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.
@article{arxiv.2409.15496,
title = {Continuous Variable Quantum Key Distribution with Single Quadrature Measurement at Arbitrary Reference Frame},
author = {Vinod N. Rao and Emma Tien Hwai Medlock and Timothy Spiller and Rupesh Kumar},
journal= {arXiv preprint arXiv:2409.15496},
year = {2025}
}