There is strong astrophysical evidence that dark matter (DM) makes up some 27% of all mass in the universe. Yet, beyond gravitational interactions, little is known about its properties or how it may connect to the Standard Model. Multiple frameworks have been proposed, and precision measurements at low energy have proven useful to help restrict the parameter space for many of these models. One set of models predicts that DM is a scalar field that "clumps" into regions of high local density, rather than being uniformly distributed throughout the galaxy. If this DM field couples to the Standard Model, its interaction with matter can be thought of as changing the effective values of fundamental constants. One generic consequence of time variation of fundamental constants (or their spatial variation as the Earth passes through regions of varying density) is the presence of an anomalous, composition-dependent acceleration. Here we show how this anomalous acceleration can be measured using superconducting accelerometers, and demonstrate that >20 years of archival data from the International Geodynamics and Earth Tide Services (IGETS) network can be utilized to set new bounds on these models. Furthermore, we show how LIGO and other gravitational wave detectors can be used as exquisitely sensitive probes for narrow ranges of the parameter space. While limited to DM models that feature spatial gradients, these two techniques complement the networks of precision measurement devices already in use for direct detection and identification of dark matter.

We present the first experimental demonstration of radiation pressure force deflection and direct laser cooling for barium monohydride (BaH) molecules resulting from multiple photon scattering. Despite a small recoil velocity (2.7 mm s(-1)) and a long excited state lifetime (137 ns), we use 1060 nm laser light exciting theX -> Aelectronic transition of BaH to deflect a cryogenic buffer-gas beam and reduce its transverse velocity spread. Multiple experimental methods are employed to characterize the optical cycling dynamics and benchmark theoretical estimates based on rate equation models as well as solutions of the Lindblad master equation for the complete multilevel system. Broader implications for laser cooling and magneto-optical trapping of heavy-metal-containing molecules with narrow transition linewidths are presented. Our results pave the way for producing a new class of ultracold molecules-alkaline earth monohydrides-via direct laser cooling and trapping, opening the door to realizing a new method for delivering ultracold hydrogen atoms (Lane 2015Phys.Rev.A92, 022511).

Recent theoretical investigations have indicated that rapid optical cycling should be feasible in complex polyatomic molecules with diverse constituents, geometries and symmetries. However, as a composite molecular mass grows, so does the required number of photon scattering events necessary to decelerate and confine molecular beams using laser light. Utilizing coherent momentum exchange between light fields and molecules can suppress spontaneous emission and significantly reduce experimental complexity for slowing and trapping. Working with BaH as a test species, we have identified a robust, experimentally viable configuration to achieve large molasses-like cooling forces for molecules using polychromatic optical fields addressing both $X-A$ and $X-B$ electronic transitions, simultaneously. Using numerical solutions of the time-dependent density matrix as well as Monte Carlo simulations, we demonstrate that creation of Suppressed Emission Rate (SupER) molasses with large capture velocities ($\sim 40$ m/s) is generically feasible for polyatomic molecules of increasing complexity that have an optical cycling center. Proposed SupER molasses are anticipated to not only extend quantum control to novel molecular species with abundant vibrational decay channels, but also significantly increase trapped densities for previously laser-cooled diatomic and triatomic species.

Submitted for the DAMOP19 Meeting of The American Physical Society Laser Cooling of Diatomic Metal Monohydrides for Producing Ultracold Hydrogen1 IVAN KOZYRYEV, REES MCNALLY, TANYA ZELEVINSKY, Columbia University — Despite a tremendous progress in laser technology in recent years, direct laser cooling of the most prevalent atomic species of chemical and biological interest including hydrogen, carbon, oxygen, and nitrogen still remains out of reach. However, many diatomic and polyatomic metal-ligand radicals can support optical cycling on the metal-localized valence electron, potentially enabling concomitant laser cooling of diverse constituents [1]. We will describe our progress on laser cooling and trapping of barium monohydride (BaH) molecules as a precursor for producing ultracold atomic hydrogen using optical methods. Despite a low recoil velocity (2.7 mm/s) and a relatively slow scattering rate (106 s−1), we were able to use 1060 nm laser light exciting theX → A electronic transition to reduce the transverse velocity spread of the cryogenic buffer-gas beam of BaH, characterizing the cooling dynamics and benchmarking theoretical estimates. A large atomic mass mismatch between the BaH constituents will be highly beneficial for future kinetic cooling of hydrogen to ultracold temperatures using precision photodissociation of trapped molecules [2]. [1] Kozyryev et al., ChemPhysChem 17, 3641 (2016). [2] I. C. Lane, PRA 92, 022511 (2015). 1This work is supported by the ONR and AFOSR. Ivan Kozyryev Columbia University Date submitted: 31 Jan 2019 Electronic form version 1.4

We demonstrate frequency comb generation in the visible optical spectrum via excitation of higher-order modes in silicon nitride microresonators. Anomalous group-velocity dispersion from the higher-order mode allows for broadband comb generation spanning 45 THz.

A cryogenic buffer-gas cooled beam of barium monohydride for laser slowing, cooling, and trapping Geoffrey Zerbinatti Iwata Ultracold molecules promise a revolutionary test bed for quantum science with applications ranging from experiments that probe the nature of our universe, to hosting new platforms for quantum computing. Cooling and trapping molecules in the ultracold regime is the first step to unlocking the wide array of proposed applications, and developing these techniques to control molecules is a key but challenging research field. In this thesis, we describe progress towards a new apparatus designed to cool and trap barium monohydride (BaH), a molecule that is amenable to laser cooling and has prospects as a precursor for ultracold atomic hydrogen. The same complexity that makes molecules interesting objects of study creates challenges for optical control. To mitigate some of these challenges, we first cool the molecules using cryogenic techniques and technologies. Our apparatus uses a cryogenic buffer gas to thermalize BaH within a contained cell. The molecules are extracted into a beam with millikelvin transverse temperature, and forward velocities <100 m/s. The BaH beam in this work is the brightest hydride beam to date, with molecule density and kinetic characteristics well suited for laser cooling and trapping. This thesis presents preliminary studies of BaH’s suitability for laser cooling, details of the design and construction of our molecular beam source, experiments that uncover the hyperfine properties of the molecules, and describes ongoing work for laser slowing, cooling, and trapping of the molecules. Finally, we discuss the possibility of using our molecules to create trapped ultracold atomic hydrogen – a long-standing goal of atomic, molecular, and optical physics.

The accuracy of atmospheric density measurements inferred from satellite drag is limited by errors in drag coefficient estimates. In this work, we use a unique opportunity in which the Drag and Atmospheric Neutral Density Explorer satellite and three Polar Orbiting Passive Atmospheric Calibration Spheres are deployed from a common launch vehicle. Each object flies through similar atmospheric conditions but has a different area-to-mass ratio. This allows aerodynamic analysis that is independent of atmospheric density via comparisons of measured and modeled ballistic coefficient ratios. A test particle method combined with a satellite energy accommodation model is used to model the aerodynamics of these objects. Fitted ballistic coefficients computed as a result of special-perturbations orbit analysis are then compared to the model results. The drag coefficient model and observations agree at the 1-2% level when coefficient ratios are compared. Comparisons of an additional shape with model predictions are made possible when one of the satellites shed its launch adapter. This work validates the aerodynamic model used here and can be applied in future research to improve models of atmospheric density and predictions of satellite drag. Beyond potential improvements to atmospheric models, the technique presented here is shown to identify objects based on their aerodynamic signature.

The pursuit of better atomic clocks has advanced many research areas, providing better quantum state control, new insights in quantum science, tighter limits on fundamental constant variation, and improved tests of relativity. The record for the best stability and accuracy is currently held by optical lattice clocks. This work takes an important step towards realizing the full potential of a many-particle clock with a state-of-the-art stable laser. Our 87Sr optical lattice clock now achieves fractional stability of 2.2e-16 at 1 s. With this improved stability, we perform a new accuracy evaluation of our clock, reducing many systematic uncertainties that limited our previous measurements, such as those in the lattice ac Stark shift, the atoms' thermal environment, and the atomic response to room-temperature BBR. Our combined measurements have reduced the total uncertainty of the JILA Sr clock to 2.1e-18 in fractional frequency units.

Submitted for the DAMOP14 Meeting of The American Physical Society The Sr optical lattice clock at JILA: A new record in atomic clock performance TRAVIS NICHOLSON, BENJAMIN BLOOM, JASON WILLIAMS, SARA CAMPBELL, MICHAEL BISHOF, XIBO ZHANG, WEI ZHANG, SARAH BROMLEY, ROSS HUTSON, REES MCNALLY, JUN YE, JILA — The exquisite control exhibited over quantum states of individual particles has revolutionized the field of precision measurement, as exemplified by highly accurate atomic clocks. Optical clocks have been the most accurate frequency standards for the better part of a decade, surpassing even the cesium microwave fountains upon which the SI second is based. Two classes of optical clocks have outperformed cesium: singleion clocks and optical lattice clocks. Historically ion clocks have always been more accurate, and the precision of ion clocks and lattice clocks has been comparable. For years it has been unclear if lattice clocks can overcome key systematics and become more accurate than ion clocks. In this presentation I report the first lattice clock that has surpassed ion clocks in both precision and accuracy. These measurements represent a tenfold improvement in precision and a factor of 20 improvement in accuracy over the previous best lattice clock results. This work paves the way for a better realization of SI units, the development of more sophisticated quantum sensors, and precision tests of the fundamental laws of nature. Travis Nicholson JILA Date submitted: 31 Jan 2014 Electronic form version 1.4

The Drag & Atmospheric Neutral Density Explorer (DANDE) spacecraft represents a novel approach in the study of the near Earth atmospheric environment. Incorporating both a Wind & Temperature Spectrometer (WTS), and an accelerometer package, DANDE is capable of measuring density directly, minimizing the need for model input. DANDE incorporates several very unique systems, enabling accuracy of measurement traditionally not achievable on space-craft of its price. The most notable of these systems is the accelerometer package, and the time off-set measurement program. These enable sub micro-g measurements from navigation grade accelerometers, and temporal data correlation accurate down to micro-seconds respectively.