In practical quantum key distribution （QKD）, weak coherent states as the photon source have a limit in the secure key rate and transmission distance because of the existence of multi-photon pulses and heavy loss in ...In practical quantum key distribution （QKD）, weak coherent states as the photon source have a limit in the secure key rate and transmission distance because of the existence of multi-photon pulses and heavy loss in transmission line. The decoy-state method and the nonorthogonal encoding protocol are two important methods to combat these effects. Here, we combine both the methods and propose an efficient method that can substantially improve the performance of QKD. We find a 78-kin increase over the prior record using the decoy-state method and a 123-km increase over the result of the SARG04 protocol in transmission distance.展开更多
The decoy-state method is a useful method in resisting the attacks on quantum key distribution. However, how to choose the intensities of decoy states and the ratio of the decoy states and the signal state is still an...The decoy-state method is a useful method in resisting the attacks on quantum key distribution. However, how to choose the intensities of decoy states and the ratio of the decoy states and the signal state is still an open question. We present a simple formula to analyse the problem. We also give a simple method to derive the bounds of the necessary counting rates and quantum bit error rates for BB84 and SARG04; the latter was previously proposed by Scarani et al. [Phys. Rev. Lett. 92 （2004）057901] We then propose a multi-signal-state method which employs different coherent states either as the decoy state or as the signal state to carry out quantum key distribution. We find our protocol more efficient and feasible.展开更多
文摘In practical quantum key distribution （QKD）, weak coherent states as the photon source have a limit in the secure key rate and transmission distance because of the existence of multi-photon pulses and heavy loss in transmission line. The decoy-state method and the nonorthogonal encoding protocol are two important methods to combat these effects. Here, we combine both the methods and propose an efficient method that can substantially improve the performance of QKD. We find a 78-kin increase over the prior record using the decoy-state method and a 123-km increase over the result of the SARG04 protocol in transmission distance.
文摘The decoy-state method is a useful method in resisting the attacks on quantum key distribution. However, how to choose the intensities of decoy states and the ratio of the decoy states and the signal state is still an open question. We present a simple formula to analyse the problem. We also give a simple method to derive the bounds of the necessary counting rates and quantum bit error rates for BB84 and SARG04; the latter was previously proposed by Scarani et al. [Phys. Rev. Lett. 92 （2004）057901] We then propose a multi-signal-state method which employs different coherent states either as the decoy state or as the signal state to carry out quantum key distribution. We find our protocol more efficient and feasible.
