Atomic Sensors Research University of Wisconsin-Madison Thad Walker Anna Korver Dan Thrasher Mike Bulatowicz Todays Agenda Atomic Sensors Overview (Thad Walker) Synchronous Spin-Exchange Optical Pumping(Anna Korver) Feedback Narrowing of NMR lines (Dan Thrasher) Dual Species Pumping (Dan) Near future (Thad) Quantum Based Sensors Quantum Measurement Limit Spin-Exchange Optical Pumping T.W. and W. Happer, Rev. Mod. Phys. 69, 629 (1997) Hyperpolarized MRI Spin-polarized targets (JLAB) Neutron spin-filters NMR NMR Oscillator Oscillator advantages Precession frequency is precisely the resonance frequency Direct readout of fundamental quantum oscillations Feedback allows the bandwidth of the oscillator to greatly exceed 1/T 2 Nuclei decoupled from physical apparatus while drive coils are not---sensitivity to inertial rotations Fabulous fundamental quantum noise level Dual Species NMR for Non-Magnetic Interactions x=rotation, edm, fifth force, etc. Quantum-enhanced NMR detection Northrop-Grumman Test Station Xe NMR w/ alkali comagnetometer Magnetic field detected by Rb atoms is 500X bigger than the actual classical field produced by the nuclei Alkali Field Alkali atoms also produce a magnetic field that is seen by the noble-gas nuclei: This is a substantial systematic error that must be accounted for. Cancels in dual Xe NMR Monopole-Dipole Search Use 129-Xe as magnetometer Phys Rev Lett 111, (2013) Co-magnetometry Co-magnetometry Systematic checks Rod In/Out (Axion signal) Flip alkali polarization Flip magnetic field direction Change magnetic field magnitude Isotope effect in alkali field Monopole-Dipole shift Makulski Magn. Reson. Chem. 2015, 53, (1) including XeXe shift Systematic Errors in Dual NMR Oscillators Magnetic responserotation Quadrupole ( 131 Xe) Gyro: use one isotope to stabilize the magnetic field, the other isotope senses r, plus drifts in P A, Q Synchronously Pumped NMR Oscillator Synchronous Pumping Spin-Exchange occurs in rotating frame No drive field needed (or desired) 2 pulses put alkali at zero field Oscillator NMR Signal Xe-131 Oscillator Resonance Projections for Rb-131-Xe oscillator T/rt(Hz)= 350 nHz/rt(Hz) =.007 deg/rt(hr).01 Hz T/rt(Hz)/10 -8 T =100 nHz/rt(Hz) Summary of Jan 2015 Review Observation and explanation of spin-exchange broadening Idea of spin-exchange narrowing using feedback Summary of Jan-Sept 2015 Activities Spin-Exchange Broadening: Alkali field torque Anna and Dans Amazing Compensation Field Sub-Harmonic Pumping p=1 131-Xe and p=3 129-Xe resonance frequencies differ by only 10% Dual Species Pumping Resonance condition Pulse Timing Modulation Idea: since 2=0 for the Rb, we can apply the modulation by changing the repetition frequency of the 2 pulses Linewidth nulling with z-field feedback Infinite quadrature slope Near term projects Sept (Dual species pumping, close loop, noise) Oct (new NGC cubic cell characterization) Nov (Rotatable, axion reprise?) In parallel: NMR gyro review paper (TW & MEL) Dec: A. Korver Ph.D. defense