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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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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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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5
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Vilas NB, Robichaud P, Hallas C, Li GK, Anderegg L, Doyle JM. An optical tweezer array of ultracold polyatomic molecules. Nature 2024; 628:282-286. [PMID: 38570690 DOI: 10.1038/s41586-024-07199-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2023] [Accepted: 02/13/2024] [Indexed: 04/05/2024]
Abstract
Polyatomic molecules have rich structural features that make them uniquely suited to applications in quantum information science1-3, quantum simulation4-6, ultracold chemistry7 and searches for physics beyond the standard model8-10. However, a key challenge is fully controlling both the internal quantum state and the motional degrees of freedom of the molecules. Here we demonstrate the creation of an optical tweezer array of individual polyatomic molecules, CaOH, with quantum control of their internal quantum state. The complex quantum structure of CaOH results in a non-trivial dependence of the molecules' behaviour on the tweezer light wavelength. We control this interaction and directly and non-destructively image individual molecules in the tweezer array with a fidelity greater than 90%. The molecules are manipulated at the single internal quantum state level, thus demonstrating coherent state control in a tweezer array. The platform demonstrated here will enable a variety of experiments using individual polyatomic molecules with arbitrary spatial arrangement.
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Affiliation(s)
- Nathaniel B Vilas
- Department of Physics, Harvard University, Cambridge, MA, USA.
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA.
| | - Paige Robichaud
- Department of Physics, Harvard University, Cambridge, MA, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
| | - Christian Hallas
- Department of Physics, Harvard University, Cambridge, MA, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
| | - Grace K Li
- Department of Physics, Harvard University, Cambridge, MA, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA, USA
| | - Loïc Anderegg
- Department of Physics, Harvard University, Cambridge, MA, USA
- Harvard-MIT Center for Ultracold Atoms, 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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6
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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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7
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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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8
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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: 5] [Impact Index Per Article: 5.0] [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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9
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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] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2022] [Revised: 12/16/2022] [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
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10
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Augenbraun BL, Burchesky S, Winnicki A, Doyle JM. High-Resolution Laser Spectroscopy of a Functionalized Aromatic Molecule. J Phys Chem Lett 2022; 13:10771-10777. [PMID: 36374523 DOI: 10.1021/acs.jpclett.2c03041] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/16/2023]
Abstract
We present a high-resolution laser spectroscopic study of the Ã2B2-X̃2A1 and B̃2B1-X̃2A1 transitions of calcium(I) phenoxide, CaOPh (CaOC6H5). The rotationally resolved band systems are analyzed using an effective Hamiltonian model and are accurately modeled as independent perpendicular (b- or c-type) transitions. The structure of calcium monophenoxide is compared to previously observed Ca-containing radicals, and implications for direct laser cooling are discussed. This work demonstrates that functionalization of aromatic molecules with optical cycling centers can preserve many of the properties needed for laser-based control.
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Affiliation(s)
- Benjamin L Augenbraun
- Department of Physics, Harvard University, Cambridge, Massachusetts02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts02138, United States
| | - Sean Burchesky
- Department of Physics, Harvard University, Cambridge, Massachusetts02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts02138, United States
| | - Andrew Winnicki
- Department of Physics, Harvard University, Cambridge, Massachusetts02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts02138, United States
| | - John M Doyle
- Department of Physics, Harvard University, Cambridge, Massachusetts02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts02138, United States
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11
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Mitra D, Lasner ZD, Zhu GZ, Dickerson CE, Augenbraun BL, Bailey AD, Alexandrova AN, Campbell WC, Caram JR, Hudson ER, Doyle JM. Pathway toward Optical Cycling and Laser Cooling of Functionalized Arenes. J Phys Chem Lett 2022; 13:7029-7035. [PMID: 35900113 DOI: 10.1021/acs.jpclett.2c01430] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
Rapid and repeated photon cycling has enabled precision metrology and the development of quantum information systems using atoms and simple molecules. Extending optical cycling to structurally complex molecules would provide new capabilities in these areas, as well as in ultracold chemistry. Increased molecular complexity, however, makes realizing closed optical transitions more difficult. Building on already established strong optical cycling of diatomic, linear triatomic, and symmetric top molecules, recent work has pointed the way to cycling of larger molecules, including phenoxides. The paradigm for these systems is an optical cycling center bonded to a molecular ligand. Theory has suggested that cycling may be extended to even larger ligands, like naphthalene, pyrene, and coronene. Herein, we study optical excitation and fluorescent vibrational branching of CaO-[Formula: see text], SrO-[Formula: see text], and CaO-[Formula: see text] and find only weak decay to excited vibrational states, indicating a promising path to full quantum control and laser cooling of large arene-based molecules.
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Affiliation(s)
- Debayan Mitra
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, United States
| | - Zack D Lasner
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, United States
| | - Guo-Zhu Zhu
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States
- Center for Quantum Science and Engineering, University of California, Los Angeles, California 90095, United States
- Challenge Institute for Quantum Computation, University of California, Los Angeles, California 90095, United States
| | - Claire E Dickerson
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Benjamin L Augenbraun
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, United States
| | - Austin D Bailey
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Anastassia N Alexandrova
- Center for Quantum Science and Engineering, University of California, Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Wesley C Campbell
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States
- Center for Quantum Science and Engineering, University of California, Los Angeles, California 90095, United States
- Challenge Institute for Quantum Computation, University of California, Los Angeles, California 90095, United States
| | - Justin R Caram
- Center for Quantum Science and Engineering, University of California, Los Angeles, California 90095, United States
- Department of Chemistry and Biochemistry, University of California, Los Angeles, California 90095, United States
| | - Eric R Hudson
- Department of Physics and Astronomy, University of California, Los Angeles, California 90095, United States
- Center for Quantum Science and Engineering, University of California, Los Angeles, California 90095, United States
- Challenge Institute for Quantum Computation, University of California, Los Angeles, California 90095, United States
| | - John M Doyle
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, United States
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, United States
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12
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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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13
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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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14
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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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15
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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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16
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Abstract
Advances in atomic, molecular, and optical physics techniques allowed the cooling of simple molecules down to the ultracold regime ([Formula: see text]1 mK) and opened opportunities to study chemical reactions with unprecedented levels of control. This review covers recent developments in studying bimolecular chemistry at ultralow temperatures. We begin with a brief overview of methods for producing, manipulating, and detecting ultracold molecules. We then survey experimental works that exploit the controllability of ultracold molecules to probe and modify their long-range interactions. Further combining the use of physical chemistry techniques such as mass spectrometry and ion imaging significantly improved the detection of ultracold reactions and enabled explorations of their dynamics in the short range. We discuss a series of studies on the reaction KRb + KRb → K2 + Rb2 initiated below 1 [Formula: see text]K, including the direct observation of a long-lived complex, the demonstration of product rotational state control via conserved nuclear spins, and a test of the statistical model using the complete quantum state distribution of the products. Expected final online publication date for the Annual Review of Physical Chemistry, Volume 73 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.
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Affiliation(s)
- Yu Liu
- Time and Frequency Division, National Institute of Standards and Technology, Boulder, Colorado 80305, USA; .,Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Kang-Kuen Ni
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA; .,Harvard-Massachusetts Institute of Technology Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
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17
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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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18
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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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19
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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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20
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Visualizing the electron's quantization with a ruler. Sci Rep 2021; 11:10703. [PMID: 34035337 PMCID: PMC8149853 DOI: 10.1038/s41598-021-89714-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2021] [Accepted: 04/28/2021] [Indexed: 11/28/2022] Open
Abstract
More than 100 years ago, Robert Millikan demonstrated the quantization of the electron using charged, falling droplets, but the statistical analysis on many falling droplets did not allow a direct visualization of the quantization of charge. Instead of letting the droplets fall, we have used optical levitation to create a single droplet version of Millikan’s experiment where the effects of a single electron removal can be observed by the naked eye and measured with a ruler. As we added charges to the levitated droplet, we observed that its equilibrium position jumped vertically in quantized steps. The discrete nature of the droplet’s jumps is a direct consequence of the single-electron changes in the charge on the droplet, and therefore clearly demonstrates the quantization of charge. The steps were optically magnified onto a wall and filmed. We anticipate that the video of these single electron additions can become a straightforward demonstration of the quantization of charge for a general audience.
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21
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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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22
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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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23
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Cairncross WB, Zhang JT, Picard LRB, Yu Y, Wang K, Ni KK. Assembly of a Rovibrational Ground State Molecule in an Optical Tweezer. PHYSICAL REVIEW LETTERS 2021; 126:123402. [PMID: 33834818 DOI: 10.1103/physrevlett.126.123402] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2021] [Accepted: 02/24/2021] [Indexed: 06/12/2023]
Abstract
We demonstrate the coherent creation of a single NaCs molecule in its rotational, vibrational, and electronic (rovibronic) ground state in an optical tweezer. Starting with a weakly bound Feshbach molecule, we locate a two-photon transition via the |c^{3}Σ_{1},v^{'}=26⟩ excited state and drive coherent Rabi oscillations between the Feshbach state and a single hyperfine level of the NaCs rovibronic ground state |X^{1}Σ,v^{''}=0,N^{''}=0⟩ with a binding energy of D_{0}=h×147044.63(11) GHz. We measure a lifetime of 3.4±1.6 s for the rovibronic ground state molecule, which possesses a large molecule-frame dipole moment of 4.6D and occupies predominantly the motional ground state. These long-lived, fully quantum-state-controlled individual dipolar molecules provide a key resource for molecule-based quantum simulation and information processing.
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Affiliation(s)
- William B Cairncross
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Jessie T Zhang
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Lewis R B Picard
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Yichao Yu
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Kenneth Wang
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
| | - Kang-Kuen Ni
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, Massachusetts 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, Massachusetts 02138, USA
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24
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Matsuda K, De Marco L, Li JR, Tobias WG, Valtolina G, Quéméner G, Ye J. Resonant collisional shielding of reactive molecules using electric fields. Science 2021; 370:1324-1327. [PMID: 33303614 DOI: 10.1126/science.abe7370] [Citation(s) in RCA: 24] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/11/2020] [Accepted: 11/09/2020] [Indexed: 11/03/2022]
Abstract
Full control of molecular interactions, including reactive losses, would open new frontiers in quantum science. We demonstrate extreme tunability of ultracold chemical reaction rates by inducing resonant dipolar interactions by means of an external electric field. We prepared fermionic potassium-rubidium molecules in their first excited rotational state and observed a modulation of the chemical reaction rate by three orders of magnitude as we tuned the electric field strength by a few percent across resonance. In a quasi-two-dimensional geometry, we accurately determined the contributions from the three dominant angular momentum projections of the collisions. Using the resonant features, we shielded the molecules from loss and suppressed the reaction rate by an order of magnitude below the background value, thereby realizing a long-lived sample of polar molecules in large electric fields.
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Affiliation(s)
- Kyle Matsuda
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.
| | - Luigi De Marco
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Jun-Ru Li
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - William G Tobias
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Giacomo Valtolina
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA
| | - Goulven Quéméner
- Université Paris-Saclay, CNRS, Laboratoire Aimé Cotton, 91405 Orsay, France
| | - Jun Ye
- JILA, National Institute of Standards and Technology, and Department of Physics, University of Colorado, Boulder, CO 80309, USA.
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25
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Chae E. Entanglement via rotational blockade of MgF molecules in a magic potential. Phys Chem Chem Phys 2021; 23:1215-1220. [PMID: 33355327 DOI: 10.1039/d0cp04042h] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Diatomic polar molecules are one of the most promising platforms of quantum computing due to their rich internal states and large electric dipole moments. Here, we propose entangling rotational states of MgF molecules in an optical tweezer array via strong electric dipole-dipole interactions. We employ two rotational states with the projection quantum number of the total angular momentum MF = 0 to maximize the dipole-dipole interaction with a given separation distance. The splitting of 1.27 kHz between two entangled states is predicted for MgF molecules separated by 1 μm. The resolution of the entangled states can be achieved in a magic optical potential where the rotational states have the same trap frequencies. The magic potential can be formed by tuning the angle between the molecules' quantization axis and the linear polarization of trapping light to a "magic angle". We calculate the magic angle for MgF molecules under reasonable experimental conditions and obtain that the trap frequencies of the two involved states can be matched within a few 10s of Hz. By establishing an entanglement scheme for the molecules, our results provide a first step towards quantum computing using MgF molecules.
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Affiliation(s)
- Eunmi Chae
- Department of Physics, Korea University, Seoul, Republic of Korea.
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26
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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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27
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Dawid A, Tomza M. Magnetic properties and quench dynamics of two interacting ultracold molecules in a trap. Phys Chem Chem Phys 2020; 22:28140-28153. [PMID: 33290463 DOI: 10.1039/d0cp05542e] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
We theoretically investigate the magnetic properties and nonequilibrium dynamics of two interacting ultracold polar and paramagnetic molecules in a one-dimensional harmonic trap in external electric and magnetic fields. The molecules interact via a multichannel two-body contact potential, incorporating the short-range anisotropy of intermolecular interactions. We show that various magnetization states arise from the interplay of the molecular interactions, electronic spins, dipole moments, rotational structures, external fields, and spin-rotation coupling. The rich magnetization diagrams depend primarily on the anisotropy of the intermolecular interaction and the spin-rotation coupling. These specific molecular properties are challenging to calculate or measure. Therefore, we propose the quench dynamics experiments for extracting them from observing the time evolution of the analyzed system. Our results indicate the possibility of controlling the molecular few-body magnetization with the external electric field and pave the way towards studying the magnetization of ultracold molecules trapped in optical tweezers or optical lattices and their application in quantum simulation of molecular multichannel many-body Hamiltonians and quantum information storing.
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Affiliation(s)
- Anna Dawid
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland.
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28
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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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29
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He M, Lv C, Lin HQ, Zhou Q. Universal relations for ultracold reactive molecules. SCIENCE ADVANCES 2020; 6:6/51/eabd4699. [PMID: 33355137 DOI: 10.1126/sciadv.abd4699] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/24/2020] [Accepted: 11/03/2020] [Indexed: 06/12/2023]
Abstract
The realization of ultracold polar molecules in laboratories has pushed physics and chemistry to new realms. In particular, these polar molecules offer scientists unprecedented opportunities to explore chemical reactions in the ultracold regime where quantum effects become profound. However, a key question about how two-body losses depend on quantum correlations in interacting many-body systems remains open so far. Here, we present a number of universal relations that directly connect two-body losses to other physical observables, including the momentum distribution and density correlation functions. These relations, which are valid for arbitrary microscopic parameters, such as the particle number, the temperature, and the interaction strength, unfold the critical role of contacts, a fundamental quantity of dilute quantum systems, in determining the reaction rate of quantum reactive molecules in a many-body environment. Our work opens the door to an unexplored area intertwining quantum chemistry; atomic, molecular, and optical physics; and condensed matter physics.
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Affiliation(s)
- Mingyuan He
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
- Shenzhen JL Computational Science and Applied Research Institute, Shenzhen 518109, China
- Department of Physics, Hong Kong University of Science and Technology, Clear Water Bay, Hong Kong, China
| | - Chenwei Lv
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA
| | - Hai-Qing Lin
- Beijing Computational Science Research Center, Beijing 100193, China
| | - Qi Zhou
- Department of Physics and Astronomy, Purdue University, West Lafayette, IN 47907, USA.
- Purdue Quantum Science and Engineering Institute, Purdue University, West Lafayette, IN 47907, USA
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30
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Quantum entanglement between an atom and a molecule. Nature 2020; 581:273-277. [DOI: 10.1038/s41586-020-2257-1] [Citation(s) in RCA: 28] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/12/2019] [Accepted: 03/02/2020] [Indexed: 02/03/2023]
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