GOALI: Synchronously Pumped NMR Oscillator

University Of Wisconsin-Madison, Madison WI

Investigators

Abstract

This project, an Industry-University Collaborative Project between the University of Wisconsin-Madison and scientists and engineers at Northrop-Grumman Corporation, studies a new approach to making extremely precise and sensitive measurements using Nuclear Magnetic Resonance (NMR). NMR forms the basis for the MRI (magnetic resonance imaging) that a medical patient might receive, and for various types of chemical analysis. This project will investigate a new NMR method designed for use as either a compact, high precision gyroscope for navigation, or for a tool to search for evidence of previously unobserved types of forces between matter and nuclear spins. Any new forces so observed would likely give important information on the properties of so-called "dark matter" which is believed to make up most of the universe but which has never been directly observed. Even if such forces are not detected, the project will place constraints on theoretical models which seek to go beyond the so-called "standard model" of particle physics. The applications of the new method for navigation involve a possible means to make compact quantum-based measurements of rotation with unprecedented sensitivity and accuracy. As a collaborative effort between university researchers and industrial scientists and engineers, the project will promote practical applications of nuclear spins for such measurements, promote technology transfer between university and industry, and expose young researchers to an industrial research and development laboratory. The underlying principles rely on the application of NMR bias magnetic fields in the form of sequences of short pulses of well-defined areas that act, in concert with time dependent optical pumping, to allow alkali atoms and noble-gas nuclei to precess at the same frequency despite having magnetic moments that are different by 3 orders of magnitude. Both species can then be polarized and precess entirely transverse to the bias field. This greatly suppresses the dominant systematic errors that are known to affect traditional designs of such instruments, but retains the benefits of ultrasensitive readout of the NMR precession using the embedded alkali magnetometer. Estimates of technical noise indicate the system has a potential frequency noise level of better than 10 nano-Hertz per square-root Hertz bandwidth, with fundamental limits that are much better. The system will be used to set new stringent limits on the potential couplings of axions to nuclei. The basic physics principles of this approach have now been demonstrated in the laboratory and the key systematic errors have been shown to be suppressed by at least a factor of 2500. The next steps are to realize the high sensitivity promise in dual-species experiments that promise exceptionally good magnetic noise and drift suppression. In this context the system will be tested as a precision NMR gyroscope, of great interest to the industrial partners, and will be used to set new mass and sensitivity limits in searches for axion-like particles.