Bulletin of the American Physical Society
50th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics APS Meeting
Volume 64, Number 4
Monday–Friday, May 27–31, 2019; Milwaukee, Wisconsin
Session W05: Cold Molecule Interactions and Control |
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Chair: Ivan Antonov, Northwestern University Room: Wisconsin Center 102C |
Friday, May 31, 2019 10:30AM - 10:42AM |
W05.00001: Investigation of molecule-molecule collisions in a trap Isabel Rabey, Thomas Gantner, Manuel Koller, Florian Jung, Martin Zeppenfeld, Gerhard Rempe Understanding molecular collisions at low energies is a prerequisite for future sympathetic and evaporative cooling of molecules. However, experimental investigation of molecular collisions in this temperature regime is still in its infancy. Our \textit{cryofuge} setup, the combination of cryogenic buffer gas cooling and centrifuge deceleration [1], produces slow and cold molecular beams with a flux of $10^{10}$/s and densities up to $10^9$cm$^{-3}$ at velocities below 20m/s. This low velocity allows molecules to be loaded into an electrostatic trap [2], where they can be held for several seconds. With this long interaction time, studies of both elastic and inelastic collisions are possible. Our method is also entirely generic relying only on the electric dipole moment of the molecule. This will allow a variety of complex polyatomic molecules to be studied including CH$_3$F, ND$_3$ and CF$_3$CCH. \newline [1] X. Wu \textit{et al.}, Science \textbf{358}, 645 (2017) \newline [2] B. G. U. Englert \textit{et al.}, PRL \textbf{107}, 263003 (2011) [Preview Abstract] |
Friday, May 31, 2019 10:42AM - 10:54AM |
W05.00002: Arbitrary internal state control of molecular ions through optical pumping Patrick Stollenwerk, Ivan Antonov, Sruthi Venkataramanababu, Brian Odom Despite the significant challenges associated with controlling the internal modes of molecules, a number of successful techniques for efficiently populating the rovibrational ground state have been demonstrated. Fewer techniques have been implemented for arbitrary state control and none have been used to sustain high energy rotations. Robust, sustainable, arbitrary state preparation is especially useful for trapped ions as they are capable of long trapping lifetimes. We demonstrate a technique relying on spectral pulse shaping of a single broadband laser for populating arbitrary target rotational states of SiO$^{\mathrm{+}}$ up to rotational quanta exceeding N$=$65 including ground state preparation with sub-Kelvin internal temperatures. Additionally, the technique is extended to populating the first excited vibrational mode. In contrast to coherent manipulation or selective filtering methods, optical pumping represents a driven, dissipative method of control and therefore, neglecting chemical reactions, population in the target state can be sustained indefinitely. We also discuss some of the potential applications of control as well as our progress on direct fluorescent imaging of SiO$^{\mathrm{+}}$. [Preview Abstract] |
Friday, May 31, 2019 10:54AM - 11:06AM |
W05.00003: Effects of Fermi statistics on vibrationally-excited Rydberg molecules Roger Ding, Soumya Kanungo, Joseph Whalen, Haad Rathore, Yu Wang, F. Barry Dunning, Thomas Killian, John Sous, Hossein Sadeghpour, Marcel Wagner, Richard Schmidt, Shuhei Yoshida, Joachim Burgdörfer Rydberg molecules, composed of one or many ground-state atoms bound to a nearby Rydberg atom by the scattering of the Rydberg electron, are novel tools for probing interparticle correlations due to the $n^2$-scaling of the Rydberg wave function length scale. We present progress towards observing the effects of Fermi statistics on the photoexcitation rates of vibrationally-excited Rydberg molecules. Focusing on the Rydberg dimers (one ground-state atom and one Rydberg atom), we compare the excitation rates from spin-polarized and unpolarized cold gases of fermionic {\textsuperscript{87}Sr} ({$I=9/2$}) to the ground and vibrationally-excited dimer states. Due to the localization of these vibrational states on length scales comparable to and smaller than the de Broglie wavelength, we expect Fermi statistics to modify these excitation rates when comparing the spin-polarized and unpolarized samples and we present spectra at {$n\sim30-40$} towards that goal. [Preview Abstract] |
Friday, May 31, 2019 11:06AM - 11:18AM |
W05.00004: Ultra-long-range molecule engineering via Rydberg-dressing Jia Wang, Robin Cote We predict a new type of binding mechanism between ground state atoms based on aspects of three recent applications of Rydberg physics: Rydberg blockade, Rydberg dressing, and ultra-long-range Rydberg molecules. We show that it is possible to bind ground state atoms within the blockade volume using lasers to dress their interactions with a Rydberg trilobite-like state. As a result, pairs of atoms can be bound in potential wells at separations of thousands of Bohr radii. By choosing the Rydberg state judiciously, one can also affect the spatial orientation of the long-range Rydberg dressed ground state molecules. We explore how the dressed potentials can be tuned by selecting the parameters of the dressing lasers, which allows engineering of the molecular bond and its geometry. [Preview Abstract] |
Friday, May 31, 2019 11:18AM - 11:30AM |
W05.00005: Toward the individual trapping and probing of ultracold polar molecules Michael Highman, Ming Li, Svetlana Kotochigova, Brian DeMarco, Bryce Gadway Rotational states of ultracold polar molecules are long lived, noise insensitive, and host natural entangling interactions that stem from the molecules' large internal electric dipole moment. Such properties, alongside the fact that they can be manipulated through many of the same methods developed for neutral atoms, make them enticing for use in a wide range of applications in quantum computation or analog quantum simulation. However, unlike on neutral atom systems, no general-purpose, high-fidelity probing process currently exists for generic molecules due to their complex internal structure. We discuss a new approach to nondestructively image molecules that exploits their optical birefringence when prepared in rotationally excited states. We then detail current experimental progress toward creating individually trapped ground state sodium-rubidium molecules as well as our plans for implementing this nondestructive imaging scheme. [Preview Abstract] |
Friday, May 31, 2019 11:30AM - 11:42AM |
W05.00006: Intermolecular interactions involving ultracold linear polyatomic molecules Jonathan Smucker, John Montgomery, Robin C\^ot\'e Recent advances in cooling molecules are making it possible to reach ultracold temperatures for simple polyatomic molecules. In this work, we investigate the interactions between such molecules. In particular, we consider linear polyatomic molecules such as CaOH, SrOH, CaOCH$_3$ or SrOCH$_3$ that are being pursued experimentally. We report their dipole, quadrupole, and octupole moments appearing in the multipole expansion of the long-range interaction between molecules. The multipole moments are calculated using coupled cluster theory with single and double excitations (CCSD) and the correlation consistent basis sets. We also show results from {\it ab initio} calculations of the interaction energy curves for specific molecular orientations, also calculated using couple cluster methods. We also consider mixed molecular species. [Preview Abstract] |
Friday, May 31, 2019 11:42AM - 11:54AM |
W05.00007: Microwave shielding of ultracold polar molecules Tijs Karman, Jeremy Hutson We use microwaves to engineer repulsive long-range interactions between ultracold polar molecules. The resulting shielding suppresses various loss mechanisms and provides large elastic cross sections. Hyperfine interactions limit the shielding under realistic conditions, but a magnetic field allows suppression of the losses to below $10^{-14}$~cm$^3$~s$^{-1}$. The mechanism and optimum conditions for shielding differ substantially from those proposed by Gorshkov \emph{et al.}\ [Phys.\ Rev.\ Lett.\ {\bf 101}, 073201 (2008)], and do not require cancelation of the long-range dipole-dipole interaction that is vital to many applications. \newline \newline [1] T.~Karman and J.M.~Hutson, Phys. Rev. Lett. {\bf 121}, 163401 (2018) [Preview Abstract] |
Friday, May 31, 2019 11:54AM - 12:06PM |
W05.00008: Transfer matrix theory of surface spin-echo experiments with molecules Joshua T. Cantin, Gil Alexandrowicz, Roman V. Krems ${}^3$He spin-echo experiments have been used to study surface morphology, atomic surface diffusion, and phase transitions of ionic liquids. By replacing ${}^3$He atoms with molecules, one may be able to exploit additional molecular degrees of freedom, such as rotation, to provide even more insight into surface dynamics. Indeed, a recent experiment used \textit{ortho}-hydrogen to probe the orientation of a Cu(115) surface [1]. However, the large manifold of molecular states and magnetic field-induced couplings between these states preclude a semi-classical description for these new experiments. Here, we build an efficient, fully quantum mechanical theoretical framework that connects the experimental signal to the elements of the molecule-surface scattering matrix. To do this, we derive a one-dimensional transfer matrix method that includes the molecular hyperfine degrees of freedom. We apply our framework to the case of \textit{ortho}-hydrogen, show that the calculated experimental signal is sensitive to the scattering matrix elements, and present a preliminary comparison to experiment. This work sets the stage for machine learning techniques to determine the details of molecule-surface interactions from experimental data. [1] Godsi et al., Nat. Comm. \textbf{8}, 15357 (2017). [Preview Abstract] |
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