Semi-device-independent quantum key agreement protocol

In quantum key agreement (QKA), a shared key is established among two or more parties where each participant equally contributes its part to the shared key, and none of the participants can determine the shared key alone. Zhou et al. (Electron Lett 40(18):1149, 2004) gave the first QKA protocol based on quantum teleportation and since then quite a few variants and extensions have been proposed. However, none of the existing protocols are device-independent, i.e., all of them assume implicitly that the single-photon states or entangled states supplied to the participants are of certain form. In this work, we exploit the idea of the device-independent dimension witness for independent preparation and measurement devices proposed by Tavakoli (Phys Rev Lett 125:15050, 2020) and connect it with the QKA protocol (Chong and Hwang in Opt Commun 283:1192-1195, 2010) to present the concept of semi-device-independent QKA protocol for the first time.