Non-Gaussian dephasing in flux qubits due to 1/f-noise

TL;DR

This paper challenges the Gaussian noise assumption in flux qubit decoherence studies, using an exactly solvable spin-fluctuator model to better understand 1/f noise effects on echo signals.

Contribution

It introduces a non-Gaussian model for 1/f noise in flux qubits, providing a more accurate analysis of decoherence mechanisms.

Findings

Gaussian assumption may be insufficient for describing decoherence

Non-Gaussian effects significantly alter echo signal decay

Revises understanding of 1/f noise impact on qubit coherence

Abstract

Recent experiments by F. Yoshihara et al. [Phys. Rev. Lett. 97, 167001 (2006)] and by K. Kakuyanagi et al. (cond-mat/0609564) provided information on decoherence of the echo signal in Josephson-junction flux qubits at various bias conditions. These results were interpreted assuming a Gaussian model for the decoherence due to 1/f noise. Here we revisit this problem on the basis of the exactly solvable spin-fluctuator model reproducing detailed properties of the 1/f noise interacting with a qubit. We consider the time dependence of the echo signal and conclude that the results based on the Gaussian assumption need essential reconsideration.