Qubit decoherence by low-frequency noise

TL;DR

This paper derives a non-perturbative formula for qubit decoherence caused by low-frequency noise, highlighting how noise spectral density and correlation time influence coherence decay, supported by Monte Carlo simulations.

Contribution

It provides a new explicit non-perturbative expression for qubit decoherence due to low-frequency noise, applicable to both Gaussian and non-Gaussian noise.

Findings

Decoherence strength depends on zero-frequency noise spectral density.

Correlation time determines crossover from $1/\sqrt{t}$ to exponential decay.

Monte Carlo simulations confirm analytical results.

Abstract

We have derived explicit non-perturbative expression for decoherence of quantum oscillations in a qubit by low-frequency noise. Decoherence strength is controlled by the noise spectral density at zero frequency while the noise correlation time $\tau$ determines the time $t$ of crossover from the $1/\sqrt{t}$ to the exponential suppression of coherence. We also performed Monte Carlo simulations of qubit dynamics with noise which agree with the analytical results and show that most of the conclusions are valid for both Gaussian and non-Gaussian noise.