We report a precise determination of the static polarizability of the 8s 2 S 1/2 state of atomic cesium, carried out jointly through experimental measurements of the dc Stark shift of the 6s 2 S 1/2 → 8s 2 S 1/2 transition using Doppler-free two-photon absorption and theoretical computations based on a relativistic all-order method. We enhance the precision of the measurement by imposing phase-modulation sidebands on the laser beam and by using a pair of vapor cells, one of which serves as a reference, and measuring the absorption spectrum in each cell with a single scan of the laser frequency. The measured value for the polarizability of the 8s state is 38,060± 250a 0 3 , in very good agreement with our theoretical value of 38,260± 290a 0 3 . In addition, the small difference in the Stark shift measurement for the two hyperfine states that we examine yields a variation in the polarizability due to the magnetic dipole contact interaction of 290± 30a 0 3 .

We have developed a two-color, two-pathway coherent control technique to detect and measure weak optical transitions in atoms by coherently beating the transition amplitude for the weak transition with that of a much stronger transition. We demonstrate the technique in atomic cesium, exciting the 6s(2)S(1/2) --> 8s(2)S(1/2) transition via a strong two-photon transition and a weak controllable Stark-induced transition. We discuss the enhancement in the signal-to-noise ratio for this measurement technique over that of direct detection of the weak transition rate, and project future refinements that may further improve its sensitivity and application to the measurement of other weak atomic interactions.

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We present a simple method for diode laser frequency stabilization that makes use of a Doppler-broadened vapor cell absorption signals of two frequency-shifted laser beams. Using second-order-diffracted, double-passed beams from an acousto-optic modulator, we achieve a frequency separation roughly equal to the Doppler half width. The differential transmission signals of the two beams provide an error signal with a very large linear feature, allowing frequency stabilization over a range of greater than 1 GHz by means of standard proportional-integral-derivative servo feedback to the piezoelectric control of the grating in our external cavity diode laser. We have applied this technique to two different diode laser systems, one used to lock to the 410 nm E1 transition in indium and another for locking to the M1/E2 transition in thallium at 1283 nm. In both cases the technique reduces frequency fluctuation to roughly 1 MHz over time scales from 10(-3) to 10(2) s.

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