Guiding Diamond Spin Qubit Growth with Computational Methods

TL;DR

This paper introduces a computational approach to guide the growth of diamond NV center spin qubits, aiming to improve their coherence and scalability for quantum sensing applications.

Contribution

It integrates theoretical decoherence calculations into the synthesis process, enabling deterministic control over NV spin bath properties and improving qubit performance.

Findings

Coherence times depend on spin bath dimensionality and density.

Maximum likelihood estimator accurately characterizes NV samples.

Dimensionality impacts the yield of strongly coupled electron spin systems.

Abstract

The nitrogen vacancy (NV) center in diamond, a well-studied, optically active spin defect, is the prototypical system in many state of the art quantum sensing and communication applications. In addition to the enticing properties intrinsic to the NV center, its diamond host's nuclear and electronic spin baths can be leveraged as resources for quantum information, rather than considered solely as sources of decoherence. However, current synthesis approaches result in stochastic defect spin positions, reducing the technology's potential for deterministic control and yield of NV-spin bath systems, as well as scalability and integration with other technologies. Here, we demonstrate the use of theoretical calculations of electronic central spin decoherence as an integral part of an NV-spin bath synthesis workflow, providing a path forward for the quantitative design of NV center-based quantum sensing systems. We use computationally generated coherence data to characterize the properties of single NV center qubits across relevant growth parameters to find general trends in coherence time distributions dependent on spin bath dimensionality and density. We then build a maximum likelihood estimator with our theoretical model, enabling the characterization of a test sample through NV T2* measurements. Finally, we explore the impact of dimensionality on the yield of strongly coupled electron spin systems. The methods presented herein are general and applicable to other qubit platforms that can be appropriately simulated.