Continuous Variable Quantum Key Distribution with Single Quadrature Measurement at Arbitrary Reference Frame

TL;DR

This paper introduces a simplified continuous variable quantum key distribution scheme that uses homodyne detection at arbitrary angles, eliminating the need for quadrature switching and phase modulation, thus enhancing practicality for free-space and fiber systems.

Contribution

It presents a measurement scheme for GMCS CV-QKD that operates without quadrature switching and accommodates arbitrary measurement reference frames, including thermal drifts.

Findings

Scheme converges to GMCS with switching quadrature protocol.

No phase modulator needed for random quadrature measurement.

Advantageous for practical free-space and fiber-based CV-QKD systems.

Abstract

We propose a simplified measurement scheme for a Gaussian modulated coherent state (GMCS) protocol for continuous variable quantum key distribution (CV-QKD), utilizing homodyne detection without quadrature switching. The reference frame of measurement is taken to be at an arbitrary angle, however, reconciliation converges the proposed scheme to GMCS with switching quadrature protocol. The arbitrary frame of measurement could also include the unknown random thermal drift within Bob's optical measurement setup. We found this scheme is advantageous for practical free-space and fibre-based GMCS protocol based CV-QKD systems as it does not require a phase modulator for random measurement selection quadrature at Bob.