We form ultracold Na2 molecules by single-photon photoassociation of a Bose-Einstein condensate, measuring the photoassociation rate, linewidth, and light shift of the J = 1, v = 135 vibrational level of the A1 Sigma (+)(u) molecular state. The photoassociation rate constant increases linearly with intensity, even where it is predicted that many-body effects might limit the rate. Our observations are in good agreement with a two-body theory having no free parameters.

I propose an electromagnetically induced phase grating based on the giant Kerr nonlinearity of an atomic medium under electromagnetically induced transparency. The atomic phase grating behaves similarly to an ideal sinusoidal phase grating, and it is capable of producing a pi phase excursion across a weak probe beam along with high transmissivity. The grating is created with arbitrarily weak fields, and diffraction efficiencies as high as 30% are predicted.

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By using a weak measurement technique, we investigated the interplay between the angular and lateral Goos-Hänchen shift of a focused He-Ne laser beam for incidence near the critical angle. We verified that this interplay dramatically affect the composite Goos-Hänchen shift of the propagated beam. The experimental results confirm theoretical predictions that recently appeared in the literature.

A triangular aperture illuminated with a vortex beam creates a truncated lattice diffraction pattern that identifies the charge of the vortex. In this Letter, we demonstrate the measurement of vortex charge via this approach for vortex beams up to charge ±7. We also demonstrate the use of this technique for measuring femtosecond vortices and noninteger vortices, comparing these results with numerical modeling. It is shown that this technique is simple and reliable, but care must be taken when interpreting the results for the noninteger case.

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We investigate the excitation of an atomic degenerate-⌳ system by a train of ultrashort pulses. An iterative analytic solution to the optical Bloch equations is found describing the temporal evolution of the density matrix elements. We show that electromagnetically induced transparency of the excitation pulses develops through the coherent accumulation of excitation ͑population and coherence͒ between the degenerate lower states. The influence of the pulse train parameters ͑area, repetition period, and phase between successive pulses͒ on establishing the transparency is investigated.