By Yumang Jing and Mohsen Razavi.
Submitted to arXiv on 28 May 2021.
We investigate the explicit implementation of quantum repeater protocols that rely on three-qubit repetition codes using nitrogen-vacancy (NV) centers in diamond as quantum memories. NV centers offer a two-qubit register, corresponding to their electron and nuclear spins, which makes it possible to perform deterministic two-qubit operations within one NV center. For quantum repeater applications, we however need to do joint operations on two separate NV centers. Here, we study two NV-based repeater structures that enable such deterministic joint operations. One structure offers less consumption of classical communication, hence is more resilient to decoherence effects, whereas the other one relies on fewer numbers of physical resources and operations. We assess and compare their performance for the task of secret key generation under the influence of noise and decoherence with current and near-term experimental parameters. We quantify the regimes of operation, where one structure outperforms the other, and find the regions where encoded QRs offer practical advantages over their non-encoded counterparts.