Massachusetts Institute of Technology

Matthew Steinecker

John Francis Barry

Danielle Ann Braje

Jessica Kedziora

Daniel Kenneth Freeman

Linh M Pham

Michael F O'Keeffe

Erik R Eisenach

Jonah A Majumder

Reed Anderson Irion

Jennifer Schloss

Peter Moulton

We have developed a high-performance, low-volume, low-weight, and low-power sensor based on a self-sustaining oscillator. The techniques described here may be used for sensing various fields; we demonstrate magnetic sensing. The oscillator is based on a dielectric resonator that contains paramagnetic defects and is connected to a sustaining amplifier in a feedback loop. The resonance frequency of the dielectric resonator shifts in response to changes in the magnetic field, resulting in a shift in the frequency of the self-sustaining oscillator. The value of the magnetic field is thereby encoded in the shift or modulation output of the self-sustaining oscillator. The sensor as demonstrated uses no optics, no input microwaves, and, not including digitization electronics, consumes less than 300 mW of power and exhibits a sensitivity at or below tens of pT/√{square root over (Hz)}. In some implementations, the sensor is less than 1 mL in volume.

Oscillator-based solid-state spin sensor

Ferrimagnetic oscillator magnetometers do not use lasers to stimulate fluorescence emission from defect centers in solid-state hosts (e.g., nitrogen vacancies in diamonds). Instead, in a ferrimagnetic oscillator magnetometer, the applied magnetic field shifts the resonance of entangled electronic spins in a ferrimagnetic crystal. These spins are entangled and can have an ensemble resonance linewidth of approximately 370 kHz to 10 MHz. The resonance shift produces microwave sidebands with amplitudes proportional to the magnetic field strength at frequencies proportional to the magnetic field oscillation frequency. These sidebands can be coherently averaged, digitized, and coherently processed, yielding magnetic field measurements with sensitivities possibly approaching the spin projection limit of 1 attotesla/&#x221a;{square root over (Hz)}. The encoding of magnetic signals in frequency rather than amplitude relaxes or removes otherwise stringent requires on the digitizer.

Ferrimagnetic oscillator magnetometer

Growing community of inventors

Medford, MA, United States of America

Matthew Steinecker