Using Multiple Reference Pulses for Phase Reference Sharing in Continuous-Variable Quantum Key Distribution

In continuous-variable quantum key distribution protocols, the information is usually encoded in the first and second quadratures of optical pulses. So Alice and Bob, at the two ends of the quantum channel, need to share their definition of the very first quadrature (and the second one), i.e. their phase references, by sending reference pulses along with the signal pulses. In this paper, we discuss the strategy of using multiple reference pulses for the benefit of one signal pulse and try to calculate the amount of phase noise emerged in this way. The strategy sounds to be useful in some cases.