Abstract
Measurement-device-independent quantum key distribution (MDI-QKD) with the active decoy state method can remove all detector loopholes, and resist the imperfections of sources. But it may lead to side channel attacks and break the security of QKD system. In this paper, we apply the passive decoy state method to the MDI-QKD based on polarization encoding mode. Not only all attacks on detectors can be removed, but also the side channel attacks on sources can be overcome. We get that the MDI-QKD with our passive decoy state method can have a performance comparable to the protocol with the active decoy state method. To fit for the demand of practical application, we discuss intensity fluctuation in the security analysis of MDI-QKD protocol using passive decoy state method, and derive the key generation rate for our protocol with intensity fluctuation. It shows that intensity fluctuation has an adverse effect on the key generation rate which is non-negligible, especially in the case of small data size of total transmitting signals and long distance transmission. We give specific simulations on the relationship between intensity fluctuation and the key generation rate. Furthermore, the statistical fluctuation due to the finite length of data is also taken into account.
Highlights
Quantum key distribution (QKD) has been widely studied in both theoretical and experimental aspects[1,2,3] since its initial proposal[4]
We compare the key generation rate of measurement-device-independent quantum key distribution (MDI-QKD) given by our passive decoy state method which based on polarization encoding mode with that based on phase encoding mode in ref. 29, due to these two encoding modes are both applied in practical systems
We applied the passive decoy state method in the MDI-QKD based on polarization encoding mode, and gave a security analysis of this protocol
Summary
Alice generates phase-randomized pulses using two weak coherent sources with intensities μ1 and μ2, respectively. These two pulses interfere at a beam splitter (BS) with a transmittance of 50%; there are two outcome signals which have the classically correlated photon number statistics. Alice passively generates signal or decoy states. The state Alice generated is a joint-distribution state according to the result of detector a0. Corresponding to the detector’s modes, the output a has two modes, c0 and c1, which describe the signal state and decoy state, respectively. Ξa cosθa , μ ξnao=clickμi1nμt2haenddeθtaec=torφaa[02] c−anφbae[1] is the phase difference. expressed by
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