Flux channeling induced nano-confinement and enhancement of microwaves imaged by Rabi oscillation mapping

TL;DR

This paper demonstrates that flux-channeling from a permalloy nanowire can locally modulate RF fields, enabling high-resolution mapping with Rabi oscillations and significant power enhancement, advancing qubit control and RF technology.

Contribution

It introduces a novel method using flux-channeling for localized RF field modulation and high-resolution mapping with Rabi oscillations in NV centers.

Findings

Achieved ~16× microwave power enhancement in sub-300 nm regions.

Demonstrated stable modulation over a 20 dBm power range.

Confirmed field modulation origin via micromagnetic simulations.

Abstract

With rapid advances in qubit technologies, techniques for localizing, modulating, and measuring RF fields and their impact on qubit performance are of the utmost importance. Here, we demonstrate that flux-channeling from a permalloy nanowire can be used to achieve localized spatial modulation of an RF field and that the modulated field can be mapped with high resolution using the Rabi oscillations of an NV center. Rabi maps reveal ~100 mm wavelength microwaves concentrated in sub-300 nm-scale regions with up to ~16$\times$ power enhancement. This modulation is robust over a 20 dBm power range and has no adverse impact on NV $T_2$ coherence time. Micromagnetic simulations confirm that the modulated field results from the nanowire's stray field through its constructive/destructive interference with the incident RF field. Our findings provide a new pathway for controlling qubits, amplifying RF signals, and mapping local fields in various on-chip RF technologies.