Circularly polarized microwaves for magnetic resonance study in the GHz range: application to nitrogen-vacancy in diamonds

TL;DR

This paper presents a microstrip circuit capable of generating highly efficient, arbitrarily polarized microwave magnetic fields for magnetic resonance experiments, demonstrated on nitrogen-vacancy centers in diamond.

Contribution

Introduction of a microstrip circuit that produces strong, controllable polarization microwave fields for magnetic resonance, enabling low-power, targeted spin state manipulation.

Findings

Achieved 85% circular polarization of microwaves.

Enabled selective spin state addressing in diamond NV centers.

Demonstrated effective Rabi oscillations with low power input.

Abstract

The ability to create time-dependent magnetic fields of controlled polarization is essential for many experiments with magnetic resonance. We describe a microstrip circuit that allows us to generate strong magnetic field at microwave frequencies with arbitrary adjusted polarization. The circuit performance is demonstrated by applying it to an optically detected magnetic resonance and Rabi nutation experiments in nitrogen-vacancy color centers in diamond. Thanks to high efficiency of the proposed microstrip circuit and degree of circular polarization of 85% it is possible to address the specific spin states of a diamond sample using a low power microwave generator.