Full control of quadruple quantum dot circuit charge states in the single electron regime

TL;DR

This paper demonstrates the creation and control of a quadruple quantum dot array in the single electron regime, advancing the development of scalable solid-state spin qubit architectures.

Contribution

It introduces the first realization of a four-dot quantum circuit with tunable charge states and analyzes its charge configurations for future spin blockade applications.

Findings

Successfully fabricated a quadruple quantum dot array in the single electron regime.

Developed a capacitive model to predict charge state diagrams.

Experimentally confirmed charge states align with model predictions.

Abstract

We report the realization of an array of four tunnel coupled quantum dots in the single electron regime, which is the first required step toward a scalable solid state spin qubit architecture. We achieve an efficient tunability of the system but also find out that the conditions to realize spin blockade readout are not as straightforwardly obtained as for double and triple quantum dot circuits. We use a simple capacitive model of the series quadruple quantum dots circuit to investigate its complex charge state diagrams and are able to find the most suitable configurations for future Pauli spin blockade measurements. We then experimentally realize the corresponding charge states with a good agreement to our model.