Quantum repeaters with encoding on nitrogen-vacancy center platforms

TL;DR

This paper explores quantum repeater protocols using nitrogen-vacancy centers in diamond, comparing two structures for deterministic joint operations, and evaluates their performance for secure key generation under realistic noise conditions.

Contribution

It introduces and compares two NV-center based quantum repeater structures that enable deterministic joint operations for encoding-based quantum communication.

Findings

One structure reduces classical communication at the cost of more computation.

The other uses fewer physical resources and operations.

Encoded repeaters can outperform non-encoded ones under certain conditions.

Abstract

We investigate 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-center based repeater structures that enable such deterministic joint operations. One structure offers less consumption of classical communication, at the cost of more computation overhead, whereas the other one relies on a fewer number 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 quantum repeaters offer practical advantages over their non-encoded counterparts.