Surface code architecture for donors and dots in silicon with imprecise and nonuniform qubit couplings

TL;DR

This paper proposes a silicon-based quantum computing architecture using donor spins and quantum dots, employing adiabatic SWAP operations and global control to enable scalable, noise-robust quantum error correction.

Contribution

It introduces a novel silicon architecture with long-coherence donors and electron shuttling, relaxing placement precision and simplifying control for surface code implementation.

Findings

Adiabatic SWAP operations are robust and do not require nanometer-scale donor placement.

The architecture enables scalable surface code with minimal local control.

Electron shuttling facilitates coupling without precise gate control structures.

Abstract

A scaled quantum computer with donor spins in silicon would benefit from a viable semiconductor framework and a strong inherent decoupling of the qubits from the noisy environment. Coupling neighbouring spins via the natural exchange interaction according to current designs requires gate control structures with extremely small length scales. We present a silicon architecture where bismuth donors with long coherence times are coupled to electrons that can shuttle between adjacent quantum dots, thus relaxing the pitch requirements and allowing space between donors for classical control devices. An adiabatic SWAP operation within each donor/dot pair solves the scalability issues intrinsic to exchange-based two-qubit gates, as it does not rely on sub-nanometer precision in donor placement and is robust against noise in the control fields. We use this SWAP together with well established global microwave Rabi pulses and parallel electron shuttling to construct a surface code that needs minimal, feasible local control.