Measurement of tunnel coupling in a Si double quantum dot based on charge sensing

TL;DR

This paper introduces a four-level model for accurately measuring tunnel coupling in silicon double quantum dots using charge sensing, accounting for valley effects that complicate electron dynamics.

Contribution

It presents a novel theoretical scheme to extract intra- and inter-valley tunnel couplings in Si DQDs, improving precision and robustness over previous methods.

Findings

The model accurately determines tunnel couplings despite valley complexities.

Charge sensing can be effectively used for tunnel coupling measurement in Si DQDs.

The approach is robust against variations in valley splittings.

Abstract

In Si quantum dots, valley degree of freedom, in particular the generally small valley splitting and the dot-dependent valley-orbit phase, adds complexities to the low-energy electron dynamics and the associated spin qubit manipulation. Here we propose a four-level model to extract tunnel coupling information for a Si double quantum dot (DQD). This scheme is based on a charge sensing measurement on the ground state as proposed in the widely used protocol for a GaAs double dot [DiCarlo et. al., PRL 92. 226801]. Our theory can help determine both intra- and inter-valley tunnel coupling with high accuracy, and is robust against system parameters such as valley splittings in the individual quantum dots.