Spin-valley coupling anisotropy and noise in CMOS quantum dots

TL;DR

This paper demonstrates single-electron spin detection in CMOS nanowire quantum dots, measures valley splitting and anisotropy, and investigates charge noise effects on qubit energy stability.

Contribution

It provides the first measurement of spin-valley coupling anisotropy and noise characteristics in CMOS-fabricated quantum dots.

Findings

Valley splitting of 0.3 meV and 0.16 meV in two devices

Spin-valley anisotropy follows local confinement symmetry

Charge noise induces qubit energy fluctuations of 0.6 GHz/√Hz

Abstract

One of the main advantages of silicon spin qubits over other solid-state qubits is their inherent scalability and compatibility with the 300 mm CMOS fabrication technology that is already widely used in the semiconductor industry, whilst maintaining high readout and gate fidelities. We demonstrate detection of a single electron spin using energy-selective readout in a CMOS-fabricated nanowire device with an integrated charge detector. We measure a valley splitting of 0.3 meV and 0.16 meV in two similar devices. The anisotropy of the spin-valley mixing is measured and shown to follow the dependence expected from the symmetry of the local confinement, indicating low disorder in the region of the quantum dot. Finally the charge noise in the spin-valley coupling regime is investigated and found to induce fluctuations in the qubit energy in the range of $0.6GHz/\sqrt{Hz}$.