Magnetooptical and electrooptical spectra and effects PACS 32.80.Xx -Level crossing and optical pumping PACS 42.50.Gy -Effects of atomic coherence on propagation, absorption, and amplification of light; electromagnetically induced transparency and absorption PACS 32.10.Dk -Electric and magnetic moments, polarizabilitiesAbstract. -We have developed a technique for precise measurement of small magnetic fields using nonlinear magneto-optic rotation (NMOR). The technique relies on the resonant laser beam being chopped. During the on time, the atoms are optically pumped into an aligned ground state (∆m = 2 coherence). During the off time, they freely precess around the magnetic field at the Larmor frequency. If the on-off modulation frequency matches (twice) the Larmor precession frequency, the rotation is resonantly enhanced in every cycle, thereby making the process like a repeated Ramsey measurement of the Larmor frequency. We study chopped-NMOR in a paraffincoated Cs vapor cell. The out-of-phase demodulated rotation shows a Lorentzian peak of linewidth 85 µG, corresponding to a sensitivity of 0.15 nG/ √ Hz. We discuss the potential of this technique for the measurement of an atomic electric-dipole moment.

Do knurls improve torque capability? A "pop-bottle" size lid (28 mm diameter, 15 mm high) was varied with six designs: 1) a smooth lid, 2) a lid with 13 knurls/cm, 3) a lid with 7.9 knurls/cm, 4) a lid with 3.9 knurls/cm, 5) a lid with 3.9 knurls/cm but for only 4 mm of height, and 6) a lid with 2 protrusions ("radiator type"). The 18 subjects rotated each lid. Using the smooth lid torque of 1.49 Nm as loo%, the lid with 7.9 knurls/cm had 170%, the radiator type had 164%, the 13 knurls/cm had 163%, the 3.9 knurls/cm had 141%, and the 3.9 knurls/cm for only 4 mm had 110%.

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