Quantum Key Distribution with Minimal Qubit Transmission Based on MultiQubit Greenberger Horne Zeilinger State

Abstract: Conventional Quantum Key Distribution (QKD) requires the transmission of multiple qubits equivalent to the length of the key. As quantum networks are still in their infancy thus, they are expected to have a limited capacity, necessitating too many qubit transmissions for QKD might limit the effective use of limited network bandwidth of quantum networks. To address this challenge and enhance the practicality of QKD, we propose a Multi-Qubit Greenberger Horne Zeilinger (GHZ) State-based QKD scheme that requires a small number of qubit transmissions. The proposed method transmits one qubit between endpoints and reuses it for the transmission of multiple classical bits with the help of Quantum nondemolition (QND) measurements. We show that one can transfer L-1 classical bits by generating an L-qubit GHZ state and transferring one to the remote party. We further show that the proposed QKD algorithm can be extended to enable multi-party QKD. It can also support QKD between parties with minimal quantum resources. As a result, the proposed scheme offers a quantum network-efficient alternative QKD.