# Non-Gaussian noise spectroscopy with a superconducting qubit sensor

## TL;DR

This paper demonstrates a quantum control protocol that characterizes non-Gaussian noise affecting superconducting qubits, enabling more accurate noise modeling beyond Gaussian assumptions.

## Contribution

It introduces the first experimental validation of non-Gaussian noise spectroscopy using a superconducting qubit sensor, capturing higher-order noise spectra.

## Key findings

- Successfully reconstructs non-Gaussian noise spectra
- Validates the protocol with engineered noise sources
- Advances spectral estimation tools for quantum devices

## Abstract

Accurate characterization of the noise influencing a quantum system of interest has far-reaching implications across quantum science, ranging from microscopic modeling of decoherence dynamics to noise-optimized quantum control. While the assumption that noise obeys Gaussian statistics is commonly employed, noise is generically non-Gaussian in nature. In particular, the Gaussian approximation breaks down whenever a qubit is strongly coupled to discrete noise sources or has a non-linear response to the environmental degrees of freedom. Thus, in order to both scrutinize the applicability of the Gaussian assumption and capture distinctive non-Gaussian signatures, a tool for characterizing non-Gaussian noise is essential. Here, we experimentally validate a quantum control protocol which, in addition to the spectrum, reconstructs the leading higher-order spectrum of engineered non-Gaussian dephasing noise using a superconducting qubit as a sensor. This first experimental demonstration of non-Gaussian noise spectroscopy represents a major step toward demonstrating a complete spectral estimation toolbox for quantum devices.