Polarization- and frequency-tunable microwave circuit for selective excitation of nitrogen-vacancy spins in diamond

TL;DR

This paper introduces a planar microwave resonator capable of generating arbitrarily polarized magnetic fields for selective excitation of NV center spins in diamond, with tunable frequency and uniform field distribution.

Contribution

The authors developed a polarization- and frequency-tunable microwave circuit compatible with (111)-oriented diamond for precise NV spin control.

Findings

Achieved near-perfect circular polarization of magnetic fields.

Demonstrated frequency tuning from 2 to 3.2 GHz using varactor diodes.

Provided spatially uniform magnetic field distribution over a 4 mm diameter area.

Abstract

We report on a planar microwave resonator providing arbitrarily polarized oscillating magnetic fields that enable selective excitation of the electronic spins of nitrogen-vacancy (NV) centers in diamond. The polarization plane is parallel to the surface of diamond, which makes the resonator fully compatible with (111)-oriented diamond. The field distribution is spatially uniform in a circular area with a diameter of 4 mm, and a near-perfect circular polarization is achieved. We also demonstrate that the original resonance frequency of 2.8 GHz can be varied in the range of 2-3.2 GHz by introducing varactor diodes that serve as variable capacitors.