Numerical simulation of coherent spin-shuttling in a QuBus with charged defects

TL;DR

This paper presents a simulation framework to analyze how charged defects in Si/SiGe heterostructures affect the coherence of spin qubits during conveyor-mode shuttling, crucial for scalable quantum computing.

Contribution

The authors developed a numerical simulation tool to study the effects of device imperfections, especially charged point defects, on spin qubit coherence during shuttling in Si/SiGe structures.

Findings

Identified critical defect density thresholds for maintaining qubit coherence.

Quantified the impact of single charged defects on spin coherence.

Analyzed effects of defect location, orbital states, and electron-phonon interactions.

Abstract

Recent advances in coherent conveyor-mode spin qubit shuttling are paving the way for large-scale quantum computing platforms with qubit connectivity achieved by spin qubit shuttles. We developed a simulation tool to investigate numerically the impact of device imperfections on the spin-coherence of conveyor-mode shuttling in Si/SiGe. We simulate the quantum evolution of a mobile electron spin-qubit under the influence of sparse and singly charged point defects placed in the Si/SiGe heterostructure in close proximity to the shuttle lane. We consider different locations of a single charge defect with respect to the center of the shuttle lane, multiple orbital states of the electron in the shuttle with $g$-factor differences between the orbital levels, and orbital relaxation induced by electron-phonon interaction. With this simulation framework, we identify the critical defect density of charged point defects in the heterostructure for conveyor-mode spin qubit shuttle devices and quantify the impact of a single defect on the coherence of a qubit.