A Three-Dimensional Array of Quantum Dots

TL;DR

This paper demonstrates the construction and control of a three-dimensional array of quantum dots in a silicon-germanium heterostructure, enabling complex quantum operations and paving the way for advanced quantum hardware.

Contribution

It introduces a three-dimensional quantum dot array architecture with coherent control, extending beyond planar geometries for scalable quantum computing.

Findings

Successfully realized an eight-quantum dot 3D array.

Achieved coherent spin control and spin rotations via electron shuttling.

Showcased potential for high-connectivity quantum circuits.

Abstract

Quantum dots can confine single electrons or holes to define spin qubits that can be operated with high fidelity. Experimental work has progressed from linear to two-dimensional arrays of quantum dots, enabling qubit interactions that are essential for quantum simulation and computation. Here, we explore architectures beyond planar geometries by constructing quantum dot arrays in three dimensions. We realize an eight-quantum dot system in a silicon-germanium heterostructure comprising two stacked germanium quantum wells, where quantum dots are positioned at the vertices of a cuboid. Using electrostatic gate control, we load a single hole into any of the eight quantum dots. To demonstrate the potential of multilayer quantum dot systems, we show coherent spin control and hopping-induced spin rotations by shuttling between the quantum wells. The ability to extend quantum dot arrays in three dimensions provides opportunities for novel quantum hardware and high-connectivity quantum circuits.