Detecting Axial Ratio of Microwave Field with High Resolution Using NV Centers in Diamond

Area of Science:

• Quantum Optics
• Materials Science
• Microwave Engineering

Background:

• High-speed, high-resolution characterization of microwave (MW) fields is essential for advancing quantum technologies and satellite communications.
• Circularly-polarized MW fields are critical components in these advanced technological domains.
• Existing methods for MW field characterization often lack the required speed and resolution.

Purpose of the Study:

• To propose and demonstrate a novel scheme for detecting the axial ratio of MW fields with optical diffraction limit resolution.
• To enable high-speed, wide-field characterization of MW magnetic fields at the submillimeter scale.
• To facilitate precise measurement of MW field polarization properties for technological applications.

Main Methods:

• Utilizing a single nitrogen vacancy (NV) center in a type-IIa CVD diamond with a confocal microscope for polarization-selective MW magnetic field detection.
• Achieving a sensitivity of 1.7 μT/√Hz using the single NV center system.
• Combining wide-field microscopy with ensemble NV centers in general CVD diamond for high-speed, wide-field MW field characterization.
• Measuring the magnitudes of two counter-rotating circularly-polarized MW magnetic fields to determine the axial ratio.

Main Results:

• Demonstrated polarization-selective detection of MW magnetic fields with a single NV center.
• Achieved high-speed, wide-field characterization of MW magnetic fields at the submillimeter scale using ensemble NV centers.
• Successfully detected the precision axial ratio of MW fields by measuring counter-rotating circularly-polarized components.
• Enabled high-speed testing of small-scale microwave devices through wide-field axial ratio and strength parameter detection.

Conclusions:

• The proposed scheme effectively characterizes MW field polarization with high speed and resolution.
• NV centers in diamond provide a powerful platform for advanced MW field metrology.
• This technique supports the development and testing of microwave devices for quantum technologies and satellite communications.