Measurement of valley splitting in high-symmetry Si/SiGe quantum dots

TL;DR

This paper reports the measurement of valley splitting in high-symmetry Si/SiGe quantum dots, demonstrating the lifting of valley degeneracy with implications for quantum computing qubits.

Contribution

It provides experimental measurements of valley splitting in Si/SiGe quantum dots, indicating atomically sharp interfaces and advancing understanding of quantum dot properties.

Findings

Valley splittings of 120 and 270 μeV in Si/SiGe quantum dots.

Quantum dots exhibit high spatial symmetry and shell structure.

Two devices show a singlet ground state at low magnetic fields.

Abstract

We have demonstrated few-electron quantum dots in Si/SiGe and InGaAs, with occupation number controllable from N = 0. These display a high degree of spatial symmetry and identifiable shell structure. Magnetospectroscopy measurements show that two Si-based devices possess a singlet N =2 ground state at low magnetic field and therefore the two-fold valley degeneracy is lifted. The valley splittings in these two devices were 120 and 270 {\mu}eV, suggesting the presence of atomically sharp interfaces in our heterostructures.