Efficient creation of dipolar coupled nitrogen-vacancy spin qubits in diamond

TL;DR

This paper presents an optimized ion implantation method using electron-beam lithography masks to reliably create dipolar coupled nitrogen-vacancy spin qubits in diamond, advancing scalable quantum information processing.

Contribution

It introduces an optimized implantation parameter estimation and demonstrates a practical approach to produce coupled NV defect pairs with improved probability.

Findings

Optimized implantation parameters increase the likelihood of creating coupled qubits.

Electron-beam lithography masks enable precise defect placement.

Scaling analysis suggests pathways for more efficient spin architecture engineering.

Abstract

Coherently coupled pairs or multimers of nitrogen-vacancy defect electron spins in diamond have many promising applications especially in quantum information processing (QIP) but also in nanoscale sensing applications. Scalable registers of spin qubits are essential to the progress of QIP. Ion implantation is the only known technique able to produce defect pairs close enough to allow spin coupling via dipolar interaction. Although several competing methods have been proposed to increase the resulting resolution of ion implantation, the reliable creation of working registers is still to be demonstrated. The current limitation are residual radiation-induced defects, resulting in degraded qubit performance as trade-off for positioning accuracy. Here we present an optimized estimation of nanomask implantation parameters that are most likely to produce interacting qubits under standard conditions. We apply our findings to a well-established technique, namely masks written in electron-beam lithography, to create coupled defect pairs with a reasonable probability. Furthermore, we investigate the scaling behavior and necessary improvements to efficiently engineer interacting spin architectures.