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NEWS:

December 16, 2013 -- Where does the photoionization process happen within the volume of a Rydberg atom? We have used an optical lattice as a light probe to investigate this question. We studied photoionization rates of Rydberg D states (principal quantum numbers between 45 and 65) in a one-dimensional optical lattice of wavelength 1064 nm. In our setup, the Rydberg-atom size is on the order of the lattice period. The lattice light-field maxima are placed either near the atom's center or within the lobes of the electronic probability distribution. The measured rates are consistent with photoionization occurring primarily near the atomic nucleus, and not where the Rydberg electronic probability distribution is highest. We have therefore provided direct experimental evidence of an assumption underpinning many experiments with Rydberg atoms in optical fields, i.e. that the photoionization process for Rydberg atoms occurs near the nucleus.

The paper reporting our results, entitled "Ionization of Rydberg atoms by standing-wave light fields," has been published in Nature Communications. The paper can also be viewed here.

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New Projects Underway

We are currently constructing a new setup to facilitate investigations of Rydberg atoms in deep optical lattices. Until now, the depth of the optical lattice in our experiments has been limited (~10 MHz) due to power restrictions of the optical fiber that carries the lattice light to the experiment chamber. We plan to overcome this obstacle by placing a field enhancement cavity (two highly reflective mirrors) inside a new chamber, allowing us to achieve lattice depths on the order of GHz. Theoretical work on Rydberg atoms in deep optical lattices can be found at New J. Phys. 12, 023031 (2010).

We also have an effort underway to perform a high-precision measurement of the Rydberg constant using circular Rydberg states trapped in an optical lattice. More information can be found here.

This work is supported by the National Science Foundation and the U.S. Department of Energy.

GO BLUE!

A cloud of atoms from our magneto-optical trap distorted into the shape of a Michigan 'M'.