Higher-rate relativistic quantum key distribution

Abstract

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.

More optimal relativistic quantum key distribution

“…The proposed scheme, which could be regarded as a combination of the setups introduced in Refs. 38 , 48 , 51 , is characterized with the illustration in Fig. 1 .…”

“…Optical interference is one of the practical tools for constructing secure quantum key distribution systems between two parties 38 , 39 , 48 . The process of interference allows the development of the so-called relativistic quantum key distribution 48 – 51 . This type of QKD relies mainly on interferometric setup and the principles of relativity 52 – 54 in order to provide a way to detect the presence of a third party (eavesdropper).…”

“…So, they could be used for further improving such schemes. Throughout the years, several relativistic schemes are introduced 48 – 51 . In Ref.…”

“…The work of Ref. 51 reports a setup in which two high-dimensional WCP states (both polarization and phase encoding are applied on the WCPs) interfere at the recipient. It is characterized with a rate of 2 bits per relevant setup use.…”

“…Also, in order for the relativistic key distribution to be as secure as possible, its transfer rate acquires relatively low values 48 , 50 . A way to increase the rate is to incorporate quantum phenomena into the transfer process of the relativistic quantum key distribution 51 .…”