High error-rate quantum key distribution for long-distance communication

TL;DR

This paper introduces a quantum key distribution protocol that tolerates higher noise levels by leveraging increased error rates in higher-dimensional photon states, enabling longer-distance secure communication.

Contribution

It proposes a new QKD scheme using mutually unbiased bases and higher-dimensional states, enhancing noise tolerance and distance without intermediate nodes.

Findings

Higher-dimensional states increase security against eavesdroppers.

The protocol allows for longer communication distances.

It tolerates more noise compared to traditional BB84.

Abstract

In the original BB84 protocol by Bennett and Brassard, an eavesdropper is detected because his attempts to intercept information result in a quantum bit error rate (QBER) of at least 25%. Here we design an alternative quantum key distribution protocol, where Alice and Bob use two mutually unbiased bases with one of them encoding a "0" and the other one encoding a "1." The security of the scheme is due to a minimum index transmission error rate (ITER) introduced by an eavesdropper which increases significantly for higher-dimensional photon states. This allows for more noise in the transmission line, thereby increasing the possible distance between Alice and Bob without the need for intermediate nodes.