Quantum computing with defects

TL;DR

This paper discusses identifying and designing defect-based qubits in solid-state systems, focusing on the nitrogen-vacancy center in diamond and similar defects in other semiconductors, using electronic structure theory.

Contribution

It introduces physical criteria and a systematic approach to find and compare defect centers suitable for quantum computing applications.

Findings

Electronic structure calculations of NV-1 in diamond and deep centers in SiC.

Proposed criteria for identifying similar quantum defects in other semiconductors.

Comparison of defect properties to guide future qubit development.

Abstract

Identifying and designing physical systems for use as qubits, the basic units of quantum information, are critical steps in the development of a quantum computer. Among the possibilities in the solid state, a defect in diamond known as the nitrogen-vacancy (NV-1) center stands out for its robustness - its quantum state can be initialized, manipulated, and measured with high fidelity at room temperature. Here we describe how to systematically identify other deep center defects with similar quantum-mechanical properties. We present a list of physical criteria that these centers and their hosts should meet and explain how these requirements can be used in conjunction with electronic structure theory to intelligently sort through candidate defect systems. To illustrate these points in detail, we compare electronic structure calculations of the NV-1 center in diamond with those of several deep centers in 4H silicon carbide (SiC). We then discuss the proposed criteria for similar defects in other tetrahedrally-coordinated semiconductors.