Versatile High-Sensitivity EPR Using Superconducting Spiral Microresonators

Area of Science:

• Physics
• Chemistry
• Materials Science

Background:

• Electron paramagnetic resonance (EPR) spectroscopy is vital for studying paramagnetic centers across biology, chemistry, and quantum technologies.
• Conventional EPR instrumentation, while established, has limitations in sensitivity for certain applications.

Purpose of the Study:

• To significantly increase the spin number sensitivity of X-band pulsed EPR.
• To achieve this enhancement while maintaining compatibility with existing EPR instruments and sample conditions.

Main Methods:

• Fabrication of planar spiral-shaped microresonators using yttrium barium copper oxide (YBCO) high-temperature superconductor.
• Integration of a 7 nL mode volume microresonator into a standard EPR tube for use in conventional EPR cavities.
• Utilization of microfluidic microstructures matched to the microresonator's mode profile for sample placement.

Main Results:

• Achieved a three-order-of-magnitude increase in spin number sensitivity.
• Demonstrated high-fidelity spin control with a sensitivity of 10^7 spins/G/√Hz.
• Validated performance through pulsed EPR experiments including dipolar and hyperfine spectroscopies on standard samples.

Conclusions:

• Superconducting microresonators offer a versatile and readily applicable tool for dramatically enhancing EPR sensitivity.
• This advancement broadens the scope and applicability of EPR spectroscopy in diverse scientific disciplines.
• The developed approach paves the way for more sensitive investigations of paramagnetic species.