Dephasing of a Qubit due to Quantum and Classical Noise

TL;DR

This paper investigates how quantum and classical noise sources cause decoherence in qubits, comparing their effects to understand the limits of classical models and analyze different dissipation regimes.

Contribution

It provides a detailed comparison between quantum and classical noise effects on qubit decoherence, including Ohmic and non-Ohmic dissipation models.

Findings

Quantum noise leads to different decoherence characteristics than classical noise.

Limits of classical noise models are established based on quantum noise analysis.

Analysis of Ohmic and non-Ohmic dissipation regimes enhances understanding of decoherence mechanisms.

Abstract

The qubit (or a system of two quantum dots) has become a standard paradigm for studying quantum information processes. Our focus is Decoherence due to interaction of the qubit with its environment, leading to noise. We consider quantum noise generated by a dissipative quantum bath. A detailed comparative study with the results for a classical noise source such as generated by a telegraph process, enables us to set limits on the applicability of this process vis a vis its quantum counterpart, as well as lend handle on the parameters that can be tuned for analyzing decoherence. Both Ohmic and non-Ohmic dissipations are treated and appropriate limits are analyzed for facilitating comparison with the telegraph process.