Characterizing High-Quality High-Dimensional Quantum Key Distribution by State Mapping Between Different Degrees of Freedom

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