Bulletin of the American Physical Society
54th Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 68, Number 7
Monday–Friday, June 5–9, 2023; Spokane, Washington
Session Q04: Focus Session: Advances in Cooling and Control of Ultracold MoleculesFocus Live Streamed
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Chair: David DeMille, University of Chicago Room: Conference Theater |
Thursday, June 8, 2023 8:00AM - 8:30AM |
Q04.00001: Laser cooling alkaline-earth-like diatomic molecules Invited Speaker: Stefan Truppe We present our recent progress on laser cooling AlF molecules using deep UV lasers. AlF is distinctively different from the molecular species that have been laser-cooled so far: it is a stable molecule that can be produced in large quantities and it has a strong A1Π←X1Σ+ transition near 227.5 nm that can be used for rapid slowing and cooling in a magneto-optical trap (MOT) with a large capture velocity. The electronic structure allows using a Zeeman slower to significantly enhance the number of molecules in the MOT. Similar to alkaline-earth and alkaline-earth-like atoms, AlF has narrow, spin-forbidden a3Π←X1Σ+ transitions near 367 nm for precision spectroscopy and narrow-line cooling. We aim to study collisions between AlF molecules and use the narrow line to explore direct laser cooling to quantum degeneracy. |
Thursday, June 8, 2023 8:30AM - 9:00AM |
Q04.00002: Laser Cooled Polyatomic Molecules for Fundamental Physics and Quantum Science Invited Speaker: Loic Anderegg Laser cooled polyatomic molecules represent a new frontier in ultracold physics, complementing and sometimes surpassing the scientific capabilities of ultracold diatomic molecules. Notably, polyatomic molecules generically possess low-lying, closely spaced energy levels with opposite parity. These "parity doublets" result in long-lived, fully polarizable quantum states with minimal sensitivity to external perturbations the hold the promise of significant improvements to searches for physics beyond the Standard Model, including probing for the electron's electric dipole moment (eEDM). Here we present results on laser-cooling and optical trapping of polyatomic molecules. We establish coherent control of individual quantum states in CaOH to demonstrate a powerful method for searching for the eEDM. Optically trapped, ultracold CaOH molecules are prepared in a single quantum state, polarized in an electric field, and coherently transferred into an eEDM sensitive state where an electron spin precession measurement is performed. To extend the coherence time of the measurement, we utilize eEDM sensitive states with tunable, near-zero magnetic field sensitivity. These results establish a path for eEDM searches with trapped polyatomic molecules, towards orders-of-magnitude improved experimental sensitivity to time-reversal-violating physics. Finally, we present progress towards establishing individual particle control and high-fidelity readout using optical tweezer arrays of polyatomic molecules. |
Thursday, June 8, 2023 9:00AM - 9:12AM |
Q04.00003: Optical cycling in CH radicals – a path towards ultracold organic chemistry Jamie Shaw, Mark Semco, William Wortley, Daniel McCarron Techniques to directly laser cool and trap molecules at ultracold temperatures have revealed a new route towards the full quantum control of a diverse group of species with a variety of internal structures and properties. Our experimental effort capitalizes on this generality by aiming to directly laser cool and trap CH radicals for tests of ultracold organic chemistry. The low mass and blue optical transitions in this species lead to high recoil velocities which can significantly reduce the required photon budget and rovibrational closure to slow, cool and trap a molecular beam from our cryogenic source. Here we will present an experimental update including our latest results demonstrating optical cycling in CH radicals. |
Thursday, June 8, 2023 9:12AM - 9:24AM |
Q04.00004: Coherent Interactions and Entanglement Between CaF Molecules in a Reconfigurable Tweezer Array Connor M Holland, Yukai Lu, Samuel J Li, Lawrence W Cheuk Reconfigurable optical tweezer arrays of polar molecules are a promising platform for quantum simulation and quantum information processing. In this talk, we report on recent advances in controlling molecules in this platform. Specifically, we have achieved the capability to prepare arbitrary 1D arrays of single CaF molecules and the ability to initialize them into a single internal state. In addition, we have observed coherent dipolar spin-exchange interactions between pairs of molecules, and entangled them into Bell pairs by implementing a two-qubit iSWAP gate. Our results demonstrate key building blocks needed for quantum information processing and simulation of quantum spin models. More generally, these advances lay the groundwork for using molecular tweezer arrays for quantum science. |
Thursday, June 8, 2023 9:24AM - 9:36AM |
Q04.00005: Magic polarization trapping of polar molecules for tunable dipolar interactions Gabriel E Patenotte, Annie Jihyun Park, Lewis R Picard, Kang-Kuen Ni Ultracold polar molecules interact via the electric dipole-dipole coupling, which induces rotational transitions that entangle the individual molecules. These rotational transitions' intrinsic coherence and abundance make polar molecules an attractive platform for quantum simulation and computation. We prepare an optical tweezer array of individual NaCs molecules in the ground state of their internal and motional degrees of freedom. With < 0.5 um control over molecule position and site-selective rotational state control, we expect coherent kHz rate dipolar oscillations. Our decoherence is dominated by tweezer intensity noise due to the differential polarizability between rotational states. We reduce the difference in polarizability by three orders of magnitude by changing the tweezer polarization to a 'magic' ellipticity. We observe an order of magnitude increase in coherence time with a spin-echo pulse sequence. Due to NaCs' relatively small hyperfine coupling, we can further rotate the tweezer polarization to tune and maximize the dipolar interaction rate. The achieved coherence time should be sufficient to observe dipolar exchange interactions in adjacent molecule pairs, bringing tunable interactions to an array of individually trapped molecules. |
Thursday, June 8, 2023 9:36AM - 9:48AM |
Q04.00006: Towards high-fidelity state preparation and entanglement in a molecular tweezer array Yukai Lu, Connor M Holland, Samuel J Li, Lawrence W Cheuk Recently, coherent dipolar spin-exchange interactions and entanglement have been observed in molecular tweezer arrays of CaF molecules. Specifically, Bell pairs of molecules have been generated with SPAM-corrected fidelities at the ~0.8 level. In this talk, we discuss the factors that limit state preparation and Bell state fidelities, and potential solutions to address them. In detail, we report on a robust state preparation scheme that prepares optically trapped molecules into a single internal state. With regards to the coherence of spin-exchange interactions and Bell state fidelities, we identify the molecular temperature as a major determining factor, and discuss methods to further cool molecules within optical tweezers. Progress on this front could yield high-fidelity two-qubit gates and provide a competitive platform for quantum simulation and quantum information processing using ultracold molecules. |
Thursday, June 8, 2023 9:48AM - 10:00AM |
Q04.00007: Progress towards a 3D MOT of CaH molecules Jinyu Dai, Qi Sun, Isaac Pope, Debayan Mitra, Tanya Zelevinsky Directly laser-cooled and trapped samples of calcium monohydride (CaH) molecules would be useful for ultracold chemistry experiments and potentially serve as a promising route to a dilute, trapped gas of ultracold hydrogen atoms. We previously demonstrated scattering of ~100 photons in CaH, but capturing the molecules in a magneto-optical trap (MOT) requires scattering thousands of photons. A nonradiative decay pathway known as predissociation could limit optical cycling in the process of slowing the molecules to the MOT capture velocity. We present theoretical and experimental estimates of the predissociation probabilities in the states of interest, and demonstrate that a nearly-closed optical cycling scheme is possible. Next, we present our progress on longitudinal white-light slowing and a 3D radio-frequency MOT for CaH. We also show how we could leverage predissociation to engineer an efficient, quantum-state-controlled dissociation pathway to generate ultracold hydrogen. |
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