A frequency-coded QKD scheme with an extension to qu-quarts

TL;DR

This paper introduces a novel frequency-based QKD scheme using quantum frequency translation in optical fibers, extending it to a four-character alphabet for enhanced security, promising longer-distance quantum communication.

Contribution

It presents a new frequency-encoded QKD protocol and extends it to a qu-quarts scheme, improving robustness and security over traditional polarization-based methods.

Findings

Frequency-encoded QKD can reach longer distances.

Extension to qu-quarts enhances security.

Robustness against fiber fluctuations is improved.

Abstract

We propose a novel scheme to implement the BB84 quantum key distribution (QKD) protocol in optical fibers based on a quantum frequency-translation (QFT) process. Unlike conventional QKD systems, which rely on photon polarization/phase to encode qubits, our proposal utilizes photons of different frequencies. Qubits are thus expected to reach longer propagation distances due to the photon frequency state being more robust against mechanical and/or thermal fluctuations of the transmitting medium. Finally, we put forth an extension to a security-enhanced four-character-alphabet (qu-quarts) QKD scheme.