Nonstationary dephasing of two level systems

TL;DR

This paper studies how nonstationary 1/f^mu noise from interacting defects causes unusual dephasing in quantum two-level systems, revealing non-exponential decay and age-dependent effects.

Contribution

It provides an exact analysis of dephasing under nonstationary, non-Gaussian noise, highlighting new anomalous dephasing behaviors in quantum systems.

Findings

Dephasing exhibits non-exponential decay.

Dephasing time depends on the age of the noise.

Critical coupling strength influences dephasing regimes.

Abstract

We investigate the influence of nonstationary 1/f^mu noise, produced by interacting defects, on a quantum two-level system. Adopting a simple phenomenological model for this noise we describe exactly the corresponding dephasing in various regimes. The nonstationarity and pronounced non-Gaussian features of this noise induce new anomalous dephasing scenarii. Beyond a history-dependent critical coupling strength the dephasing time exhibits a strong dependence on the age of the noise and the decay of coherence is not exponential.