Optical Trapping in Novel Geometries

Benjamin P. Stein

Lorena C. Bianchet

In this thesis, a single-atom trap in a "Maltese cross'' geometry (MCG) was designed, built up and characterized. A MCG atom trap uses four in-vacuum lenses to achieve four-directional high-numerical-aperture optical coupling to single trapped atoms and small atomic arrays. Here, we describe the theoretical background, the design, and the optical methods used for trapping and cooling atoms in a MCG geometry optimized for high coupling efficiency. We also characterize the resulting properties of the trap and trapped atoms. For this propose we measure occupancy, loading rate, lifetime, temperature, fluorescence anti-bunching and trap frequencies using current best practices. We also report another use of the optical control and coupling offered by the MCG: we use the two on-trap-axis lenses to produce a 1D optical lattice, the sites of which are stochastically filled and emptied by the trap loading process. The two off-trap-axis lenses are used for imaging and single-mode collection. Correlations of single-mode and imaging fluorescence signals are then used to map the single-mode collection efficiency. We observe trap characteristics comparable to what has been reported for single-atom traps with one- or two-lens optical systems. This shows that four-direction high-NA coupling can be achieved with little reduction in trap performance. Finally, we conclude with the near-future plans of the experiment.

Hong Jun Gao, Matthew Pasienski, Matthew White +1 more

Lorena C. Bianchet, Natalia Fernandes de Oliveira Alves, Laura Zarraoa +2 more

We describe optical methods for trapping, cooling, and observing single $^{87}$Rb atoms in a four-lens "Maltese cross" geometry (MCG). The use of four high numerical-aperture lenses in the cardinal directions enables efficient collection of light from non-collinear directions, but also restricts the optical access for cooling and optical pumping tasks. We demonstrate three-dimensional atom localization with sub-wavelength precision, and present measurements of the trap lifetime, temperature and transverse trap frequency in this geometry. We observe a trap performance comparable to what has been reported for single-atom traps with one- or two-lens optical systems, and conclude that the additional coupling directions provided by the MCG come at little cost to other trap characteristics.

Robert Pool

Makoto Morinaga, T. Kishimoto

A new geometry to trap neutral particles with an ac electric field using a simple electrodes structure is described. In this geometry, all electrodes are placed on a single chip plane, while particles are levitated above the chip. This provides an easy construction of the trap and a good optical access to the trap. particle storage, atom optics, laser cooling 1