Bulletin of the American Physical Society
53rd Annual Meeting of the APS Division of Atomic, Molecular and Optical Physics
Volume 67, Number 7
Monday–Friday, May 30–June 3 2022; Orlando, Florida
Session X08: Ultracold Plasmas and MoleculesRecordings Available
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Chair: Tom Killian, Rice Room: Salon 7/8 |
Friday, June 3, 2022 8:00AM - 8:12AM |
X08.00001: Ion thermometry in ultracold neutral plasmas Scott D Bergeson, CHAN HYUN PAK Disorder-induced heating (DIH) is a well-known feature of ultracold neutral plasmas (UNPs). It occurs as excess electrical potential energy is converted to kinetic energy during a global relaxation of the plasma towards equilibrium. Fluorescence methods are used to measure the ion temperature. In this talk I will present three analysis methods for determining the ion temperature. PMT measurements give spatially-averaged temperatures with excellent time resolution. Except at very early times in the plasma expansion, these 'temperatures' are compromised by the hydrodynamic velocity. Spatially resolved fluorescence images can be analyzed pixel by pixel to produce a temperature map at a particular time. These high-resolution images often suffer from poor signal-to-noise characteristics. We demonstrate that ion temperatures can be obtained from a single image at late times in the plasma expansion. We will discuss ion temperature measurements in both magnetized and un-magnetized plasmas. |
Friday, June 3, 2022 8:12AM - 8:24AM |
X08.00002: Optimal production of AlCl via laser ablation Boerge Hemmerling, Taylor Lewis, Chen Wang, John R Daniel, Madhav Dhital, Brian K Kendrick, Chris Bardeen Ultracold polar molecules allow for a range of novel studies, including many-body physics of quantum degenerate gases, quantum computing, precision measurements and tests of fundamental symmetries. Laser cooling has been key as a first step towards implementing similar applications with atoms. Applying the same schemes to molecules, however, is challenging due to their additional degrees of freedom, which interrupt the photon cycling process by a decay into dark states. With an estimated Franck-Condon factor of 99.88%, AlCl is an excellent candidate for laser cooling. Starting with a cryogenic buffer-gas beam source, we use pulsed-laser ablation to produce AlCl in the gas phase and a frequency-tripled Ti:Saph laser system to carry out precise spectroscopy on AlCl. To maximize the yield of AlCl, we have systematically studied and compared various precursor targets, including mixtures of KCl:Al, NaCl:Al, CaCl2:Al, MgCl2:Al, and AlCl3. Here, we will give an update on the status of the experiment, our target studies and discuss our progress towards slowing and cooling AlCl. |
Friday, June 3, 2022 8:24AM - 8:36AM |
X08.00003: Towards magneto-optical trapping of AlF molecules Simon Hofsaess, Sidney Wright, Maximilian J Doppelbauer, Sebastian Kray, Eduardo Padilla, Boris Sartakov, Jesus Perez Rios, Gerard Meijer, Stefan Truppe Aluminum monofluoride (AlF) is a promising candidate to produce a dense, ultracold gas through laser cooling. We present our recent progress towards implementing a Zeeman slower for the molecules, transverse and rotational cooling, and magento-optical trapping of AlF molecules. We also present a thorough characterisation of a MOT of Cd atoms using the 1P1 ← 1S0 transition near 229 nm. Cd is an excellent species to test our MOT apparatus as it shares many properties with the more complex case of AlF. |
Friday, June 3, 2022 8:36AM - 8:48AM |
X08.00004: Optical cycling functionalization of aromatic molecules, towards laser cooling Debayan Mitra, Guo-Zhu Zhu, Zack Lasner, Claire Dickerson, Benjamin Augenbraun, Guanming Lao, Michael Frim, Austin Bailey, Anastassia Alexandrova, Wesley C Campbell, Justin R Caram, Eric R Hudson, John M Doyle Laser cooling relies on photon cycling, which can be enabled in polyatomic molecules when an “optical cycling center” (OCC) is attached to an electronegative ligand. It was proposed that molecules with a (metal) alkaline-earth(I)-oxide-radical structure, would have good OCC properties and, thus, would be amenable to laser cooling [1]. More recent theoretical work has indicated that the alkaline-earth(I)-oxide unit attached to a benzene ring would offer a good OCC that would be tunable by substituting the ring hydrogen atoms with more electronegative species [2]. Theory has also indicated that larger rings (such as naphthalene, pyrene, and coronene) can also provide good optical cycling properties [3]. We report the results of dispersed fluorescence measurements on CaO-Ph-X (Ph : phenyl, X = F, CH3, CF3) in a cryogenic buffer gas at 9 K. We find that the vibrational branching ratio (VBR) to the ground vibrational state is >90% for all species and 99% for CaO-Ph-3,4,5F [4]. We also study the napthol-based molecules CaO-Nap and SrO-Nap, and find that the 2-naphthyl positional variant of CaO-Nap also has a highly diagonal VBR, 96% [5]. These results demonstrate that the same principles that have led to laser cooling of di-, tri- and poly-atomic molecules (e.g. SrF, CaOH and CaOCH3) can likely be extended to phenolic and aromatic molecules. |
Friday, June 3, 2022 8:48AM - 9:00AM |
X08.00005: The formation of Heavy Magnetic Lanthanide Molecules Eite Tiesinga, Jacek Klos, Ming Li, Alexander Petrov, Svetlana Kotochigova The electronic structure of magnetic lanthanide atoms is fascinating from a fundamental perspective. |
Friday, June 3, 2022 9:00AM - 9:12AM |
X08.00006: Optical Pumping of SiO+: How an Intervening Electronic State aids in Ground Rotational State Preparation James Dragan, Ivan O Antonov, Brian C Odom State preparation of molecules is a crucial first step in experiments of metrology, fundamental physics, and quantum information. Recently, control over the quantum states of SiO+ has been demonstrated1,2. With an X, A, and B electronic state structure, spectral filtering of light that cycles population between the X and B states can lead to ground or excited rotational state preparation. Here, we present our results modeling the state population dynamics involved. Our results indicate that the electronic A state aids in this process by acting as a pathway for parity flipping. By simulating the rotational population as a function of time, we fit the rates at which rotational state parity is changed and match this to the experiment1. We find the B-A branching is likely stronger than predicted and in fact beneficial when optical pumping to the ground rotational state. Relevant timescales of other processes that affect state population are modeled and shown, providing a near complete description of optical pumping in SiO+. |
Friday, June 3, 2022 9:12AM - 9:24AM |
X08.00007: Strong ortho/para effect in the predissociation spectra of the 35Cl-(H2) complex and its isotopologue 35Cl-(D2) recently measured in an ionic trap at low temperature thierry stoecklin, Miguel Lara Moreno, philippe Halvick The predissociation spectra of the 35Cl-(H2) and 35Cl-(D2) complexes are determined within an accurate quantum approach and compared to those recently measured in an ionic trap at 8 K and 22 K. [1,2,3] The calculations are performed using an existing three-dimensional potential energy surface [4]. A variational approach is used for the accurate quantum calculations of the rovibrational bound states. Several methods are compared for the search and the characterization of the resonant states. A good agreement between the calculated and measured spectra is obtained, despite a slight shift to the red of the calculated spectra. The comparison shows that only the ortho or para contribution is observed in the measured 35Cl-(H2) or 35Cl-(D2) spectrum, respectively. This result is attributed to the rapid para <-> ortho conversion of the complexes by collision with H2 or D2 molecules inside the trap at low temperature. Quantum numbers are assigned to the rovibrational resonant states. It demonstrates that the main features observed in the measured predissociation spectra correspond to a progression in the intermonomer vibrational stretching mode. |
Friday, June 3, 2022 9:24AM - 9:36AM |
X08.00008: Quantum state tracking and control of a single molecular ion in a thermal environment Yu Liu, Julian Schmidt, David Leibrandt, Dietrich Leibfried, Chin-wen Chou Over the past decade, cold molecular ions have emerged as a powerful platform for precision spectroscopy, controlled chemistry, and quantum information, yet the efficient control of their quantum states remains challenging. Recently, the use of quantum-logic spectroscopy (QLS), which maps information between a molecular ion and a motionally-coupled atomic ion, has enabled the state preparation/detection and coherent manipulation of diatomic ions [C.-W. Chou et al., Nature 545, 203 (2017)]. While QLS can project a molecular ion into a pure state, it only does so probabilistically. At room temperature, one must contend with the statistical population of hundreds to thousands of molecular states driven by black-body radiation. Here, we demonstrate a protocol to trap the population of a single CaH+ ion in its ground state |X1Σ, v = 0, J = 0〉against the effects of thermal depopulation. Through repeated detection of population in |J = 1〉, we can catch and reverse the population driven out of |J = 0〉, thus effectively extending the lifetime of the |J = 0〉 state. We also show that the improved state control can lead to substantially higher data rates for precision spectroscopy. The generalizability of this protocol makes it a valuable tool for controlling larger molecular species. |
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