Bulletin of the American Physical Society
52nd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 66, Number 6
Monday–Friday, May 31–June 4 2021; Virtual; Time Zone: Central Daylight Time, USA
Session Z02: Focus Session: Collisions under Extreme ConditionsFocus Live
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Chair: John Bohn, University of Colorado |
Friday, June 4, 2021 10:30AM - 11:00AM Live |
Z02.00001: Quantum control of chemical reactivity at ultralow temperatures: Insights from quantum dynamical calculations Invited Speaker: Timur Tscherbul Ultracold molecules offer unique opportunities for probing molecular collisions and chemical reactivity at the most fundamental level, where rovibrational degrees of freedom of the reactants, and even those of reaction complexes, can be precisely controlled. Quantum scattering calculations play an essential role in exploring and leveraging these opportunities by providing a connection between the collision observables and the underlying microscopic interactions within the reaction complex. Significant progress has been achieved in recent years, with field-free quantum dynamics of ultracold three-atom reactions now amenable to rigorous computational studies [1]. I will discuss how the quantum dynamics of ultracold barrierless chemical reactions (such as NaLi + Na $\to$ Na$_2$ + Li) can be controlled by spin polarizing the reactants in an external magnetic field [2,3]. I will then introduce quantum interference-based coherent control as an efficient tool to tune ultracold molecular collisions by varying the relative populations and phases of initial coherent superpositions of degenerate molecular states [4,5]. I will conclude by arguing that rapid development of efficient theoretical methodologies [1,6] will soon make it possible to perform numerically exact quantum dynamical simulations of a wide variety of triatomic chemical reactions in the absence or presence of external electromagnetic fields, enabling full exploration of ultracold controlled reaction dynamics. |
Friday, June 4, 2021 11:00AM - 11:30AM Live |
Z02.00002: New Paths to Molecular Ion Quantum Logic Invited Speaker: Eric R Hudson Molecular ion quantum systems may offer advantages over current platforms for certain tasks in quantum sensing, communication, and computation. Before these advantages can be realized, control of molecular ion qubits, e.g. quantum state preparation/measurement and entangling operations, must be improved to levels similar to those in atomic systems. Recent work has deciphered several long-standing riddles for one of these important steps: preparing molecular ions in a single internal quantum state via sympathetic cooling with laser-cooled gases. We will review these developments, which involve both ion-ion and ion-neutral collision physics. We will also discuss several new ideas for quantum logic using both dipolar and dipole-phonon interactions between these cooled molecular ions, which hold promise for rapidly advancing the field. |
Friday, June 4, 2021 11:30AM - 11:42AM Live |
Z02.00003: Collisions Between Laser-Cooled Atoms and Molecules Sarunas Jurgilas Recent work has demonstrated direct laser cooling of diatomic molecules to temperatures of around 5 μK. A promising route to increase the phase-space density is sympathetic cooling with evaporatively cooled atoms. This requires a favourable ratio of elastic to inelastic collisions rates. |
Friday, June 4, 2021 11:42AM - 11:54AM Live |
Z02.00004: Feshbach Resonances in NaLi Molecule and Na Atom Collisions Juliana J Park, Hyungmok Son, Yu-Kun Lu, Michal Tomza, Tijs Karman, Alan Jamison, Wolfgang Ketterle The opportunities to study quantum chemistry, many-body physics, and quantum information processing with molecules can be uncovered by the ability to manipulate both internal and external states of molecules. 23Na6Li is a fermionic molecule that has weak singlet-triplet mixing making it a suitable system to study the triplet ground state. It is notable for its both non-zero electric and magnetic dipole moments and small two-body scattering rate, as predicted by universal model for cold collision. Additionally, NaLi is the lightest bi-alkali molecule, and the theoretical simulation of collisions is relatively feasible compared to other heavy molecules which makes it a promising benchmark system for theoretical quantum scattering calculations. We have previously seen state dependent collisional loss between NaLi molecules and Na atoms. In case of molecules and atoms both in their upper stretched hyperfine states, more than an order of magnitude lower collisional loss compared to universal limit was observed. We report our recent results on magnetic field dependent collision rate between molecules and Na atoms which is enhanced beyond universal rate at Feshbach resonances due to quantum interference. |
Friday, June 4, 2021 11:54AM - 12:06PM Live |
Z02.00005: Suppression of Unitary Three-body Loss in a Degenerate Bose-Fermi Mixture Xing-Yan Chen, Marcel Duda, Andreas Schindewolf, Roman Bause, Immanuel F Bloch, Xin-Yu Luo We study three-body loss in a mixture of 23Na and 40K, where the potassium atoms are Fermi degenerate. We find that at unitarity, where the interspecies scattering length diverges, the usual inverse-squared temperature scaling of the three-body loss found in nondegenerate systems is strongly modified, specifically, the loss is suppressed with the increasing degeneracy of the Fermi gas. The observed suppression is stronger than the prediction from the zero-range theory, suggesting the presence of many-body effects. |
Friday, June 4, 2021 12:06PM - 12:18PM Live |
Z02.00006: Lifetimes of intermediate complexes formed during collisions of ultracold molecules James Croft The lifetimes of intermediate complexes formed during collisions of ultracold molecules are often assumed to be determined by the RRKM decay rate. |
Friday, June 4, 2021 12:18PM - 12:30PM Live |
Z02.00007: Collisions of Magnetically Trapped Cold Methyl Radicals with Atoms Manish Vashishta, Jiahong Hu Manish Vashishta, Jiahong Hu, Pavle Djuricanin, Tony Mittertreiner, Takamasa Momose |
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