Wavelet correlation noise analysis for qubit operation variable time series

TL;DR

This paper introduces wavelet-based analysis methods to characterize and understand complex noise in qubit systems, aiding in improving coherence and fidelity in quantum computing.

Contribution

It applies wavelet analysis to quantum noise data, revealing correlations and noise sources in two-qubit SiMOS quantum dot experiments, a novel approach in this context.

Findings

Identified correlations related to two-level fluctuators and nuclear spins.

Enhanced understanding of noise features at specific times and frequencies.

Demonstrated wavelet analysis effectiveness in quantum noise characterization.

Abstract

In quantum computing, characterizing the full noise profile of qubits can aid in increasing coherence times and fidelities by developing error-mitigating techniques specific to the noise present. This characterization also supports efforts in advancing device fabrication to remove sources of noise. Qubit properties can be subject to non-trivial correlations in space and time, for example, spin qubits in MOS quantum dots are exposed to noise originating from the complex glassy behavior of two-level fluctuator ensembles. Engineering progress in spin qubit experiments generates large amounts of data, necessitating analysis techniques from fields experienced in managing large data sets. Fields such as astrophysics, finance, and climate science use wavelet-based methods to enhance their data analysis. Here, we propose and demonstrate wavelet-based analysis techniques to decompose signals into frequency and time components, enhancing our understanding of noise sources in qubit systems by identifying features at specific times. We apply the analysis to a state-of-the-art two-qubit experiment in a pair of SiMOS quantum dots with feedback applied to relevant operation variables. The observed correlations serve to identify common microscopic causes of noise, such as two-level fluctuators and hyperfine coupled nuclei, as well as to elucidate pathways for multi-qubit operation with more scalable feedback systems.