Inferring charge-noise source locations from correlations in spin qubits

TL;DR

This paper studies low-frequency charge noise in silicon spin qubits, revealing that a few two-level fluctuators dominate the noise and that cross-correlations can locate these noise sources spatially.

Contribution

It introduces a method to infer the spatial locations of charge noise sources using cross-correlations in spin qubit energy fluctuations.

Findings

Charge noise is dominated by a few two-level fluctuators.

Cross-correlations reveal the spatial location of TLFs.

Noise spectra deviate from simple power-law behavior.

Abstract

We investigate low-frequency noise in a spin-qubit device made in isotopically purified Si/Si-Ge. Observing sizable cross-correlations among energy fluctuations of different qubits, we conclude that these fluctuations are dominated by charge noise. At low frequencies, the noise spectra are not well described by a power law; instead, they reveal the presence of a few individual two-level fluctuators (TLFs). We demonstrate that the noise cross-correlations allow one to get information on the spatial location of such individual TLFs.