Interferometry in an Atomic Fountain with Ytterbium Bose-Einstein Condensates

We present enabling experimental tools and atom interferometer implementations in a vertical "fountain" geometry with ytterbium Bose-Einstein condensates. To meet the unique challenge of the heavy, non-magnetic atom, we apply a shaped optical potential to balance against gravity following evaporative cooling and demonstrate a double Mach-Zehnder interferometer suitable for applications such as gravity gradient measurements. Furthermore, we also investigate the use of a pulsed optical potential to act as a matter wave lens in the vertical direction during expansion of the Bose-Einstein condensate. This method is shown to be even more effective and results in a reduction of velocity spread (or equivalently an increase in source brightness) of more than a factor of five, which we demonstrate using a two-pulse momentum-space Ramsey interferometer. The vertical geometry implementation of our diffraction beams ensures that the atomic center of mass maintains overlap with the pulsed atom optical elements, thus allowing extension of atom interferometer times beyond what is possible in a horizontal geometry. Our results thus provide useful tools for enhancing the precision of atom interferometry with ultracold ytterbium atoms.Comment: 11 pages, 7 figure

Bloch Oscillation Phases investigated by Multi-path Stuckelberg Atom Interferometry

Atoms undergoing Bloch oscillations (BOs) in an accelerating optical lattice acquire momentum of two photon recoils per BO. This technique provides a large momentum transfer tool for atom optics, but its full exploitation for atom interferometric sensors requires experimental characterization of associated phases. Each BO involves a Landau-Zener crossing with multiple crossings inducing interference known as Stuckelberg interference. We develop a multi-path Stuckelberg interferometer and investigate atomic phase evolution during BOs, up to 100 photon recoil momentum transfer. We compare to numerically calculated single-particle Schrodinger evolution, demonstrate highly coherent BO sequences, and assess phase stability requirements for BO-enhanced precision interferometry in fundamental physics and sensing applications.Comment: 11 pages including supplemental material, 9 figures, 1 tabl

Vertical Contrast Interferometry and Bloch-Band Approach to Atom Optics

Thesis (Ph.D.)--University of Washington, 2020This dissertation covers a series of atom interferometry experiments with a focus on applying the Bloch-band model to atom optics and performing vertical interferometry with a magnetically neutral atom. This approach lets us analyze the diffraction processes from a pulsed optical lattice in terms of the Bloch solutions for the atom in the periodic lattice Hamiltonian. Using a ytterbium (174Yb) Bose-Einstein condesate as the matter-wave source, measurements of Rabi frequencies, as well as those of diffraction phase and amplitude, demonstrate the validity of the Bloch-band approach over a regime which is typically satisfied within an atom interferometer. Applications for this model are discussed, including the use of an interferometric phase measurement to determine an unknown band structure. Additionally, a unique feature of the excited Bloch-bands—the magic depth—is exploited to improve the phase stability of atom interferometers which use Bloch oscillations for large momentum transfer. We also demonstrate the technique of delta-kick cooling as a fruitful method for reduction of the BEC’s vertical velocity distribution, allowing for more efficient momentum transfer with a vertical optical lattice. This is a crucial tool for non-magnetic atoms such as 174Yb, which we use to perform vertical interferometry in our system with both a contrast interferometer geometry and a double Mach-Zehnder interferometer. Lastly, the effect of Landau-Zener-St¨uckelberg interference during Bloch oscillations is studied in its relation to momentum transfer efficiency for precision interferometry

Interferometry in an Atomic Fountain with Ytterbium Bose–Einstein Condensates

We present enabling experimental tools and atom interferometer implementations in a vertical “fountain” geometry with ytterbium Bose–Einstein condensates. To meet the unique challenge of the heavy, non-magnetic atom, we apply a shaped optical potential to balance against gravity following evaporative cooling and demonstrate a double Mach–Zehnder interferometer suitable for applications such as gravity gradient measurements. Furthermore, we also investigate the use of a pulsed optical potential to act as a matter wave lens in the vertical direction during expansion of the Bose–Einstein condensate. This method is shown to be even more effective than the aforementioned shaped optical potential. The application of this method results in a reduction of velocity spread (or equivalently an increase in source brightness) of more than a factor of five, which we demonstrate using a two-pulse momentum-space Ramsey interferometer. The vertical geometry implementation of our diffraction beams ensures that the atomic center of mass maintains overlap with the pulsed atom optical elements, thus allowing extension of atom interferometer times beyond what is possible in a horizontal geometry. Our results thus provide useful tools for enhancing the precision of atom interferometry with ultracold ytterbium atoms