Robustness of electron charge shuttling: Architectures, pulses, charge defects and noise thresholds

TL;DR

This study uses numerical simulations to analyze the robustness of electron charge shuttling in silicon-based devices, demonstrating high fidelity under various imperfections and noise conditions, supporting its use in quantum connectivity.

Contribution

The paper provides a detailed numerical analysis of electron shuttling robustness, highlighting the effectiveness of simple electrode architectures in realistic noisy environments.

Findings

High adiabatic fidelity with minimal electrodes despite noise

Charge defects at certain locations can disrupt shuttling

Shuttling remains robust under pulse imperfections and noise

Abstract

In semiconductor-based quantum technologies, the capability to shuttle charges between components is profoundly enabling. We numerically simulated various "conveyor-belt" shuttling scenarios for simple Si/SiO2 devices, explicitly modelling the electron's wave function using grid-based split-operator methods and a time-dependent 2D potential (obtained from a Poisson solver). This allowed us to fully characterise the electron loss probability and excitation fraction. Remarkably, with as few as three independent electrodes the process can remain near-perfectly adiabatic even in the presence of pulse imperfection, nearby charge defects, and Johnson-Nyquist noise. Only a substantial density of charge defects, or defects at 'adversarial' locations, can catastrophically disrupt the charge shuttling. While we do not explicitly model the spin or valley degrees of freedom, our results from this charge propagation study support the conclusion that conveyor-belt shuttling is an excellent candidate for providing connectivity in semiconductor quantum devices.