Long distance measurement-device-independent quantum key distribution with coherent-state superpositions

摘要

Measurement-device-independent quantum key distribution (MDI-QKD) withdecoy-state method is believed to be securely applied to defeat various hackingattacks in practical quantum key distribution systems. Recently, thecoherent-state superpositions (CSS) have emerged as an alternative tosingle-photon qubits for quantum information processing and metrology. Here, inthis Letter, CSS are exploited as the source in MDI-QKD. We present ananalytical method which gives two tight formulas to estimate the lower bound ofyield and the upper bound of bit error rate. We exploit the standardstatistical analysis and Chernoff bound to perform the parameter estimation.Chernoff bound can provide good bounds in the long distance MDI-QKD. Ourresults show that with CSS, both the security transmission distance and securekey rate are significantly improved compared with those of the weak coherentstates in the finite-data case.