Abstract
Quantum conference key agreement (CKA) enables key sharing among multiple trusted users with information-theoretic security. Currently, the key rates of most quantum CKA protocols suffer from the limit of the total efficiency among quantum channels. Inspired by the coherent one-way and twin-field quantum key distribution (QKD) protocols, we propose a quantum CKA protocol of three users. Exploiting coherent states with intensity 0 and μ to encode logic bits, our protocol can break the limit. Additionally, the requirements of phase randomization and multiple intensity modulation are removed in our protocol, making its experimental demonstration simple.
Highlights
The establishment of quantum network is the ultimate goal of quantum communication, where quantum key distribution (QKD) is the most mature subfield for applications
Conference key rates in our protocol can break the limit of the total efficiency among quantum channels when the misalignment rate of interference basis e′d is lower than 3%
Since Charlie encodes logic bits with a nonempty coherent state and a vacuum state, the key feature of our scheme is removing the lar requirement of to the key idea coincidence of twin-field detection, which QKD
Summary
The establishment of quantum network is the ultimate goal of quantum communication, where QKD is the most mature subfield for applications. A three-party quantum CKA [20], inspired by the twin-field QKD [26,27,28], is presented to overcome this limit in a practical way. This protocol [20] requires to exploit the decoy-state method [29, 30], including the active and high precision phase randomization and multiple intensity modulation, which increases the experimental complexity in quantum state preparation. We propose a simple scheme for three-party quantum CKA protocol to break this limit by combining the methods of coherent one-way QKD [31] and twin-field. Our protocol promotes the practical process of quantum CKA and may have a good application prospect
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