Characterizing high-quality high-dimensional quantum key distribution by state mapping between different degree of freedoms

TL;DR

This paper demonstrates a high-quality high-dimensional quantum key distribution method using polarization-OAM hybrid states, achieving low QBER and high secret key rate with a simple, stable setup.

Contribution

It introduces a novel state mapping approach between different degrees of freedom for high-dimensional QKD, enhancing simplicity and stability.

Findings

Achieved 0.60% QBER in four-dimensional QKD.

Generated 1.849 bits secret key rate per sifted signal.

Verified the method's effectiveness with weak coherent light and decoy states.

Abstract

Quantum key distribution (QKD) guarantees the secure communication between legitimate parties with quantum mechanics. High-dimensional QKD (HDQKD) not only increases the secret key rate but also tolerates higher quantum bit error rate (QBER). Many HDQKD experiments have been realized by utilizing orbital-angular-momentum (OAM) photons as the degree of freedom (DOF) of OAM of the photon is a prospective resource for HD quantum information. In this work we proposed and characterized that a high-quality HDQKD based on polarization-OAM hybrid states can be realized by utilizing state mapping between different DOFs. Both the preparation and measurement procedures of the proof-of-principle verification experiment are simple and stable. Our experiment verified that $(0.60\pm 0.06)\%$ QBER and $1.849\pm 0.008$ bits secret key rate per sifted signal can be achieved for a four-dimensional QKD with the weak coherent light source and decoy state method.