# Low-frequency charge noise in Si/SiGe quantum dots

## TL;DR

This study investigates how low-frequency charge noise in Si/SiGe quantum dots depends on temperature and dielectric thickness, revealing that noise likely originates from surface two-level systems with varied activation energies.

## Contribution

It provides new insights into the dependence of charge noise on dielectric thickness and temperature, highlighting the role of surface two-level systems in noise origins.

## Key findings

- Charge noise increases with aluminum oxide thickness.
- Significant dot-to-dot variation in temperature dependence of noise.
- Charge noise likely caused by non-uniform distribution of surface two-level systems.

## Abstract

Electron spins in silicon have long coherence times and are a promising qubit platform. However, electric field noise in semiconductors poses a challenge for most single- and multi-qubit operations in quantum-dot spin qubits. Here, we investigate the dependence of low-frequency charge noise spectra on temperature and aluminum-oxide gate dielectric thickness in Si/SiGe quantum dots with overlapping gates. We find that charge noise increases with aluminum oxide thickness. We also find strong dot-to-dot variations in the temperature dependence of the noise magnitude and spectrum. These findings suggest that each quantum dot experiences noise caused by a distinct ensemble of two-level systems, each of which has a non-uniform distribution of thermal activation energies. Taken together, our results suggest that charge noise in Si/SiGe quantum dots originates at least in part from a non-uniform distribution of two-level systems near the surface of the semiconductor.