Non-Gaussian signatures and collective effects in charge noise affecting a dynamically-decoupled qubit

TL;DR

This paper analyzes how classical charge fluctuators impact the coherence of a dynamically-decoupled qubit, providing analytical and numerical insights into noise behavior and potential microscopic models.

Contribution

It derives exact and approximate formulas for charge noise effects on qubit coherence at various working positions, enhancing understanding of noise scaling and system dependence.

Findings

Noise scales with the number of fluctuators and control pulses.

Distinct dynamics occur at different qubit working positions.

Results aid in noise spectroscopy to identify microscopic charge models.

Abstract

The effects of a collection of classical two-level charge fluctuators on the coherence of a dynamically-decoupled qubit are studied. Distinct dynamics are found at different qubit working positions. Exact analytical formulae are derived at pure dephasing and approximate solutions are found at the general working position, for weakly- and strongly-coupled fluctuators. Analysis of these solutions, combined with numerical simulations of the multiple random telegraph processes, reveal the scaling of the noise with the number of fluctuators and the number of control pulses, as well as dependence on other parameters of the qubit-fluctuators system. These results can be used to determine potential microscopic models for the charge environment by performing noise spectroscopy.