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Arrowsmith-Kron G, Athanasakis-Kaklamanakis M, Au M, Ballof J, Berger R, Borschevsky A, Breier AA, Buchinger F, Budker D, Caldwell L, Charles C, Dattani N, de Groote RP, DeMille D, Dickel T, Dobaczewski J, Düllmann CE, Eliav E, Engel J, Fan M, Flambaum V, Flanagan KT, Gaiser AN, Garcia Ruiz RF, Gaul K, Giesen TF, Ginges JSM, Gottberg A, Gwinner G, Heinke R, Hoekstra S, Holt JD, Hutzler NR, Jayich A, Karthein J, Leach KG, Madison KW, Malbrunot-Ettenauer S, Miyagi T, Moore ID, Moroch S, Navratil P, Nazarewicz W, Neyens G, Norrgard EB, Nusgart N, Pašteka LF, N Petrov A, Plaß WR, Ready RA, Pascal Reiter M, Reponen M, Rothe S, Safronova MS, Scheidenerger C, Shindler A, Singh JT, Skripnikov LV, Titov AV, Udrescu SM, Wilkins SG, Yang X. Opportunities for fundamental physics research with radioactive molecules. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2024; 87:084301. [PMID: 38215499 DOI: 10.1088/1361-6633/ad1e39] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/10/2023] [Accepted: 01/12/2024] [Indexed: 01/14/2024]
Abstract
Molecules containing short-lived, radioactive nuclei are uniquely positioned to enable a wide range of scientific discoveries in the areas of fundamental symmetries, astrophysics, nuclear structure, and chemistry. Recent advances in the ability to create, cool, and control complex molecules down to the quantum level, along with recent and upcoming advances in radioactive species production at several facilities around the world, create a compelling opportunity to coordinate and combine these efforts to bring precision measurement and control to molecules containing extreme nuclei. In this manuscript, we review the scientific case for studying radioactive molecules, discuss recent atomic, molecular, nuclear, astrophysical, and chemical advances which provide the foundation for their study, describe the facilities where these species are and will be produced, and provide an outlook for the future of this nascent field.
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Affiliation(s)
- Gordon Arrowsmith-Kron
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824, United States of America
| | - Michail Athanasakis-Kaklamanakis
- Experimental Physics Department, CERN, CH-1211 Geneva 23, Switzerland
- KU Leuven, Department of Physics and Astronomy, Instituut voor Kern- en Stralingsfysica, B-3001 Leuven, Belgium
| | - Mia Au
- CERN, Geneva, Switzerland
- Johannes Gutenberg-Universität Mainz, Mainz, Germany
| | - Jochen Ballof
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824, United States of America
- Accelerator Systems Department, CERN, 1211 Geneva 23, Switzerland
| | - Robert Berger
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Anastasia Borschevsky
- Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Groningen, The Netherlands
| | - Alexander A Breier
- Institute of Physics, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | | | - Dmitry Budker
- Helmholtz-Institut, GSI Helmholtzzentrum fur Schwerionenforschung and Johannes Gutenberg University, Mainz 55128, Germany
- Department of Physics, University of California at Berkeley, Berkeley, CA 94720-7300, United States of America
| | - Luke Caldwell
- JILA, NIST and University of Colorado, Boulder, CO 80309, United States of America
- Department of Physics, University of Colorado, Boulder, CO 80309, United States of America
| | - Christopher Charles
- TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada
- University of Western Ontario, 1151 Richmond St. N., London, Ontario N6A 5B7, Canada
| | - Nike Dattani
- HPQC Labs, Waterloo, Ontario, Canada
- HPQC College, Waterloo, Ontario, Canada
| | - Ruben P de Groote
- Instituut voor Kern- en Stralingsfysica, KU Leuven, Leuven, Belgium
- Department of Physics, University of Jyväskylä, Jyväskylä, Finland
| | - David DeMille
- University of Chicago, Chicago, IL, United States of America
- Argonne National Laboratory, Lemont, IL, United States of America
| | - Timo Dickel
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
- II. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany
| | - Jacek Dobaczewski
- School of Physics, Engineering and Technology, University of York, Heslington, York YO10 5DD, United Kingdom
- Institute of Theoretical Physics, Faculty of Physics, University of Warsaw, ul. Pasteura 5, PL-02-093 Warsaw, Poland
| | - Christoph E Düllmann
- Department of Chemistry-TRIGA Site, Johannes Gutenberg University, Fritz-Strassmann-Weg 2, 55128 Mainz, Germany
- GSI Helmholtzzentrum für Schwerionenforschung, Planckstr. 1, 64291 Darmstadt, Germany
- Helmholtz Institute Mainz, Staudingerweg 18, 55128 Mainz, Germany
| | - Ephraim Eliav
- School of Chemistry, Tel Aviv University, Ramat Aviv, Tel Aviv 69978, Israel
| | - Jonathan Engel
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, NC 27599-3255, United States of America
| | - Mingyu Fan
- Department of Physics, University of California, Santa Barbara, CA 93106, United States of America
| | | | - Kieran T Flanagan
- Photon Science Institute, Department of Physics and Astronomy, University of Manchester, Manchester M13 9PL, United Kingdom
| | - Alyssa N Gaiser
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824, United States of America
| | - Ronald F Garcia Ruiz
- Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America
| | - Konstantin Gaul
- Fachbereich Chemie, Philipps-Universität Marburg, Hans-Meerwein-Straße 4, 35032 Marburg, Germany
| | - Thomas F Giesen
- Institute of Physics, University of Kassel, Heinrich-Plett-Str. 40, 34132 Kassel, Germany
| | - Jacinda S M Ginges
- School of Mathematics and Physics, The University of Queensland, Brisbane QLD 4072, Australia
| | | | - Gerald Gwinner
- Department of Physics and Astronomy, University of Manitoba, Winnipeg, MB R3T 3M9, Canada
| | | | - Steven Hoekstra
- Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Groningen, The Netherlands
- Nikhef, National Institute for Subatomic Physics, Amsterdam, The Netherlands
| | - Jason D Holt
- TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada
- Department of Physics, McGill University, Montreal, QC H3A 2T8, Canada
| | - Nicholas R Hutzler
- California Institute of Technology, Pasadena, CA 91125, United States of America
| | - Andrew Jayich
- Department of Physics, University of California, Santa Barbara, CA 93106, United States of America
| | - Jonas Karthein
- Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America
| | - Kyle G Leach
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824, United States of America
- Colorado School of Mines, Golden, CO 80401, United States of America
| | - Kirk W Madison
- Department of Physics and Astronomy, University of British Columbia, Vancouver, BC V6T1Z1, Canada
| | - Stephan Malbrunot-Ettenauer
- TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada
- Department of Physics, University of Toronto, 60 St. George St., Toronto, Ontario, Canada
| | | | - Iain D Moore
- Accelerator Laboratory, Department of Physics, University of Jyväskylä, Jyväskylä 40014, Finland
| | - Scott Moroch
- Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America
| | - Petr Navratil
- TRIUMF, 4004 Wesbrook Mall, Vancouver, BC V6T 2A3, Canada
| | - Witold Nazarewicz
- Facility for Rare Isotope Beams and Department of Physics and Astronomy, Michigan State University, East Lansing, MI 48824, United States of America
| | - Gerda Neyens
- KU Leuven, Department of Physics and Astronomy, Instituut voor Kern- en Stralingsfysica, B-3001 Leuven, Belgium
| | - Eric B Norrgard
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, United States of America
| | - Nicholas Nusgart
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI 48824, United States of America
| | - Lukáš F Pašteka
- Van Swinderen Institute for Particle Physics and Gravity, University of Groningen, Groningen, The Netherlands
- Department of Physical and Theoretical Chemistry, Faculty of Natural Sciences, Comenius University, Bratislava, Slovakia
| | - Alexander N Petrov
- Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Center 'Kurchatov Institute' (NRC 'Kurchatov Institute'-PNPI), 1 Orlova roscha mcr., Gatchina 188300, Leningrad Region, Russia
- Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Wolfgang R Plaß
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
- II. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany
| | - Roy A Ready
- Department of Physics, University of California, Santa Barbara, CA 93106, United States of America
| | - Moritz Pascal Reiter
- School of Physics & Astronomy, The University of Edinburgh, Peter Guthrie Tait Road, EH9 3FD Edinburgh, United Kingdom
| | - Mikael Reponen
- Accelerator Laboratory, Department of Physics, University of Jyväskylä, Jyväskylä 40014, Finland
| | | | - Marianna S Safronova
- Department of Physics and Astronomy, University of Delaware, Newark, DE 19716, United States of America
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, MD 20742, United States of America
| | - Christoph Scheidenerger
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, 64291 Darmstadt, Germany
- II. Physikalisches Institut, Justus-Liebig-Universität Gießen, 35392 Gießen, Germany
- Helmholtz Forschungsakademie Hessen für FAIR (HFHF), Campus Gießen, Gießen, Germany
| | - Andrea Shindler
- Facility for Rare Isotope Beams & Physics Department, Michigan State University, East Lansing, MI 48824, United States of America
| | - Jaideep T Singh
- Facility for Rare Isotope Beams, Michigan State University, East Lansing, MI, United States of America
| | - Leonid V Skripnikov
- Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Center 'Kurchatov Institute' (NRC 'Kurchatov Institute'-PNPI), 1 Orlova roscha mcr., Gatchina 188300, Leningrad Region, Russia
- Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Anatoly V Titov
- Petersburg Nuclear Physics Institute named by B.P. Konstantinov of National Research Center 'Kurchatov Institute' (NRC 'Kurchatov Institute'-PNPI), 1 Orlova roscha mcr., Gatchina 188300, Leningrad Region, Russia
- Saint Petersburg State University, 7/9 Universitetskaya nab., St. Petersburg 199034, Russia
| | - Silviu-Marian Udrescu
- Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America
| | - Shane G Wilkins
- Massachusetts Institute of Technology, Cambridge, MA 02139, United States of America
| | - Xiaofei Yang
- School of Physics and State Key Laboratory of Nuclear Physics and Technology, Peking University, Beijing 100871, People's Republic of China
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2
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Li SJ, Holland CM, Lu Y, Cheuk LW. Blue-Detuned Magneto-optical Trap of CaF Molecules. PHYSICAL REVIEW LETTERS 2024; 132:233402. [PMID: 38905654 DOI: 10.1103/physrevlett.132.233402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 05/14/2024] [Indexed: 06/23/2024]
Abstract
A key method to produce trapped and laser-cooled molecules is the magneto-optical trap (MOT), which is conventionally created using light red detuned from an optical transition. In this work, we report a MOT for CaF molecules created using blue-detuned light. The blue-detuned MOT (BDM) achieves temperatures well below the Doppler limit and provides the highest densities and phase-space densities reported to date in CaF MOTs. Our results suggest that BDMs are likely achievable in many relatively light molecules including polyatomic ones, but our measurements suggest that BDMs will be challenging to realize in substantially heavier molecules due to sub-mK trap depths. In addition to record temperatures and densities, we find that the BDM substantially simplifies and enhances the loading of molecules into optical tweezer arrays, which are a promising platform for quantum simulation and quantum information processing. Notably, the BDM reduces molecular number requirements ninefold compared to a conventional red-detuned MOT, while not requiring additional hardware. Our work therefore substantially simplifies preparing large-scale molecular tweezer arrays, which are a novel platform for simulation of quantum many-body dynamics and quantum information processing with molecular qubits.
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3
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Walraven EF, Tarbutt MR, Karman T. Scheme for Deterministic Loading of Laser-Cooled Molecules into Optical Tweezers. PHYSICAL REVIEW LETTERS 2024; 132:183401. [PMID: 38759201 DOI: 10.1103/physrevlett.132.183401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2024] [Accepted: 03/27/2024] [Indexed: 05/19/2024]
Abstract
We propose to repeatedly load laser-cooled molecules into optical tweezers, and transfer them to storage states that are rotationally excited by two additional quanta. Collisional loss of molecules in these storage states is suppressed, and a dipolar blockade prevents the accumulation of more than one molecule. Applying three cycles loads tweezers with single molecules at an 80% success rate, limited by residual collisional loss. This improved loading efficiency reduces the time needed for rearrangement of tweezer arrays, which would otherwise limit the scalability of neutral molecule quantum computers.
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Affiliation(s)
- Etienne F Walraven
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - Michael R Tarbutt
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - Tijs Karman
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
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4
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Holland CM, Lu Y, Cheuk LW. Bichromatic Imaging of Single Molecules in an Optical Tweezer Array. PHYSICAL REVIEW LETTERS 2023; 131:053202. [PMID: 37595242 DOI: 10.1103/physrevlett.131.053202] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 07/04/2023] [Indexed: 08/20/2023]
Abstract
We report on a novel bichromatic fluorescent imaging scheme for background-free detection of single CaF molecules trapped in an optical tweezer array. By collecting fluorescence on one optical transition while using another for laser cooling, we achieve an imaging fidelity of 97.7(2)% and a nondestructive detection fidelity of 95.5(6)%. Notably, these fidelities are achieved with a modest photon budget, suggesting that the method could be extended to more complex laser-coolable molecules with less favorable optical cycling properties. We also report on a framework and new methods to characterize various loss mechanisms that occur generally during fluorescent detection of trapped molecules, including two-photon decay and admixtures of higher excited states that are induced by the trapping light. In particular, we develop a novel method to dispersively measure transition matrix elements between electronically excited states. The method could also be used to measure arbitrarily small Franck-Condon factors between electronically excited states, which could significantly aid in ongoing efforts to laser cool complex polyatomic molecules.
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Affiliation(s)
- Connor M Holland
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Yukai Lu
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Lawrence W Cheuk
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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5
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Zhang C, Hutzler NR, Cheng L. Intensity-Borrowing Mechanisms Pertinent to Laser Cooling of Linear Polyatomic Molecules. J Chem Theory Comput 2023. [PMID: 37384588 DOI: 10.1021/acs.jctc.3c00408] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/01/2023]
Abstract
A study of the intensity-borrowing mechanisms important to optical cycling transitions in laser-coolable polyatomic molecules arising from non-adiabatic coupling, contributions beyond the Franck-Condon approximation, and Fermi resonances is reported. It has been shown to be necessary to include non-adiabatic coupling to obtain computational accuracy that is sufficient to be useful for laser cooling of molecules. The predicted vibronic branching ratios using perturbation theory based on the non-adiabatic mechanisms have been demonstrated to agree well with those obtained from variational discrete variable representation calculations for representative molecules including CaOH, SrOH, and YbOH. The electron-correlation and basis-set effects on the calculated transition properties, including the vibronic coupling constants, the spin-orbit coupling matrix elements, and the transition dipole moments, and on the calculated branching ratios have been thoroughly studied. The vibronic branching ratios predicted using the present methodologies demonstrate that RaOH is a promising radioactive molecule candidate for laser cooling.
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Affiliation(s)
- Chaoqun Zhang
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
| | - Nicholas R Hutzler
- Division of Physics, Mathematics, and Astronomy, California Institute of Technology, Pasadena, California 91125, United States
| | - Lan Cheng
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, United States
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6
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Gao Y, Wang X, Yu N, Wong BM. Harnessing deep reinforcement learning to construct time-dependent optimal fields for quantum control dynamics. Phys Chem Chem Phys 2022; 24:24012-24020. [PMID: 36128792 DOI: 10.1039/d2cp02495k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We present an efficient deep reinforcement learning (DRL) approach to automatically construct time-dependent optimal control fields that enable desired transitions in dynamical chemical systems. Our DRL approach gives impressive performance in constructing optimal control fields, even for cases that are difficult to converge with existing gradient-based approaches. We provide a detailed description of the algorithms and hyperparameters as well as performance metrics for our DRL-based approach. Our results demonstrate that DRL can be employed as an effective artificial intelligence approach to efficiently and autonomously design control fields in quantum dynamical chemical systems.
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Affiliation(s)
- Yuanqi Gao
- Department of Electrical and Computer Engineering, University of California-Riverside, Riverside, CA, USA
| | - Xian Wang
- Department of Physics and Astronomy, University of California-Riverside, Riverside, CA, USA
| | - Nanpeng Yu
- Department of Electrical and Computer Engineering, University of California-Riverside, Riverside, CA, USA.
| | - Bryan M Wong
- Department of Chemical and Environmental Engineering, Materials Science and Engineering Program, Department of Chemistry, and Department of Physics and Astronomy, University of California-Riverside, Riverside, CA, USA.
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7
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Lu Y, Holland CM, Cheuk LW. Molecular Laser Cooling in a Dynamically Tunable Repulsive Optical Trap. PHYSICAL REVIEW LETTERS 2022; 128:213201. [PMID: 35687464 DOI: 10.1103/physrevlett.128.213201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2021] [Revised: 03/31/2022] [Accepted: 05/03/2022] [Indexed: 06/15/2023]
Abstract
Recent work with laser-cooled molecules in attractive optical traps has shown that the differential ac Stark shifts arising from the trap light itself can become problematic, limiting collisional shielding efficiencies, rotational coherence times, and laser-cooling temperatures. In this Letter, we explore trapping and laser cooling of CaF molecules in a ring-shaped repulsive optical trap. The observed dependences of loss rates on temperature and barrier height show characteristic behavior of repulsive traps and indicate strongly suppressed average ac Stark shifts. Within the trap, we find that Λ-enhanced gray molasses cooling is effective, producing similar minimum temperatures as those obtained in free space. By combining in-trap laser cooling with dynamical reshaping of the trap, we also present a method that allows highly efficient and rapid transfer from molecular magneto-optical traps into conventional attractive optical traps, which has been an outstanding challenge for experiments to date. Notably, our method could allow nearly lossless transfer over millisecond timescales.
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Affiliation(s)
- Yukai Lu
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
- Department of Electrical and Computer Engineering, Princeton University, Princeton, New Jersey 08544, USA
| | - Connor M Holland
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Lawrence W Cheuk
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
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8
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Koller M, Jung F, Phrompao J, Zeppenfeld M, Rabey IM, Rempe G. Electric-Field-Controlled Cold Dipolar Collisions between Trapped CH_{3}F Molecules. PHYSICAL REVIEW LETTERS 2022; 128:203401. [PMID: 35657871 DOI: 10.1103/physrevlett.128.203401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2022] [Accepted: 04/21/2022] [Indexed: 06/15/2023]
Abstract
Reaching high densities is a key step toward cold-collision experiments with polyatomic molecules. We use a cryofuge to load up to 2×10^{7} CH_{3}F molecules into a boxlike electric trap, achieving densities up to 10^{7}/cm^{3} at temperatures around 350 mK where the elastic dipolar cross section exceeds 7×10^{-12} cm^{2}. We measure inelastic rate constants below 4×10^{-8} cm^{3}/s and control these by tuning a homogeneous electric field that covers a large fraction of the trap volume. Comparison to ab initio calculations gives excellent agreement with dipolar relaxation. Our techniques and findings are generic and immediately relevant for other cold-molecule collision experiments.
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Affiliation(s)
- M Koller
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - F Jung
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - J Phrompao
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - M Zeppenfeld
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - I M Rabey
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
| | - G Rempe
- Max-Planck-Institut für Quantenoptik, Hans-Kopfermann-Strasse 1, 85748 Garching, Germany
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9
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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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10
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Zhang C, Augenbraun BL, Lasner ZD, Vilas NB, Doyle JM, Cheng L. Accurate prediction and measurement of vibronic branching ratios for laser cooling linear polyatomic molecules. J Chem Phys 2021; 155:091101. [PMID: 34496585 DOI: 10.1063/5.0063611] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
We report a generally applicable computational and experimental approach to determine vibronic branching ratios in linear polyatomic molecules to the 10-5 level, including for nominally symmetry-forbidden transitions. These methods are demonstrated in CaOH and YbOH, showing approximately two orders of magnitude improved sensitivity compared with the previous state of the art. Knowledge of branching ratios at this level is needed for the successful deep laser cooling of a broad range of molecular species.
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Affiliation(s)
- Chaoqun Zhang
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
| | | | - Zack D Lasner
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Nathaniel B Vilas
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - John M Doyle
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Lan Cheng
- Department of Chemistry, The Johns Hopkins University, Baltimore, Maryland 21218, USA
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11
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Anderegg L, Burchesky S, Bao Y, Yu SS, Karman T, Chae E, Ni KK, Ketterle W, Doyle JM. Observation of microwave shielding of ultracold molecules. Science 2021; 373:779-782. [PMID: 34385393 DOI: 10.1126/science.abg9502] [Citation(s) in RCA: 32] [Impact Index Per Article: 10.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2021] [Accepted: 07/07/2021] [Indexed: 11/03/2022]
Abstract
Harnessing the potential wide-ranging quantum science applications of molecules will require control of their interactions. Here, we used microwave radiation to directly engineer and tune the interaction potentials between ultracold calcium monofluoride (CaF) molecules. By merging two optical tweezers, each containing a single molecule, we probed collisions in three dimensions. The correct combination of microwave frequency and power created an effective repulsive shield, which suppressed the inelastic loss rate by a factor of six, in agreement with theoretical calculations. The demonstrated microwave shielding shows a general route to the creation of long-lived, dense samples of ultracold polar molecules and evaporative cooling.
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Affiliation(s)
- Loïc Anderegg
- Department of Physics, Harvard University, Cambridge, MA, USA. .,Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
| | - Sean Burchesky
- Department of Physics, Harvard University, Cambridge, MA, USA.,Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
| | - Yicheng Bao
- Department of Physics, Harvard University, Cambridge, MA, USA.,Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
| | - Scarlett S Yu
- Department of Physics, Harvard University, Cambridge, MA, USA.,Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
| | - Tijs Karman
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, USA.,Radboud University, Institute for Molecules and Materials, Heijendaalseweg 135, 6525 AJ Nijmegen, Netherlands
| | - Eunmi Chae
- Department of Physics, Korea University, Seongbuk-gu, Seoul, Republic of Korea
| | - Kang-Kuen Ni
- Department of Physics, Harvard University, Cambridge, MA, USA.,Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA.,Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA, USA
| | - Wolfgang Ketterle
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA.,Department of Physics, Massachusetts Institute of Technology, Cambridge, MA, USA
| | - John M Doyle
- Department of Physics, Harvard University, Cambridge, MA, USA.,Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
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12
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Heazlewood BR. Quantum-State Control and Manipulation of Paramagnetic Molecules with Magnetic Fields. Annu Rev Phys Chem 2021; 72:353-373. [PMID: 33492979 DOI: 10.1146/annurev-physchem-090419-053842] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
Since external magnetic fields were first employed to deflect paramagnetic atoms in 1921, a range of magnetic field-based methods have been introduced to state-selectively manipulate paramagnetic species. These methods include magnetic guides, which selectively filter paramagnetic species from all other components of a beam, and magnetic traps, where paramagnetic species can be spatially confined for extended periods of time. However, many of these techniques were developed for atomic-rather than molecular-paramagnetic species. It has proven challenging to apply some of these experimental methods developed for atoms to paramagnetic molecules. Thanks to the emergence of new experimental approaches and new combinations of existing techniques, the past decade has seen significant progress toward the manipulation and control of paramagnetic molecules. This review identifies the key methods that have been implemented for the state-selective manipulation of paramagnetic molecules-discussing the motivation, state of the art, and future prospects of the field. Key applications include the ability to control chemical interactions, undertake precise spectroscopic measurements, and challenge our understanding of chemical reactivity at a fundamental level.
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13
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Jurgilas S, Chakraborty A, Rich CJH, Caldwell L, Williams HJ, Fitch NJ, Sauer BE, Frye MD, Hutson JM, Tarbutt MR. Collisions between Ultracold Molecules and Atoms in a Magnetic Trap. PHYSICAL REVIEW LETTERS 2021; 126:153401. [PMID: 33929220 DOI: 10.1103/physrevlett.126.153401] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/05/2021] [Revised: 02/19/2021] [Accepted: 03/04/2021] [Indexed: 06/12/2023]
Abstract
We prepare mixtures of ultracold CaF molecules and Rb atoms in a magnetic trap and study their inelastic collisions. When the atoms are prepared in the spin-stretched state and the molecules in the spin-stretched component of the first rotationally excited state, they collide inelastically with a rate coefficient k_{2}=(6.6±1.5)×10^{-11} cm^{3}/s at temperatures near 100 μK. We attribute this to rotation-changing collisions. When the molecules are in the ground rotational state we see no inelastic loss and set an upper bound on the spin-relaxation rate coefficient of k_{2}<5.8×10^{-12} cm^{3}/s with 95% confidence. We compare these measurements to the results of a single-channel loss model based on quantum defect theory. The comparison suggests a short-range loss parameter close to unity for rotationally excited molecules, but below 0.04 for molecules in the rotational ground state.
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Affiliation(s)
- S Jurgilas
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - A Chakraborty
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - C J H Rich
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - L Caldwell
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - H J Williams
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - N J Fitch
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - B E Sauer
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - Matthew D Frye
- Joint Quantum Centre (JQC) Durham-Newcastle, Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Jeremy M Hutson
- Joint Quantum Centre (JQC) Durham-Newcastle, Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - M R Tarbutt
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
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14
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Gong T, Ji Z, Du J, Zhao Y, Xiao L, Jia S. Microwave-assisted coherent control of ultracold polar molecules in a ladder-type configuration of rotational states. Phys Chem Chem Phys 2021; 23:4271-4276. [PMID: 33587738 DOI: 10.1039/d1cp00202c] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We demonstrate microwave-assisted coherent control of ultracold 85Rb133Cs molecules in a ladder-type configuration of rotational states. Specifically, we use a probe and a control MW field to address the transitions between the J = 1 → 2 and J = 2 → 3 rotational states of the X1Σ+(v = 0) vibrational level, respectively, and use the control field to modify the response of the probe MW transition by coherently reducing the population of the intermediate J = 2 state. We observe that an increased Rabi frequency of the control field leads to broadening of the probe spectrum splitting and a shift of the central frequency. We apply Akaike's information criterion (AIC) to conclude that the observed coherent spectral response appears across the crossover regime between electromagnetically induced transparency and Aulter-Townes splitting. Our work is a significant development in microwave-assisted quantum control of ultracold polar molecules with multilevel configuration.
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Affiliation(s)
- Ting Gong
- Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Wucheng Rd 92, 030006 Taiyuan, China. and Shanxi University, Collaborative Innovation Center of Extreme Optics, Wucheng Rd 92, 030006 Taiyuan, China
| | - Zhonghua Ji
- Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Wucheng Rd 92, 030006 Taiyuan, China. and Shanxi University, Collaborative Innovation Center of Extreme Optics, Wucheng Rd 92, 030006 Taiyuan, China
| | - Jiaqi Du
- Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Wucheng Rd 92, 030006 Taiyuan, China. and Shanxi University, Collaborative Innovation Center of Extreme Optics, Wucheng Rd 92, 030006 Taiyuan, China
| | - Yanting Zhao
- Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Wucheng Rd 92, 030006 Taiyuan, China. and Shanxi University, Collaborative Innovation Center of Extreme Optics, Wucheng Rd 92, 030006 Taiyuan, China
| | - Liantuan Xiao
- Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Wucheng Rd 92, 030006 Taiyuan, China. and Shanxi University, Collaborative Innovation Center of Extreme Optics, Wucheng Rd 92, 030006 Taiyuan, China
| | - Suotang Jia
- Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Wucheng Rd 92, 030006 Taiyuan, China. and Shanxi University, Collaborative Innovation Center of Extreme Optics, Wucheng Rd 92, 030006 Taiyuan, China
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15
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Abstract
The prospect of cooling matter down to temperatures that are close to absolute zero raises intriguing questions about how chemical reactivity changes under these extreme conditions. Although some types of chemical reaction still occur at 1 μK, they can no longer adhere to the conventional picture of reactants passing over an activation energy barrier to become products. Indeed, at ultracold temperatures, the system enters a fully quantum regime, and quantum mechanics replaces the classical picture of colliding particles. In this Review, we discuss recent experimental and theoretical developments that allow us to explore chemical reactions at temperatures that range from 100 K to 500 nK. Although the field is still in its infancy, exceptional control has already been demonstrated over reactivity at low temperatures.
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16
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Caldwell L, Tarbutt MR. Enhancing Dipolar Interactions between Molecules Using State-Dependent Optical Tweezer Traps. PHYSICAL REVIEW LETTERS 2020; 125:243201. [PMID: 33412074 DOI: 10.1103/physrevlett.125.243201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/07/2020] [Accepted: 11/02/2020] [Indexed: 06/12/2023]
Abstract
We show how state-dependent optical potentials can be used to trap a pair of molecules in different internal states at a separation much smaller than the wavelength of the trapping light. This close spacing greatly enhances the dipole-dipole interaction and we show how it can be used to implement two-qubit gates between molecules that are 100 times faster than existing protocols and than rotational coherence times already demonstrated. We analyze complications due to hyperfine structure, tensor light shifts, photon scattering, and collisional loss, and conclude that none is a barrier to implementing the scheme.
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Affiliation(s)
- L Caldwell
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - M R Tarbutt
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
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17
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Wang X, Kumar A, Shelton CR, Wong BM. Harnessing deep neural networks to solve inverse problems in quantum dynamics: machine-learned predictions of time-dependent optimal control fields. Phys Chem Chem Phys 2020; 22:22889-22899. [PMID: 32935687 DOI: 10.1039/d0cp03694c] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Inverse problems continue to garner immense interest in the physical sciences, particularly in the context of controlling desired phenomena in non-equilibrium systems. In this work, we utilize a series of deep neural networks for predicting time-dependent optimal control fields, E(t), that enable desired electronic transitions in reduced-dimensional quantum dynamical systems. To solve this inverse problem, we investigated two independent machine learning approaches: (1) a feedforward neural network for predicting the frequency and amplitude content of the power spectrum in the frequency domain (i.e., the Fourier transform of E(t)), and (2) a cross-correlation neural network approach for directly predicting E(t) in the time domain. Both of these machine learning methods give complementary approaches for probing the underlying quantum dynamics and also exhibit impressive performance in accurately predicting both the frequency and strength of the optimal control field. We provide detailed architectures and hyperparameters for these deep neural networks as well as performance metrics for each of our machine-learned models. From these results, we show that machine learning, particularly deep neural networks, can be employed as cost-effective statistical approaches for designing electromagnetic fields to enable desired transitions in these quantum dynamical systems.
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Affiliation(s)
- Xian Wang
- Department of Physics & Astronomy, University of California-Riverside, Riverside, CA 92521, USA
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18
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Jansen P, Merkt F. Manipulating beams of paramagnetic atoms and molecules using inhomogeneous magnetic fields. PROGRESS IN NUCLEAR MAGNETIC RESONANCE SPECTROSCOPY 2020; 120-121:118-148. [PMID: 33198967 DOI: 10.1016/j.pnmrs.2020.08.002] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/29/2020] [Revised: 08/07/2020] [Accepted: 08/10/2020] [Indexed: 06/11/2023]
Abstract
We review methods to manipulate the motion of pulsed supersonic atomic and molecular beams using time-independent and -dependent inhomogeneous magnetic fields. In addition, we discuss current and possible future applications and research directions.
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Affiliation(s)
- Paul Jansen
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland.
| | - Frédéric Merkt
- Laboratory of Physical Chemistry, ETH Zurich, CH-8093 Zurich, Switzerland
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19
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Cheuk LW, Anderegg L, Bao Y, Burchesky S, Yu SS, Ketterle W, Ni KK, Doyle JM. Observation of Collisions between Two Ultracold Ground-State CaF Molecules. PHYSICAL REVIEW LETTERS 2020; 125:043401. [PMID: 32794819 DOI: 10.1103/physrevlett.125.043401] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/04/2020] [Revised: 05/07/2020] [Accepted: 06/29/2020] [Indexed: 06/11/2023]
Abstract
We measure inelastic collisions between ultracold CaF molecules by combining two optical tweezers, each containing a single molecule. We observe collisions between ^{2}Σ CaF molecules in the absolute ground state |X,v=0,N=0,F=0⟩, and in excited hyperfine and rotational states. In the absolute ground state, we find a two-body loss rate of 7(4)×10^{-11} cm^{3}/s, which is below, but close to, the predicted universal loss rate.
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Affiliation(s)
- Lawrence W Cheuk
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Princeton University, Princeton, New Jersey 08544, USA
| | - Loïc Anderegg
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Yicheng Bao
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Sean Burchesky
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Scarlett S Yu
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Wolfgang Ketterle
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Kang-Kuen Ni
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, 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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20
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Ji Z, Gong T, He Y, Hutson JM, Zhao Y, Xiao L, Jia S. Microwave coherent control of ultracold ground-state molecules formed by short-range photoassociation. Phys Chem Chem Phys 2020; 22:13002-13007. [PMID: 32478355 DOI: 10.1039/d0cp01191f] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We report the observation of microwave coherent control of rotational states of ultracold 85Rb133Cs molecules formed in their vibronic ground state by short-range photoassociation. Molecules are formed in the single rotational state X(v = 0, J = 1) by exciting pairs of atoms to the short-range state (2)3Π0-(v = 11, J = 0), followed by spontaneous decay. We use depletion spectroscopy to record the dynamic evolution of the population distribution and observe clear Rabi oscillations while irradiating on a microwave transition between coupled neighbouring rotational levels. A density-matrix formalism that accounts for longitudinal and transverse decay times reproduces both the dynamic evolution during the coherent process and the equilibrium population. The coherent control reported here is valuable both for investigating coherent quantum effects and for applications of cold polar molecules produced by continuous short-range photoassociation.
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Affiliation(s)
- Zhonghua Ji
- Shanxi University, State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Wucheng Rd. 92, 030006 Taiyuan, China.
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21
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Gregory PD, Blackmore JA, Bromley SL, Cornish SL. Loss of Ultracold ^{87}Rb^{133}Cs Molecules via Optical Excitation of Long-Lived Two-Body Collision Complexes. PHYSICAL REVIEW LETTERS 2020; 124:163402. [PMID: 32383932 DOI: 10.1103/physrevlett.124.163402] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2020] [Accepted: 03/27/2020] [Indexed: 06/11/2023]
Abstract
We show that the lifetime of ultracold ground-state ^{87}Rb^{133}Cs molecules in an optical trap is limited by fast optical excitation of long-lived two-body collision complexes. We partially suppress this loss mechanism by applying square-wave modulation to the trap intensity, such that the molecules spend 75% of each modulation cycle in the dark. By varying the modulation frequency, we show that the lifetime of the collision complex is 0.53±0.06 ms in the dark. We find that the rate of optical excitation of the collision complex is 3_{-2}^{+4}×10^{3} W^{-1} cm^{2} s^{-1} for λ=1550 nm, leading to a lifetime of <100 ns for typical trap intensities. These results explain the two-body loss observed in experiments on nonreactive bialkali molecules.
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Affiliation(s)
- Philip D Gregory
- Department of Physics, Joint Quantum Centre (JQC) Durham-Newcastle, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Jacob A Blackmore
- Department of Physics, Joint Quantum Centre (JQC) Durham-Newcastle, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Sarah L Bromley
- Department of Physics, Joint Quantum Centre (JQC) Durham-Newcastle, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - Simon L Cornish
- Department of Physics, Joint Quantum Centre (JQC) Durham-Newcastle, Durham University, South Road, Durham DH1 3LE, United Kingdom
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22
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Baum L, Vilas NB, Hallas C, Augenbraun BL, Raval S, Mitra D, Doyle JM. 1D Magneto-Optical Trap of Polyatomic Molecules. PHYSICAL REVIEW LETTERS 2020; 124:133201. [PMID: 32302203 DOI: 10.1103/physrevlett.124.133201] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/29/2020] [Accepted: 03/09/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate a 1D magneto-optical trap of the polar free radical calcium monohydroxide (CaOH). A quasiclosed cycling transition is established to scatter ∼10^{3} photons per molecule, predominantly limited by interaction time. This enables radiative laser cooling of CaOH while compressing the molecular beam, leading to a significant increase in on axis beam brightness and reduction in temperature from 8.4 to 1.4 mK.
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Affiliation(s)
- Louis Baum
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Nathaniel B Vilas
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Christian Hallas
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Benjamin L Augenbraun
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Shivam Raval
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Debayan Mitra
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - John M Doyle
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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23
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Caldwell L, Williams HJ, Fitch NJ, Aldegunde J, Hutson JM, Sauer BE, Tarbutt MR. Long Rotational Coherence Times of Molecules in a Magnetic Trap. PHYSICAL REVIEW LETTERS 2020; 124:063001. [PMID: 32109098 DOI: 10.1103/physrevlett.124.063001] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/30/2019] [Accepted: 12/17/2019] [Indexed: 06/10/2023]
Abstract
Polar molecules in superpositions of rotational states exhibit long-range dipolar interactions, but maintaining their coherence in a trapped sample is a challenge. We present calculations that show many laser-coolable molecules have convenient rotational transitions that are exceptionally insensitive to magnetic fields. We verify this experimentally for CaF where we find a transition with sensitivity below 5 Hz G^{-1} and use it to demonstrate a rotational coherence time of 6.4(8) ms in a magnetic trap. Simulations suggest it is feasible to extend this to more than 1 s using a smaller cloud in a biased magnetic trap.
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Affiliation(s)
- L Caldwell
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - H J Williams
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - N J Fitch
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - J Aldegunde
- Departamento de Quimica Fisica, Universidad de Salamanca, E-37008 Salamanca, Spain
| | - Jeremy M Hutson
- Joint Quantum Centre (JQC) Durham-Newcastle, Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom
| | - B E Sauer
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - M R Tarbutt
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
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24
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Toscano J, Lewandowski HJ, Heazlewood BR. Cold and controlled chemical reaction dynamics. Phys Chem Chem Phys 2020; 22:9180-9194. [DOI: 10.1039/d0cp00931h] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/14/2022]
Abstract
State-to-state chemical reaction dynamics, with complete control over the reaction parameters, offers unparalleled insight into fundamental reactivity.
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Affiliation(s)
- Jutta Toscano
- JILA and the Department of Physics
- University of Colorado
- Boulder
- USA
| | | | - Brianna R. Heazlewood
- Physical and Theoretical Chemistry Laboratory (PTCL)
- Department of Chemistry
- University of Oxford
- Oxford
- UK
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25
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Ding S, Wu Y, Finneran IA, Burau JJ, Ye J. Sub-Doppler Cooling and Compressed Trapping of YO Molecules at μK Temperatures. PHYSICAL REVIEW. X 2020; 10:10.1103/physrevx.10.021049. [PMID: 33643688 PMCID: PMC7909871 DOI: 10.1103/physrevx.10.021049] [Citation(s) in RCA: 27] [Impact Index Per Article: 6.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/06/2023]
Abstract
Complex molecular structure demands customized solutions to laser cooling by extending its general set of principles and practices. Compared with other laser-cooled molecules, yttrium monoxide (YO) exhibits a large electron-nucleus interaction, resulting in a dominant hyperfine interaction over the electron spin-rotation coupling. The YO ground state is thus comprised of two manifolds of closely spaced states, with one of them possessing a negligible Landé g factor. This unique energy level structure favors dual-frequency dc magneto-optical trapping (MOT) and gray molasses cooling (GMC). We report exceptionally robust cooling of YO at 4 μK over a wide range of laser intensity, detunings (one- and two-photon), and magnetic field. The magnetic insensitivity enables the spatial compression of the molecular cloud by alternating GMC and MOT under the continuous operation of the quadrupole magnetic field. A combination of these techniques produces a laser-cooled molecular sample with the highest phase space density in free space.
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Affiliation(s)
- Shiqian Ding
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA; Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
| | - Yewei Wu
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA; Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
| | - Ian A. Finneran
- JILA, National Institute of Standards and Technology and the University of Colorado, Boulder, Colorado 80309-0440, USA; 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; Department of Physics, University of Colorado, Boulder, Colorado 80309-0390, USA
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26
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Urbańczyk T, Koperski J. Ro-vibrational cooling of diatomic molecules Cd2 and Yb2: rotational energy structure included. Mol Phys 2019. [DOI: 10.1080/00268976.2019.1694712] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
Affiliation(s)
- Tomasz Urbańczyk
- Smoluchowski Institute of Physcics, Jagiellonian University, Kraków, Poland
| | - Jarosław Koperski
- Smoluchowski Institute of Physcics, Jagiellonian University, Kraków, Poland
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27
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Anderegg L, Cheuk LW, Bao Y, Burchesky S, Ketterle W, Ni KK, Doyle JM. An optical tweezer array of ultracold molecules. Science 2019; 365:1156-1158. [DOI: 10.1126/science.aax1265] [Citation(s) in RCA: 136] [Impact Index Per Article: 27.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2019] [Accepted: 07/31/2019] [Indexed: 11/02/2022]
Abstract
Ultracold molecules have important applications that range from quantum simulation and computation to precision measurements probing physics beyond the Standard Model. Optical tweezer arrays of laser-cooled molecules, which allow control of individual particles, offer a platform for realizing this full potential. In this work, we report on creating an optical tweezer array of laser-cooled calcium monofluoride molecules. This platform has also allowed us to observe ground-state collisions of laser-cooled molecules both in the presence and absence of near-resonant light.
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28
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Caldwell L, Devlin JA, Williams HJ, Fitch NJ, Hinds EA, Sauer BE, Tarbutt MR. Deep Laser Cooling and Efficient Magnetic Compression of Molecules. PHYSICAL REVIEW LETTERS 2019; 123:033202. [PMID: 31386461 DOI: 10.1103/physrevlett.123.033202] [Citation(s) in RCA: 21] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/19/2018] [Revised: 02/27/2019] [Indexed: 06/10/2023]
Abstract
We introduce a scheme for deep laser cooling of molecules based on robust dark states at zero velocity. By simulating this scheme, we show it to be a widely applicable method that can reach the recoil limit or below. We demonstrate and characterize the method experimentally, reaching a temperature of 5.4(7) μK. We solve a general problem of measuring low temperatures for large clouds by rotating the phase-space distribution and then directly imaging the complete velocity distribution. Using the same phase-space rotation method, we rapidly compress the cloud. Applying the cooling method a second time, we compress both the position and velocity distributions.
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Affiliation(s)
- L Caldwell
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - J A Devlin
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - H J Williams
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - N J Fitch
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - E A Hinds
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - B E Sauer
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
| | - M R Tarbutt
- Centre for Cold Matter, Blackett Laboratory, Imperial College London, Prince Consort Road, London SW7 2AZ, United Kingdom
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29
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González-Sánchez L, Gómez-Carrasco S, Santadaría AM, Wester R, Gianturco FA. Collisional Quantum Dynamics for MgH - ( 1Σ +) With He as a Buffer Gas: Ionic State-Changing Reactions in Cold Traps. Front Chem 2019; 7:64. [PMID: 30809520 PMCID: PMC6379277 DOI: 10.3389/fchem.2019.00064] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/03/2019] [Accepted: 01/23/2019] [Indexed: 11/17/2022] Open
Abstract
We present in this paper a detailed theoretical and computational analysis of the quantum inelastic dynamics involving the lower rotational levels of the MgH− (X1Σ+) molecular anion in collision with He atoms which provide the buffer gas in a cold trap. The interaction potential between the molecular partner and the He (1S) gaseous atoms is obtained from accurate quantum chemical calculations at the post-Hartree-Fock level as described in this paper. The spatial features and the interaction strength of the present potential energy surface (PES) are analyzed in detail and in comparison with similar, earlier results involving the MgH+ (1Σ) cation interacting with He atoms. The quantum, multichannel dynamics is then carried out using the newly obtained PES and the final inelastic rats constants, over the range of temperatures which are expected to be present in a cold ion trap experiment, are obtained to generate the multichannel kinetics of population changes observed for the molecular ion during the collisional cooling process. The rotational populations finally achieved at specific temperatures are linked to state-selective laser photo-detachment experiments to be carried out in our laboratory.All intermediate steps of the quantum modeling are also compared with the behavior of the corresponding MgH+ cation in the trap and the marked differences which exist between the collisional dynamics of the two systems are dicussed and explained. The feasibility of the present anion to be involved in state-selective photo-detachment experiments is fully analyzed and suggestions are made for the best performing conditions to be selected during trap experiments.
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Affiliation(s)
| | | | | | - Roland Wester
- Department of Physics, Institut für Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Innsbruck, Austria
| | - Francesco A Gianturco
- Department of Physics, Institut für Ionenphysik und Angewandte Physik, Universitaet Innsbruck, Innsbruck, Austria
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30
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Barker DS, Norrgard EB, Klimov NN, Fedchak JA, Scherschligt J, Eckel S. Single-beam Zeeman slower and magneto-optical trap using a nanofabricated grating. PHYSICAL REVIEW APPLIED 2019; 11:77. [PMID: 33299903 DOI: 10.1038/s42005-019-0181-1] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2019] [Accepted: 06/07/2019] [Indexed: 05/22/2023]
Abstract
We demonstrate a compact (0.25 L) system for laser cooling and trapping atoms from a heated dispenser source. Our system uses a nanofabricated diffraction grating to generate a magnetooptical trap (MOT) using a single input laser beam. An aperture in the grating allows atoms from the dispenser to be loaded from behind the chip, increasing the interaction distance of atoms with the cooling light. To take full advantage of this increased distance, we extend the magnetic field gradient of the MOT to create a Zeeman slower. The MOT traps approximately 106 7Li atoms emitted from an effusive source with loading rates greater than 106 s-1. Our design is portable to a variety of atomic and molecular species and could be a principal component of miniaturized cold-atom-based technologies.
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Affiliation(s)
- D S Barker
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - E B Norrgard
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - N N Klimov
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - J A Fedchak
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - J Scherschligt
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
| | - S Eckel
- Sensor Science Division, National Institute of Standards and Technology, Gaithersburg, MD 20899, USA
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31
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Collopy AL, Ding S, Wu Y, Finneran IA, Anderegg L, Augenbraun BL, Doyle JM, Ye J. 3D Magneto-Optical Trap of Yttrium Monoxide. PHYSICAL REVIEW LETTERS 2018; 121:213201. [PMID: 30517816 DOI: 10.1103/physrevlett.121.213201] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/02/2018] [Indexed: 06/09/2023]
Abstract
We report three-dimensional trapping of an oxide molecule (YO), using a radio-frequency magneto-optical trap (MOT). The total number of molecules trapped is ∼1.5×10^{4}, with a temperature of 4.1(5) mK. This diversifies the frontier of molecules that are laser coolable and paves the way for the second-stage narrow-line cooling in this molecule to the microkelvin regime. Futhermore, the new challenges of creating a 3D MOT of YO resolved here indicate that MOTs of more complex nonlinear molecules should be feasible as well.
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Affiliation(s)
- Alejandra L Collopy
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Shiqian Ding
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Yewei Wu
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ian A Finneran
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Loïc Anderegg
- Department of Physics and Center for Ultracold Atoms, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Benjamin L Augenbraun
- Department of Physics and Center for Ultracold Atoms, Harvard University, Cambridge, Massachusetts 02138, USA
| | - John M Doyle
- Department of Physics and Center for Ultracold Atoms, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Jun Ye
- JILA, National Institute of Standards and Technology and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
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32
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Cheuk LW, Anderegg L, Augenbraun BL, Bao Y, Burchesky S, Ketterle W, Doyle JM. Λ-Enhanced Imaging of Molecules in an Optical Trap. PHYSICAL REVIEW LETTERS 2018; 121:083201. [PMID: 30192609 DOI: 10.1103/physrevlett.121.083201] [Citation(s) in RCA: 33] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/31/2018] [Indexed: 06/08/2023]
Abstract
We report on nondestructive imaging of optically trapped calcium monofluoride molecules using in situ Λ-enhanced gray molasses cooling. 200 times more fluorescence is obtained compared to destructive on-resonance imaging, and the trapped molecules remain at a temperature of 20 μK. The achieved number of scattered photons makes possible nondestructive single-shot detection of single molecules with high fidelity.
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Affiliation(s)
- Lawrence W Cheuk
- 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
| | - Benjamin L Augenbraun
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Yicheng Bao
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Sean Burchesky
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Wolfgang Ketterle
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
- Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, 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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33
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McCarron DJ, Steinecker MH, Zhu Y, DeMille D. Magnetic Trapping of an Ultracold Gas of Polar Molecules. PHYSICAL REVIEW LETTERS 2018; 121:013202. [PMID: 30028161 DOI: 10.1103/physrevlett.121.013202] [Citation(s) in RCA: 35] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/05/2017] [Indexed: 06/08/2023]
Abstract
We demonstrate the efficient transfer of molecules from a magneto-optical trap into a conservative magnetic quadrupole trap. Our scheme begins with a blue-detuned optical molasses to cool SrF molecules to ≈50 μK. Next, we optically pump the molecules into a strongly trapped sublevel. This two-step process reliably transfers ≈40% of the molecules initially trapped in the magneto-optical trap into a single quantum state in the magnetic trap. Once loaded, the molecule cloud is compressed by increasing the magnetic field gradient. We observe a magnetic trap lifetime of over 1 s. This opens a promising new path to study ultracold molecular collisions, and potentially to produce quantum-degenerate molecular gases via sympathetic cooling with co-trapped atoms.
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Affiliation(s)
- D J McCarron
- Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520, USA
| | - M H Steinecker
- Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520, USA
| | - Y Zhu
- Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520, USA
| | - D DeMille
- Department of Physics, Yale University, P.O. Box 208120, New Haven, Connecticut 06520, USA
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