Professor Raithel utilizes laser-cooling and trapping of neutral atoms to push boundaries in cold-atom physics. In 2007, the Raithel group has obtained the first Bose-Einstein condensate (BEC) in Michigan. In initial research with this BEC, the superfluid-insulator transition in a one-dimensional optical lattice applied to a three-dimensional quantum gas in a weak external trap has been observed and analyzed. An atom cavity consisting of a Bragg-reflecting atom mirror and a magnetic trap has been studied. Nonlinear effects in Bloch oscillations have been observed and analyzed. Presently, the research group is investigating the interactions between BECs and impurity particles, such as cold ions. Professor Raithel further pursues a continuous-wave atom laser based on the magnetic guiding of atoms. The objective there is to provide a continuous, phase- and amplitude-stable Bose-Einstein condensate. This source will be the ideal starting point for the development of atom-interferometric atom and field sensors.

The group studies Rydberg-atom interactions and cold-plasma dynamics in field-free space and in strong magnetic fields. The so-called Rydberg excitation blockade serves as the foundation of certain quantum control and quantum information processing schemes. Evidence for the Rydberg excitation blockade has been obtained using a novel statistical method developed in the Raithel group. At present, the group investigates blockade-induced structures in the pair correlation function of dense, cold Rydberg-atom samples. Further, the trapping of Rydberg atoms using ponderomotive optical lattices is studied.

The group is interested in trapping mesoscopic, dielectric matter in solution using spatially periodic optical tweezers.

Professor Raithel is a Fellow of the American Physical Society and is currently the Director of the NSF-funded Physics Frontier Center “Frontiers in Optical, Coherent and Ultrafast Science” (FOCUS).

**Selected Publications**

Rotary Echo Tests of Rydberg Atom Coherence, (K. C. Younge and G. Raithel), *New J. Phys.* **11**, 043006 (2009).

Atom Interferometry Using Kapitza-Dirac Scattering in a Magnetic Trap, (R. E. Sapiro, R. Zhang, and G. Raithel), *Phys. Rev. ***A 79**, 043630 (2009).

Mesoscopic Rydberg Ensembles: Beyond the Pairwise Interaction Approximation, (K. C. Younge, A. Reinhard, T. Pohl, P. R. Berman, G. Raithel), *Phys. Rev. ***A 79**, 043420 (2009).

Reversible Loss of Superfluidity of a Bose-Einstein Condensate in a 1D Optical Lattice, (R. E. Sapiro, R. Zhang and G. Raithel), *New J. Phys.* **11**, 013013 (10) (2009).

Role of the Mean Field in Bloch Oscillations of a Bose-Einstein Condensate in an Optical Lattice and Harmonic Trap, (R. Zhang, R. E. Sapiro, R. R. Mhaskar, and G. Raithel), *Phys. Rev. ***A 78**, 053607-1-7 (2008).

Effect of Foerster Resonances on the Excitation Statistics of Many-Body Rydberg Systems, (A. Reinhard, K. C. Younge, and G. Raithel), *Phys. Rev. ***A 78**, 060702(R)-1-4 (2008).

Bose-Einstein Condensate Inside a Bragg-Reflecting Atom Cavity, (R. Zhang, R. E. Sapiro, N. V. Morrow, R. R. Mhaskar, and G. Raithel), *Phys. Rev. ***A 77**, 063615 (2008).

Observation of Superfluorescent Emissions from Laser-Cooled Atoms, (E. Paradis, B. Barrett, and A. Kumarakrishnan, R. Zhang and G. Raithel), *Phys. Rev. ***A 77**, 043419 (2008).

Rydberg-Rydberg Collisions: Resonant Enhancement of State Mixing and Penning Ionization, (A. Reinhard, T. Cubel Liebisch, K. C. Younge, P. R. Berman, G. Raithel), *Phys. Rev. Lett.* **100**, 123007-1-4 (2008).

Double-Resonance Spectroscopy of Interacting Rydberg-Atom Systems, (A. Reinhard, K. C. Younge, T. Cubel Liebisch, B. Knuffman, P. R. Berman, and G. Raithel), *Phys. Rev. Lett.* **100**, 233201 (2008).

Trapping and Evolution Dynamics of Ultracold Two-Component Plasmas, (J. H. Choi, B. Knuffman, X. Zhang, A. P. Povilus, and G. Raithel), *Phys. Rev. Lett.* **100**, 175002-1-4 (2008).