Theory of spin qubits and the path to scalability

TL;DR

This paper reviews the theoretical foundations, experimental progress, and future pathways for spin qubits in quantum computing, emphasizing scalability and various coupling mechanisms.

Contribution

It provides a comprehensive overview of spin qubit implementations, coupling strategies, and a new proposal involving topological spin textures for scalable quantum information processing.

Findings

Long coherence times and small footprint of spin qubits.

Experimental demonstrations of long-range coupling mechanisms.

Proposal for linking spin qubits with topological spin textures.

Abstract

Spin qubits have emerged as a leading platform for quantum information processing due to their long coherence times, small footprint, and compatibility with the existing semiconductor industry. We first provide an introduction to the different qubit implementations currently being investigated, including single electron-spin qubits, hole-spin qubits, donor qubits, and multispin encodings. We discuss how the confinement and strain present in semiconductor heterostructures produce addressable levels whose spin degree of freedom can be used to encode a qubit. A large emphasis is placed on reviewing the theoretical foundations and recent experimental demonstrations of proposed mechanisms for long-range coupling, including hybrid approaches based on circuit QED and Andreev qubits, as well as spin shuttling. Finally, we review a recent proposal for linking spin qubits using topological spin textures.