Resonant tunneling spectroscopy of valley eigenstates on a hybrid double quantum dot

TL;DR

This paper demonstrates direct measurement of valley splitting in a silicon quantum dot using resonant tunneling spectroscopy, revealing controllable valley splitting values crucial for spin qubit implementation.

Contribution

First direct observation of valley splitting in a silicon quantum dot via resonant tunneling spectroscopy, showing electric field tunability between 160-240 ueV.

Findings

Valley splitting ranges from 160 to 240 ueV.

Valley splitting is tunable with electric field (1.2 ± 0.2 meV/(MV/m)).

Resonant tunneling peaks reveal valley eigenstates.

Abstract

We report electronic transport measurements through a silicon hybrid double quantum dot consisting of a donor and a quantum dot. Transport spectra show resonant tunneling peaks involving different valley states, which illustrate the valley splitting in a quantum dot on a Si/SiO2 interface. The detailed gate bias dependence of double dot transport allows a first direct observation of the valley splitting in the quantum dot, which is controllable between 160-240 ueV with an electric field dependence 1.2 +- 0.2 meV/(MV/m). A large valley splitting is an essential requirement to implement a physical electron spin qubit in a silicon quantum dot.