High-Fidelity Electron Spin Gates for Scaling Diamond Quantum Register

TL;DR

This paper presents a robust entangling gate for NV electron spins in diamond, achieving record fidelity under ambient conditions and identifying key error sources to advance scalable quantum registers.

Contribution

The authors design and experimentally demonstrate a high-fidelity, easy-to-implement NV-NV entangling gate and analyze its error sources, surpassing previous fidelity benchmarks.

Findings

Achieved a gate fidelity of 96.0% under ambient conditions.

Identified dominant error sources affecting gate performance.

Provided a pathway towards scalable diamond-based quantum registers.

Abstract

Diamond is a promising platform for quantum information processing as it can host highly coherent qubits that could allow for the construction of large quantum registers. A prerequisite for such devices is a coherent interaction between nitrogen vacancy (NV) electron spins. Entanglement between dipolar-coupled NV spin pairs has been demonstrated, but with a limited entanglement fidelity and its error sources have not been characterized. Here, we design and implement a robust, easy to implement entangling gate between NV spins in diamond and quantify the influence of multiple error sources on the gate performance. Experimentally, we demonstrate a record gate fidelity of $F=(96.0 \pm 2.5)$ % under ambient conditions. Our identification of the dominant errors paves the way towards NV-NV gates beyond the error correction threshold.