TY - JFULL AU - Sudeshna Bhattacharya and Pratyush Pandey and Pradeep Kumar K PY - 2012/4/ TI - Decoy-pulse Protocol for Frequency-coded Quantum Key Distribution T2 - International Journal of Nuclear and Quantum Engineering SP - 296 EP - 301 VL - 6 SN - 1307-6892 UR - https://publications.waset.org/pdf/9765 PU - World Academy of Science, Engineering and Technology NX - Open Science Index 63, 2012 N2 - We propose a decoy-pulse protocol for frequency-coded implementation of B92 quantum key distribution protocol. A direct extension of decoy-pulse method to frequency-coding scheme results in security loss as an eavesdropper can distinguish between signal and decoy pulses by measuring the carrier photon number without affecting other statistics. We overcome this problem by optimizing the ratio of carrier photon number of decoy-to-signal pulse to be as close to unity as possible. In our method the switching between signal and decoy pulses is achieved by changing the amplitude of RF signal as opposed to modulating the intensity of optical signal thus reducing system cost. We find an improvement by a factor of 100 approximately in the key generation rate using decoy-state protocol. We also study the effect of source fluctuation on key rate. Our simulation results show a key generation rate of 1.5×10-4/pulse for link lengths up to 70km. Finally, we discuss the optimum value of average photon number of signal pulse for a given key rate while also optimizing the carrier ratio. ER -