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Zhao H, Sun Z. An improved method for reactive scatterings in ultra-cold conditions using the time-dependent approach. Phys Chem Chem Phys 2024; 26:22790-22797. [PMID: 39163005 DOI: 10.1039/d4cp02340d] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/21/2024]
Abstract
A new efficient method for considering the long-range effect of reactive scattering processes in ultra-cold conditions has been developed using the time-dependent quantum wave packet theory, where the initial wave packet could be placed at a position near the interaction region. This is in contrast to previous methods, where the initial wave packet has to be placed far from the interaction region. The new method reduces the numerical effort significantly. Typical reactions, such as S(1D) + H2, D+ + H2, and 7Li + 7Li2 (v0 = 1, j0 = 0), under cold or ultra-cold conditions, are used to demonstrate the numerical efficiency of the new method.
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Affiliation(s)
- Hailin Zhao
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China.
| | - Zhigang Sun
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian 116023, P. R. China.
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2
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Li P, He W, Ju P, Ji L, Liu X, Wu F, Lu Z, Li H, Chen L, Liu J, Zhou H, Chen J. Acquisition of molecular rolling lubrication by self-curling of graphite nanosheet at cryogenic temperature. Nat Commun 2024; 15:5747. [PMID: 38982069 PMCID: PMC11233547 DOI: 10.1038/s41467-024-49994-4] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/27/2023] [Accepted: 06/24/2024] [Indexed: 07/11/2024] Open
Abstract
Friction as a fundamental physical phenomenon dominates nature and human civilization, among which the achievement of molecular rolling lubrication is desired to bring another breakthrough, like the macroscale design of wheel. Herein, an edge self-curling nanodeformation phenomenon of graphite nanosheets (GNSs) at cryogenic temperature is found, which is then used to promote the formation of graphite nanorollers in friction process towards molecular rolling lubrication. The observation of parallel nanorollers at the friction interface give the experimental evidence for the occurrence of molecular rolling lubrication, and the graphite exhibits abnormal lubrication performance in vacuum with ultra-low friction and wear at macroscale. The molecular rolling lubrication mechanism is elucidated from the electronic interaction perspective. Experiments and theoretical simulations indicate that the driving force of the self-curling is the uneven atomic shrinkage induced stress, and then the shear force promotes the intact nanoroller formation, while the constraint of atomic vibration decreases the dissipation of driving stress and favors the nanoroller formation therein. It will open up a new pathway for controlling friction at microscale and nanostructural manipulation.
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Affiliation(s)
- Panpan Li
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Wenhao He
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China
| | - Pengfei Ju
- Shanghai Aerospace Equipment Manufacture, Shanghai, China
| | - Li Ji
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
| | - Xiaohong Liu
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China
| | - Fan Wu
- Changchun Institute of Applied Chemistry, Chinese Academy of Sciences, Changchun, China
| | - Zhibin Lu
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
| | - Hongxuan Li
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
| | - Lei Chen
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Jingzhou Liu
- Shanghai Aerospace Equipment Manufacture, Shanghai, China
| | - Huidi Zhou
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China
| | - Jianmin Chen
- State Key Laboratory of Solid Lubrication, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou, China.
- Center of Materials Science and Optoelectronics Engineering, University of Chinese Academy of Sciences, Beijing, China.
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3
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Chen XY, Biswas S, Eppelt S, Schindewolf A, Deng F, Shi T, Yi S, Hilker TA, Bloch I, Luo XY. Ultracold field-linked tetratomic molecules. Nature 2024; 626:283-287. [PMID: 38297128 PMCID: PMC10849947 DOI: 10.1038/s41586-023-06986-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/05/2023] [Accepted: 12/15/2023] [Indexed: 02/02/2024]
Abstract
Ultracold polyatomic molecules offer opportunities1 in cold chemistry2,3, precision measurements4 and quantum information processing5,6, because of their rich internal structure. However, their increased complexity compared with diatomic molecules presents a challenge in using conventional cooling techniques. Here we demonstrate an approach to create weakly bound ultracold polyatomic molecules by electroassociation7 (F.D. et al., manuscript in preparation) in a degenerate Fermi gas of microwave-dressed polar molecules through a field-linked resonance8-11. Starting from ground-state NaK molecules, we create around 1.1 × 103 weakly bound tetratomic (NaK)2 molecules, with a phase space density of 0.040(3) at a temperature of 134(3) nK, more than 3,000 times colder than previously realized tetratomic molecules12. We observe a maximum tetramer lifetime of 8(2) ms in free space without a notable change in the presence of an optical dipole trap, indicating that these tetramers are collisionally stable. Moreover, we directly image the dissociated tetramers through microwave-field modulation to probe the anisotropy of their wavefunction in momentum space. Our result demonstrates a universal tool for assembling weakly bound ultracold polyatomic molecules from smaller polar molecules, which is a crucial step towards Bose-Einstein condensation of polyatomic molecules and towards a new crossover from a dipolar Bardeen-Cooper-Schrieffer superfluid13-15 to a Bose-Einstein condensation of tetramers. Moreover, the long-lived field-linked state provides an ideal starting point for deterministic optical transfer to deeply bound tetramer states16-18.
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Affiliation(s)
- Xing-Yan Chen
- Max-Planck-Institut für Quantenoptik, Garching, Germany
- Munich Center for Quantum Science and Technology, Munich, Germany
| | - Shrestha Biswas
- Max-Planck-Institut für Quantenoptik, Garching, Germany
- Munich Center for Quantum Science and Technology, Munich, Germany
| | - Sebastian Eppelt
- Max-Planck-Institut für Quantenoptik, Garching, Germany
- Munich Center for Quantum Science and Technology, Munich, Germany
| | - Andreas Schindewolf
- Max-Planck-Institut für Quantenoptik, Garching, Germany
- Munich Center for Quantum Science and Technology, Munich, Germany
| | - Fulin Deng
- School of Physics and Technology, Wuhan University, Wuhan, China
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China
| | - Tao Shi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China.
- AS Center for Excellence in Topological Quantum Computation & School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China.
| | - Su Yi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, China
- AS Center for Excellence in Topological Quantum Computation & School of Physical Sciences, University of Chinese Academy of Sciences, Beijing, China
- Peng Huanwu Collaborative Center for Research and Education, Beihang University, Beijing, China
| | - Timon A Hilker
- Max-Planck-Institut für Quantenoptik, Garching, Germany
- Munich Center for Quantum Science and Technology, Munich, Germany
| | - Immanuel Bloch
- Max-Planck-Institut für Quantenoptik, Garching, Germany
- Munich Center for Quantum Science and Technology, Munich, Germany
- Fakultät für Physik, Ludwig-Maximilians-Universität, Munich, Germany
| | - Xin-Yu Luo
- Max-Planck-Institut für Quantenoptik, Garching, Germany.
- Munich Center for Quantum Science and Technology, Munich, Germany.
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4
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Koch J, Menon K, Cuestas E, Barbosa S, Lutz E, Fogarty T, Busch T, Widera A. A quantum engine in the BEC-BCS crossover. Nature 2023; 621:723-727. [PMID: 37758889 PMCID: PMC10533395 DOI: 10.1038/s41586-023-06469-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2022] [Accepted: 07/21/2023] [Indexed: 09/29/2023]
Abstract
Heat engines convert thermal energy into mechanical work both in the classical and quantum regimes1. However, quantum theory offers genuine non-classical forms of energy, different from heat, which so far have not been exploited in cyclic engines. Here we experimentally realize a quantum many-body engine fuelled by the energy difference between fermionic and bosonic ensembles of ultracold particles that follows from the Pauli exclusion principle2. We employ a harmonically trapped superfluid gas of 6Li atoms close to a magnetic Feshbach resonance3 that allows us to effectively change the quantum statistics from Bose-Einstein to Fermi-Dirac, by tuning the gas between a Bose-Einstein condensate of bosonic molecules and a unitary Fermi gas (and back) through a magnetic field4-10. The quantum nature of such a Pauli engine is revealed by contrasting it with an engine in the classical thermal regime and with a purely interaction-driven device. We obtain a work output of several 106 vibrational quanta per cycle with an efficiency of up to 25%. Our findings establish quantum statistics as a useful thermodynamic resource for work production.
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Affiliation(s)
- Jennifer Koch
- Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Kaiserslautern, Germany
| | | | - Eloisa Cuestas
- OIST Graduate University, Onna, Japan
- Enrique Gaviola Institute of Physics, National Scientific and Technical Research Council of Argentina and National University of Córdoba, Córdoba, Argentina
| | - Sian Barbosa
- Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Kaiserslautern, Germany
| | - Eric Lutz
- Institute for Theoretical Physics I, University of Stuttgart, Stuttgart, Germany
| | | | | | - Artur Widera
- Department of Physics and Research Center OPTIMAS, RPTU Kaiserslautern-Landau, Kaiserslautern, Germany.
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5
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Harrison N, Chan MK. Magic Gap Ratio for Optimally Robust Fermionic Condensation and Its Implications for High-T_{c} Superconductivity. PHYSICAL REVIEW LETTERS 2022; 129:017001. [PMID: 35841553 DOI: 10.1103/physrevlett.129.017001] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/26/2021] [Revised: 03/22/2022] [Accepted: 05/24/2022] [Indexed: 06/15/2023]
Abstract
Bardeen-Schrieffer-Cooper (BCS) and Bose-Einstein condensation (BEC) occur at opposite limits of a continuum of pairing interaction strength between fermions. A crossover between these limits is readily observed in a cold atomic Fermi gas. Whether it occurs in other systems such as the high temperature superconducting cuprates has remained an open question. We uncover here unambiguous evidence for a BCS-BEC crossover in the cuprates by identifying a universal magic gap ratio 2Δ/k_{B}T_{c}≈6.5 (where Δ is the pairing gap and T_{c} is the transition temperature) at which paired fermion condensates become optimally robust. At this gap ratio, corresponding to the unitary point in a cold atomic Fermi gas, the measured condensate fraction N_{0} and the height of the jump δγ(T_{c}) in the coefficient γ of the fermionic specific heat at T_{c} are strongly peaked. In the cuprates, δγ(T_{c}) is peaked at this gap ratio when Δ corresponds to the antinodal spectroscopic gap, thus reinforcing its interpretation as the pairing gap. We find the peak in δγ(T_{c}) also to coincide with a normal state maximum in γ, which is indicative of a pairing fluctuation pseudogap above T_{c}.
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Affiliation(s)
- N Harrison
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - M K Chan
- National High Magnetic Field Laboratory, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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6
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Zhang TC, Zhang J, Chen SC, Saada B. A Novel Prediction Model for Brain Glioma Image Segmentation Based on the Theory of Bose-Einstein Condensate. Front Med (Lausanne) 2022; 9:794125. [PMID: 35372409 PMCID: PMC8971582 DOI: 10.3389/fmed.2022.794125] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2021] [Accepted: 01/14/2022] [Indexed: 11/26/2022] Open
Abstract
Background The input image of a blurry glioma image segmentation is, usually, very unclear. It is difficult to obtain the accurate contour line of image segmentation. The main challenge facing the researchers is to correctly determine the area where the points on the contour line belong to the glioma image. This article highlights the mechanism of formation of glioma and provides an image segmentation prediction model to assist in the accurate division of glioma contour points. The proposed prediction model of segmentation associated with the process of the formation of glioma is innovative and challenging. Bose-Einstein Condensate (BEC) is a microscopic quantum phenomenon in which atoms condense to the ground state of energy as the temperature approaches absolute zero. In this article, we propose a BEC kernel function and a novel prediction model based on the BEC kernel to detect the relationship between the process of the BEC and the formation of a brain glioma. Furthermore, the theoretical derivation and proof of the prediction model are given from micro to macro through quantum mechanics, wave, oscillation of glioma, and statistical distribution of laws. The prediction model is a distinct segmentation model that is guided by BEC theory for blurry glioma image segmentation. Results Our approach is based on five tests. The first three tests aimed at confirming the measuring range of T and μ in the BEC kernel. The results are extended from −10 to 10, approximating the standard range to T ≤ 0, and μ from 0 to 6.7. Tests 4 and 5 are comparison tests. The comparison in Test 4 was based on various established cluster methods. The results show that our prediction model in image evaluation parameters of P, R, and F is the best amongst all the existent ten forms except for only one reference with the mean value of F that is between 0.88 and 0.93, while our approach returns between 0.85 and 0.99. Test 5 aimed to further compare our results, especially with CNN (Convolutional Neural Networks) methods, by challenging Brain Tumor Segmentation (BraTS) and clinic patient datasets. Our results were also better than all reference tests. In addition, the proposed prediction model with the BEC kernel is feasible and has a comparative validity in glioma image segmentation. Conclusions Theoretical derivation and experimental verification show that the prediction model based on the BEC kernel can solve the problem of accurate segmentation of blurry glioma images. It demonstrates that the BEC kernel is a more feasible, valid, and accurate approach than a lot of the recent year segmentation methods. It is also an advanced and innovative model of prediction deducing from micro BEC theory to macro glioma image segmentation.
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Affiliation(s)
- Tian Chi Zhang
- School of Information Science and Engineering, Chongqing Jiaotong University, Chongqing, China
| | - Jing Zhang
- School of Information Science and Engineering, University of Jinan, Jinan, China
- Shandong Provincial Key Laboratory of Network-Based Intelligent Computing, Jinan, China
- *Correspondence: Jing Zhang
| | - Shou Cun Chen
- School of Information Science and Engineering, University of Jinan, Jinan, China
- Shandong Provincial Key Laboratory of Network-Based Intelligent Computing, Jinan, China
| | - Bacem Saada
- Cancer Institute, Eighth Affiliated Hospital of Sun Yat-sen University, Shenzhen, China
- Department of Animal Biosciences, University of Guelph, Guelph, ON, Canada
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7
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Hirzler H, Lous RS, Trimby E, Pérez-Ríos J, Safavi-Naini A, Gerritsma R. Observation of Chemical Reactions between a Trapped Ion and Ultracold Feshbach Dimers. PHYSICAL REVIEW LETTERS 2022; 128:103401. [PMID: 35333077 DOI: 10.1103/physrevlett.128.103401] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/27/2021] [Accepted: 02/01/2022] [Indexed: 06/14/2023]
Abstract
We measure chemical reactions between a single trapped ^{174}Yb^{+} ion and ultracold Li_{2} dimers. This produces LiYb^{+} molecular ions that we detect via mass spectrometry. We explain the reaction rates by modeling the dimer density as a function of the magnetic field and obtain excellent agreement when we assume the reaction to follow the Langevin rate. Our results present a novel approach towards the creation of cold molecular ions and point to the exploration of ultracold chemistry in ion molecule collisions. What is more, with a detection sensitivity below molecule densities of 10^{14} m^{-3}, we provide a new method to detect low-density molecular gases.
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Affiliation(s)
- H Hirzler
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - R S Lous
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - E Trimby
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
| | - J Pérez-Ríos
- Fritz-Haber-Institut der Max-Planck-Gesellschaft, Faradayweg 4-6, 14195 Berlin, Germany
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
- Department of Physics and Astronomy, Stony Brook University, Stony Brook, New York 11794, USA
| | - A Safavi-Naini
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
- Institute for Theoretical Physics, Institute of Physics, University of Amsterdam, Science Park 904, 1098 XH Amsterdam, The Netherlands
| | - R Gerritsma
- Van der Waals-Zeeman Institute, Institute of Physics, University of Amsterdam, 1098 XH Amsterdam, The Netherlands
- QuSoft, Science Park 123, 1098 XG Amsterdam, The Netherlands
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8
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Kurz N, Fischer D, Pfeifer T, Dorn A. Reaction microscope for investigating ionization dynamics of weakly bound alkali dimers. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2021; 92:123202. [PMID: 34972432 DOI: 10.1063/5.0069506] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2021] [Accepted: 11/12/2021] [Indexed: 06/14/2023]
Abstract
We report on the implementation of a far-off-resonant, optical dipole force trap in a reaction microscope combined with a magneto-optical trap. Kinematically complete multi-photon ionization experiments were performed on optically trapped 6Li atoms and photo-associated 6Li2 molecules in their highest vibrational state. The apparatus allows us to distinguish different ionization mechanisms related to the presence of the IR field of the optical dipole trap that can occur during ionization of 6Li and 6Li2 in strong fields. In a series of proof-of-principle experiments, we detect weakly bound dimers via three-photon ionization with femtosecond pulses (τ = 30 fs) at a central wavelength of 780 nm and measure directly the momenta of the photoelectrons in coincidence with recoil ions.
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Affiliation(s)
- N Kurz
- Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - D Fischer
- Physics Department and LAMOR, Missouri University of Science and Technology, Rolla, Missouri 65409, USA
| | - T Pfeifer
- Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
| | - A Dorn
- Max-Planck Institut für Kernphysik, Saupfercheckweg 1, 69117 Heidelberg, Germany
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9
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Hachmann M, Kiefer Y, Riebesehl J, Eichberger R, Hemmerich A. Quantum Degenerate Fermi Gas in an Orbital Optical Lattice. PHYSICAL REVIEW LETTERS 2021; 127:033201. [PMID: 34328765 DOI: 10.1103/physrevlett.127.033201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2020] [Accepted: 06/21/2021] [Indexed: 06/13/2023]
Abstract
Spin-polarized samples and spin mixtures of quantum degenerate fermionic atoms are prepared in selected excited Bloch bands of an optical checkerboard square lattice. For the spin-polarized case, extreme band lifetimes above 10 s are observed, reflecting the suppression of collisions by Pauli's exclusion principle. For spin mixtures, lifetimes are reduced by an order of magnitude by two-body collisions between different spin components, but still remarkably large values of about 1 s are found. By analyzing momentum spectra, we can directly observe the orbital character of the optical lattice. The observations demonstrated here form the basis for exploring the physics of Fermi gases with two paired spin components in orbital optical lattices, including the regime of unitarity.
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Affiliation(s)
- M Hachmann
- Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany
| | - Y Kiefer
- Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany
| | - J Riebesehl
- Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
| | - R Eichberger
- Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany
| | - A Hemmerich
- Institut für Laserphysik, Universität Hamburg, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, 22761 Hamburg, Germany
- The Hamburg Center for Ultrafast Imaging, Universität Hamburg, 22761 Hamburg, Germany
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10
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Cuestas E, Majtey AP. A generalized molecule approach capturing the Feshbach-induced pairing physics in the BEC-BCS crossover. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2021; 33:255601. [PMID: 33848988 DOI: 10.1088/1361-648x/abf7a2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/24/2021] [Accepted: 04/13/2021] [Indexed: 06/12/2023]
Abstract
By including the effect of a trap with characteristic energy given by the Fermi temperatureTFin a two-body two-channel model for Feshbach resonances, we reproduce the measured binding energy of ultracold molecules in a40K atomic Fermi gas. We also reproduce the experimental closed-channel fractionZacross the BEC-BCS crossover and into the BCS regime of a6Li atomic Fermi gas. We obtain the expected behaviorZ∝TFat unitarity, together with the recently measured proportionality constant. Our results are also in agreement with recent measurements of theZdependency onTFon the BCS side, where a significant quantitative discrepancy between experimental data and theory's predictions has been repeatedly reported. In order to contrast with future experiments we report the proportionality constant at unitarity betweenZandTFpredicted by our model for a40K atomic Fermi gas.
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Affiliation(s)
- Eloisa Cuestas
- Facultad de Matemática, Astronomía, Física y Computación (FaMAF), Universidad Nacional de Córdoba (UNC), Av. Medina Allende s/n, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
- Instituto de Física Enrique Gaviola (IFEG), Consejo de Investigaciones Científicas y Técnicas de la República Argentina (CONICET), Córdoba, Argentina
| | - Ana P Majtey
- Facultad de Matemática, Astronomía, Física y Computación (FaMAF), Universidad Nacional de Córdoba (UNC), Av. Medina Allende s/n, Ciudad Universitaria, X5000HUA, Córdoba, Argentina
- Instituto de Física Enrique Gaviola (IFEG), Consejo de Investigaciones Científicas y Técnicas de la República Argentina (CONICET), Córdoba, Argentina
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11
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Abstract
We investigate the statistical distribution for ideal Bose gases with constant particle density in the 3D box of volume V=L3. By changing linear size L and imposing different boundary conditions on the system, we present a numerical analysis on the characteristic temperature and condensate fraction and find that a smaller linear size is efficient to increase the characteristic temperature and condensate fraction. Moreover, there is a singularity under the antiperiodic boundary condition.
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12
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Kurkjian H, Tempere J, Klimin SN. Linear response of a superfluid Fermi gas inside its pair-breaking continuum. Sci Rep 2020; 10:11591. [PMID: 32665570 PMCID: PMC7360786 DOI: 10.1038/s41598-020-65371-9] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/18/2019] [Accepted: 04/20/2020] [Indexed: 11/09/2022] Open
Abstract
We study the signatures of the collective modes of a superfluid Fermi gas in its linear response functions for the order-parameter and density fluctuations in the Random Phase Approximation (RPA). We show that a resonance associated to the Popov-Andrianov (or sometimes "Higgs") mode is visible inside the pair-breaking continuum at all values of the wavevector q, not only in the (order-parameter) modulus-modulus response function but also in the modulus-density and density-density responses. At nonzero temperature, the resonance survives in the presence of thermally broken pairs even until the vicinity of the critical temperature Tc, and coexists with both the Anderson-Bogoliubov modes at temperatures comparable to the gap Δ and with the low-velocity phononic mode predicted by RPA near Tc. The existence of a Popov-Andrianov-"Higgs" resonance is thus a robust, generic feature of the high-energy phenomenology of pair-condensed Fermi gases, and should be accessible to state-of-the-art cold atom experiments.
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Affiliation(s)
- H Kurkjian
- TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610, Antwerp, Belgium.
| | - J Tempere
- TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610, Antwerp, Belgium
| | - S N Klimin
- TQC, Universiteit Antwerpen, Universiteitsplein 1, B-2610, Antwerp, Belgium
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13
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Abstract
We study the dilute and ultracold unitary Bose gas, characterized by a universal equation of state due to the diverging s-wave scattering length, under a transverse harmonic confinement. From the hydrodynamic equations of superfluids we derive an effective one-dimensional nonpolynomial Schrödinger equation (1D NPSE) for the axial wavefunction which, however, also takes into account the transverse wavefunction. By solving the 1D NPSE we obtain meaningful analytical formulas for the dark (gray and black) solitons of the bosonic system.
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14
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Oscillatory-like expansion of a Fermionic superfluid. Sci Bull (Beijing) 2020; 65:7-11. [PMID: 36659071 DOI: 10.1016/j.scib.2019.10.022] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2019] [Revised: 09/25/2019] [Accepted: 10/14/2019] [Indexed: 01/21/2023]
Abstract
We study the expansion behaviors of a Fermionic superfluid in a cigar-shaped optical dipole trap for the whole BEC-BCS crossover and various temperatures. At low temperature (0.06(1)TF), the atom cloud undergoes an anisotropic hydrodynamic expansion over 30 ms, which behaves like oscillation in the horizontal plane. By analyzing the expansion dynamics according to the superfluid hydrodynamic equation, the effective polytropic index γ¯ of Equation-of-State (EoS) of Fermionic superfluid is extracted. The γ¯ values show a non-monotonic behavior over the BEC-BCS crossover, and have a good agreement with the theoretical results in the unitarity and BEC side. The normalized quasi-frequencies of the oscillatory expansion are measured, which drop significantly from the BEC side to the BCS side and reach a minimum value of 1.73 around 1/kFa=-0.25. Our work improves the understanding of the dynamic properties of strongly interacting Fermi gas.
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15
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Simonelli C, Neri E, Ciamei A, Goti I, Inguscio M, Trenkwalder A, Zaccanti M. Realization of a high power optical trapping setup free from thermal lensing effects. OPTICS EXPRESS 2019; 27:27215-27228. [PMID: 31674587 DOI: 10.1364/oe.27.027215] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/29/2019] [Accepted: 07/01/2019] [Indexed: 06/10/2023]
Abstract
Transmission of high power laser beams through partially absorbing materials modifies the light propagation via a thermally-induced effect known as thermal lensing. This may cause changes in the beam waist position and degrade the beam quality. Here we characterize the effect of thermal lensing associated with the different elements typically employed in an optical trapping setup for cold atoms experiments. We find that the only relevant thermal lens is represented by the TeO2 crystal of the acousto-optic modulator exploited to adjust the laser power on the atomic sample. We then devise a simple and totally passive scheme that enables to realize an inexpensive optical trapping apparatus essentially free from thermal lensing effects.
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16
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Park JW, Ko B, Shin Y. Critical Vortex Shedding in a Strongly Interacting Fermionic Superfluid. PHYSICAL REVIEW LETTERS 2018; 121:225301. [PMID: 30547641 DOI: 10.1103/physrevlett.121.225301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/22/2018] [Indexed: 06/09/2023]
Abstract
We study the critical vortex shedding in a strongly interacting fermionic superfluid of ^{6}Li across the BEC-BCS crossover. By moving an optical obstacle in the sample and directly imaging the vortices after the time of flight, the critical velocity u_{vor} for vortex shedding is measured as a function of the obstacle travel distance L. The observed u_{vor} increases with decreasing L, where the rate of increase is the highest in the unitary regime. In the deep Bose-Einstein condensation regime, an empirical dissipation model well captures the dependence of u_{vor} on L, characterized by a constant value of η=-[d(1/u_{vor})/d(1/L)]. However, as the system is tuned across the resonance, a step increase of η develops about a characteristic distance L_{c} as L is increased, where L_{c} is comparable to the obstacle size. This bimodal behavior is strengthened as the system is tuned towards the BCS regime. We attribute this evolution of u_{vor} to the emergence of the underlying fermionic degree of freedom in the vortex-shedding dynamics of a Fermi condensate.
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Affiliation(s)
- Jee Woo Park
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
| | - Bumsuk Ko
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
| | - Y Shin
- Department of Physics and Astronomy, and Institute of Applied Physics, Seoul National University, Seoul 08826, Korea
- Center for Correlated Electron Systems, Institute for Basic Science, Seoul 08826, Korea
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17
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Gänger B, Phieler J, Nagler B, Widera A. A versatile apparatus for fermionic lithium quantum gases based on an interference-filter laser system. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:093105. [PMID: 30278689 DOI: 10.1063/1.5045827] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/25/2018] [Accepted: 08/25/2018] [Indexed: 06/08/2023]
Abstract
We report on the design and construction of a versatile setup for experiments with ultracold lithium (Li) gases. We discuss our methods to prepare an atomic beam and laser cool it in a Zeeman slower and a subsequent magneto-optical trap, which rely on established methods. We focus on our laser system based on a stable interference-filter-stabilized, linear-extended-cavity diode laser, so far unreported for lithium wavelengths. Moreover, we describe our optical setup to combine various laser frequencies for cooling, manipulation, and detection of Li atoms. We characterize the performance of our system preparing degenerate samples of Li atoms via forced evaporation in a hybrid crossed-beam optical-dipole trap plus confining magnetic trap. Our apparatus allows one to produce quantum gases of N ≈ 105…106 fermionic lithium-6 atoms at nanokelvin temperatures in cycle times below 10 s. Our optical system is particularly suited to study the dynamics of fermionic superfluids in engineered optical potentials.
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Affiliation(s)
- Benjamin Gänger
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Jan Phieler
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Benjamin Nagler
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
| | - Artur Widera
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, 67663 Kaiserslautern, Germany
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18
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Shkedrov C, Florshaim Y, Ness G, Gandman A, Sagi Y. High-Sensitivity rf Spectroscopy of a Strongly Interacting Fermi Gas. PHYSICAL REVIEW LETTERS 2018; 121:093402. [PMID: 30230882 DOI: 10.1103/physrevlett.121.093402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/07/2018] [Revised: 06/25/2018] [Indexed: 06/08/2023]
Abstract
rf spectroscopy is one of the most powerful probing techniques in the field of ultracold gases. We report on a novel rf spectroscopy scheme with which we can detect very weak signals of only a few atoms. Using this method, we extended the experimentally accessible photon-energies range by an order of magnitude compared to previous studies. We directly verify a universal property of fermions with short-range interactions which is a power-law scaling of the rf spectrum tail all the way up to the interaction scale. We also determine, with high precision, the trap average contact parameter for different interaction strength. Finally, we employ our technique to precisely measure the binding energy of Feshbach molecules in an extended range of magnetic fields. These data are used to extract a new calibration of the Feshbach resonance between the two lowest energy levels of ^{40}K.
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Affiliation(s)
- Constantine Shkedrov
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Yanay Florshaim
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Gal Ness
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Andrey Gandman
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
| | - Yoav Sagi
- Physics Department, Technion-Israel Institute of Technology, Haifa 32000, Israel
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19
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Tennyson J, McKemmish LK, Rivlin T. Low-temperature chemistry using the R-matrix method. Faraday Discuss 2018; 195:31-48. [PMID: 27711838 DOI: 10.1039/c6fd00110f] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
Techniques for producing cold and ultracold molecules are enabling the study of chemical reactions and scattering at the quantum scattering limit, with only a few partial waves contributing to the incident channel, leading to the observation and even full control of state-to-state collisions in this regime. A new R-matrix formalism is presented for tackling problems involving low- and ultra-low energy collisions. This general formalism is particularly appropriate for slow collisions occurring on potential energy surfaces with deep wells. The many resonance states make such systems hard to treat theoretically but offer the best prospects for novel physics: resonances are already being widely used to control diatomic systems and should provide the route to steering ultracold reactions. Our R-matrix-based formalism builds on the progress made in variational calculations of molecular spectra by using these methods to provide wavefunctions for the whole system at short internuclear distances, (a regime known as the inner region). These wavefunctions are used to construct collision energy-dependent R-matrices which can then be propagated to give cross sections at each collision energy. The method is formulated for ultracold collision systems with differing numbers of atoms.
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Affiliation(s)
- Jonathan Tennyson
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK.
| | - Laura K McKemmish
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK.
| | - Tom Rivlin
- Department of Physics and Astronomy, University College London, London WC1E 6BT, UK.
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20
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Thomas O, Lippe C, Eichert T, Ott H. Experimental realization of a Rydberg optical Feshbach resonance in a quantum many-body system. Nat Commun 2018; 9:2238. [PMID: 29884824 PMCID: PMC5993778 DOI: 10.1038/s41467-018-04684-w] [Citation(s) in RCA: 19] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Accepted: 05/10/2018] [Indexed: 11/08/2022] Open
Abstract
Feshbach resonances are a powerful tool to tune the interaction in an ultracold atomic gas. The commonly used magnetic Feshbach resonances are specific for each species and are restricted with respect to their temporal and spatial modulation. Optical Feshbach resonances are an alternative which can overcome this limitation. Here, we show that ultra-long-range Rydberg molecules can be used to implement an optical Feshbach resonance. Tuning the on-site interaction of a degenerate Bose gas in a 3D optical lattice, we demonstrate a similar performance compared to recent realizations of optical Feshbach resonances using intercombination transitions. Our results open up a class of optical Feshbach resonances with a plenitude of available lines for many atomic species and the possibility to further increase the performance by carefully selecting the underlying Rydberg state.
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Affiliation(s)
- O Thomas
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
- Graduate School Materials Science in Mainz, Staudinger Weg 9, 55128, Mainz, Germany
| | - C Lippe
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - T Eichert
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany
| | - H Ott
- Department of Physics and Research Center OPTIMAS, Technische Universität Kaiserslautern, Erwin-Schrödinger-Straße 46, 67663, Kaiserslautern, Germany.
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21
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He L, Hu H, Liu XJ. Realizing Fulde-Ferrell Superfluids via a Dark-State Control of Feshbach Resonances. PHYSICAL REVIEW LETTERS 2018; 120:045302. [PMID: 29437455 DOI: 10.1103/physrevlett.120.045302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/16/2017] [Indexed: 06/08/2023]
Abstract
We propose that the long-sought Fulde-Ferrell superfluidity with nonzero momentum pairing can be realized in ultracold two-component Fermi gases of ^{40}K or ^{6}Li atoms by optically tuning their magnetic Feshbach resonances via the creation of a closed-channel dark state with a Doppler-shifted Stark effect. In this scheme, two counterpropagating optical fields are applied to couple two molecular states in the closed channel to an excited molecular state, leading to a significant violation of Galilean invariance in the dark-state regime and hence to the possibility of Fulde-Ferrell superfluidity. We develop a field theoretical formulation for both two-body and many-body problems and predict that the Fulde-Ferrell state has remarkable properties, such as anisotropic single-particle dispersion relation, suppressed superfluid density at zero temperature, anisotropic sound velocity, and rotonic collective mode. The latter two features can be experimentally probed using Bragg spectroscopy, providing a smoking-gun proof of Fulde-Ferrell superfluidity.
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Affiliation(s)
- Lianyi He
- Department of Physics and State Key Laboratory of Low-Dimensional Quantum Physics, Tsinghua University, Beijing 100084, China
| | - Hui Hu
- Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne 3122, Australia
| | - Xia-Ji Liu
- Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne 3122, Australia
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22
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Cui Y, Shen C, Deng M, Dong S, Chen C, Lü R, Gao B, Tey MK, You L. Observation of Broad d-Wave Feshbach Resonances with a Triplet Structure. PHYSICAL REVIEW LETTERS 2017; 119:203402. [PMID: 29219388 DOI: 10.1103/physrevlett.119.203402] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2017] [Indexed: 06/07/2023]
Abstract
High partial-wave (l≥2) Feshbach resonance (FR) in an ultracold mixture of ^{85}Rb-^{87}Rb atoms is investigated experimentally aided by a partial-wave insensitive analytic multichannel quantum-defect theory. Two "broad" resonances from coupling between d waves in both the open and closed channels are observed and characterized. One of them shows a fully resolved triplet structure with a splitting ratio well explained by the perturbation to the closed channel due to interatomic spin-spin interaction. These tunable "broad" d-wave resonances, especially the one in the lowest-energy open channel, could find important applications in simulating d-wave coupling dominated many-body systems. In addition, we find that there is generally a time and temperature requirement, associated with tunneling through the angular momentum barrier, to establish and observe resonant coupling in nonzero partial waves.
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Affiliation(s)
- Yue Cui
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Chuyang Shen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Min Deng
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Shen Dong
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Cheng Chen
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
| | - Rong Lü
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Bo Gao
- Department of Physics and Astronomy, University of Toledo, Mailstop 111, Toledo, Ohio 43606, USA
| | - Meng Khoon Tey
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
| | - Li You
- State Key Laboratory of Low Dimensional Quantum Physics, Department of Physics, Tsinghua University, Beijing 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, China
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23
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24
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Balakrishnan N. Perspective: Ultracold molecules and the dawn of cold controlled chemistry. J Chem Phys 2016; 145:150901. [DOI: 10.1063/1.4964096] [Citation(s) in RCA: 157] [Impact Index Per Article: 19.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- N. Balakrishnan
- Department of Chemistry, University of Nevada, Las Vegas, Nevada 89154, USA
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25
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Chen Q. Effect of the particle-hole channel on BCS-Bose-Einstein condensation crossover in atomic Fermi gases. Sci Rep 2016; 6:25772. [PMID: 27183875 PMCID: PMC4868972 DOI: 10.1038/srep25772] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2016] [Accepted: 04/22/2016] [Indexed: 11/09/2022] Open
Abstract
BCS-Bose-Einstein condensation (BEC) crossover is effected by increasing pairing strength between fermions from weak to strong in the particle-particle channel, and has attracted a lot of attention since the experimental realization of quantum degenerate atomic Fermi gases. Here we study the effect of the (often dropped) particle-hole channel on the zero T gap Δ(0), superfluid transition temperature Tc, the pseudogap at Tc, and the mean-field ratio 2Δ(0)/, from BCS through BEC regimes, using a pairing fluctuation theory which includes self-consistently the contributions of finite-momentum pairs and features a pseudogap in single particle excitation spectrum. Summing over the infinite particle-hole ladder diagrams, we find a complex dynamical structure for the particle-hole susceptibility χph, and conclude that neglecting the self-energy feedback causes a serious over-estimate of χph. While our result in the BCS limit agrees with Gor'kov et al., the particle-hole channel effect becomes more complex and pronounced in the crossover regime, where χph is reduced by both a smaller Fermi surface and a big (pseudo)gap. Deep in the BEC regime, the particle-hole channel contributions drop to zero. We predict a density dependence of the magnetic field at the Feshbach resonance, which can be used to quantify χph and test different theories.
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Affiliation(s)
- Qijin Chen
- Department of Physics and Zhejiang Institute of Modern Physics, Zhejiang University, Hangzhou, Zhejiang 310027, China
- Synergetic Innovation Center of Quantum Information and Quantum Physics, Hefei, Anhui 230026, China
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26
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Doçaj A, Wall ML, Mukherjee R, Hazzard KRA. Ultracold Nonreactive Molecules in an Optical Lattice: Connecting Chemistry to Many-Body Physics. PHYSICAL REVIEW LETTERS 2016; 116:135301. [PMID: 27081984 DOI: 10.1103/physrevlett.116.135301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2015] [Indexed: 06/05/2023]
Abstract
We derive effective lattice models for ultracold bosonic or fermionic nonreactive molecules (NRMs) in an optical lattice, analogous to the Hubbard model that describes ultracold atoms in a lattice. In stark contrast to the Hubbard model, which is commonly assumed to accurately describe NRMs, we find that the single on-site interaction parameter U is replaced by a multichannel interaction, whose properties we elucidate. Because this arises from complex short-range collisional physics, it requires no dipolar interactions and thus occurs even in the absence of an electric field or for homonuclear molecules. We find a crossover between coherent few-channel models and fully incoherent single-channel models as the lattice depth is increased. We show that the effective model parameters can be determined in lattice modulation experiments, which, consequently, measure molecular collision dynamics with a vastly sharper energy resolution than experiments in a free-space ultracold gas.
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Affiliation(s)
- Andris Doçaj
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Michael L Wall
- JILA, NIST and University of Colorado, Boulder, Colorado 80309-0440, USA
| | - Rick Mukherjee
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
| | - Kaden R A Hazzard
- Department of Physics and Astronomy, Rice University, Houston, Texas 77005, USA
- Rice Center for Quantum Materials, Rice University, Houston, Texas 77005, USA
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27
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ElOualhazi R, Berriche H. Electronic Structure and Spectra of the MgLi+ Ionic Molecule. J Phys Chem A 2016; 120:452-65. [DOI: 10.1021/acs.jpca.5b10209] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. ElOualhazi
- Laboratory
of Interfaces and Advanced Materials, Faculty of Science, University of Monastir, 5019 Monastir, Tunisia
| | - H. Berriche
- Laboratory
of Interfaces and Advanced Materials, Faculty of Science, University of Monastir, 5019 Monastir, Tunisia
- Department
of Mathematics and Natural Sciences, School of Arts and Sciences, American University of Ras Al Khaimah, RAK, P.O. Box 10021, UAE
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28
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Genkina D, Aycock LM, Stuhl BK, Lu HI, Williams RA, Spielman IB. Feshbach enhanced s-wave scattering of fermions: direct observation with optimized absorption imaging. NEW JOURNAL OF PHYSICS 2016; 18:013001. [PMID: 26903778 PMCID: PMC4759653 DOI: 10.1088/1367-2630/18/1/013001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We directly measured the normalized s-wave scattering cross-section of ultracold 40K atoms across a magnetic-field Feshbach resonance by colliding pairs of degenerate Fermi gases (DFGs) and imaging the scattered atoms. We extracted the scattered fraction for a range of bias magnetic fields, and measured the resonance location to be B0 = 20.206(15) mT with width Δ = 1.0(5) mT. To optimize the signal-to-noise ratio of atom number in scattering images, we developed techniques to interpret absorption images in a regime where recoil induced detuning corrections are significant. These imaging techniques are generally applicable to experiments with lighter alkalis that would benefit from maximizing signal-to-noise ratio on atom number counting at the expense of spatial imaging resolution.
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Affiliation(s)
- D Genkina
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, MD, 20899 USA
| | - LM Aycock
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, MD, 20899 USA
- Physics Department, Cornell University, Ithaca, NY 14850 USA
| | - BK Stuhl
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, MD, 20899 USA
| | - H-I Lu
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, MD, 20899 USA
| | - RA Williams
- National Physical Laboratory, Hampton Road, Teddington, Middlesex, TW11 0LW, UK
| | - IB Spielman
- Joint Quantum Institute, National Institute of Standards and Technology, and University of Maryland, Gaithersburg, MD, 20899 USA
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29
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Pagano G, Mancini M, Cappellini G, Livi L, Sias C, Catani J, Inguscio M, Fallani L. Strongly Interacting Gas of Two-Electron Fermions at an Orbital Feshbach Resonance. PHYSICAL REVIEW LETTERS 2015; 115:265301. [PMID: 26764999 DOI: 10.1103/physrevlett.115.265301] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/14/2015] [Indexed: 06/05/2023]
Abstract
We report on the experimental observation of a strongly interacting gas of ultracold two-electron fermions with an orbital degree of freedom and magnetically tunable interactions. This realization has been enabled by the demonstration of a novel kind of Feshbach resonance occurring in the scattering of two (173)Yb atoms in different nuclear and electronic states. The strongly interacting regime at resonance is evidenced by the observation of anisotropic hydrodynamic expansion of the two-orbital Fermi gas. These results pave the way towards the realization of new quantum states of matter with strongly correlated fermions with an orbital degree of freedom.
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Affiliation(s)
- G Pagano
- Department of Physics and Astronomy, University of Florence, I-50019 Sesto Fiorentino, Italy
| | - M Mancini
- Department of Physics and Astronomy, University of Florence, I-50019 Sesto Fiorentino, Italy
| | - G Cappellini
- LENS European Laboratory for Nonlinear Spectroscopy, I-50019 Sesto Fiorentino, Italy
| | - L Livi
- LENS European Laboratory for Nonlinear Spectroscopy, I-50019 Sesto Fiorentino, Italy
| | - C Sias
- LENS European Laboratory for Nonlinear Spectroscopy, I-50019 Sesto Fiorentino, Italy
- INRIM Istituto Nazionale di Ricerca Metrologica, I-10135 Torino, Italy
| | - J Catani
- LENS European Laboratory for Nonlinear Spectroscopy, I-50019 Sesto Fiorentino, Italy
- INO-CNR Istituto Nazionale di Ottica del CNR, Sezione di Sesto Fiorentino, I-50019 Sesto Fiorentino, Italy
- INFN Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, I-50019 Sesto Fiorentino, Italy
| | - M Inguscio
- Department of Physics and Astronomy, University of Florence, I-50019 Sesto Fiorentino, Italy
- LENS European Laboratory for Nonlinear Spectroscopy, I-50019 Sesto Fiorentino, Italy
- INRIM Istituto Nazionale di Ricerca Metrologica, I-10135 Torino, Italy
| | - L Fallani
- Department of Physics and Astronomy, University of Florence, I-50019 Sesto Fiorentino, Italy
- LENS European Laboratory for Nonlinear Spectroscopy, I-50019 Sesto Fiorentino, Italy
- INFN Istituto Nazionale di Fisica Nucleare, Sezione di Firenze, I-50019 Sesto Fiorentino, Italy
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30
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Frisch A, Mark M, Aikawa K, Baier S, Grimm R, Petrov A, Kotochigova S, Quéméner G, Lepers M, Dulieu O, Ferlaino F. Ultracold Dipolar Molecules Composed of Strongly Magnetic Atoms. PHYSICAL REVIEW LETTERS 2015; 115:203201. [PMID: 26613437 DOI: 10.1103/physrevlett.115.203201] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Indexed: 06/05/2023]
Abstract
In a combined experimental and theoretical effort, we demonstrate a novel type of dipolar system made of ultracold bosonic dipolar molecules with large magnetic dipole moments. Our dipolar molecules are formed in weakly bound Feshbach molecular states from a sample of strongly magnetic bosonic erbium atoms. We show that the ultracold magnetic molecules can carry very large dipole moments and we demonstrate how to create and characterize them, and how to change their orientation. Finally, we confirm that the relaxation rates of molecules in a quasi-two-dimensional geometry can be reduced by using the anisotropy of the dipole-dipole interaction and that this reduction follows a universal dipolar behavior.
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Affiliation(s)
- A Frisch
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - M Mark
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - K Aikawa
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - S Baier
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
| | - R Grimm
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - A Petrov
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - S Kotochigova
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - G Quéméner
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, 91405 Orsay, France
| | - M Lepers
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, 91405 Orsay, France
| | - O Dulieu
- Laboratoire Aimé Cotton, CNRS, Université Paris-Sud, ENS Cachan, 91405 Orsay, France
| | - F Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
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31
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Braun J, Drut JE, Roscher D. Zero-temperature equation of state of mass-imbalanced resonant Fermi gases. PHYSICAL REVIEW LETTERS 2015; 114:050404. [PMID: 25699425 DOI: 10.1103/physrevlett.114.050404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/29/2014] [Indexed: 06/04/2023]
Abstract
We calculate the zero-temperature equation of state of mass-imbalanced resonant Fermi gases in an ab initio fashion, by implementing the recent proposal of imaginary-valued mass difference to bypass the sign problem in lattice Monte Carlo calculations. The fully nonperturbative results thus obtained are analytically continued to real mass-imbalance to yield the physical equation of state, providing predictions for upcoming experiments with mass-imbalanced atomic Fermi gases. In addition, we present an exact relation for the rate of change of the equation of state at small mass imbalances, showing that it is fully determined by the energy of the mass-balanced system.
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Affiliation(s)
- Jens Braun
- Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, D-64289 Darmstadt, Germany and ExtreMe Matter Institute EMMI, GSI, Planckstraße 1, D-64291 Darmstadt, Germany
| | - Joaquín E Drut
- Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, D-64289 Darmstadt, Germany and ExtreMe Matter Institute EMMI, GSI, Planckstraße 1, D-64291 Darmstadt, Germany and Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Dietrich Roscher
- Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, D-64289 Darmstadt, Germany
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32
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Gou D, Kuang X, Gao Y, Huo D. Theoretical study on the ground state of the polar alkali-metal-barium molecules: potential energy curve and permanent dipole moment. J Chem Phys 2015; 142:034308. [PMID: 25612710 DOI: 10.1063/1.4906049] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
In this paper, we systematically investigate the electronic structure for the (2)Σ(+) ground state of the polar alkali-metal-alkaline-earth-metal molecules BaAlk (Alk = Li, Na, K, Rb, and Cs). Potential energy curves and permanent dipole moments (PDMs) are determined using power quantum chemistry complete active space self-consistent field and multi-reference configuration interaction methods. Basic spectroscopic constants are derived from ro-vibrational bound state calculation. From the calculations, it is shown that BaK, BaRb, and BaCs molecules have moderate values of PDM at the equilibrium bond distance (BaK:1.62 D, BaRb:3.32 D, and BaCs:4.02 D). Besides, the equilibrium bond length (4.93 Å and 5.19 Å) and dissociation energy (0.1825 eV and 0.1817 eV) for the BaRb and BaCs are also obtained.
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Affiliation(s)
- Dezhi Gou
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Xiaoyu Kuang
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Yufeng Gao
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
| | - Dongming Huo
- Institute of Atomic and Molecular Physics, Sichuan University, Chengdu 610065, China
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33
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Goldman N, Juzeliūnas G, Öhberg P, Spielman IB. Light-induced gauge fields for ultracold atoms. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:126401. [PMID: 25422950 DOI: 10.1088/0034-4885/77/12/126401] [Citation(s) in RCA: 181] [Impact Index Per Article: 18.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Gauge fields are central in our modern understanding of physics at all scales. At the highest energy scales known, the microscopic universe is governed by particles interacting with each other through the exchange of gauge bosons. At the largest length scales, our Universe is ruled by gravity, whose gauge structure suggests the existence of a particle-the graviton-that mediates the gravitational force. At the mesoscopic scale, solid-state systems are subjected to gauge fields of different nature: materials can be immersed in external electromagnetic fields, but they can also feature emerging gauge fields in their low-energy description. In this review, we focus on another kind of gauge field: those engineered in systems of ultracold neutral atoms. In these setups, atoms are suitably coupled to laser fields that generate effective gauge potentials in their description. Neutral atoms 'feeling' laser-induced gauge potentials can potentially mimic the behavior of an electron gas subjected to a magnetic field, but also, the interaction of elementary particles with non-Abelian gauge fields. Here, we review different realized and proposed techniques for creating gauge potentials-both Abelian and non-Abelian-in atomic systems and discuss their implication in the context of quantum simulation. While most of these setups concern the realization of background and classical gauge potentials, we conclude with more exotic proposals where these synthetic fields might be made dynamical, in view of simulating interacting gauge theories with cold atoms.
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Affiliation(s)
- N Goldman
- College de France, 11 place Marcelin Berthelot & Laboratoire Kastler Brossel, CNRS, UPMC, ENS, 24 rue Lhomond, 75005 Paris, France
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34
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Using thermal boundary conditions to engineer the quantum state of a bulk magnet. Proc Natl Acad Sci U S A 2014; 111:3689-94. [PMID: 24567389 DOI: 10.1073/pnas.1316070111] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
The degree of contact between a system and the external environment can alter dramatically its proclivity to quantum mechanical modes of relaxation. We show that controlling the thermal coupling of cubic-centimeter-sized crystals of the Ising magnet LiHo(x)Y(1-x)F4 to a heat bath can be used to tune the system between a glassy state dominated by thermal excitations over energy barriers and a state with the hallmarks of a quantum spin liquid. Application of a magnetic field transverse to the Ising axis introduces both random magnetic fields and quantum fluctuations, which can retard and speed the annealing process, respectively, thereby providing a mechanism for continuous tuning between the destination states. The nonlinear response of the system explicitly demonstrates quantum interference between internal and external relaxation pathways.
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35
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Affiliation(s)
- Mikhail Lemeshko
- a ITAMP, Harvard-Smithsonian Center for Astrophysics , Cambridge , MA , 02138 , USA
- b Physics Department , Harvard University , Cambridge , MA , 02138 , USA
- c Kavli Institute for Theoretical Physics , University of California , Santa Barbara , CA , 93106 , USA
| | - Roman V. Krems
- c Kavli Institute for Theoretical Physics , University of California , Santa Barbara , CA , 93106 , USA
- d Department of Chemistry , University of British Columbia , BC V6T 1Z1, Vancouver , Canada
| | - John M. Doyle
- b Physics Department , Harvard University , Cambridge , MA , 02138 , USA
| | - Sabre Kais
- e Departments of Chemistry and Physics , Purdue University , West Lafayette , IN , 47907 , USA
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36
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Xiao KL, Yang CL, Wang MS, Ma XG, Liu WW. An ab initio study of the ground and low-lying excited states of KBe with the effect of inner-shell electrons. J Chem Phys 2013; 139:074305. [PMID: 23968090 DOI: 10.1063/1.4818452] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
The potential energy curves (PECs) of 1(2)Σ(+), 2(2)Σ(+), 1(2)Π, and 2(2)Π states of KBe are calculated using multireference configuration interaction method and large all-electron basis sets. Four sets of frozen core orbitals (FCOs) are considered to examine the effect of inner-shell correlation electrons on the molecular properties. The ro-vibrational energy levels are obtained by solving the Schrödinger equation of nuclear motion based on the ab initio PECs. The spectroscopic parameters are determined from the ro-vibrational levels with Dunham expansion. The PECs are fitted into analytical potential energy functions using the Morse long-range potential function. The dipole moment functions of the states for KBe calculated with different FCOs are presented. The transition dipole moments for KBe between 1(2)Σ(+) and 2(2)Σ(+) states, 1(2)Π and 1(2)Σ(+) states, and 2(2)Π and 1(2)Σ(+) states are also obtained.
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Affiliation(s)
- Ke-La Xiao
- School of Physics and Optoelectronics Engineering, Ludong University, Yantai 264025, People's Republic of China
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37
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Bugnion PO, Lofthouse JA, Conduit GJ. Inhomogeneous state of few-fermion superfluids. PHYSICAL REVIEW LETTERS 2013; 111:045301. [PMID: 23931378 DOI: 10.1103/physrevlett.111.045301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2013] [Indexed: 06/02/2023]
Abstract
The few-fermion atomic gas is an ideal setting to explore inhomogeneous superfluid pairing analogous to the Larkin-Ovchinnikov state. Two up and one down-spin atom is the minimal configuration that displays an inhomogeneous pairing density, whereas imbalanced systems containing more fermions present a more complex pairing topology. With more than eight atoms trapped the system approaches the macroscopic superfluid limit. An oblate trap with a central barrier offers a direct experimental probe of pairing inhomogeneity.
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Affiliation(s)
- P O Bugnion
- Cavendish Laboratory, J.J. Thomson Avenue, Cambridge CB3 0HE, United Kingdom
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38
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Sidorenkov LA, Tey MK, Grimm R, Hou YH, Pitaevskii L, Stringari S. Second sound and the superfluid fraction in a Fermi gas with resonant interactions. Nature 2013; 498:78-81. [DOI: 10.1038/nature12136] [Citation(s) in RCA: 138] [Impact Index Per Article: 12.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/09/2013] [Accepted: 03/26/2013] [Indexed: 11/09/2022]
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39
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Yan M, DeSalvo BJ, Ramachandhran B, Pu H, Killian TC. Controlling condensate collapse and expansion with an optical Feshbach resonance. PHYSICAL REVIEW LETTERS 2013; 110:123201. [PMID: 25166803 DOI: 10.1103/physrevlett.110.123201] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/07/2012] [Indexed: 06/03/2023]
Abstract
We demonstrate control of the collapse and expansion of an (88)Sr Bose-Einstein condensate using an optical Feshbach resonance near the (1)S(0)-(3)P(1) intercombination transition at 689 nm. Significant changes in dynamics are caused by modifications of scattering length by up to ± 10a(bg), where the background scattering length of (88)Sr is a(bg) = -2a(0) (1a(0) = 0.053 nm). Changes in scattering length are monitored through changes in the size of the condensate after a time-of-flight measurement. Because the background scattering length is close to zero, blue detuning of the optical Feshbach resonance laser with respect to a photoassociative resonance leads to increased interaction energy and a faster condensate expansion, whereas red detuning triggers a collapse of the condensate. The results are modeled with the time-dependent nonlinear Gross-Pitaevskii equation.
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Affiliation(s)
- Mi Yan
- Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA
| | - B J DeSalvo
- Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA
| | - B Ramachandhran
- Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA
| | - H Pu
- Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA
| | - T C Killian
- Department of Physics and Astronomy, Rice University, Houston, Texas 77251, USA
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40
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Tey MK, Sidorenkov LA, Guajardo ERS, Grimm R, Ku MJH, Zwierlein MW, Hou YH, Pitaevskii L, Stringari S. Collective modes in a unitary Fermi gas across the superfluid phase transition. PHYSICAL REVIEW LETTERS 2013; 110:055303. [PMID: 23414029 DOI: 10.1103/physrevlett.110.055303] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2012] [Indexed: 06/01/2023]
Abstract
We provide a joint theoretical and experimental investigation of the temperature dependence of the collective oscillations of first sound nature exhibited by a highly elongated harmonically trapped Fermi gas at unitarity, including the region below the critical temperature for superfluidity. Differently from the lowest axial breathing mode, the hydrodynamic frequencies of the higher-nodal excitations show a temperature dependence, which is calculated starting from Landau two-fluid theory and using the available experimental knowledge of the equation of state. The experimental results agree with high accuracy with the predictions of theory and provide the first evidence for the temperature dependence of the collective frequencies near the superfluid phase transition.
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Affiliation(s)
- Meng Khoon Tey
- Institut für Quantenoptik und Quanteninformation (IQOQI), Österreichische Akademie der Wissenschaften and Institut für Experimentalphysik, Universität Innsbruck, 6020 Innsbruck, Austria
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41
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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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42
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Wu CH, Park JW, Ahmadi P, Will S, Zwierlein MW. Ultracold fermionic Feshbach molecules of 23Na40K. PHYSICAL REVIEW LETTERS 2012; 109:085301. [PMID: 23002753 DOI: 10.1103/physrevlett.109.085301] [Citation(s) in RCA: 32] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/22/2012] [Indexed: 06/01/2023]
Abstract
We report on the formation of ultracold weakly bound Feshbach molecules of 23Na40K, the first fermionic molecule that is chemically stable in its absolute ground state. The lifetime of the nearly degenerate molecular gas exceeds 100 ms in the vicinity of the Feshbach resonance. The measured dependence of the molecular binding energy on the magnetic field demonstrates the open-channel character of the molecules over a wide field range and implies significant singlet admixture. This will enable efficient transfer into the singlet vibrational ground state, resulting in a stable molecular Fermi gas with strong dipolar interactions.
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Affiliation(s)
- Cheng-Hsun Wu
- MIT-Harvard Center for Ultracold Atoms, Department of Physics, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA
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43
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Guillon G, Viel A, Launay JM. Full dimension Rb2He ground triplet potential energy surface and quantum scattering calculations. J Chem Phys 2012; 136:174307. [DOI: 10.1063/1.4709433] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
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44
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García-Vela A, Cabanillas-Vidosa I, Ferrero JC, Pino GA. The role of orbiting resonances in the vibrational relaxation of I(2)(B,v' = 21) by collisions with He at very low energies: a theoretical and experimental study. Phys Chem Chem Phys 2012; 14:5570-80. [PMID: 22434127 DOI: 10.1039/c2cp24061k] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/06/2023]
Abstract
The low-energy collisions of I(2)(B,v' = 21) with He involving collision-induced vibrational relaxation of I(2) are investigated both experimentally and by means of wave packet simulations. The theoretical cross sections exhibit a structure of peaks originated by orbiting resonances of the I(2)(B,v' = 21) - He van der Waals complex formed in the I(2) + He collisions. Such a structure has similar characteristics as the structure of peaks found in the experimental cross sections. In fact, four of the five peaks of the measured cross sections appear at positions nearly coincident with those of four of the peaks found in the theoretical cross sections. Thus this result confirms the experimental finding that enhancement of I(2) vibrational relaxation is caused by the population of I(2)(B,v' = 21) - He orbiting resonances populated upon the low-energy collisions. The possibility of using this mechanism in the vibrational cooling of diatomic molecules is discussed.
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Affiliation(s)
- Alberto García-Vela
- Instituto de Física Fundamental, C.S.I.C., Serrano 123, 28006 Madrid, Spain.
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45
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He L, Huang XG. BCS-BEC crossover in 2D Fermi gases with Rashba spin-orbit coupling. PHYSICAL REVIEW LETTERS 2012; 108:145302. [PMID: 22540803 DOI: 10.1103/physrevlett.108.145302] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2011] [Indexed: 05/31/2023]
Abstract
We present a systematic theoretical study of the BCS-BEC crossover in two-dimensional Fermi gases with Rashba spin-orbit coupling (SOC). By solving the exact two-body problem in the presence of an attractive short-range interaction we show that the SOC enhances the formation of the bound state: the binding energy E(B) and effective mass m(B) of the bound state grows along with the increase of the SOC. For the many-body problem, even at weak attraction, a dilute Fermi gas can evolve from a BCS superfluid state to a Bose condensation of molecules when the SOC becomes comparable to the Fermi momentum. The ground-state properties and the Berezinskii-Kosterlitz-Thouless (BKT) transition temperature are studied, and analytical results are obtained in various limits. For large SOC, the BKT transition temperature recovers that for a Bose gas with an effective mass m(B). We find that the condensate and superfluid densities have distinct behaviors in the presence of SOC: the condensate density is generally enhanced by the SOC due to the increase of the molecule binding; the superfluid density is suppressed because of the nontrivial molecule effective mass m(B).
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Affiliation(s)
- Lianyi He
- Frankfurt Institute for Advanced Studies and Institute for Theoretical Physics, J. W. Goethe University, 60438 Frankfurt am Main, Germany.
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46
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Augustovičová L, Soldán P. Ab initio properties of MgAlk (Alk = Li, Na, K, Rb, Cs). J Chem Phys 2012; 136:084311. [PMID: 22380046 DOI: 10.1063/1.3690459] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022] Open
Abstract
High level ab initio calculations are performed on the ground electronic state of diatomic molecules MgAlk (Alk = Li, Na, K, Rb, Cs). Potential energy curves and dipole moment functions are determined making use of the single-reference unrestricted and restricted coupled-cluster methods with large basis sets. Basic spectroscopic properties of the ground electronic states are derived from ro-vibrational bound state calculations.
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Affiliation(s)
- L Augustovičová
- Department of Chemical Physics and Optics, Faculty of Mathematics and Physics, Charles University in Prague, Ke Karlovu 3, CZ-12116 Prague 2, Czech Republic
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47
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Feng E, Shao X, Yu C, Sun C, Huang W. Low energy collisions of CN(X 2Σ+) with He in magnetic fields. J Chem Phys 2012; 136:054302. [DOI: 10.1063/1.3679869] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Eryin Feng
- Department of Physics, Anhui normal university, Wuhu 241000, People's Republic of China
| | - Xi Shao
- Department of Physics, Anhui normal university, Wuhu 241000, People's Republic of China
| | - Chunhua Yu
- Department of Physics, Anhui normal university, Wuhu 241000, People's Republic of China
| | - Chunyan Sun
- Department of Physics, Anhui normal university, Wuhu 241000, People's Republic of China
| | - Wuying Huang
- Department of Physics, Anhui normal university, Wuhu 241000, People's Republic of China
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48
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49
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Zhong WP, Belić MR, Malomed BA, Huang T. Solitary waves in the nonlinear Schrödinger equation with Hermite-Gaussian modulation of the local nonlinearity. Phys Rev E 2011; 84:046611. [PMID: 22181300 DOI: 10.1103/physreve.84.046611] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/27/2011] [Indexed: 11/07/2022]
Abstract
We demonstrate "hidden solvability" of the nonlinear Schrödinger (NLS) equation whose nonlinearity coefficient is spatially modulated by Hermite-Gaussian functions of different orders and the external potential is appropriately chosen. By means of an explicit transformation, this equation is reduced to the stationary version of the classical NLS equation, which makes it possible to use the bright and dark solitons of the latter equation to generate solitary-wave solutions in our model. Special kinds of explicit solutions, such as oscillating solitary waves, are analyzed in detail. The stability of these solutions is verified by means of direct integration of the underlying NLS equation. In particular, our analytical results suggest a way of controlling the dynamics of solitary waves by an appropriate spatial modulation of the nonlinearity strength in Bose-Einstein condensates, through the Feshbach resonance.
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Affiliation(s)
- Wei-Ping Zhong
- Department of Electronic and Information Engineering, Shunde Polytechnic, Guangdong Province, Shunde 528300, China.
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50
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Wells N, Lane IC. Prospects for ultracold carbon via charge exchange reactions and laser cooled carbides. Phys Chem Chem Phys 2011; 13:19036-51. [PMID: 21971563 DOI: 10.1039/c1cp21304k] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/12/2023]
Abstract
Strategies to produce an ultracold sample of carbon atoms are explored and assessed with the help of quantum chemistry. After a brief discussion of the experimental difficulties using conventional methods, two strategies are investigated. The first attempts to exploit charge exchange reactions between ultracold metal atoms and sympathetically cooled C(+) ions. Ab initio calculations including electron correlation have been conducted on the molecular ions [LiC](+) and [BeC](+) to determine whether alkali or alkaline earth metals are a suitable buffer gas for the formation of C atoms but strong spontaneous radiative charge exchange ensure they are not ideal. The second technique involves the stimulated production of ultracold C atoms from a gas of laser cooled carbides. Calculations on LiC suggest that the alkali carbides are not suitable but the CH radical is a possible laser cooling candidate thanks to very favourable Frank-Condon factors. A scheme based on a four pulse STIRAP excitation pathway to a Feshbach resonance is outlined for the production of atomic fragments with near zero centre of mass velocity.
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Affiliation(s)
- Nathan Wells
- Innovative Molecular Materials Group, School of Chemistry and Chemical Engineering, Queen's University of Belfast, Stranmillis Road, Belfast, UK BT9 5AG
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