R. E. Sapiro

Reversible loss of superfluidity of a Bose–Einstein condensate in a 1D optical lattice

We apply a one-dimensional (1D) optical lattice, formed by two laser beams with a wavelength of 852 nm, to a 3D 87Rb Bose–Einstein condensate (BEC) in a shallow magnetic trap. We use Kapitza–Dirac scattering to determine the depth of the optical lattice. A qualitative change in behavior of the BEC is observed at a lattice depth of 30Erec, where the quantum gas undergoes a reversible transition from a superfluid state to a state that lacks well-to-well phase coherence. Our observations are consistent with a 1D Mott insulator transition, but could also be explained by mean-field effects.

Guiding of Rydberg atoms in a high-gradient magnetic guide

We study the guiding of

Transition of laser cooling between standard and Raman optical lattices

^{87}

Role of the Mean-field in Bloch Oscillations of a Bose-Einstein Condensate in an Optical Lattice and Harmonic Trap

Rb 59D

Imaging spatial correlations of Rydberg excitations in cold atom clouds.

_{5/2}

Atom interferometry using Kapitza-Dirac scattering in a magnetic trap

Rydberg atoms in a linear, high-gradient, two-wire magnetic guide. Time delayed microwave ionization and ion detection are used to probe the Rydberg atom motion. We observe guiding of Rydberg atoms over a period of 5 ms following excitation. The decay time of the guided atom signal is about five times that of the initial state. We attribute the lifetime increase to an initial phase of

Production and trapping of cold circular Rydberg atoms

l

Analysis of atomic density distributions in optical lattices using an optical mask

-changing collisions and thermally induced Rydberg-Rydberg transitions. Detailed simulations of Rydberg atom guiding reproduce most experimental observations and offer insight into the internal-state evolution.

High-Resolution Near-Field Imaging and Far-Field Antenna Measurements with Atomic Sensors

Reduced-period optical lattices based on Raman transitions allow for sub-Doppler laser cooling. An important parameter of this Raman optical lattice is the frequency difference {delta}{sub d} between two virtual energy levels involved in the atom-field interaction scheme. In this work, we use experimental time-of-flight data and quantum simulations to characterize laser cooling in the Raman lattice as a function of {delta}{sub d}. Two different domains of laser cooling are identified. For small {delta}{sub d}, atoms are cooled due to a well-known mechanism that also occurs in standard optical lattices. For large {delta}{sub d}, atoms are cooled based on Raman transitions. We study the transition between the two domains of laser cooling in detail.

High-Resolution Antenna Near-Field Imaging and Sub-THz Measurements with a Small Atomic Vapor-Cell Sensing Element

Using the Crank-Nicholson method, we study the evolution of a Bose-Einstein condensate in an optical lattice and harmonic trap. The condensate is excited by displacing it from the center of the harmonic trap. The mean field plays an important role in the Bloch-like oscillations that occur after sufficiently large initial displacement. We find that a moderate mean field significantly suppresses the dispersion of the condensate in momentum space. When the mean field becomes large, soliton and vortex structures appear in the condensate wavefunction.