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Collisional cooling of ultracold molecules. Nature 2020; 580:197-200. [DOI: 10.1038/s41586-020-2141-z] [Citation(s) in RCA: 45] [Impact Index Per Article: 11.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2019] [Accepted: 01/27/2020] [Indexed: 11/09/2022]
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2
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Green A, Li H, Toh JHS, Tang X, McCormick KC, Li M, Tiesinga E, Kotochigova S, Gupta S. Feshbach Resonances in p-Wave Three-Body Recombination within Fermi-Fermi Mixtures of Open-Shell 6Li and Closed-Shell 173Yb Atoms. PHYSICAL REVIEW. X 2020; 10:10.1103/PhysRevX.10.031037. [PMID: 34408918 PMCID: PMC8369980 DOI: 10.1103/physrevx.10.031037] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Indexed: 06/13/2023]
Abstract
We report on the observation of magnetic Feshbach resonances in a Fermi-Fermi mixture of ultracold atoms with extreme mass imbalance and on their unique p-wave dominated three-body recombination processes. Our system consists of open-shell alkali-metal 6Li and closed-shell 173Yb atoms, both spin polarized and held at various temperatures between 1 and 20 μK. We confirm that Feshbach resonances in this system are solely the result of a weak separation-dependent hyperfine coupling between the electronic spin of 6Li and the nuclear spin of 173Yb. Our analysis also shows that three-body recombination rates are controlled by the identical fermion nature of the mixture, even in the presence of s-wave collisions between the two species and with recombination rate coefficients outside the Wigner threshold regime at our lowest temperature. Specifically, a comparison of experimental and theoretical line shapes of the recombination process indicates that the characteristic asymmetric line shape as a function of applied magnetic field and a maximum recombination rate coefficient that is independent of temperature can only be explained by triatomic collisions with nonzero, p-wave total orbital angular momentum. The resonances can be used to form ultracold doublet ground-state molecules and to simulate quantum superfluidity in mass-imbalanced mixtures.
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Affiliation(s)
- Alaina Green
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Hui Li
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Jun Hui See Toh
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Xinxin Tang
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | | | - Ming Li
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - Eite Tiesinga
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, National Institute of Standards and Technology and University of Maryland, Gaithersburg, Maryland 20899, USA
| | | | - Subhadeep Gupta
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
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3
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Roy R, Green A, Bowler R, Gupta S. Two-Element Mixture of Bose and Fermi Superfluids. PHYSICAL REVIEW LETTERS 2017; 118:055301. [PMID: 28211743 DOI: 10.1103/physrevlett.118.055301] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2016] [Indexed: 06/06/2023]
Abstract
We report on the production of a stable mixture of bosonic and fermionic superfluids composed of the elements ^{174}Yb and ^{6}Li which feature a strong mismatch in mass and distinct electronic properties. We demonstrate elastic coupling between the superfluids by observing the shift in dipole oscillation frequency of the bosonic component due to the presence of the fermions. The measured magnitude of the shift is consistent with a mean-field model and its direction determines the previously unknown sign of the interspecies scattering length to be positive. We also observe the exchange of angular momentum between the superfluids from the excitation of a scissors mode in the bosonic component through interspecies interactions. We explain this observation using an analytical model based on superfluid hydrodynamics.
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Affiliation(s)
- Richard Roy
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Alaina Green
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Ryan Bowler
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Subhadeep Gupta
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
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4
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Deng L, Gou D, Chai J. The theoretical study of the ground-state polar chromium-alkali-metal-atom molecules. Chem Phys Lett 2016. [DOI: 10.1016/j.cplett.2016.03.001] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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Bowden W, Gunton W, Semczuk M, Dare K, Madison KW. An adaptable dual species effusive source and Zeeman slower design demonstrated with Rb and Li. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2016; 87:043111. [PMID: 27131658 DOI: 10.1063/1.4945567] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We present a dual-species effusive source and Zeeman slower designed to produce slow atomic beams of two elements with a large mass difference and with very different oven temperature requirements. We demonstrate this design for the case of (6)Li and (85)Rb and achieve magneto-optical trap (MOT) loading rates equivalent to that reported in prior work on dual species (Rb+Li) Zeeman slowers operating at the same oven temperatures. Key design choices, including thermally separating the effusive sources and using a segmented coil design to enable computer control of the magnetic field profile, ensure that the apparatus can be easily modified to slow other atomic species. By performing the final slowing using the quadrupole magnetic field of the MOT, we are able to shorten our Zeeman slower length making for a more compact system without compromising performance. We outline the construction and analyze the emission properties of our effusive sources. We also verify the performance of the source and slower, and we observe sequential loading rates of 12 × 10(8) atoms/s for a Rb oven temperature of 140 °C and 1.1 × 10(8) atoms/s for a Li reservoir at 460 °C, corresponding to reservoir lifetimes for continuous operation of 10 and 4 years, respectively.
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Affiliation(s)
- William Bowden
- The Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Will Gunton
- The Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Mariusz Semczuk
- The Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Kahan Dare
- The Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Kirk W Madison
- The Department of Physics and Astronomy, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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Tohme SN, Korek M, Awad R. Ab initio calculations of the electronic structure of the low-lying states for the ultracold LiYb molecule. J Chem Phys 2015; 142:114312. [PMID: 25796254 DOI: 10.1063/1.4914472] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/30/2023] Open
Abstract
Ab initio techniques have been applied to investigate the electronic structure of the LiYb molecule. The potential energy curves have been computed in the Born-Oppenheimer approximation for the ground and 29 low-lying doublet and quartet excited electronic states. Complete active space self-consistent field, multi-reference configuration interaction, and Rayleigh Schrödinger perturbation theory to second order calculations have been utilized to investigate these states. The spectroscopic constants, ωe, Re, Be, …, and the static dipole moment, μ, have been investigated by using the two different techniques of calculation with five different types of basis. The eigenvalues, Ev, the rotational constant, Bv, the centrifugal distortion constant, Dv, and the abscissas of the turning points, Rmin and Rmax, have been calculated by using the canonical functions approach. The comparison between the values of the present work, calculated by different techniques, and those available in the literature for several electronic states shows a very good agreement. Twenty-one new electronic states have been studied here for the first time.
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Affiliation(s)
- Samir N Tohme
- Faculty of Science, Beirut Arab University, P.O. Box 11-5020 Riad El Solh, Beirut 1107 2809, Lebanon
| | - Mahmoud Korek
- Faculty of Science, Beirut Arab University, P.O. Box 11-5020 Riad El Solh, Beirut 1107 2809, Lebanon
| | - Ramadan Awad
- Faculty of Science, Beirut Arab University, P.O. Box 11-5020 Riad El Solh, Beirut 1107 2809, Lebanon
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Tomza M, González-Férez R, Koch CP, Moszynski R. Controlling magnetic Feshbach resonances in polar open-shell molecules with nonresonant light. PHYSICAL REVIEW LETTERS 2014; 112:113201. [PMID: 24702365 DOI: 10.1103/physrevlett.112.113201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/31/2013] [Indexed: 06/03/2023]
Abstract
Magnetically tunable Feshbach resonances for polar paramagnetic ground-state diatomics are too narrow to allow for magnetoassociation starting from trapped, ultracold atoms. We show that nonresonant light can be used to engineer the Feshbach resonances in their position and width. For nonresonant field intensities of the order of 10(9) W/cm(2), we find the width to be increased by 3 orders of magnitude, reaching a few Gauss. This opens the way for producing ultracold molecules with sizable electric and magnetic dipole moments and thus for many-body quantum simulations with such particles.
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Affiliation(s)
- Michał Tomza
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland and Instituto 'Carlos I' de Física Teórica y Computacional and Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, 18071 Granada, Spain and Theoretische Physik, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
| | - Rosario González-Férez
- Instituto 'Carlos I' de Física Teórica y Computacional and Departamento de Física Atómica, Molecular y Nuclear, Universidad de Granada, 18071 Granada, Spain and The Hamburg Center for Ultrafast Imaging, University of Hamburg, 22761 Hamburg, Germany
| | - Christiane P Koch
- Theoretische Physik, Universität Kassel, Heinrich-Plett-Straße 40, 34132 Kassel, Germany
| | - Robert Moszynski
- Faculty of Chemistry, University of Warsaw, Pasteura 1, 02-093 Warsaw, Poland
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Khramov A, Hansen A, Dowd W, Roy RJ, Makrides C, Petrov A, Kotochigova S, Gupta S. Ultracold heteronuclear mixture of ground and excited state atoms. PHYSICAL REVIEW LETTERS 2014; 112:033201. [PMID: 24484136 DOI: 10.1103/physrevlett.112.033201] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/29/2013] [Indexed: 06/03/2023]
Abstract
We report on the realization of an ultracold mixture of lithium atoms in the ground state and ytterbium atoms in an excited metastable (3P2) state. Such a mixture can support broad magnetic Feshbach resonances which may be utilized for the production of ultracold molecules with an electronic spin degree of freedom, as well as novel Efimov trimers. We investigate the interaction properties of the mixture in the presence of an external magnetic field and find an upper limit for the background interspecies two-body inelastic decay coefficient of K2'<3×10(-12) cm3/s for the 3P2 mJ=-1 substate. We calculate the dynamic polarizabilities of the Yb(3P2) magnetic substates for a range of wavelengths, and find good agreement with our measurements at 1064 nm. Our calculations also allow the identification of magic frequencies where Yb ground and metastable states are identically trapped and the determination of the interspecies van der Waals coefficients.
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Affiliation(s)
- Alexander Khramov
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Anders Hansen
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - William Dowd
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | - Richard J Roy
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
| | | | - Alexander Petrov
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA and St. Petersburg Nuclear Physics Institute, Gatchina 188300, Russia, and Division of Quantum Mechanics, St. Petersburg State University, St. Petersburg 198904, Russia
| | | | - Subhadeep Gupta
- Department of Physics, University of Washington, Seattle, Washington 98195, USA
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Krois G, Pototschnig JV, Lackner F, Ernst WE. Spectroscopy of cold LiCa molecules formed on helium nanodroplets. J Phys Chem A 2013; 117:13719-31. [PMID: 24028555 PMCID: PMC3871282 DOI: 10.1021/jp407818k] [Citation(s) in RCA: 26] [Impact Index Per Article: 2.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/05/2013] [Revised: 09/11/2013] [Indexed: 11/30/2022]
Abstract
We report on the formation of mixed alkali-alkaline earth molecules (LiCa) on helium nanodroplets and present a comprehensive experimental and theoretical study of the ground and excited states of LiCa. Resonance enhanced multiphoton ionization time-of-flight (REMPI-TOF) spectroscopy and laser induced fluorescence (LIF) spectroscopy were used for the experimental investigation of LiCa from 15000 to 25500 cm(-1). The 4(2)Σ(+) and 3(2)Π states show a vibrational structure accompanied by distinct phonon wings, which allows us to determine molecular parameters as well as to study the interaction of the molecule with the helium droplet. Higher excited states (4(2)Π, 5(2)Σ(+), 5(2)Π, and 6(2)Σ(+)) are not vibrationally resolved and vibronic transitions start to overlap. The experimental spectrum is well reproduced by high-level ab initio calculations. By using a multireference configuration interaction (MRCI) approach, we calculated the 19 lowest lying potential energy curves (PECs) of the LiCa molecule. On the basis of these calculations, we could identify previously unobserved transitions. Our results demonstrate that the helium droplet isolation approach is a powerful method for the characterization of tailor-made alkali-alkaline earth molecules. In this way, important contributions can be made to the search for optimal pathways toward the creation of ultracold alkali-alkaline earth ground state molecules from the corresponding atomic species. Furthermore, a test for PECs calculated by ab initio methods is provided.
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Affiliation(s)
- Günter Krois
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Johann V. Pototschnig
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Florian Lackner
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
| | - Wolfgang E. Ernst
- Institute of Experimental Physics, Graz University of Technology, Petersgasse 16, A-8010 Graz, Austria
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Safronova MS, Porsev SG, Clark CW. Ytterbium in quantum gases and atomic clocks: van der Waals interactions and blackbody shifts. PHYSICAL REVIEW LETTERS 2012; 109:230802. [PMID: 23368178 DOI: 10.1103/physrevlett.109.230802] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2012] [Indexed: 06/01/2023]
Abstract
We evaluated the C(6) coefficients of Yb-Yb, Yb-alkali, and Yb-group II van der Waals interactions with 2% uncertainty. The only existing experimental result for such quantities is for the Yb-Yb dimer. Our value, C(6)=1929(39) a.u., is in excellent agreement with the recent experimental determination of 1932(35) a.u. We have also developed a new approach for the calculation of the dynamic correction to the blackbody radiation shift. We have calculated this quantity for the Yb 6s(2) (1)S(0)-6s6p (3)P(0)(o) clock transition with 3.5% uncertainty. This reduces the fractional uncertainty due to the blackbody radiation shift in the Yb optical clock at 300 K to the 10(-18) level.
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Affiliation(s)
- M S Safronova
- Department of Physics and Astronomy, University of Delaware, Newark, Delaware 19716, USA
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Spethmann N, Kindermann F, John S, Weber C, Meschede D, Widera A. Dynamics of single neutral impurity atoms immersed in an ultracold gas. PHYSICAL REVIEW LETTERS 2012; 109:235301. [PMID: 23368215 DOI: 10.1103/physrevlett.109.235301] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/30/2012] [Revised: 08/14/2012] [Indexed: 06/01/2023]
Abstract
We report on controlled doping of an ultracold Rb gas with single neutral Cs impurity atoms. Elastic two-body collisions lead to a rapid thermalization of the impurity inside the Rb gas, representing the first realization of an ultracold gas doped with a precisely known number of impurity atoms interacting via s-wave collisions. Inelastic interactions are restricted to a single three-body recombination channel in a highly controlled and pure setting, which allows us to determine the Rb-Rb-Cs three-body loss rate with unprecedented precision. Our results pave the way for a coherently interacting hybrid system of individually controllable impurities in a quantum many-body system.
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Affiliation(s)
- Nicolas Spethmann
- Institut für Angewandte Physik, Universität Bonn, Wegelerstrasse 8, 53115 Bonn, Germany
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Affiliation(s)
- Goulven Quéméner
- JILA, University of Colorado,
Boulder, CO 80309-0440, United States
| | - Paul S. Julienne
- Joint Quantum Institute, NIST
and the University of Maryland, Gaithersburg, Maryland 20899-8423,
United States
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Brue DA, Hutson JM. Magnetically tunable Feshbach resonances in ultracold Li-Yb mixtures. PHYSICAL REVIEW LETTERS 2012; 108:043201. [PMID: 22400838 DOI: 10.1103/physrevlett.108.043201] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/08/2011] [Revised: 10/25/2011] [Indexed: 05/31/2023]
Abstract
We investigate the possibility of forming Li+Yb ultracold molecules by magnetoassociation in mixtures of ultracold atoms. We find that magnetically tunable Feshbach resonances exist, but are extremely narrow for even-mass ytterbium isotopes, which all have zero spin. For odd-mass Yb isotopes, however, there is a new mechanism due to hyperfine coupling between the electron spin and the Yb nuclear magnetic moment. This mechanism produces Feshbach resonances for fermionic Yb isotopes that can be more than 2 orders of magnitude larger than for the bosonic counterparts.
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Affiliation(s)
- Daniel A Brue
- Department of Chemistry, Durham University, South Road, Durham DH1 3LE, United Kingdom.
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Kotochigova S, Petrov A, Linnik M, Kłos J, Julienne PS. Ab initio properties of Li-group-II molecules for ultracold matter studies. J Chem Phys 2011; 135:164108. [DOI: 10.1063/1.3653974] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
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Hara H, Takasu Y, Yamaoka Y, Doyle JM, Takahashi Y. Quantum degenerate mixtures of alkali and alkaline-earth-like atoms. PHYSICAL REVIEW LETTERS 2011; 106:205304. [PMID: 21668241 DOI: 10.1103/physrevlett.106.205304] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/16/2011] [Revised: 04/22/2011] [Indexed: 05/30/2023]
Abstract
We realize simultaneous quantum degeneracy in mixtures consisting of the alkali and alkaline-earth-like atoms Li and Yb. This is accomplished within an optical trap by sympathetic cooling of the fermionic isotope ⁶Li with evaporatively cooled bosonic ¹⁷⁴Yb and, separately, fermionic ¹⁷³Yb. Using cross-thermalization studies, we also measure the elastic s-wave scattering lengths of both Li-Yb combinations, |a(⁶Li-¹⁷⁴Yb)| = 1.0 ± 0.2 nm and |a(⁶Li-¹⁷³Yb)| = 0.9 ± 0.2 nm. The equality of these lengths is found to be consistent with mass-scaling analysis. The quantum degenerate mixtures of Li and Yb, as realized here, can be the basis for creation of ultracold molecules with electron spin degrees of freedom, studies of novel Efimov trimers, and impurity probes of superfluid systems.
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Affiliation(s)
- Hideaki Hara
- Department of Physics, Graduate School of Science, Kyoto University, Kyoto 606-8502, Japan
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Münchow F, Bruni C, Madalinski M, Görlitz A. Two-photon photoassociation spectroscopy of heteronuclear YbRb. Phys Chem Chem Phys 2011; 13:18734-7. [DOI: 10.1039/c1cp21219b] [Citation(s) in RCA: 46] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
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