Modeling of Low and High Frequency Noise by Slow and Fast Fluctuators

TL;DR

This paper models low and high frequency noise in quantum systems using a spin-fluctuator approach, effectively capturing dephasing effects and matching experimental data in superconducting flux qubits.

Contribution

It introduces a simplified two-ensemble fluctuator model to analyze quantum dephasing, bridging theoretical predictions with experimental observations.

Findings

Good agreement between theory and experiments on flux qubits

Effective modeling of 1/f and high-frequency noise

Applicable to various quantum systems

Abstract

We study the dynamics of dephasing in a quantum two-level system by modeling both 1/f and high-frequency noise by random telegraph processes. Our approach is based on a so-called spin-fluctuator model in which a noisy environment is modeled by a large number of fluctuators. In the continuous limit we obtain an effective random process (ERP) that is described by a distribution function of the fluctuators. In a simplified model, we reduce the ERP to the two (slow and fast) ensembles of fluctuators. Using this model, we study decoherence in a superconducting flux qubit and we compare our theoretical results with the available experimental data. We demonstrate good agreement of our theoretical predictions with the experiments. Our approach can be applied to many quantum systems, such as biological complexes, semiconductors, superconducting and spin qubits, where the effects of interaction with the environment are essential.