Decoherence by Quantum Telegraph Noise

TL;DR

This paper studies how a charge qubit's coherence evolves under quantum telegraph noise from a defect, revealing unique oscillations and echo behavior distinct from Gaussian noise, with implications for quantum decoherence understanding.

Contribution

It provides an exact numerical analysis of qubit decoherence under quantum telegraph noise, highlighting phenomena not seen with traditional Gaussian environments.

Findings

Coherence oscillations occur in the strong-coupling regime.

Distinct time-evolution of the echo signal in spin-echo experiments.

Results differ markedly from Gaussian noise models.

Abstract

We investigate the time-evolution of a charge qubit subject to quantum telegraph noise produced by a single electronic defect level. We obtain results for the time-evolution of the coherence that are strikingly different from the usual case of a harmonic oscillator bath (Gaussian noise). When the coupling strength crosses a certain temperature-dependent threshold, we observe coherence oscillations in the strong-coupling regime. Moreover, we present the time-evolution of the echo signal in a spin-echo experiment. Our analysis relies on a numerical evaluation of the exact solution for the density matrix of the qubit.