1
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Bigagli N, Yuan W, Zhang S, Bulatovic B, Karman T, Stevenson I, Will S. Observation of Bose-Einstein condensation of dipolar molecules. Nature 2024; 631:289-293. [PMID: 38831053 DOI: 10.1038/s41586-024-07492-z] [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: 12/18/2023] [Accepted: 04/30/2024] [Indexed: 06/05/2024]
Abstract
Ensembles of particles governed by quantum mechanical laws exhibit intriguing emergent behaviour. Atomic quantum gases1,2, liquid helium3,4 and electrons in quantum materials5-7 all exhibit distinct properties because of their composition and interactions. Quantum degenerate samples of ultracold dipolar molecules promise the realization of new phases of matter and new avenues for quantum simulation8 and quantum computation9. However, rapid losses10, even when reduced through collisional shielding techniques11-13, have so far prevented evaporative cooling to a Bose-Einstein condensate (BEC). Here we report on the realization of a BEC of dipolar molecules. By strongly suppressing two- and three-body losses via enhanced collisional shielding, we evaporatively cool sodium-caesium molecules to quantum degeneracy and cross the phase transition to a BEC. The BEC reveals itself by a bimodal distribution when the phase-space density exceeds 1. BECs with a condensate fraction of 60(10)% and a temperature of 6(2) nK are created and found to be stable with a lifetime close to 2 s. This work opens the door to the exploration of dipolar quantum matter in regimes that have been inaccessible so far, promising the creation of exotic dipolar droplets14, self-organized crystal phases15 and dipolar spin liquids in optical lattices16.
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Affiliation(s)
- Niccolò Bigagli
- Department of Physics, Columbia University, New York, NY, USA
| | - Weijun Yuan
- Department of Physics, Columbia University, New York, NY, USA
| | - Siwei Zhang
- Department of Physics, Columbia University, New York, NY, USA
| | - Boris Bulatovic
- Department of Physics, Columbia University, New York, NY, USA
| | - Tijs Karman
- Institute for Molecules and Materials, Radboud University, Nijmegen, The Netherlands
| | - Ian Stevenson
- Department of Physics, Columbia University, New York, NY, USA
| | - Sebastian Will
- Department of Physics, Columbia University, New York, NY, USA.
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2
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Yang Z, Chen H, Buren B, Chen M. Globally Accurate Gaussian Process Potential Energy Surface and Quantum Dynamics Studies on the Li(2S) + Na2 → LiNa + Na Reaction at Low Collision Energies. Molecules 2023; 28:molecules28072938. [PMID: 37049701 PMCID: PMC10096016 DOI: 10.3390/molecules28072938] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/03/2023] [Revised: 03/22/2023] [Accepted: 03/23/2023] [Indexed: 03/29/2023] Open
Abstract
The LiNa2 reactive system has recently received great attention in the experimental study of ultracold chemical reactions, but the corresponding theoretical calculations have not been carried out. Here, we report the first globally accurate ground-state LiNa2 potential energy surface (PES) using a Gaussian process model based on only 1776 actively selected high-level ab initio training points. The constructed PES had high precision and strong generalization capability. On the new PES, the quantum dynamics calculations on the Li(2S) + Na2(v = 0, j = 0) → LiNa + Na reaction were carried out in the 0.001–0.01 eV collision energy range using an improved time-dependent wave packet method. The calculated results indicate that this reaction is dominated by a complex-forming mechanism at low collision energies. The presented dynamics data provide guidance for experimental research, and the newly constructed PES could be further used for ultracold reaction dynamics calculations on this reactive system.
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3
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Bause R, Christianen A, Schindewolf A, Bloch I, Luo XY. Ultracold Sticky Collisions: Theoretical and Experimental Status. J Phys Chem A 2023; 127:729-741. [PMID: 36624934 PMCID: PMC9884084 DOI: 10.1021/acs.jpca.2c08095] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Collisional complexes, which are formed as intermediate states in molecular collisions, are typically short-lived and decay within picoseconds. However, in ultracold collisions involving bialkali molecules, complexes can live for milliseconds, completely changing the collision dynamics. This can lead to unexpected two-body loss in samples of nonreactive molecules. During the past decade, such "sticky" collisions have been a major hindrance in the preparation of dense and stable molecular samples, especially in the quantum-degenerate regime. Currently, the behavior of the complexes is not fully understood. For example, in some cases, their lifetime has been measured to be many orders of magnitude longer than recent models predict. This is not only an intriguing problem in itself but also practically relevant, since understanding molecular complexes may help to mitigate their detrimental effects. Here, we review the recent experimental and theoretical progress in this field. We treat the case of molecule-molecule as well as molecule-atom collisions.
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Affiliation(s)
- Roman Bause
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany
| | - Arthur Christianen
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany
| | - Andreas Schindewolf
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany
| | - Immanuel Bloch
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany,Fakultät
für Physik, Ludwig-Maximilians-Universität, 80799München, Germany
| | - Xin-Yu Luo
- Max-Planck-Institut
für Quantenoptik, 85748Garching, Germany,Munich
Center for Quantum Science and Technology, 80799München, Germany,E-mail:
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4
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Liu Y, Huang J, Yang D, Xie D, Guo H. Global Full-Dimensional Potential Energy Surface for the Reaction 23Na 87Rb + 23Na 87Rb → 23Na 2 + 87Rb 2 and the Formation Rate and Lifetime of the 23Na 287Rb 2 Collision Complex. J Phys Chem A 2022; 126:9008-9021. [DOI: 10.1021/acs.jpca.2c06438] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
Affiliation(s)
- Yilang Liu
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
| | - Jing Huang
- Institute of Chemical Materials, China Academy of Engineering Physics, Mianyang, Sichuan 621900, China
| | - Dongzheng Yang
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210093, China
- Hefei National Laboratory, Hefei 230088, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
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5
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Su Z, Yang H, Cao J, Wang XY, Rui J, Zhao B, Pan JW. Resonant Control of Elastic Collisions between ^{23}Na^{40}K Molecules and ^{40}K Atoms. PHYSICAL REVIEW LETTERS 2022; 129:033401. [PMID: 35905340 DOI: 10.1103/physrevlett.129.033401] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2022] [Revised: 04/24/2022] [Accepted: 07/01/2022] [Indexed: 06/15/2023]
Abstract
We have demonstrated the resonant control of the elastic scattering cross sections in the vicinity of Feshbach resonances between ^{23}Na^{40}K molecules and ^{40}K atoms by studying the thermalization between them. The elastic scattering cross sections vary by more than 2 orders of magnitude close to the resonance, and can be well described by an asymmetric Fano profile. The parameters that characterize the magnetically tunable s-wave scattering length are determined from the elastic scattering cross sections. The observation of resonantly controlled elastic scattering cross sections opens up the possibility to study strongly interacting atom-molecule mixtures and improve our understanding of the complex atom-molecule Feshbach resonances.
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Affiliation(s)
- Zhen Su
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Huan Yang
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jin Cao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Xin-Yao Wang
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jun Rui
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Bo Zhao
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
| | - Jian-Wei Pan
- Hefei National Research Center for Physical Sciences at the Microscale and School of Physical Sciences, University of Science and Technology of China, Hefei 230026, China; Shanghai Research Center for Quantum Science and CAS Center for Excellence in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China; and Hefei National Laboratory, University of Science and Technology of China, Hefei 230088, China
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6
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Lin J, He J, Jin M, Chen G, Wang D. Seconds-Scale Coherence on Nuclear Spin Transitions of Ultracold Polar Molecules in 3D Optical Lattices. PHYSICAL REVIEW LETTERS 2022; 128:223201. [PMID: 35714238 DOI: 10.1103/physrevlett.128.223201] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/18/2021] [Accepted: 05/05/2022] [Indexed: 06/15/2023]
Abstract
Ultracold polar molecules (UPMs) are emerging as a novel and powerful platform for fundamental applications in quantum science. Here, we report characterization of the coherence between nuclear spin levels of ultracold ground-state sodium-rubidium molecules loaded into a 3D optical lattice with a nearly photon scattering limited trapping lifetime of 9(1) seconds. After identifying and compensating the main sources of decoherence, we achieve a maximum nuclear spin coherence time of T_{2}^{*}=3.3(6) s with two-photon Ramsey spectroscopy. Furthermore, based on the understanding of the main factor limiting the coherence of the two-photon Rabi transition, we obtain a Rabi line shape with linewidth below 0.8 Hz. The simultaneous realization of long lifetime and coherence time, and ultrahigh spectroscopic resolution in our system unveils the great potentials of Ultracold polar molecules in quantum simulation, computation, and metrology.
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Affiliation(s)
- Junyu Lin
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Junyu He
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Mucan Jin
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Guanghua Chen
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
| | - Dajun Wang
- Department of Physics, The Chinese University of Hong Kong, Shatin, Hong Kong, China
- The Chinese University of Hong Kong Shenzhen Research Institute, Shenzhen 518057, China
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7
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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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8
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Zhao B, Pan JW. Quantum control of reactions and collisions at ultralow temperatures. Chem Soc Rev 2022; 51:1685-1701. [PMID: 35169822 DOI: 10.1039/d1cs01040a] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
At temperatures close to absolute zero, the molecular reactions and collisions are dominantly governed by quantum mechanics. Remarkable quantum phenomena such as quantum tunneling, quantum threshold behavior, quantum resonances, quantum interference, and quantum statistics are expected to be the main features in ultracold reactions and collisions. Ultracold molecules offer great opportunities and challenges in the study of these intriguing quantum phenomena in molecular processes. In this article, we review the recent progress in the preparation of ultracold molecules and the study of ultracold reactions and collisions using ultracold molecules. We focus on the controlled ultracold chemistry and the scattering resonances at ultralow temperatures. The challenges in understanding the complex ultracold reactions and collisions are also discussed.
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Affiliation(s)
- Bo Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China. .,Shanghai Branch, CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China.,Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
| | - Jian-Wei Pan
- Hefei National Laboratory for Physical Sciences at the Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China. .,Shanghai Branch, CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China.,Shanghai Research Center for Quantum Sciences, Shanghai 201315, China
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9
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Gu J, Xiao Z, Yu C, Zhang Q, Chen Y, Zhao D. High resolution laser excitation spectra and Franck-Condon factors of A2Π− X2Σ + electronic transition of MgF. CHINESE J CHEM PHYS 2022. [DOI: 10.1063/1674-0068/cjcp2109151] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Magnesium monofluoride (MgF) is proposed as an ideal candidate radical for direct laser cooling. Here, the rotationally resolved laser spectra of MgF for the A2Π− X2Σ+ electronic transition system were recorded by using laser induced fluorescence technique. The MgF radicals were produced by discharging SF6/Ar gas mixtures between the tips of two magnesium needles in a supersonic jet expansion. We recorded a total of 19 vibrational bands belonging to three sequences of Δ v=0, ±1 in the region of 348-370 nm. Accurate spectroscopic constants for both X2Σ+ and A2Π states are determined from rotational analysis of the experimental spectra. Spectroscopic parameters, including the Franck-Condon factors (FCFs), are determined from the experimental results and the Rydberg-Klein-Rees (RKR) calculations. Significant discrepancies between the experimentally measured and RKR-calculated FCFs are found, indicating that the FCFs are nearly independent of the spin-orbit coupling in the A2Π state. Potential energy curves (PECs) and FCFs determined here provide necessary data for the theoretical simulation of the laser-cooling scheme of MgF.
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Affiliation(s)
- Jingwang Gu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Zengjun Xiao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Chunting Yu
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Qiang Zhang
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Yang Chen
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
| | - Dongfeng Zhao
- Hefei National Laboratory for Physical Sciences at the Microscale, Department of Chemical Physics, University of Science and Technology of China, Hefei 230026, China
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10
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Theoretical Study of the FrLi Molecule: Computation of Adiabatic and Diabatic Potential Energy Curves, Spectroscopic Constants, Dipole Moment, Radiative Lifetime and Spectrum Absorption. ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING 2022. [DOI: 10.1007/s13369-021-05732-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
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11
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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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12
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Gersema P, Voges KK, Meyer Zum Alten Borgloh M, Koch L, Hartmann T, Zenesini A, Ospelkaus S, Lin J, He J, Wang D. Probing Photoinduced Two-Body Loss of Ultracold Nonreactive Bosonic ^{23}Na^{87}Rb and ^{23}Na^{39}K Molecules. PHYSICAL REVIEW LETTERS 2021; 127:163401. [PMID: 34723573 DOI: 10.1103/physrevlett.127.163401] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 09/16/2021] [Indexed: 06/13/2023]
Abstract
We probe photoinduced loss for chemically stable bosonic ^{23}Na^{87}Rb and ^{23}Na^{39}K molecules in chopped optical dipole traps, where the molecules spend a significant time in the dark. We expect the effective two-body decay to be significantly suppressed due to the small expected complex lifetimes of about 13 and 6 μs for ^{23}Na^{87}Rb and ^{23}Na^{39}K, respectively. However, instead we do not observe any suppression of the two-body loss in parameter ranges where large loss suppressions are expected. We believe these unexpected results are most probably due to drastic underestimation of the complex lifetime by at least 1-2 orders of magnitude.
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Affiliation(s)
- Philipp Gersema
- Institut für Quantenoptik, Leibniz Universität Hannover, 30167 Hannover, Germany
| | - Kai K Voges
- Institut für Quantenoptik, Leibniz Universität Hannover, 30167 Hannover, Germany
| | | | - Leon Koch
- Institut für Quantenoptik, Leibniz Universität Hannover, 30167 Hannover, Germany
| | - Torsten Hartmann
- Institut für Quantenoptik, Leibniz Universität Hannover, 30167 Hannover, Germany
| | - Alessandro Zenesini
- Institut für Quantenoptik, Leibniz Universität Hannover, 30167 Hannover, Germany
- INO-CNR BEC Center, Dipartimento di Fisica, Università di Trento and TIFPA-INFN, 38123 Povo, Italy
| | - Silke Ospelkaus
- Institut für Quantenoptik, Leibniz Universität Hannover, 30167 Hannover, Germany
| | - Junyu Lin
- Department of Physics, The Chinese University of Hong Kong, Hong Kong, China
| | - Junyu He
- Department of Physics, The Chinese University of Hong Kong, Hong Kong, China
| | - Dajun Wang
- Department of Physics, The Chinese University of Hong Kong, Hong Kong, China
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13
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Lewis TN, Wang C, Daniel JR, Dhital M, Bardeen CJ, Hemmerling B. Optimizing pulsed-laser ablation production of AlCl molecules for laser cooling. Phys Chem Chem Phys 2021; 23:22785-22793. [PMID: 34610064 DOI: 10.1039/d1cp03515k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Aluminum monochloride (AlCl) has been proposed as a promising candidate for laser cooling to ultracold temperatures, and recent spectroscopy results support this prediction. It is challenging to produce large numbers of AlCl molecules because it is a highly reactive open-shell molecule and must be generated in situ. Here we show that pulsed-laser ablation of stable, non-toxic mixtures of Al with alkali or alkaline earth chlorides, denoted XCln, can provide a robust and reliable source of cold AlCl molecules. Both the chemical identity of XCln and the Al : XCln molar ratio are varied, and the yield of AlCl is monitored using absorption spectroscopy in a cryogenic gas. For KCl, the production of Al and K atoms was also monitored. We model the AlCl production in the limits of nonequilibrium recombination dominated by first-encounter events. The non-equilibrium model is in agreement with the data and also reproduces the observed trend with different XCln precursors. We find that AlCl production is limited by the solid-state densities of Al and Cl atoms and the recondensation of Al atoms in the ablation plume. We suggest future directions for optimizing the production of cold AlCl molecules using laser ablation.
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Affiliation(s)
- Taylor N Lewis
- Department of Chemistry, University of California, Riverside, CA 92521, USA.
| | - Chen Wang
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA.
| | - John R Daniel
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA.
| | - Madhav Dhital
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA.
| | | | - Boerge Hemmerling
- Department of Physics and Astronomy, University of California, Riverside, CA 92521, USA.
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14
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Burchesky S, Anderegg L, Bao Y, Yu SS, Chae E, Ketterle W, Ni KK, Doyle JM. Rotational Coherence Times of Polar Molecules in Optical Tweezers. PHYSICAL REVIEW LETTERS 2021; 127:123202. [PMID: 34597100 DOI: 10.1103/physrevlett.127.123202] [Citation(s) in RCA: 15] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2021] [Accepted: 08/19/2021] [Indexed: 06/13/2023]
Abstract
Qubit coherence times are critical to the performance of any robust quantum computing platform. For quantum information processing using arrays of polar molecules, a key performance parameter is the molecular rotational coherence time. We report a 93(7) ms coherence time for rotational state qubits of laser cooled CaF molecules in optical tweezer traps, over an order of magnitude longer than previous systems. Inhomogeneous broadening due to the differential polarizability between the qubit states is suppressed by tuning the tweezer polarization and applied magnetic field to a "magic" angle. The coherence time is limited by the residual differential polarizability, implying improvement with further cooling. A single spin-echo pulse is able to extend the coherence time to nearly half a second. The measured coherence times demonstrate the potential of polar molecules as high fidelity qubits.
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Affiliation(s)
- Sean Burchesky
- 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
| | - Yicheng Bao
- 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
| | - Eunmi Chae
- Department of Physics, Korea University, Seongbuk-gu, Seoul 02841, South Korea
| | - 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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15
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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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16
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Kłos J, Guan Q, Li H, Li M, Tiesinga E, Kotochigova S. Roaming pathways and survival probability in real-time collisional dynamics of cold and controlled bialkali molecules. Sci Rep 2021; 11:10598. [PMID: 34011983 PMCID: PMC8134521 DOI: 10.1038/s41598-021-90004-0] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2021] [Accepted: 04/30/2021] [Indexed: 11/25/2022] Open
Abstract
Perfectly controlled molecules are at the forefront of the quest to explore chemical reactivity at ultra low temperatures. Here, we investigate for the first time the formation of the long-lived intermediates in the time-dependent scattering of cold bialkali \documentclass[12pt]{minimal}
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\begin{document}$$^{23}\hbox {Na}^{87}$$\end{document}23Na87Rb molecules with and without the presence of infrared trapping light. During the nearly 50 nanoseconds mean collision time of the intermediate complex, we observe unconventional roaming when for a few tens of picoseconds either NaRb or \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Na}_2$$\end{document}Na2 and \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Rb}_2$$\end{document}Rb2 molecules with large relative separation are formed before returning to the four-atom complex. We also determine the likelihood of molecular loss when the trapping laser is present during the collision. We find that at a wavelength of 1064 nm the \documentclass[12pt]{minimal}
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\begin{document}$$\hbox {Na}_2\hbox {Rb}_2$$\end{document}Na2Rb2 complex is quickly destroyed and thus that the \documentclass[12pt]{minimal}
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\begin{document}$$^{23}\hbox {Na}^{87}$$\end{document}23Na87Rb molecules are rapidly lost.
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Affiliation(s)
- Jacek Kłos
- Department of Physics, Temple University, Philadelphia, PA, 19122, USA.,Joint Quantum Institute, University of Maryland, College Park, MD, 20742, USA
| | - Qingze Guan
- Department of Physics, Temple University, Philadelphia, PA, 19122, USA
| | - Hui Li
- Department of Physics, Temple University, Philadelphia, PA, 19122, USA
| | - Ming Li
- Department of Physics, Temple University, Philadelphia, PA, 19122, USA
| | - Eite Tiesinga
- Joint Quantum Institute, University of Maryland, College Park, MD, 20742, USA.,National Institute of Standards and Technology, Gaithersburg, MD, 20899, USA
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17
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Kendrick BK. Quantum reactive scattering calculations for the cold and ultracold Li + LiNa → Li 2 + Na reaction. J Chem Phys 2021; 154:124303. [PMID: 33810695 DOI: 10.1063/5.0045712] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
Abstract
A first-principles based quantum dynamics study of the Li + LiNa(v = 0, j = 0) → Li2(v', j') + Na reaction is reported for collision energies spanning the ultracold (1 nK) to cold (1 K) regimes. A full-dimensional ab initio potential energy surface for the ground electronic state of Li2Na is utilized that includes an accurate treatment of the long-range interactions. The Li + LiNa reaction is barrierless and exoergic and exhibits a deep attractive potential well that supports complex formation. Thus, significant reactivity occurs even for collision temperatures approaching absolute zero. The reactive scattering calculations are based on a numerically exact time-independent quantum dynamics methodology in hyperspherical coordinates. Total and rotationally resolved rate coefficients are reported at 56 collision energies and include all contributing partial waves. Several shape resonances are observed in many of the rotationally resolved rate coefficients and a small resonance feature is also reported in the total rate coefficient near 50 mK. Of particular interest, the angular distributions or differential cross sections are reported as a function of both the collision energy and scattering angle. Unique quantum fingerprints (bumps, channels, and ripples) are observed in the angular distributions for each product rotational state due to quantum interference and shape resonance contributions. The Li + LiNa reaction is under active experimental investigation so that these intriguing features could be verified experimentally when sufficient product state resolution becomes feasible for collision energies below 1 K.
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Affiliation(s)
- Brian K Kendrick
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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18
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Kendrick BK, Li H, Li M, Kotochigova S, Croft JFE, Balakrishnan N. Non-adiabatic quantum interference in the ultracold Li + LiNa → Li 2 + Na reaction. Phys Chem Chem Phys 2021; 23:5096-5112. [PMID: 33576359 DOI: 10.1039/d0cp05499b] [Citation(s) in RCA: 17] [Impact Index Per Article: 5.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
Electronically non-adiabatic effects play an important role in many chemical reactions. However, how these effects manifest in cold and ultracold chemistry remains largely unexplored. Here for the first time we present from first principles the non-adiabatic quantum dynamics of the reactive scattering between ultracold alkali-metal LiNa molecules and Li atoms. We show that non-adiabatic dynamics induces quantum interference effects that dramatically alter the ultracold rotationally resolved reaction rate coefficients. The interference effect arises from the conical intersection between the ground and an excited electronic state that is energetically accessible even for ultracold collisions. These unique interference effects might be exploited for quantum control applications such as a quantum molecular switch. The non-adiabatic dynamics are based on full-dimensional ab initio potential energy surfaces for the two electronic states that includes the non-adiabatic couplings and an accurate treatment of the long-range interactions. A statistical analysis of rotational populations of the Li2 product reveals a Poisson distribution implying the underlying classical dynamics are chaotic. The Poisson distribution is robust and amenable to experimental verification and appears to be a universal property of ultracold reactions involving alkali metal dimers.
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Affiliation(s)
- Brian K Kendrick
- Theoretical Division (T-1, MS B221), Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA.
| | - Hui Li
- Department of Physics, Temple University, Philadelphia, PA 19122, USA
| | - Ming Li
- Department of Physics, Temple University, Philadelphia, PA 19122, USA
| | | | - James F E Croft
- Dodd-Walls Centre for Photonic and Quantum Technologies, Dunedin 9054, New Zealand and Department of Physics, University of Otago, Dunedin 9054, New Zealand
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19
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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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20
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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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21
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Huang J, Chen J, Liu S, Zhang DH. Time-Dependent Wave Packet Dynamics Calculations of Cross Sections for Ultracold Four-Atom Reactions. J Phys Chem Lett 2020; 11:8560-8564. [PMID: 32972141 DOI: 10.1021/acs.jpclett.0c02606] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/11/2023]
Abstract
We report here the first time-dependent wave packet dynamics study for an ultracold four-atom reaction. Our calculations provide accurate integral cross sections and rate constants all the way down to the Bethe-Wigner threshold regime for the benchmark OH + H2(v = 2, j = 0) → H2O + H reaction, indicating that the time-dependent wave packet method is a powerful tool for studying ultracold four-atom reactions.
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Affiliation(s)
- Jiayu Huang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
- University of Chinese Academy of Sciences, Beijing 100049, China
| | - Jun Chen
- State Key Laboratory of Structural Chemistry, Fujian Institute of Research on the Structure of Matter, Chinese Academy of Sciences, Fuzhou 350002, China
| | - Shu Liu
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
| | - Dong H Zhang
- State Key Laboratory of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, China
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22
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Zuo J, Guo H. Time-independent quantum theory on vibrational inelastic scattering between atoms and open-shell diatomic molecules: Applications to NO + Ar and NO + H scattering. J Chem Phys 2020; 153:144306. [PMID: 33086802 DOI: 10.1063/5.0026637] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
A full-dimensional rigorous quantum mechanical treatment of non-reactive inelastic scattering of an open-shell diatom [e.g., NO(2Π)] with a structureless and spinless atom is presented within the time-independent close-coupling framework. The inclusion of the diatomic vibrational degree of freedom allows the investigation of transitions between different vibrational manifolds, in addition to those between different rotational, spin-orbit, and Λ-doublet states. This method is applied to the scattering of vibrationally excited NO(2Π) with Ar and H (with its spin ignored). The former has negligible vibrational inelasticity, thanks to the weak interaction between the two collisional partners. This conclusion justifies the commonly used two-dimensional approximation in treating NO scattering with rare gas atoms. The latter, on the other hand, is shown to undergo significant vibrational relaxation, even in the ultra-cold regime, owing to a chemically bonded (HNO) complex on the lowest-lying singlet potential energy surfaces.
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Affiliation(s)
- Junxiang Zuo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
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23
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Xie T, Lepers M, Vexiau R, Orbán A, Dulieu O, Bouloufa-Maafa N. Optical Shielding of Destructive Chemical Reactions between Ultracold Ground-State NaRb Molecules. PHYSICAL REVIEW LETTERS 2020; 125:153202. [PMID: 33095632 DOI: 10.1103/physrevlett.125.153202] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2020] [Accepted: 09/09/2020] [Indexed: 06/11/2023]
Abstract
We propose a method to suppress the chemical reactions between ultracold bosonic ground-state ^{23}Na^{87}Rb molecules based on optical shielding. By applying a laser with a frequency blue-detuned from the transition between the lowest rovibrational level of the electronic ground state X^{1}Σ^{+}(v_{X}=0,j_{X}=0), and the long-lived excited level b^{3}Π_{0}(v_{b}=0,j_{b}=1), the long-range dipole-dipole interaction between the colliding molecules can be engineered, leading to a dramatic suppression of reactive and photoinduced inelastic collisions, for both linear and circular laser polarizations. We demonstrate that the spontaneous emission from b^{3}Π_{0}(v_{b}=0,j_{b}=1) does not deteriorate the shielding process. This opens the possibility for a strong increase of the lifetime of cold molecule traps and for an efficient evaporative cooling. We also anticipate that the proposed mechanism is valid for alkali-metal diatomics with sufficiently large dipole-dipole interactions.
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Affiliation(s)
- T Xie
- Université Paris-Saclay, CNRS, Laboratoire Aimé Cotton, 91405 Orsay, France
| | - M Lepers
- Laboratoire Interdisciplinaire Carnot de Bourgogne, CNRS, Université de Bourgogne Franche-Comté, 21078 Dijon, France
| | - R Vexiau
- Université Paris-Saclay, CNRS, Laboratoire Aimé Cotton, 91405 Orsay, France
| | - A Orbán
- Institute for Nuclear Research (ATOMKI), H-4001 Debrecen, Pf. 51, Hungary
| | - O Dulieu
- Université Paris-Saclay, CNRS, Laboratoire Aimé Cotton, 91405 Orsay, France
| | - N Bouloufa-Maafa
- Université Paris-Saclay, CNRS, Laboratoire Aimé Cotton, 91405 Orsay, France
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24
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Yan ZZ, Park JW, Ni Y, Loh H, Will S, Karman T, Zwierlein M. Resonant Dipolar Collisions of Ultracold Molecules Induced by Microwave Dressing. PHYSICAL REVIEW LETTERS 2020; 125:063401. [PMID: 32845680 DOI: 10.1103/physrevlett.125.063401] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/05/2020] [Revised: 06/01/2020] [Accepted: 06/22/2020] [Indexed: 06/11/2023]
Abstract
We demonstrate microwave dressing on ultracold, fermionic ^{23}Na^{40}K ground-state molecules and observe resonant dipolar collisions with cross sections exceeding 3 times the s-wave unitarity limit. The origin of these interactions is the resonant alignment of the approaching molecules' dipoles along the intermolecular axis, which leads to strong attraction. We explain our observations with a conceptually simple two-state picture based on the Condon approximation. Furthermore, we perform coupled-channel calculations that agree well with the experimentally observed collision rates. The resonant microwave-induced collisions found here enable controlled, strong interactions between molecules, of immediate use for experiments in optical lattices.
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Affiliation(s)
- Zoe Z Yan
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Jee Woo Park
- Department of Physics, Pohang University of Science and Technology, Pohang 37673, Korea
| | - Yiqi Ni
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Huanqian Loh
- Department of Physics and Centre for Quantum Technologies, National University of Singapore, 117543 Singapore
| | - Sebastian Will
- Department of Physics, Columbia University, New York 10027, USA
| | - Tijs Karman
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | - Martin Zwierlein
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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25
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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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26
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Yang D, Huang J, Hu X, Xie D, Guo H. Statistical quantum mechanical approach to diatom–diatom capture dynamics and application to ultracold KRb + KRb reaction. J Chem Phys 2020; 152:241103. [DOI: 10.1063/5.0014805] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Dongzheng Yang
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jing Huang
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
| | - Xixi Hu
- Kuang Yaming Honors School, Nanjing University, Nanjing 210023, China
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, USA
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27
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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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28
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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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29
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Yang D, Zuo J, Huang J, Hu X, Dawes R, Xie D, Guo H. A Global Full-Dimensional Potential Energy Surface for the K 2Rb 2 Complex and Its Lifetime. J Phys Chem Lett 2020; 11:2605-2610. [PMID: 32163714 DOI: 10.1021/acs.jpclett.0c00518] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
A full-dimensional global potential energy surface for the KRb + KRb → K2 + Rb2 reaction is developed from 20 759 ab initio points calculated using a coupled cluster singles, doubles, and perturbative triples (CCSD(T)) method with effective core potentials, extrapolated to the complete basis set limit. The ab initio points are represented with high fidelity (root-mean-square error of 1.86 cm-1) using the permutation-invariant polynomial-neural network method, which enforces the permutation invariance of the potential with respect to exchange of identical nuclei. The potential energy surface features two D2h minima and one Cs minimum connected by the isomerization saddle points. The Rice-Ramsperger-Kassel-Marcus lifetime of the K2Rb2 reaction intermediate estimated using the potential energy surface is 227 ns, in reasonable agreement with the latest experimental measurement.
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Affiliation(s)
- Dongzheng Yang
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Junxiang Zuo
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Jing Huang
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
| | - Xixi Hu
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Richard Dawes
- Department of Chemistry, Missouri University of Science and Technology, Rolla, Missouri 65409, United States
| | - Daiqian Xie
- Institute of Theoretical and Computational Chemistry, Key Laboratory of Mesoscopic Chemistry, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hua Guo
- Department of Chemistry and Chemical Biology, University of New Mexico, Albuquerque, New Mexico 87131, United States
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30
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Liu Y, Grimes DD, Hu MG, Ni KK. Probing ultracold chemistry using ion spectrometry. Phys Chem Chem Phys 2020; 22:4861-4874. [DOI: 10.1039/c9cp07015j] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Reactions between KRb molecules at sub-microkelvin temperatures were probed using ion spectrometry.
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Affiliation(s)
- Yu Liu
- Department of Physics
- Harvard University
- Cambridge
- USA
- Department of Chemistry and Chemical Biology
| | - David D. Grimes
- Department of Physics
- Harvard University
- Cambridge
- USA
- Department of Chemistry and Chemical Biology
| | - Ming-Guang Hu
- Department of Physics
- Harvard University
- Cambridge
- USA
- Department of Chemistry and Chemical Biology
| | - Kang-Kuen Ni
- Department of Physics
- Harvard University
- Cambridge
- USA
- Department of Chemistry and Chemical Biology
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31
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Hu MG, Liu Y, Grimes DD, Lin YW, Gheorghe AH, Vexiau R, Bouloufa-Maafa N, Dulieu O, Rosenband T, Ni KK. Direct observation of bimolecular reactions of ultracold KRb molecules. Science 2019; 366:1111-1115. [DOI: 10.1126/science.aay9531] [Citation(s) in RCA: 106] [Impact Index Per Article: 21.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2019] [Accepted: 11/04/2019] [Indexed: 11/02/2022]
Abstract
Femtochemistry techniques have been instrumental in accessing the short time scales necessary to probe transient intermediates in chemical reactions. In this study, we took the contrasting approach of prolonging the lifetime of an intermediate by preparing reactant molecules in their lowest rovibronic quantum state at ultralow temperatures, thereby markedly reducing the number of exit channels accessible upon their mutual collision. Using ionization spectroscopy and velocity-map imaging of a trapped gas of potassium-rubidium (KRb) molecules at a temperature of 500 nanokelvin, we directly observed reactants, intermediates, and products of the reaction 40K87Rb + 40K87Rb → K2Rb2* → K2 + Rb2. Beyond observation of a long-lived, energy-rich intermediate complex, this technique opens the door to further studies of quantum-state–resolved reaction dynamics in the ultracold regime.
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Affiliation(s)
- M.-G. Hu
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA 02138, USA
| | - Y. Liu
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA 02138, USA
| | - D. D. Grimes
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA 02138, USA
| | - Y.-W. Lin
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA 02138, USA
| | - A. H. Gheorghe
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - R. Vexiau
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay, 91405 Orsay cedex, France
| | - N. Bouloufa-Maafa
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay, 91405 Orsay cedex, France
| | - O. Dulieu
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay, 91405 Orsay cedex, France
| | - T. Rosenband
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - K.-K. Ni
- Department of Chemistry and Chemical Biology, Harvard University, Cambridge, MA 02138, USA
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
- Harvard-MIT Center for Ultracold Atoms, Cambridge, MA 02138, USA
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32
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Christianen A, Zwierlein MW, Groenenboom GC, Karman T. Photoinduced Two-Body Loss of Ultracold Molecules. PHYSICAL REVIEW LETTERS 2019; 123:123402. [PMID: 31633957 DOI: 10.1103/physrevlett.123.123402] [Citation(s) in RCA: 18] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2019] [Indexed: 06/10/2023]
Abstract
The lifetime of nonreactive ultracold bialkali gases was conjectured to be limited by sticky collisions amplifying three-body loss. We show that the sticking times were previously overestimated and do not support this hypothesis. We find that electronic excitation of NaK+NaK collision complexes by the trapping laser leads to the experimentally observed two-body loss. We calculate the excitation rate with a quasiclassical, statistical model employing ab initio potentials and transition dipole moments. Using longer laser wavelengths or repulsive box potentials may suppress the losses.
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Affiliation(s)
- Arthur Christianen
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Martin W Zwierlein
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
| | - Gerrit C Groenenboom
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, the Netherlands
| | - Tijs Karman
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
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33
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Liu Y, Gong T, Ji Z, Wang G, Zhao Y, Xiao L, Jia S. Production of ultracold 85Rb 133Cs molecules in the lowest ground state via the B 1Π 1 short-range state. J Chem Phys 2019; 151:084303. [PMID: 31470716 DOI: 10.1063/1.5108637] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023] Open
Abstract
We investigate the production of cold 85Rb133Cs molecules in the lowest vibronic level of the ground electronic state via the B1Π1 short-range state. The photoassociation (PA) spectra of the B1Π1 state, including newly observed transition to 2 vibronic levels, are obtained by high sensitivity time-of-flight mass spectrometry. Based on these PA spectra, the harmonic and anharmonic constants of vibronic states are obtained, resulting in predicted vibronic energies with an uncertainty of 1-2 cm-1. The B1Π1 (v = 3) state is found to have the maximum production rate for ground-state molecules with a value of 3(1) × 104 s-1, which is 3 times larger than the value via the previously studied 23Π0+ (v = 10, J = 0) state with two-photon cascade decay. The populations of J = 0, 1, and 2 rotational levels of X1Σ+ (v = 0) state molecules formed via the B1Π1 (v = 3, J = 1) state are measured to be around 20%, 40%, and 20%. To quantify the coupling strength between the B1Π1 (v = 3) state and X1Σ+ (v = 0) state, the transition dipole moment between them is measured to be 7.2(2) × 10-3ea0, which is also 3 times larger than the value between the 23Π0+ (v=10) state and X1Σ+ (v = 0) state, meaning the B1Π1 (v = 3) state has a stronger coupling with the X1Σ+ (v = 0) state. Our detailed measurements provide relevant parameters for investigation on direct stimulated Raman adiabatic passage transfer between the atomic scattering state and molecular bound state for 85Rb133Cs molecules.
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Affiliation(s)
- Yuting Liu
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
| | - Ting Gong
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
| | - Zhonghua Ji
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
| | - Gaoren Wang
- College of Physics, Dalian University of Technology, Dalian, Liaoning 116023, China
| | - Yanting Zhao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
| | - Liantuan Xiao
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
| | - Suotang Jia
- State Key Laboratory of Quantum Optics and Quantum Optics Devices, Institute of Laser Spectroscopy, Shanxi University, Taiyuan 030006, China
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34
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Collisions between cold molecules in a superconducting magnetic trap. Nature 2019; 572:189-193. [DOI: 10.1038/s41586-019-1446-2] [Citation(s) in RCA: 44] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/22/2019] [Accepted: 06/12/2019] [Indexed: 11/08/2022]
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35
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Gregory PD, Frye MD, Blackmore JA, Bridge EM, Sawant R, Hutson JM, Cornish SL. Sticky collisions of ultracold RbCs molecules. Nat Commun 2019; 10:3104. [PMID: 31308368 PMCID: PMC6629645 DOI: 10.1038/s41467-019-11033-y] [Citation(s) in RCA: 37] [Impact Index Per Article: 7.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/01/2019] [Accepted: 06/13/2019] [Indexed: 12/04/2022] Open
Abstract
Understanding and controlling collisions is crucial to the burgeoning field of ultracold molecules. All experiments so far have observed fast loss of molecules from the trap. However, the dominant mechanism for collisional loss is not well understood when there are no allowed 2-body loss processes. Here we experimentally investigate collisional losses of nonreactive ultracold 87Rb133Cs molecules, and compare our findings with the sticky collision hypothesis that pairs of molecules form long-lived collision complexes. We demonstrate that loss of molecules occupying their rotational and hyperfine ground state is best described by second-order rate equations, consistent with the expectation for complex-mediated collisions, but that the rate is lower than the limit of universal loss. The loss is insensitive to magnetic field but increases for excited rotational states. We demonstrate that dipolar effects lead to significantly faster loss for an incoherent mixture of rotational states.
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Affiliation(s)
- Philip D Gregory
- Joint Quantum Centre (JQC), Durham-Newcastle, Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - Matthew D Frye
- Joint Quantum Centre (JQC), Durham-Newcastle, Department of Chemistry, Durham University, Durham, DH1 3LE, UK
| | - Jacob A Blackmore
- Joint Quantum Centre (JQC), Durham-Newcastle, Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - Elizabeth M Bridge
- Joint Quantum Centre (JQC), Durham-Newcastle, Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - Rahul Sawant
- Joint Quantum Centre (JQC), Durham-Newcastle, Department of Physics, Durham University, Durham, DH1 3LE, UK
| | - Jeremy M Hutson
- Joint Quantum Centre (JQC), Durham-Newcastle, Department of Chemistry, Durham University, Durham, DH1 3LE, UK.
| | - Simon L Cornish
- Joint Quantum Centre (JQC), Durham-Newcastle, Department of Physics, Durham University, Durham, DH1 3LE, UK.
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36
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Abstract
Universal collisions describe the reaction of molecules and atoms as dominated by long-range interparticle interactions. Here, we calculate the universal inelastic rate coefficients for a large group of ultracold polar molecules in their lower ro-vibrational states colliding with one of their constituent atoms. The rate coefficients are solely determined by values of the dispersion coefficient and reduced mass of the collisional system. We use the ab initio coupled-cluster linear response method to compute dynamic molecular polarizabilities and obtain the dispersion coefficients for some of the collisional partners and use values from the literature for others. Our polarizability calculations agree well with available experimental measurements. Comparison of our inelastic rate coefficients with results of numerically exact quantum-mechanical calculations leads us to conjecture that collisions with heavier atoms can be expected to be more universal.
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37
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Christianen A, Karman T, Vargas-Hernández RA, Groenenboom GC, Krems RV. Six-dimensional potential energy surface for NaK–NaK collisions: Gaussian process representation with correct asymptotic form. J Chem Phys 2019; 150:064106. [DOI: 10.1063/1.5082740] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Arthur Christianen
- Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Tijs Karman
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | | | - Gerrit C. Groenenboom
- Theoretical Chemistry, Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Roman V. Krems
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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38
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Seeßelberg F, Luo XY, Li M, Bause R, Kotochigova S, Bloch I, Gohle C. Extending Rotational Coherence of Interacting Polar Molecules in a Spin-Decoupled Magic Trap. PHYSICAL REVIEW LETTERS 2018; 121:253401. [PMID: 30608826 DOI: 10.1103/physrevlett.121.253401] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/12/2018] [Indexed: 06/09/2023]
Abstract
Superpositions of rotational states in polar molecules induce strong, long-range dipolar interactions. Here we extend the rotational coherence by nearly 1 order of magnitude to 8.7(6) ms in a dilute gas of polar ^{23}Na^{40}K molecules in an optical trap. We demonstrate spin-decoupled magic trapping, which cancels first-order and reduces second-order differential light shifts. The latter is achieved with a dc electric field that decouples nuclear spin, rotation, and trapping light field. We observe density-dependent coherence times, which can be explained by dipolar interactions in the bulk gas.
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Affiliation(s)
| | - Xin-Yu Luo
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - Ming Li
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Roman Bause
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | | | - Immanuel Bloch
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Fakultät für Physik, Ludwig-Maximilians-Universität München, 80799 München, Germany
| | - Christoph Gohle
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
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39
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Lassablière L, Quéméner G. Controlling the Scattering Length of Ultracold Dipolar Molecules. PHYSICAL REVIEW LETTERS 2018; 121:163402. [PMID: 30387665 DOI: 10.1103/physrevlett.121.163402] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2018] [Indexed: 06/08/2023]
Abstract
By applying a circularly polarized and slightly blue-detuned microwave field with respect to the first excited rotational state of a dipolar molecule, one can engineer a long-range, shallow potential well in the entrance channel of the two colliding partners. As the applied microwave ac field is increased, the long-range well becomes deeper and can support a certain number of bound states, which in turn bring the value of the molecule-molecule scattering length from a large negative value to a large positive one. We adopt an adimensional approach where the molecules are described by a rescaled rotational constant B[over ˜]=B/s_{E_{3}} where s_{E_{3}} is a characteristic dipolar energy. We found that molecules with B[over ˜]>10^{8} are immune to any quenching losses when a sufficient ac field is applied, the ratio elastic to quenching processes can reach values above 10^{3}, and that the value and sign of the scattering length can be tuned. The ability to control the molecular scattering length opens the door for a rich, strongly correlated, many-body physics for ultracold molecules, similar to that for ultracold atoms.
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Affiliation(s)
- Lucas Lassablière
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay, 91405 Orsay, France
| | - Goulven Quéméner
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Paris-Saclay, Université Paris-Saclay, 91405 Orsay, France
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40
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Karman T, Hutson JM. Microwave Shielding of Ultracold Polar Molecules. PHYSICAL REVIEW LETTERS 2018; 121:163401. [PMID: 30387668 DOI: 10.1103/physrevlett.121.163401] [Citation(s) in RCA: 29] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/10/2018] [Indexed: 06/08/2023]
Abstract
We use microwaves to engineer repulsive long-range interactions between ultracold polar molecules. The resulting shielding suppresses various loss mechanisms and provides large elastic cross sections. Hyperfine interactions limit the shielding under realistic conditions, but a magnetic field allows suppression of the losses to below 10^{-14} cm^{3} s^{-1}. The mechanism and optimum conditions for shielding differ substantially from those proposed by Gorshkov et al. [Phys. Rev. Lett. 101, 073201 (2008)PRLTAO0031-900710.1103/PhysRevLett.101.073201], and do not require cancellation of the long-range dipole-dipole interaction that is vital to many applications.
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Affiliation(s)
- Tijs Karman
- 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
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