Nonlinear Optical Rotation Magnetometry University of California, Berkeley Objectives: Proof-of-principle demonstration of precision nonlinear optical rotation magnetometry with sensitivity ~10 pGs(Hz )-1/2, investigation of its ultimate performance limits Approach:  Use large enhancement of optical rotation due to NLOR  Combine the eight orders of magn. rotation enhancement demonstrated in this work with precision laser spectropolarimetry developed for atomic parity violation experiments Accomplishments: Observation of ultra-narrow effective widths (1.3 Hz) in magneto-optics Demonstration of an 8 orders of magnitude rotation enhancement compared to linear magneto-optics Realization of a prototype low-field 3-axis magnetometer Impact: Demonstration of a new method to prepare, preserve and probe long-lived atomic Zeeman coherence (alignment) Potential applications in related research involving EIT, coherent dark resonances, phaseonium; in experiments on P, T-violation Scientific Issues: Assessment of ultimate attainable sensitivity in atomic magnetometry, 3-axis low-field magnetometry, control and characterization of ultra-low magnetic field environment, fundamental physics applications Magnetic Field,  Gs  rot B max  1.4  Gs  eff  1.3 Hz

Light intensity:  100  W/cm 2. Effective laser beam diameter: ~ 2 mm. Rb-cell at room temperature. The solid line is a fit to the developed model. The insert shows a detailed scan of the near-zero B z -field region. "Nested" Effects in Nonlinear Magneto-Optical Rotation Large Dynamic Range Magnetometry 0 1 Longitudinal Magnetic Field B z (Gs) Optical Rotation  s (mrad) 5 -5 B z (  Gs)  s (mr ad) 1

Nonlinear Magneto-Optical Rotation in Arbitrarily-Directed Magnetic Fields Three Dimensional Magnetometry Observed phenomenon: Dramatic changes of the shape of NMOR in the presence of transverse magnetic fields B tr ~  B z First realization: Three Dimensional Magnetometry was used to compensate residual magnetic fields and to reach narrowest observed NLOR feature with effective resonance width:  eff  1.3 Hz Idea for application: The found strong dependence can be used for: Three Dimensional Magnetometry Optical Rotation  s (mrad) Longitudinal Magnetic Field B z (  Gs) B y  0.7  Gs B x  0  Gs B x  -1.2  Gs B x  3.7  Gs B y  0.04  Gs B y  -0.5  Gs B y  0  GsB x  2  Gs  B z  2.8  Gs