Single-Quadrature Continuous-Variable Quantum Key Distribution

TL;DR

This paper introduces and experimentally validates a simplified single-quadrature Gaussian modulation scheme for continuous-variable quantum key distribution, reducing complexity and cost while maintaining security.

Contribution

It presents a novel single-quadrature modulation method that simplifies implementation and is secure against collective attacks, advancing practical quantum key distribution.

Findings

Scheme is asymptotically secure against collective attacks

Reduces need for amplitude modulators, lowering costs

Facilitates commercialization of CV-QKD systems

Abstract

Most continuous-variable quantum key distribution schemes are based on the Gaussian modulation of coherent states followed by continuous quadrature detection using homodyne detectors. In all previous schemes, the Gaussian modulation has been carried out in conjugate quadratures thus requiring two independent modulators for their implementations. Here, we propose and experimentally test a largely simplified scheme in which the Gaussian modulation is performed in a single quadrature. The scheme is shown to be asymptotically secure against collective attacks, and considers asymmetric preparation and excess noise. A single-quadrature modulation approach renders the need for a costly amplitude modulator unnecessary, and thus facilitates commercialization of continuous-variable quantum key distribution.