Fidelity plateaus from correlated noise in isolated few-level quantum systems

TL;DR

This paper demonstrates that correlated noise in a two-level quantum system can create long-lasting fidelity plateaus during state preparation, with analytical insights into their formation and potential relevance to larger systems.

Contribution

It introduces the concept of fidelity plateaus caused by correlated noise in isolated quantum systems and provides analytical expressions for their characteristics.

Findings

Correlated noise can produce long fidelity plateaus in two-level systems.

Analytical formulas describe the start, end, and height of the plateaus.

Potential extension of the phenomenon to multi-level quantum systems.

Abstract

We show that, in an isolated two-level quantum system described by a time-dependent Hamiltonian, correlated noise in the Hamiltonian's parameters can lead to an arbitrarily long plateau in the state-preparation fidelity as a function of elapsed time. We explain the formation of this plateau using the Bloch-sphere representation, deriving analytical expressions for its start and end times and its height. We also briefly discuss the extent to which this phenomenon is expected to be visible in more general quantum systems with $N>2$ levels.