Coherence stabilization of a two-qubit gate by AC fields

TL;DR

This paper shows that applying AC fields during a two-qubit CNOT gate can significantly enhance coherence by transforming bit-flip noise into phase noise, with analytical and numerical evidence supporting the improvement.

Contribution

It introduces a method to stabilize two-qubit gate coherence using AC fields, transforming noise types and improving fidelity without increasing gate time.

Findings

Coherence improved by several orders of magnitude.

Analytical high-frequency approximation matches numerical results.

Gate fidelity and purity are enhanced through noise transformation.

Abstract

We consider a CNOT gate operation under the influence of quantum bit-flip noise and demonstrate that ac fields can change bit-flip noise into phase noise and thereby improve coherence up to several orders of magnitude while the gate operation time remains unchanged. Within a high-frequency approximation, both purity and fidelity of the gate operation are studied analytically. The numerical treatment with a Bloch-Redfield master equation confirms the analytical results.