 km. We then extend the decoy-state method to subcarrier-multiplexed FC-QKD. We show that key generation rate and secure link length improves by a factor of 5 and 40 km, respectively, compared to single-carrier with decoy-state method.
© 2013 Optical Society of America
Original Manuscript: July 16, 2012
Revised Manuscript: January 29, 2013
Manuscript Accepted: January 29, 2013
Published: March 6, 2013
Sudeshna Bhattacharya and Pradeep Kumar Krishnamurthy, "Decoy-state method for subcarrier-multiplexed frequency-coded quantum key distribution," J. Opt. Soc. Am. B 30, 782-787 (2013)