On Secure Quantum Key Distribution Using Continuous Variables of Single Photons

TL;DR

This paper explores secure quantum key distribution using the continuous variables of entangled photons, revealing limitations of existing security measures and demonstrating potential for enhanced secret key extraction.

Contribution

It introduces a new analysis of spatial entanglement in photon pairs for quantum cryptography, highlighting security measure inadequacies and proposing a method to surpass them.

Findings

Standard CV-QKD security measures are inadequate for spatial entanglement.

A simple eavesdropping attack can be detected and mitigated.

Secret keys can be distilled beyond traditional security bounds.

Abstract

We analyse the distribution of secure keys using quantum cryptography based on the continuous variable degree of freedom of entangled photon pairs. We derive the information capacity of a scheme based on the spatial entanglement of photons from a realistic source, and show that the standard measures of security known for quadrature-based continuous variable quantum cryptography (CV-QKD) are inadequate. A specific simple eavesdropping attack is analysed to illuminate how secret information may be distilled well beyond the bounds of the usual CV-QKD measures.