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 P06: FOCUS: Frontiers of ultracold molecules |
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Chair: Martin Zwierlein, Massachusetts Institute of Technology Room: Wisconsin Center 102DE |
Thursday, May 30, 2019 10:30AM - 11:00AM |
P06.00001: Trapped laser-cooled molecules: From quantum simulation to particle physics to chemistry Invited Speaker: John Doyle Due to the versatility of cold polar molecules, they are a powerful platform for both precision measurement searches of physics beyond the standard model (BSM) and for quantum science. This has led to intense efforts to control molecules at the quantum level. We report on new methods to cool and trap molecules and the creation of optical tweezer arrays of ultracold CaF molecules. We have also conducted preliminary collision studies using optical tweezers, demonstrating the potential for exploring state-selective ultra-cold quantum chemistry. These methods can be extended beyond diatomic molecules to polyatomics, which have new features advantageous for quantum computation and precision measurement. Already, a cold diatomic molecular beam experiment (ACME) provides the best limit to the electron’s EDM, which is a 3-30 TeV probe of BSM physics. Polyatomic molecules such as YbOH and YbOCH$_3$, when laser-cooled and trapped optically, will provide longer coherence times, opening the possibility for future experiments to probe BSM physics at the PeV scale. We report on preliminary progress on this front. [Preview Abstract] |
Thursday, May 30, 2019 11:00AM - 11:30AM |
P06.00002: Coherences and collisions of ultracold RbCs molecules. Invited Speaker: Simon Cornish The formation of ultracold heteronuclear molecules possessing long-range dipole-dipole interactions opens up many exciting areas of research spanning quantum computation, quantum simulation and fundamental studies of quantum matter. Long-lived, trapped samples of molecules with full quantum control of the molecular internal state are crucial to many of these applications. Here we report the results of investigations into the rotational coherence and collisional stability of ultracold RbCs molecules prepared initially in the rovibrational ground state. Using coherent microwave control of the internal state of the molecule, we study the AC Stark effect due to the trapping light in low-lying rotational levels. Our measurements reveal a rich energy structure with many avoided crossings between hyperfine states. Understanding this structure allows us to enhance the rotational coherence through a judicious choice of internal state and intensity. Understanding the trap potential also allows us to study the lifetimes of the molecules for various rotational and hyperfine states. We observe rapid loss that is insensitive to the internal state and compare our findings with the `sticky collision' hypothesis that pairs of molecules form long-lived collision complexes. We demonstrate that the loss of molecules is best described by second-order rate equations, and that the rate differs from the limit of `universal loss' for s-wave collisions. We show that dipolar effects lead to significantly faster loss for an incoherent mixture of rotational states. As an outlook, we will briefly describe our plans for imaging and addressing of single molecules in ordered arrays as a basis for quantum simulation. [Preview Abstract] |
Thursday, May 30, 2019 11:30AM - 11:42AM |
P06.00003: Towards laser cooling and trapping of aluminium monofluoride with high density Stefan Truppe, Silvio Marx, Sebastian Kray, Maximilian Doppelbauer, Simon Hofsaess, H. Christian Schewe, Boris Sartakov, Gerard Meijer The aluminum monofluoride molecule (AlF) is an excellent candidate for laser cooling and magneto-optical trapping. All Q-lines of the A$^1\Pi,v'=0$ $\leftarrow$ X$^1\Sigma^+,v''=0$ band near 227.5 nm are rotationally closed and can be used for laser cooling. With a calculated Franck-Condon factor of 0.99992, each molecule can scatter on average 10$^4$ photons from a single laser. This corresponds to a velocity change of 382 m/s, sufficient to slow a cryogenic buffer gas or a supersonic molecular beam. AlF is a closed shell molecule with a binding energy of 7 eV and the A$^1\Pi, v=0$ state has a lifetime of 1.9 ns. This permits efficient production and slowing of the molecules and results in a large capture velocity of the magneto-optical trap ($>50$ m/s), an excellent basis to trap AlF molecules with high density. We present spectroscopic results necessary for laser cooling and trapping experiments. We determine the rotational and hyperfine energy levels in X$^1\Sigma^+, v=0$ and a$^3\Pi, v=0$ with kHz and in A$^1\Pi, v=0$ with MHz accuracy and infer precise spectroscopic constants for all three states. We determine the transition strengths between these states, measure their magnetic g-factors, their electric dipole moments and the lifetime of the A$^1\Pi,v=0$ state. [Preview Abstract] |
Thursday, May 30, 2019 11:42AM - 11:54AM |
P06.00004: An Optical Tweezer Array of Ultracold Molecules Loic Anderegg, Lawrence Cheuk, Yicheng Bao, Sean Burchesky, Kang-Kuen Ni, Wolfgang Ketterle, John M. Doyle Arrays of single ultracold molecules promise to be a powerful platform for many applications ranging from quantum simulation to precision measurement. We report on the creation of an optical tweezer array of single ultracold CaF molecules with high-fidelity detection. By utilizing light-induced collisions during the laser cooling process, we trap single molecules. The high densities attained inside the tweezer traps have also enabled us to observe in the absence of light molecule-molecule collisions of laser cooled molecules for the first time. [Preview Abstract] |
Thursday, May 30, 2019 11:54AM - 12:06PM |
P06.00005: Observation of Magnetic Feshbach Resonances in Ultracold Yb+Li mixtures Jun Hui See Toh, Alaina Green, Xinxin Tang, Subhadeep Gupta, Hui Li, Ming Li, Svetlana Kotochigova We have observed multiple interspecies magnetic Feshbach resonances in ground state collisions between ${}^{173}$Yb and ${}^{6}$Li atoms. These narrow resonances in this non-bialkali collision system arise from the hyperfine coupling between the ${}^{173}$Yb nucleus and the ${}^{6}$Li valence electron. Each resonance is identified as a resonant loss of atoms from a crossed optical dipole trap with varying magnetic field. The locations of these resonances are in good agreement with theoretical predictions based on prior two-photon photoassociation spectroscopy performed in our group. We will report on our observations of YbLi Feshbach resonances and our plans to apply these resonances towards magnetoassociation of ultracold YbLi molecules in the electronic ground state. The doublet-sigma YbLi molecule possesses both electric and magnetic dipole moments that can be utilized towards quantum simulation and information science, precision measurements and ultracold chemistry. [Preview Abstract] |
Thursday, May 30, 2019 12:06PM - 12:18PM |
P06.00006: External field control of spin-dependent insertion reactions at ultralow temperatures Timur Tscherbul, Jacek Klos We present an extension of the accurate coupled-channel statistical model (CCSM) of barrierless atom-molecule insertion reactions [1] to include the effects of the hyperfine structure of the reactants in the presence of an external magnetic field. We apply the extended CCSM to the chemical reaction Li($^2${S}$_{0}$) + CaH($^2\Sigma^+$) $\to$ LiH$(^1\Sigma^+)$ + Ca($^1${S}$_0$) on a newly developed set of {\it ab initio} potential energy surfaces of singlet and triplet symmetry. The calculated reaction cross sections below 100 mK are very sensitive to the initial Zeeman states of Li and CaH, opening up the possibility of controlling barrierless insertion reactions by tuning the hyperfine states of the reactants with an external magnetic field. \\ 1. M. H. Alexander, E. J. Rackham, and D. E. Manolopoulos, J. Chem. Phys. {\bf 121}, 5221 (2004). [Preview Abstract] |
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