Higher-rate relativistic quantum key distribution.

One of the major problems in the field of quantum key distribution (QKD) is the low key rates at which the systems operate. The reasons for this are the processes used to ensure the key distribution itself: sifting, parameter estimation, key reconciliation, and privacy amplification. So, this reduction in the rate of communication is inherent to all existing quantum key distribution schemes. This paper is concerned with proposing a solution to mitigate the rate reduction of the so-called relativistic QKD. To mitigate the reduction, we introduce a modified relativistic QKD protocol, which is based on Mach-Zehnder interferometer being used as a probabilistic basis selection system (basis misalignment occurs between the parties in approximately half of the transferred qubits). The interferometric scheme allows the participating parties to correlate the mutual unbiased bases (MUBs) chosen by them. In this regard, a qubit could be used to transfer more than one bit of information. To be precise, by implementing the proposed interferometric scheme into a relativistic QKD protocol, a qubit is able to transfer two bits of information. This results in achieving a protocol, which is characterized with a greater rate of communication, two times greater than the usual rate. The modified protocol is proven to be secure against intercept-resend and collective attacks.