Direct characterization of classical dephasing noise for a qubit

Abstract:We propose a general method to characterize classical stochastic noise causing qubit dephasing through repetitive Ramsey interferometry measurements (RIMs) on the qubit. Compared to filter-function-based spectroscopy, our method with simpler pulse control is less constrained by probe coherence time and can directly detect arbitrary-order correlation functions of quasistatic noise processes. We show that each RIM with a short evolution time and suitably chosen control pulses directly samples the noise field and the $n$-point correlations of the RIM outcomes are proportional to the $n$-point correlation functions of the noise processes. We demonstrate the method numerically for two representative cases: an Ornstein-Uhlenbeck Gaussian process and a non-Gaussian ensemble of two-level fluctuators. While practical constraints such as readout contrast and sampling cost persist, our method offers a direct route to quasistatic classical noise spectroscopy across diverse platforms.

arXiv:2604.25705 [quant-ph]

(or arXiv:2604.25705v2 [quant-ph] for this version)

https://doi.org/10.48550/arXiv.2604.25705 Focus to learn more arXiv-issued DOI via DataCite

https://doi.org/10.1103/6kzz-gld6 Focus to learn more DOI(s) linking to related resources

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