1
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Mandal B, Croft JFE, Jambrina PG, Guo H, Aoiz FJ, Balakrishnan N. Stereodynamical control of cold HD + D 2 collisions. Phys Chem Chem Phys 2024; 26:18368-18381. [PMID: 38912616 DOI: 10.1039/d4cp01737d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/25/2024]
Abstract
We report full-dimensional quantum calculations of stereodynamic control of HD(v = 1, j = 2) + D2 collisions that has been probed experimentally by Perreault et al. using the Stark-induced adiabatic Raman passage (SARP) technique. Computations were performed on two highly accurate full-dimensional H4 potential energy surfaces. It is found that for both potential surfaces, rotational quenching of HD from with concurrent rotational excitation of D2 from is the dominant transition with cross sections four times larger than that of elastically scattered D2 for the same quenching transition in HD. This process was not considered in the original analysis of the SARP experiments that probed ΔjHD = -2 transitions in HD(vHD = 1, jHD = 2) + D2 collisions. Cross sections are characterized by an l = 3 resonance for ortho-D2(jD2 = 0) collisions, while both l = 1 and l = 3 resonances are observed for the para-D2(jD2 = 1) partner. While our results are in excellent agreement with prior measurements of elastic and inelastic differential cross sections, the agreement is less satisfactory with the SARP experiments, in particular for the transition for which the theoretical calculations indicate that D2 rotational excitation channel is the dominant inelastic process.
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Affiliation(s)
- Bikramaditya Mandal
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154, USA.
| | - James F E Croft
- Department of Chemistry, Durham University, South Road, Durham, DH1 3LE, UK
| | - Pablo G Jambrina
- Departamento de Química Física, University of Salamanca, Salamanca 37008, Spain
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - F Javier Aoiz
- Departamento de Química Física, Universidad Complutense, Madrid 28040, Spain
| | - Naduvalath Balakrishnan
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154, USA.
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2
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Mao L, Liu J, Habibulla N, Qiu Y. Experimental study of rotational relaxation for D2(1,12) in collisions with N2. J Chem Phys 2024; 160:154305. [PMID: 38624121 DOI: 10.1063/5.0197067] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Accepted: 03/28/2024] [Indexed: 04/17/2024] Open
Abstract
The rotational relaxation behavior of D2(1,12) in a D2-N2 mixture was investigated using coherent anti-Stokes Raman scattering (CARS) technique. The rovibrational level v = 1 and J = 12 of D2 was selectively excited through stimulated Raman pumping while monitoring the temporal evolution of population for D2(1, J ≤ 12) molecules using time-resolved CARS spectroscopy. The results demonstrate that the rotational relaxation processes of D2(1,12) encompass both multi-quantum relaxation and continuous single-quantum relaxation. When α, the molar ratio of N2, is less than 0.5, D2(1,12) predominantly undergoes a single quantum relaxation process transition. However, when α ≥ 0.5, the multi-quantum relaxation mechanism gradually predominates. The total rotational relaxation rate coefficients of D2(1,12) collisions with N2 and D2 at 295 K were determined to be 3.974 × 10-14 and 1.179 × 10-14 cm3 s-1, respectively. The temperature dependence of rotational relaxation rate of D2(1,12) was investigated within the temperature range of 295-453 K. With increasing temperature, the dominant relaxation process exhibited an accelerated behavior, while the minor relaxation process remained largely unaffected. The rotational temperature of the D2 molecule at various N2 molar ratios was determined through the utilization of Boltzmann plots. The rotational temperature undergoes a rapid decline within 2 μs, corresponding to the near-resonant rotation-vibration relaxation process of D2(1,12) collisions with N2. The system reaches a quasi-equilibrium state when the delay time is 3 μs. The findings of this study can serve as a valuable empirical basis for further validation of the kinetic theory and simulation.
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Affiliation(s)
- Lin Mao
- Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830017, China
- School of Physical Science and Technology, Xinjiang University, Urumqi 830017, China
| | - Jing Liu
- Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830017, China
- School of Physical Science and Technology, Xinjiang University, Urumqi 830017, China
| | - Nurali Habibulla
- Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830017, China
- School of Physical Science and Technology, Xinjiang University, Urumqi 830017, China
| | - Yongbao Qiu
- Xinjiang Key Laboratory of Solid State Physics and Devices, Xinjiang University, Urumqi 830017, China
- School of Physical Science and Technology, Xinjiang University, Urumqi 830017, China
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3
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Jorapur V, Langin TK, Wang Q, Zheng G, DeMille D. High Density Loading and Collisional Loss of Laser-Cooled Molecules in an Optical Trap. PHYSICAL REVIEW LETTERS 2024; 132:163403. [PMID: 38701453 DOI: 10.1103/physrevlett.132.163403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2023] [Revised: 02/23/2024] [Accepted: 03/05/2024] [Indexed: 05/05/2024]
Abstract
We report optical trapping of laser-cooled molecules at sufficient density to observe molecule-molecule collisions for the first time in a bulk gas. SrF molecules from a red-detuned magneto-optical trap (MOT) are compressed and cooled in a blue-detuned MOT. Roughly 30% of these molecules are loaded into an optical dipole trap with peak number density n_{0}≈3×10^{10} cm^{-3} and temperature T≈40 μK. We observe two-body loss with rate coefficient β=2.7_{-0.8}^{+1.2}×10^{-10} cm^{3} s^{-1}. Achieving this density and temperature opens a path to evaporative cooling towards quantum degeneracy of laser-cooled molecules.
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Affiliation(s)
- Varun Jorapur
- Department of Physics, Yale University, New Haven, Connecticut 06511, USA
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Thomas K Langin
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Qian Wang
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - Geoffrey Zheng
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
| | - David DeMille
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
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4
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Zhang C, Rittenhouse ST, Tscherbul TV, Sadeghpour HR, Hutzler NR. Sympathetic Cooling and Slowing of Molecules with Rydberg Atoms. PHYSICAL REVIEW LETTERS 2024; 132:033001. [PMID: 38307061 DOI: 10.1103/physrevlett.132.033001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/06/2023] [Accepted: 12/05/2023] [Indexed: 02/04/2024]
Abstract
We propose to sympathetically slow and cool polar molecules in a cold, low-density beam using laser-cooled Rydberg atoms. The elastic collision cross sections between molecules and Rydberg atoms are large enough to efficiently thermalize the molecules even in a low-density environment. Molecules traveling at 100 m/s can be stopped in under 30 collisions with little inelastic loss. Our method does not require photon scattering from the molecules and can be generically applied to complex species for applications in precision measurement, quantum information science, and controlled chemistry.
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Affiliation(s)
- Chi Zhang
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, California 91125, USA
| | - Seth T Rittenhouse
- Department of Physics, the United States Naval Academy, Annapolis, Maryland 21402, USA
- ITAMP, Center for Astrophysics | Harvard & Smithsonian Cambridge, Massachusetts 02138, USA
| | - Timur V Tscherbul
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
| | - H R Sadeghpour
- ITAMP, Center for Astrophysics | Harvard & Smithsonian Cambridge, Massachusetts 02138, USA
| | - Nicholas R Hutzler
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, California 91125, USA
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5
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Hallas C, Vilas NB, Anderegg L, Robichaud P, Winnicki A, Zhang C, Cheng L, Doyle JM. Optical Trapping of a Polyatomic Molecule in an ℓ-Type Parity Doublet State. PHYSICAL REVIEW LETTERS 2023; 130:153202. [PMID: 37115898 DOI: 10.1103/physrevlett.130.153202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2022] [Accepted: 02/13/2023] [Indexed: 06/19/2023]
Abstract
We report optical trapping of a polyatomic molecule, calcium monohydroxide (CaOH). CaOH molecules from a magneto-optical trap are sub-Doppler laser cooled to 20(3) μK in free space and loaded into an optical dipole trap. We attain an in-trap molecule number density of 3(1)×10^{9} cm^{-3} at a temperature of 57(8) μK. Trapped CaOH molecules are optically pumped into an excited vibrational bending mode, whose ℓ-type parity doublet structure is a potential resource for a wide range of proposed quantum science applications with polyatomic molecules. We measure the spontaneous, radiative lifetime of this bending mode state to be ∼0.7 s.
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Affiliation(s)
- Christian Hallas
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Nathaniel B Vilas
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Loïc Anderegg
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Paige Robichaud
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Andrew Winnicki
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Chaoqun Zhang
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - Lan Cheng
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | - John M Doyle
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
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6
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Croft JFE, Jambrina PG, Aoiz FJ, Guo H, Balakrishnan N. Cold Collisions of Ro-Vibrationally Excited D 2 Molecules. J Phys Chem A 2023; 127:1619-1627. [PMID: 36787203 DOI: 10.1021/acs.jpca.2c08855] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/15/2023]
Abstract
The H2 + H2 system has long been considered a benchmark system for ro-vibrational energy transfer in bimolecular collisions. However, most studies thus far have focused on collisions involving H2 molecules in the ground vibrational level or in the first excited vibrational state. While H2 + H2/HD collisions have received wide attention due to the important role they play in astrophysics, D2 + D2 collisions have received much less attention. Recently, Zhou et al. [ Nat. Chem. 2022, 14, 658-663, DOI: 10.1038/s41557-022-00926-z] examined stereodynamic aspects of rotational energy transfer in collisions of two aligned D2 molecules prepared in the v = 2 vibrational level and j = 2 rotational level. Here, we report quantum calculations of rotational and vibrational energy transfer in collisions of two D2 molecules prepared in vibrational levels up to v = 2 and identify key resonance features that contribute to the angular distribution in the experimental results of Zhou et al. The quantum scattering calculations were performed in full dimensionality and using the rigid-rotor approximation using a recently developed highly accurate six-dimensional potential energy surface for the H4 system that allows descriptions of collisions involving highly vibrationally excited H2 and its isotopologues.
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Affiliation(s)
- James F E Croft
- The Dodd-Walls Centre for Photonic and Quantum Technologies, Dunedin 9016, New Zealand.,Department of Physics, University of Otago, Dunedin 9016, New Zealand
| | - Pablo G Jambrina
- Departamento de Química Física, Universidad de Salamanca, Salamanca 37008, Spain
| | - F Javier Aoiz
- Departamento de Química Física, Universidad Complutense, Madrid 28040, Spain
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - N Balakrishnan
- Department of Chemistry and Biochemistry, University of Nevada, Las Vegas, Nevada 89154, United States
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7
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Bause R, Christianen A, Schindewolf A, Bloch I, Luo XY. Ultracold Sticky Collisions: Theoretical and Experimental Status. J Phys Chem A 2023; 127:729-741. [PMID: 36624934 PMCID: PMC9884084 DOI: 10.1021/acs.jpca.2c08095] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Collisional complexes, which are formed as intermediate states in molecular collisions, are typically short-lived and decay within picoseconds. However, in ultracold collisions involving bialkali molecules, complexes can live for milliseconds, completely changing the collision dynamics. This can lead to unexpected two-body loss in samples of nonreactive molecules. During the past decade, such "sticky" collisions have been a major hindrance in the preparation of dense and stable molecular samples, especially in the quantum-degenerate regime. Currently, the behavior of the complexes is not fully understood. For example, in some cases, their lifetime has been measured to be many orders of magnitude longer than recent models predict. This is not only an intriguing problem in itself but also practically relevant, since understanding molecular complexes may help to mitigate their detrimental effects. Here, we review the recent experimental and theoretical progress in this field. We treat the case of molecule-molecule as well as molecule-atom collisions.
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Affiliation(s)
- Roman Bause
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany
| | - Arthur Christianen
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany
| | - Andreas Schindewolf
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany
| | - Immanuel Bloch
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany,Fakultät
für Physik, Ludwig-Maximilians-Universität, 80799München, Germany
| | - Xin-Yu Luo
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany,E-mail:
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8
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Sheng X, Li M, Tang KT. An accurate potential model for the a 3Σ u+ state of the lithium dimer. Phys Chem Chem Phys 2022; 24:13325-13334. [PMID: 35608033 DOI: 10.1039/d2cp01490d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An accurate Tang-Toennies (TT) model potential is introduced to describe the interatomic potential of the lithium dimer in the a3Σu+ state. With only one well-known parameter, the ionization energy, the new model potential compares favorably with the experimentally fitted Morse/Long-range (MLR) potential of Dattani and Le Roy [J. Mol. Spectrosc., 2011, 268, 199] and is in excellent agreement with the state-of-the-art ab initio potential of Lesiuk et al. [Phys. Rev. A, 2020, 102, 062806]. With the known dispersion coefficients and the ionization energy, the new potential requires only two experimental parameters, namely the depth of the potential well De and its location Re. The new potential can be extended to the region of zero separation by the united atom limit.
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Affiliation(s)
- Xiaowei Sheng
- Anhui Province Key Laboratory of Optoelectric Materials Science and Technology, Department of Physics, Anhui Normal University, Anhui, Wuhu 241000, China
| | - Mengyuan Li
- Anhui Province Key Laboratory of Optoelectric Materials Science and Technology, Department of Physics, Anhui Normal University, Anhui, Wuhu 241000, China
| | - K T Tang
- Department of Physics, Pacific Lutheran University, Tacoma, Washington, 98447, USA.
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9
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Wu LY, Miossec C, Heazlewood BR. Low-temperature reaction dynamics of paramagnetic species in the gas phase. Chem Commun (Camb) 2022; 58:3240-3254. [PMID: 35188499 PMCID: PMC8902758 DOI: 10.1039/d1cc06394d] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/12/2021] [Accepted: 01/12/2022] [Indexed: 12/12/2022]
Abstract
Radicals are abundant in a range of important gas-phase environments. They are prevalent in the atmosphere, in interstellar space, and in combustion processes. As such, understanding how radicals react is essential for the development of accurate models of the complex chemistry occurring in these gas-phase environments. By controlling the properties of the colliding reactants, we can also gain insights into how radical reactions occur on a fundamental level. Recent years have seen remarkable advances in the breadth of experimental methods successfully applied to the study of reaction dynamics involving paramagnetic species-from improvements to the well-known crossed molecular beams approach to newer techniques involving magnetically guided and decelerated beams. Coupled with ever-improving theoretical methods, quantum features are being observed and interesting insights into reaction dynamics are being uncovered in an increasingly diverse range of systems. In this highlight article, we explore some of the exciting recent developments in the study of chemical dynamics involving paramagnetic species. We focus on low-energy reactive collisions involving neutral radical species, where the reaction parameters are controlled. We conclude by identifying some of the limitations of current methods and exploring possible new directions for the field.
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Affiliation(s)
- Lok Yiu Wu
- The Oliver Lodge, Department of Physics, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, UK.
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Chloé Miossec
- The Oliver Lodge, Department of Physics, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, UK.
- Physical and Theoretical Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QZ, UK
| | - Brianna R Heazlewood
- The Oliver Lodge, Department of Physics, University of Liverpool, Oxford Street, Liverpool, L69 7ZE, UK.
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10
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Son H, Park JJ, Lu YK, Jamison AO, Karman T, Ketterle W. Control of reactive collisions by quantum interference. Science 2022; 375:1006-1010. [PMID: 35239387 DOI: 10.1126/science.abl7257] [Citation(s) in RCA: 13] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
In this study, we achieved magnetic control of reactive scattering in an ultracold mixture of 23Na atoms and 23Na6Li molecules. In most molecular collisions, particles react or are lost near short range with unity probability, leading to the so-called universal rate. By contrast, the Na + NaLi system was shown to have only ~4% loss probability in a fully spin-polarized state. By controlling the phase of the scattering wave function via a Feshbach resonance, we modified the loss rate by more than a factor of 100, from far below to far above the universal limit. The results are explained in analogy with an optical Fabry-Perot resonator by interference of reflections at short and long range. Our work demonstrates quantum control of chemistry by magnetic fields with the full dynamic range predicted by our models.
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Affiliation(s)
- Hyungmok Son
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - Juliana J Park
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yu-Kun Lu
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Alan O Jamison
- Institute for Quantum Computing and Department of Physics and Astronomy, University of Waterloo, Waterloo, Ontario N2L 3G1, Canada
| | - Tijs Karman
- Institute for Molecules and Materials, Radboud University, Heijendaalseweg 135, 6525 AJ Nijmegen, Netherlands
| | - Wolfgang Ketterle
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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11
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Wu Y, Burau JJ, Mehling K, Ye J, Ding S. High Phase-Space Density of Laser-Cooled Molecules in an Optical Lattice. PHYSICAL REVIEW LETTERS 2021; 127:263201. [PMID: 35029467 DOI: 10.1103/physrevlett.127.263201] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2021] [Accepted: 10/26/2021] [Indexed: 06/14/2023]
Abstract
We report laser cooling and trapping of yttrium monoxide molecules in an optical lattice. We show that gray molasses cooling remains exceptionally efficient for yttrium monoxide molecules inside the lattice with a molecule temperature as low as 6.1(6) μK. This approach has produced a trapped sample of 1200 molecules, with a peak spatial density of ∼1.2×10^{10} cm^{-3}, and a peak phase-space density of ∼3.1×10^{-6}. By ramping down the lattice depth, we cool the molecules further to 1.0(2) μK, 20 times colder than previously reported for laser-cooled molecules in a trap.
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Affiliation(s)
- Yewei Wu
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
| | - Justin J Burau
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
| | - Kameron Mehling
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
| | - Jun Ye
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
| | - Shiqian Ding
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
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12
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Langin TK, Jorapur V, Zhu Y, Wang Q, DeMille D. Polarization Enhanced Deep Optical Dipole Trapping of Λ-Cooled Polar Molecules. PHYSICAL REVIEW LETTERS 2021; 127:163201. [PMID: 34723596 DOI: 10.1103/physrevlett.127.163201] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/11/2021] [Revised: 08/12/2021] [Accepted: 09/09/2021] [Indexed: 06/13/2023]
Abstract
We demonstrate loading of SrF molecules into an optical dipole trap (ODT) via in-trap Λ-enhanced gray molasses cooling. We find that this cooling can be optimized by a proper choice of relative ODT and cooling beam polarizations. In this optimized configuration, we observe molecules with temperatures as low as 14(1) μK in traps with depths up to 570 μK. With optimized parameters, we transfer ∼5% of molecules from our radio-frequency magneto-optical trap into the ODT, at a density of ∼2×10^{9} cm^{-3}, a phase space density of ∼2×10^{-7}, and with a trap lifetime of ∼1 s.
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Affiliation(s)
- Thomas K Langin
- Department of Physics, Yale University, New Haven, Connecticut, Connecticut 06520, USA
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
| | - Varun Jorapur
- Department of Physics, Yale University, New Haven, Connecticut, Connecticut 06520, USA
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
| | - Yuqi Zhu
- Department of Physics, Yale University, New Haven, Connecticut, Connecticut 06520, USA
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
| | - Qian Wang
- Department of Physics, Yale University, New Haven, Connecticut, Connecticut 06520, USA
- Yale Quantum Institute, Yale University, New Haven, Connecticut 06520, USA
| | - David DeMille
- Department of Physics, University of Chicago, Chicago, Illinois 60637, USA
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13
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Hermsmeier R, Kłos J, Kotochigova S, Tscherbul TV. Quantum Spin State Selectivity and Magnetic Tuning of Ultracold Chemical Reactions of Triplet Alkali-Metal Dimers with Alkali-Metal Atoms. PHYSICAL REVIEW LETTERS 2021; 127:103402. [PMID: 34533330 DOI: 10.1103/physrevlett.127.103402] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/13/2021] [Revised: 06/29/2021] [Accepted: 07/28/2021] [Indexed: 06/13/2023]
Abstract
We demonstrate that it is possible to efficiently control ultracold chemical reactions of alkali-metal atoms colliding with open-shell alkali-metal dimers in their metastable triplet states by choosing the internal hyperfine and rovibrational states of the reactants as well as by inducing magnetic Feshbach resonances with an external magnetic field. We base these conclusions on coupled-channel statistical calculations that include the effects of hyperfine contact and magnetic-field-induced Zeeman interactions on ultracold chemical reactions of hyperfine-resolved ground-state Na and the triplet NaLi(a^{3}Σ^{+}) producing singlet Na_{2}(^{1}Σ_{g}^{+}) and a Li atom. We find that the reaction rates are sensitive to the initial hyperfine states of the reactants. The chemical reaction of fully spin-polarized, high-spin states of rotationless NaLi(a^{3}Σ^{+},v=0,N=0) molecules with fully spin-polarized Na is suppressed by a factor of 10-100 compared to that of unpolarized reactants. We interpret these findings within the adiabatic state model, which treats the reaction as a sequence of nonadiabatic transitions between the initial nonreactive high-spin state and the final low-spin states of the reaction complex. In addition, we show that magnetic Feshbach resonances can similarly change reaction rate coefficients by several orders of magnitude. Some of these resonances are due to resonant trimer bound states dissociating to the N=2 rotational state of NaLi(a^{3}Σ^{+},v=0) and would thus exist in systems without hyperfine interactions.
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Affiliation(s)
| | - Jacek Kłos
- Department of Physics, Joint Quantum Institute, University of Maryland College Park, College Park, Maryland 20742, USA
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | | | - Timur V Tscherbul
- Department of Physics, University of Nevada, Reno, Nevada 89557, USA
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