Dielectric Resonator Antenna for Large Volume Microwave​ Magnetic Coupling to NV Centers in Diamond

The NV center is a pointdefect in diamond. The interest to this defect is rising up during the lastdecade due to many possibilities of practice applications like ultra-precisemagnetometers, biocompatible thermometry, electron... [ view full abstract ]

The NV center is a pointdefect in diamond. The interest to this defect is rising up during the lastdecade due to many possibilities of practice applications like ultra-precisemagnetometers, biocompatible thermometry, electron and nuclear magnetoresonance imaging etc. In most of the applications large ensembles of NV centersin single diamond plate are used [1] to increase the sensitivity of detectors.For sensor applications the electron spins at NV centers, localized at atomicscales, has to be manipulated. At room temperature it possible to applymagnetic field using a microwave antenna. The main requirement to the antennais the creation of uniform and strong microwave magnetic field over relativelylarge volume. A planar split-ring resonator (SRR) design foruniform and efficient coupling of microwave magnetic field into NV centers indiamond has been recently studied [2] However the SRR is not suitablefor manipulating NV centers spins in volume, because its magnetic field decaysdramatically in perpendicular direction from the SRR providing only 2D-uniformfield.

Here we present the microwavedielectric resonator antenna (DRA) for spin manipulation of large volumeensemble of NV centers in a bulk diamond. The proposed design is based on ahigh permittivity hollow dielectric resonator excited by a symmetric microstriploop resonating at the TE01δ mode of the dielectric resonator.

We have designed, fabricated and experimentally studied the DRAfor homogeneous control of spatially large spin ensembles. The Fig.1 representsthe design of the DRA, measured reflection coefficient in the comparison to thesimulated one, the Rabi oscillation frequency dependence and the calculatedaverage value of the magnetic field inside the dielectric resonator.

Demonstrated uniformity of the microwave magnetic field insidethe entire bore of the DRA is over 99% in volume of 8 cubic millimeters, whilethe magnitude of the field is enough to reach 15 MHz Rabi frequency at 5.2 Wfeeding power. This way our work paves the wave for building ultra-precisesensors, based on dense spin ensembles in solid state, such as NV centers indiamond.

[1] Clevenson, H.; Trusheim, M. E.; Schroder, T.; Teale, C.;Braje, D.; Englund, D. Nat. Phys. 2015, 11 (May), 393397.

[2] Bayat, K.; Choy, J.; Farrokh Baroughi, M.; Meesala, S.;Loncar,M. Nano Lett. 2014, 14 (3), 12081213.