High efficiency radio frequency antennas for amplifier free quantum sensing applications

At a Glance

Metadata	Details
Publication Date	2023-04-01
Journal	Review of Scientific Instruments
Authors	S. S. Mahtab, Peker Milas, D. Tim Veal, Michael G. Spencer, Birol Ozturk
Institutions	Cornell University, Morgan State University
Citations	3
Analysis	Full AI Review Included

High Efficiency RF Antennas for Quantum Sensing: Material Solutions by 6CCVD

This technical documentation analyzes the requirements for high-efficiency radio frequency (RF) antennas used in amplifier-free quantum sensing, specifically leveraging Nitrogen Vacancy (NV) defects in diamond. The findings directly inform material selection and customization services offered by 6CCVD.

Executive Summary

Amplifier-Free Quantum Sensing: Researchers successfully designed and fabricated high-efficiency coplanar RF antennas, eliminating the need for bulky RF amplifiers in Optically Detected Magnetic Resonance (ODMR) experiments.
Exceptional Performance: Antennas achieved experimental return losses (S11) up to -37 dB at the NV zero-field splitting frequency of 2.87 GHz.
Miniaturization Milestone: The high efficiency allowed ODMR experiments to run using only the 0 dB output of a standard RF signal generator, representing a critical step toward realizing field-portable, handheld quantum magnetometers.
Material Foundation: The platform relies on high-quality bulk Single Crystal Diamond (SCD) containing NV color centers for magnetic field sensing.
Design Flexibility: Resonant frequency tuning was demonstrated by varying the antenna ring size, enabling the application of these designs across various solid-state defect platforms (e.g., SiC, cubic Boron Nitride).
Fabrication Method: The antennas were fabricated using standard photolithography and wet etching techniques on specialized low-loss PCB substrates.

Technical Specifications

The following hard data points were extracted from the research detailing the antenna performance and material requirements for amplifier-free quantum sensing.

Parameter	Value	Unit	Context
Target Resonance Frequency	2.87	GHz	Negatively charged NV defect zero-field splitting (ZFS)
Maximum Experimental Return Loss (S11)	Up to -37	dB	Achieved by optimized single and double ring antennas
RF Power Requirement	0	dB	Output required from standard signal generator (No amplifier needed)
Diamond Material Used	Dtextsubscript{NV}-B14	N/A	Bulk Single Crystal Diamond (SCD)
Applied External Magnetic Field	0.5	mT	Used for ODMR measurements (Helmholtz coil)
Maximum Simulated H Field Intensity (Double Ring)	155.7	A/m	Concentrated magnetic field for maximum radiation efficiency
Antenna Substrate Dielectric Constant (Rogers-4003)	3.38	N/A	Used for double ring design
Antenna Substrate Thickness (Rogers-4003)	0.508	mm	Used for double ring design
Copper Cladding Thickness	0.035	mm	Used for antenna fabrication

Key Methodologies

The successful implementation of high-efficiency RF antennas relied on precise material selection and advanced microfabrication techniques.

Simulation and Optimization: Antenna parameters were designed and optimized using Ansys HFSS and CST Microwave Studio to achieve the 2.87 GHz resonance frequency and high return loss.
Substrate Selection: Low-loss PCB substrates (Isola IS-680-280 and Rogers-4003) were chosen specifically for their low loss tangent (tan δ < 0.0035), minimizing inherent transmission losses.
Mask Preparation: High-resolution photolithographic masks (25000DPI) were prepared based on optimized geometric parameters.
Photolithography: Positive photoresist (Microposit S1813 G2) was spin coated onto the substrates at 3000 RPM. A custom UV-exposure setup was used to transfer the pattern.
Wet Etching: The exposed copper cladding (0.035 mm thick) was removed using Ferric Chloride (FeCl₃) etching solution to define the coplanar antenna structures.
Device Integration: Coaxial female SMA connectors were soldered to the fabricated antennas for RF input.
Quantum Testing: The antennas were tested in a custom-built confocal photoluminescence setup using a 532 nm DPSS laser and a bulk SCD sample (DNV-B14) placed in the region of maximum magnetic field intensity.

6CCVD Solutions & Capabilities

6CCVD is uniquely positioned to supply the high-quality diamond materials and custom fabrication services required to replicate and advance this research toward commercial, portable quantum sensors.

Requirement from Research Paper	6CCVD Solution & Capability	Technical Advantage
Quantum Sensing Platform (Bulk DNV-B14 Diamond)	Optical Grade Single Crystal Diamond (SCD)	6CCVD supplies high-purity SCD substrates (0.1µm to 500µm thick) with controlled nitrogen incorporation, ideal for creating high-density, long-coherence NV ensembles.
Custom Dimensions (38 x 40 mm² antenna area)	Large Area & Custom Sizing	We offer plates/wafers up to 125mm (PCD) and custom laser cutting services to match precise antenna or device integration requirements.
Antenna Integration/Interconnects (Copper cladding, SMA soldering)	Advanced Metalization Services	Internal capability for depositing robust, high-conductivity metal stacks (e.g., Ti/Pt/Au, Pd, Cu) directly onto diamond surfaces, ensuring superior RF coupling and thermal dissipation for integrated quantum devices.
Surface Quality (Critical for near-surface NV sensing)	Ultra-Low Roughness Polishing	SCD surfaces are polished to Ra < 1nm, minimizing surface defects and maximizing photon collection efficiency and spin coherence near the surface. Inch-size PCD polishing is also available (Ra < 5nm).
Alternative Materials (SiC, cBN mentioned)	Boron-Doped Diamond (BDD)	6CCVD provides conductive BDD films and substrates, which can serve as highly stable, low-noise ground planes or integrated electrodes for advanced RF/microwave quantum circuits.
Engineering Support	In-House PhD Team Consultation	6CCVD’s experts can assist with material selection, thickness optimization, and metal stack design for similar NV-based quantum sensing and ODMR projects.

For custom specifications or material consultation, visit 6ccvd.com or contact our engineering team directly.

View Original Abstract

Radio frequency (RF) signals are frequently used in emerging quantum applications due to their spin state manipulation capability. Efficient coupling of RF signals into a particular quantum system requires the utilization of carefully designed and fabricated antennas. Nitrogen vacancy (NV) defects in diamond are commonly utilized platforms in quantum sensing experiments with the optically detected magnetic resonance (ODMR) method, where an RF antenna is an essential element. We report on the design and fabrication of high efficiency coplanar RF antennas for quantum sensing applications. Single and double ring coplanar RF antennas were designed with −37 dB experimental return loss at 2.87 GHz, the zero-field splitting frequency of the negatively charged NV defect in diamond. The efficiency of both antennas was demonstrated in magnetic field sensing experiments with NV color centers in diamond. An RF amplifier was not needed, and the 0 dB output of a standard RF signal generator was adequate to run the ODMR experiments due to the high efficiency of the RF antennas.

Tech Support

Original Source

DOI: https://doi.org/10.1063/5.0136233

References

2018 - Quantum computing in the NISQ era and beyond [Crossref]
2019 - Quantum Computing: Progress and Prospects
2019 - High-dimensional quantum communication: Benefits, progress, and future challenges [Crossref]
2017 - Quantum sensing [Crossref]
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2008 - High-sensitivity diamond magnetometer with nanoscale resolution [Crossref]
2022 - Nanoscale electric field imaging with an ambient scanning quantum sensor microscope [Crossref]
2021 - In situ measurements of intracellular thermal conductivity using heater-thermometer hybrid diamond nanosensors [Crossref]
2017 - Coherent control of the silicon-vacancy spin in diamond [Crossref]