Donor spins in silicon for quantum technologies

TL;DR

This paper reviews the use of ion-implanted donor spins in silicon as solid-state qubits for quantum computing, highlighting fabrication, coherence, scaling, and novel quantum phenomena enabled by these atomic-scale systems.

Contribution

It provides a comprehensive overview of donor spin qubits in silicon, including fabrication techniques, coherence properties, and pathways for scaling up for quantum processors.

Findings

Donor spins in silicon exhibit some of the longest coherence times among solid-state qubits.

Deterministic implantation and precision placement enable integration with silicon fabrication.

Heavy group-V donors enable nuclear electric resonance and strain sensing.

Abstract

Dopant atoms are ubiquitous in semiconductor technologies, providing the tailored electronic properties that underpin the modern digital information era. Harnessing the quantum nature of these atomic-scale objects represents a new and exciting technological revolution. In this article we describe the use of ion-implanted donor spins in silicon for quantum technologies. We review how to fabricate and operate single-atom spin qubits in silicon, obtaining some of the most coherent solid-state qubits, and we discuss pathways to scale up these qubits to build large quantum processors. Heavier group-V donors with large nuclear spins display electric quadrupole couplings that enable nuclear electric resonance, quantum chaos and strain sensing. Donor ensembles can be coupled to microwave cavities to develop hybrid quantum Turing machines. Counted, deterministic implantation of single donors, combined with novel methods for precision placement, will allow the integration of individual donors spins with industry-standard silicon fabrication processes, making implanted donors a prime physical platform for the second quantum revolution.