Enhanced Optical and Electric Manipulation of a Quantum Gas of KRb Molecules

Abstract

Reens on the OH Stark decellerator for invaluable advice on AC and DC electric fields.We have also had a very fruitful collaboration with Ana Maria Rey's group. In particular we worked with Michael Foss-Feig and Kaden Hazzard in the early years, and more recently Michael Wall, Martin Garttner, Arghavan Safavi-Naini, and Bihui Zhu. They have all done an excellent job being aware of what our experiment is capable of, and giving us space when we need to address technical issues. We attempted the spin-exchange measurements after Kaden and Ana Maria suggested that we would be able to observe them in the lattice even at our relatively low filling fraction at that time.The JILA instrument shop played a very significant role in much of the work in this thesis, and I have spent a lot of time working with Tracy Keep, Kels Detra, Kim Hagen, Blaine Horner, Todd Asnicar, and Hans Greene. Tracy made the primary contributions to the new apparatus, and was very helpful along the entire journey to address every problem that emerged. A lot can change in six years, and the JILA instrument shop during my PhD is an excellent example of that. Tracy recently passed away after battling with cancer. Kels left JILA a few years ago. Blaine recently retired. Nevertheless, the JILA instrument shops remains an incredible resource.The JILA electronics shop and computing team have been invaluable to our experiment.Terry Brown and Carl Sauer are always available to help us with any electrical or electronics problem, particularly high voltage or AC circuits. Their expertise has played a significant role in the electronics of the new apparatus, such as the servos for large electric fields and the rf and microwave coils for K and Rb spin flips. J. R. Raith in computing has been very helpful with all of our computing needs over the years.On a more personal note, I am thankful to Dan Gresh (Cornell group, eEDM experiment, JILA) for his friendship over the past six years, and for teaching me the art of powerlifting. I viii am also grateful to Rory Barton-Grimley (Aerospace Eng., CU-Boulder) for his friendship and for getting me back into hockey. I have enjoyed playing with him and Carrie Weidner, Seth Caliga, and Cam Straatsma (Anderson group, JILA) over the past several years. I would also like to thank my family for their constant support over the past six years, especially my fiancé Jennifer. 7.5 The electric field orientations that are possible with the electrode configuration of the new apparatus .

Microwave shielding with far-from-circular polarization

“…Even though the polarization ellipse is very eccentric and closer to linear than it is to circular, shielding of losses to below 10 −12 cm 3 /s can be achieved and requires alignment of the static field E and the z -direction only to within 5 • . Orientation of a static E field to this precision is feasible [35]. Figure 4(b) shows loss rates for 4ξ/π = 1/2, which is half way between circular and linear polarization and still too far from circular to realize shielding without the additional static field proposed here.…”

“…At zero static field, shown in panel (a), shielding is effective only for polarizations close to circular, 4ξ/π < 0.1, which corresponds to a power extinction ratio of the σ − and σ + microwave field components larger than 22 dB [30]. For an achievable [32][33][34][35] field strength of E = 1 kV/cm, shown in panel (b), effective shielding can be obtained for polarizations that are far from circular, with eccentricity up to 4ξ/π ≈ 0.8.…”

Dipolar evaporation of reactive molecules to below the Fermi temperature

“…This geometry allows us to take advantage of the anisotropic character of the dipolar potential and retain only the repulsive side-to-side dipole-dipole interactions within each 2D site, while preventing the attractive head-to-tail interactions that facilitate losses at short range. Our recent advances in the production of degenerate Fermi gases of polar molecules 7,8 , combined with precise electric field control using in-vacuum electrodes 32 (Fig. 1), allow us to perform a systematic characterization of the properties of a 2D Fermi gas of polar molecules.…”

An approach to spin-resolved molecular gas microscopy

“…The new KRb apparatus at JILA [19] has a microscope objective for high-resolution detection of polar molecules, in addition to in-vacuum electrodes for single layer selection. Currently, an objective with numerical aperture (NA=nsin(θ), where n is the index of refraction, and θ is the maximal half-angle of the cone of light that can enter or exit the lens) of 0.53 is used, which corresponds to an optical resolution of R min =900 nm at λ=780 nm, where R min =0.61λ/NA is the Rayleigh criterion for the minimum distance between resolvable points.…”

“…Efforts towards in situ single molecule detection in both optical lattices [17][18][19] and optical tweezers [20,21] are increasingly active. It is thus timely to consider single-site microscopy of polar molecules, and how two rotational states can be simultaneously detected.…”