A Crossbar Network for Silicon Quantum Dot Qubits

TL;DR

This paper proposes a scalable crossbar architecture for silicon quantum dot qubits, enabling large-scale quantum computing with shared control, high-fidelity operations, and non-nearest neighbor coupling.

Contribution

It introduces a novel scalable quantum dot qubit architecture with shared control lines, non-planar coupling, and integrated high-fidelity control mechanisms.

Findings

Design enables qubit coupling beyond nearest neighbors.

High-fidelity single-qubit rotations demonstrated.

Architecture supports large-scale quantum computation.

Abstract

The spin states of single electrons in gate-defined quantum dots satisfy crucial requirements for a practical quantum computer. These include extremely long coherence times, high-fidelity quantum operation, and the ability to shuttle electrons as a mechanism for on-chip flying qubits. In order to increase the number of qubits to the thousands or millions of qubits needed for practical quantum information we present an architecture based on shared control and a scalable number of lines. Crucially, the control lines define the qubit grid, such that no local components are required. Our design enables qubit coupling beyond nearest neighbors, providing prospects for non-planar quantum error correction protocols. Fabrication is based on a three-layer design to define qubit and tunnel barrier gates. We show that a double stripline on top of the structure can drive high-fidelity single-qubit rotations. Qubit addressability and readout are enabled by self-aligned inhomogeneous magnetic fields induced by direct currents through superconducting gates. Qubit coupling is based on the exchange interaction, and we show that parallel two-qubit gates can be performed at the detuning noise insensitive point. While the architecture requires a high level of uniformity in the materials and critical dimensions to enable shared control, it stands out for its simplicity and provides prospects for large-scale quantum computation in the near future.