Quantum key distribution protocols with slow basis choice

TL;DR

This paper proves the security of quantum key distribution protocols that use slow basis choice, enabling practical implementation without sacrificing key rate, applicable to protocols like RRDPS and BB84.

Contribution

It introduces a security proof for QKD protocols with slow basis choice, relaxing the need for rapid basis switching without reducing secret key rates.

Findings

Security of QKD with slow basis choice is proven.

The technique applies to RRDPS and BB84 protocols.

Implementation demands are significantly relaxed.

Abstract

Many quantum key distribution (QKD) protocols require random choice of measurement basis for each pulse or each train of pulses. In some QKD protocols, such as the Round-Robin Differential Phase Shift (RRDPS) QKD protocol, this requirement is a bit challenging as randomly choosing hundreds of settings for every, say, 100 pulses may be too fast with current technologies. In this paper, we solve this issue by proving the security of QKD protocols with slow basis choice without compromising the secret key rate. We also show that the random choice of the bases for the state preparation can be made slow if the signals do not leak any information on the basis. Examples of QKD protocols that our technique can apply include the RRDPS protocol and BB84-type protocols, and our technique relaxes demands for the implementation of QKD systems.