Initialization of a spin qubit in a site-controlled nanowire quantum dot

TL;DR

This paper demonstrates high-fidelity optical initialization of individual spin qubits in site-controlled nanowire quantum dots, advancing their potential use in scalable quantum computing and communication systems.

Contribution

It provides the first demonstration of spin qubit operations in nanowire quantum dots with site control, enabling scalable quantum memory applications.

Findings

High-fidelity optical spin initialization achieved

Site-controlled nanowire quantum dots used for spin qubits

Advances towards scalable quantum memory in solid-state systems

Abstract

A fault-tolerant quantum repeater or quantum computer using solid-state spin-based quantum bits will likely require a physical implementation with many spins arranged in a grid. Self-assembled quantum dots (QDs) have been established as attractive candidates for building spin-based quantum information processing devices, but such QDs are randomly positioned, which makes them unsuitable for constructing large-scale processors. Recent efforts have shown that quantum dots embedded in nanowires can be deterministically positioned in regular arrays, can store single charges, and have excellent optical properties, but so far there have been no demonstrations of spin qubit operations using nanowire quantum dots. Here we demonstrate optical pumping of individual spins trapped in site-controlled nanowire quantum dots, resulting in high-fidelity spin-qubit initialization. This represents the next step towards establishing spins in nanowire quantum dots as quantum memories suitable for use in a large-scale, fault-tolerant quantum computer or repeater based on all-optical control of the spin qubits.