James R. Kellogg

Multistage two-dimensional magneto-optical trap as a compact cold atom beam source

A compact cold atom beam source based on a multistage two-dimensional magneto-optical trap (MOT) has been demonstrated and characterized. The multiple-stage design greatly reduces the overall size of the source apparatus while providing a high flux of atoms. The cold atom beam was used to load a separate MOT in ultrahigh vacuum, and we obtained an actual trap loading rate of 1.5 x 109 atoms/s while using only 20 mW of total laser power for the source. The entire source apparatus, including optics, can fit into a 4 cm x 4 cm x 13 cm volume.

Longitudinal coherence in cold atom interferometry

We give experimental evidence to confirm that the coherence length of a cold atomic wave packet remains constant while the packets overall physical size increases in time. Doppler sensitive atom interferometry allows for atoms to be prepared in a regime where de Broglie wavelengths are much more comparable to coherence lengths than in a thermal regime. Atomic wave packet interactions are a function of coherence length which is determined by the initial velocity spread of the atom wave.

Development towards a space-flyable atom interferometer-based gravity gradiometer

An atom interferometer-based gravity gradiometer is being developed for subsurface mapping and geodesy, and fundamental physics investigations from space. We report on this design effort along with the details of the current laboratory-based instrument.