Gaussian Entanglement for Quantum Key Distribution from a Single-Mode Squeezing Source

TL;DR

This paper demonstrates the potential of a single-mode squeezed vacuum source combined with a vacuum mode for secure quantum key distribution over approximately 10 km, supported by a security proof for asymmetric Gaussian states.

Contribution

It introduces a practical EPR entanglement source for CV-QKD at 1550 nm and extends security analysis to asymmetric Gaussian states with finite samples.

Findings

Achieves secure key distribution over ~10 km distances.

Validates security for asymmetric Gaussian entangled states.

Shows feasibility with a single squeezed mode plus vacuum.

Abstract

We report the suitability of an Einstein-Podolsky-Rosen (EPR) entanglement source for gaussian continuous-variable quantum key distribution at 1550 nm. Our source is based on a single continuous-wave squeezed vacuum mode combined with a vacuum mode at a balanced beam splitter. Extending a recent security proof, we characterize the source by quantifying the extractable length of a composable secure key from a finite number of samples under the assumption of collective attacks. We show that distances in the order of 10 km are achievable with this source for a reasonable sample size despite the fact that the entanglement was generated including a vacuum mode. Our security analysis applies to all states having an asymmetry in the field quadrature variances, including those generated by superposition of two squeezed modes with different squeezing strengths.