Scalable Quantum Key Distribution via GHZ Entanglement and Qubit Reuse

2026-08-21

AI Summary

为减少量子密钥分发中的资源消耗，提出了一种基于GHZ纠缠态的方案，通过量子非破坏测量复用纠缠态来传递多比特密钥，提高了带宽受限量子网络的效率。

Abstract

Conventional Quantum Key Distribution (QKD) requires the transmission of qubits proportional to or exceeding the length of the key, as protocols such as BB84 transmit more qubits than the final key size due to basis sifting and privacy amplification. Since quantum networks are still in their infancy and have limited capacity, this overhead puts significant pressure on network resources. To address this issue, we propose a Multi-Qubit Greenberger--Horne--Zeilinger (GHZ) State-based QKD scheme that reduces the number of qubits transmitted over the quantum channel. The proposed method transmits one GHZ qubit between endpoints and reuses the resulting entanglement to convey multiple classical key bits with the help of Quantum Non-Demolition (QND) measurements. Under the stated assumptions on authenticated classical communication, local reset verification, and bounded-error QND discrimination, one can transfer $L$ classical bits by generating an (L+1)-qubit GHZ state and transferring one qubit to the remote party. We verify correctness using the NetSquid quantum network simulator: the protocol achieves 100\% raw-key fidelity for keys of length up to 12 bits under both ideal conditions and depolarizing noise up to p = 0.005 per round. We further show that the proposed QKD algorithm can be extended to multi-party QKD and server-client deployment. The proposed scheme offers a transmitted-qubit-efficient, noise-tolerant alternative for bandwidth-limited quantum networks.

Problem

• Quantum Key Distribution
• GHZ Entanglement
• Qubit Reuse
• Quantum Networks
• Bandwidth-limited

Innovation

• GHZ Entanglement
• Qubit Reuse
• Quantum Non-Demolition (QND) measurements
• transmitted-qubit-efficient