Efficient and Robust Quantum Key Distribution With Minimal State Tomography

TL;DR

The paper presents the Singapore protocol, a highly efficient, robust, and fully tomographic quantum key distribution method that surpasses standard protocols in efficiency and maintains security under significant noise levels.

Contribution

Introduction of the Singapore protocol, a novel fully tomographic quantum key distribution scheme with improved efficiency and robustness against eavesdropping.

Findings

Efficiency of 0.415 key bits per qubit under ideal conditions

Achieves 0.4 key bits per qubit with simple two-way communication

Secure against noise levels up to 38.9%

Abstract

We introduce the Singapore protocol, a qubit protocol for quantum key distribution that is fully tomographic, more efficient than other tomographic protocols, and very robust. Under ideal circumstances the efficiency is log_2(4/3)=0.415 key bits per qubit sent. This is 25% more than the efficiency of 1/3=0.333 for the standard six-state protocol, which sets the benchmark. We describe a simple two-way communication scheme that extracts 0.4 key bits per qubit and thus gets close to the information-theoretical limit. The noise thresholds that we report for a hierarchy of eavesdropping attacks demonstrate the robustness of the protocol: A secure key can be extracted if there is less than 38.9% noise.