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Shen X, Davidson N, Bruun GM, Sun M, Wu Z. Strongly Interacting Bose-Fermi Mixtures: Mediated Interaction, Phase Diagram, and Sound Propagation. PHYSICAL REVIEW LETTERS 2024; 132:033401. [PMID: 38307087 DOI: 10.1103/physrevlett.132.033401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2023] [Revised: 11/14/2023] [Accepted: 12/06/2023] [Indexed: 02/04/2024]
Abstract
Motivated by recent surprising experimental findings, we develop a strong-coupling theory for Bose-Fermi mixtures capable of treating resonant interspecies interactions while satisfying the compressibility sum rule. We show that the mixture can be stable at large interaction strengths close to resonance, in agreement with the experiment, but at odds with the widely used perturbation theory. We also calculate the sound velocity of the Bose gas in the ^{133}Cs-^{6}Li mixture, again finding good agreement with the experimental observations both at weak and strong interactions. A central ingredient of our theory is the generalization of a fermion mediated interaction to strong Bose-Fermi scatterings and to finite frequencies. This further leads to a predicted hybridization of the sound modes of the Bose and Fermi gases, which can be directly observed using Bragg spectroscopy.
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Affiliation(s)
- Xin Shen
- College of Sciences, China Jiliang University, Hangzhou 310018, China
| | - Nir Davidson
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Georg M Bruun
- Center for Complex Quantum Systems, Department of Physics and Astronomy, Aarhus University, Ny Munkegade, DK-8000 Aarhus C, Denmark
| | - Mingyuan Sun
- State Key Lab of Information Photonics and Optical Communications, Beijing University of Posts and Telecommunications, Beijing 100876, China
- School of Science, Beijing University of Posts and Telecommunications, Beijing 100876, China
| | - Zhigang Wu
- Shenzhen Institute for Quantum Science and Engineering, Southern University of Science and Technology, Shenzhen 518055, China
- Department of Physics, The University of Hong Kong, Hong Kong, China
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2
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Wu YH, Tu HH, Cheng M. Continuous Phase Transitions between Fractional Quantum Hall States and Symmetry-Protected Topological States. PHYSICAL REVIEW LETTERS 2023; 131:256502. [PMID: 38181355 DOI: 10.1103/physrevlett.131.256502] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2023] [Revised: 10/11/2023] [Accepted: 11/28/2023] [Indexed: 01/07/2024]
Abstract
We study quantum phase transitions in Bose-Fermi mixtures driven by interspecies interaction in the quantum Hall regime. In the absence of such an interaction, the bosons and fermions form their respective fractional quantum Hall (FQH) states at certain filling factors. A symmetry-protected topological (SPT) state is identified as the ground state for strong interspecies interaction. The phase transitions between them are proposed to be described by Chern-Simons-Higgs field theories. For a simple microscopic Hamiltonian, we present numerical evidence for the existence of the SPT state and a continuous transition to the FQH state. It is also found that the entanglement entropy between the bosons and fermions exhibits scaling behavior in the vicinity of this transition.
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Affiliation(s)
- Ying-Hai Wu
- School of Physics and Wuhan National High Magnetic Field Center, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Hong-Hao Tu
- Institut für Theoretische Physik, Technische Universität Dresden, 01062 Dresden, Germany
| | - Meng Cheng
- Department of Physics, Yale University, New Haven, Connecticut 06511-8499, USA
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3
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Argüello-Luengo J, González-Tudela A, González-Cuadra D. Tuning Long-Range Fermion-Mediated Interactions in Cold-Atom Quantum Simulators. PHYSICAL REVIEW LETTERS 2022; 129:083401. [PMID: 36053702 DOI: 10.1103/physrevlett.129.083401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/08/2022] [Revised: 06/10/2022] [Accepted: 07/28/2022] [Indexed: 06/15/2023]
Abstract
Engineering long-range interactions in cold-atom quantum simulators can lead to exotic quantum many-body behavior. Fermionic atoms in ultracold atomic mixtures can act as mediators, giving rise to long-range Ruderman-Kittel-Kasuya-Yosida-type interactions characterized by the dimensionality and density of the fermionic gas. Here, we propose several tuning knobs, accessible in current experimental platforms, that allow one to further control the range and shape of the mediated interactions, extending the existing quantum simulation toolbox. In particular, we include an additional optical lattice for the fermionic mediator, as well as anisotropic traps to change its dimensionality in a continuous manner. This allows us to interpolate between power-law and exponential decays, introducing an effective cutoff for the interaction range, as well as to tune the relative interaction strengths at different distances. Finally, we show how our approach allows one to investigate frustrated regimes that were not previously accessible, where symmetry-protected topological phases as well as chiral spin liquids emerge.
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Affiliation(s)
- Javier Argüello-Luengo
- ICFO-Institut de Ciències Fotòniques, The Barcelona Institute of Science and Technology, Avinguda Carl Friedrich Gauss 3, 08860 Castelldefels (Barcelona), Spain
| | | | - Daniel González-Cuadra
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, 6020 Innsbruck, Austria
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4
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Kuhlenkamp C, Knap M, Wagner M, Schmidt R, Imamoğlu A. Tunable Feshbach Resonances and Their Spectral Signatures in Bilayer Semiconductors. PHYSICAL REVIEW LETTERS 2022; 129:037401. [PMID: 35905363 DOI: 10.1103/physrevlett.129.037401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/10/2021] [Revised: 11/07/2021] [Accepted: 06/27/2022] [Indexed: 06/15/2023]
Abstract
Feshbach resonances provide an invaluable tool in atomic physics, enabling precise control of interactions and the preparation of complex quantum phases of matter. Here, we theoretically analyze a solid-state analog of a Feshbach resonance in two dimensional semiconductor heterostructures. In the presence of interlayer electron tunneling, the scattering of excitons and electrons occupying different layers can be resonantly enhanced by tuning an applied electric field. The emergence of an interlayer Feshbach molecule modifies the optical excitation spectrum, and can be understood in terms of Fermi polaron formation. We discuss potential implications for the realization of correlated Bose-Fermi mixtures in bilayer semiconductors.
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Affiliation(s)
- Clemens Kuhlenkamp
- Institute for Quantum Electronics, ETH Zürich, CH-8093 Zürich, Switzerland
- Department of Physics and Institute for Advanced Study, Technical University of Munich, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
| | - Michael Knap
- Department of Physics and Institute for Advanced Study, Technical University of Munich, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
| | - Marcel Wagner
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
- Max-Planck-Institute of Quantum Optics, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - Richard Schmidt
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
- Max-Planck-Institute of Quantum Optics, Hans-Kopfermann-Straße 1, 85748 Garching, Germany
| | - Ataç Imamoğlu
- Institute for Quantum Electronics, ETH Zürich, CH-8093 Zürich, Switzerland
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5
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Akin TG, Hemingway B, Peil S. Tellurium spectrometer for 1S 0- 1P 1 transitions in strontium and other alkaline-earth atoms. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2022; 93:053002. [PMID: 35649769 DOI: 10.1063/5.0084122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/15/2023]
Abstract
We measure the spectrum of tellurium-130 in the vicinity of the 461 nm S01-P11 cycling transition in neutral strontium, a popular element for atomic clocks, quantum information, and quantum-degenerate gases. The lack of hyperfine structure in tellurium results in a spectral density of transitions nearly 50 times lower than that available in iodine, making use of tellurium as a laser-frequency reference challenging. By frequency-offset locking two lasers, we generate the large frequency shifts required to span the difference between a tellurium line and the S01-P11 resonance in strontium or other alkaline-earth atoms. The resulting laser architecture is long-term frequency stable, widely tunable, and optimizes the available laser power. The versatility of the system is demonstrated by using it to quickly switch between any strontium isotope in a magneto-optical trap and by adapting it to spectroscopy on a thermal beam with a different alkaline-earth atom.
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Affiliation(s)
- T G Akin
- Precise Time Department, United States Naval Observatory, Washington, DC 20392, USA
| | - Bryan Hemingway
- Precise Time Department, United States Naval Observatory, Washington, DC 20392, USA
| | - Steven Peil
- Precise Time Department, United States Naval Observatory, Washington, DC 20392, USA
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6
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Chen XY, Duda M, Schindewolf A, Bause R, Bloch I, Luo XY. Suppression of Unitary Three-Body Loss in a Degenerate Bose-Fermi Mixture. PHYSICAL REVIEW LETTERS 2022; 128:153401. [PMID: 35499890 DOI: 10.1103/physrevlett.128.153401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2021] [Revised: 03/17/2022] [Accepted: 03/22/2022] [Indexed: 06/14/2023]
Abstract
We study three-body loss in an ultracold mixture of a thermal Bose gas and a degenerate Fermi gas. We find that at unitarity, where the interspecies scattering length diverges, the usual inverse-square temperature scaling of the three-body loss found in nondegenerate systems is strongly modified and reduced with the increasing degeneracy of the Fermi gas. While the reduction of loss is qualitatively explained within the few-body scattering framework, a remaining suppression provides evidence for the long-range Ruderman-Kittel-Kasuya-Yosida (RKKY) interactions mediated by fermions between bosons. Our model based on RKKY interactions quantitatively reproduces the data without free parameters, and predicts one order of magnitude reduction of the three-body loss coefficient in the deeply Fermi-degenerate regime.
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Affiliation(s)
- Xing-Yan Chen
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Marcel Duda
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Andreas Schindewolf
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Roman Bause
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
| | - Immanuel Bloch
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
- Fakultät für Physik, Ludwig-Maximilians-Universität, 80799 München, Germany
| | - Xin-Yu Luo
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology, 80799 München, Germany
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7
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Farolfi A, Trypogeorgos D, Mordini C, Lamporesi G, Ferrari G. Observation of Magnetic Solitons in Two-Component Bose-Einstein Condensates. PHYSICAL REVIEW LETTERS 2020; 125:030401. [PMID: 32745386 DOI: 10.1103/physrevlett.125.030401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2019] [Revised: 02/11/2020] [Accepted: 06/11/2020] [Indexed: 06/11/2023]
Abstract
We experimentally investigate the dynamics of spin solitary waves (magnetic solitons) in a harmonically trapped, binary superfluid mixture. We measure the in situ density of each pseudospin component and their relative local phase via an interferometric technique we developed and as such, fully characterize the magnetic solitons while they undergo oscillatory motion in the trap. Magnetic solitons exhibit nondispersive, dissipationless longtime dynamics. By imprinting multiple magnetic solitons in our ultracold gas sample, we engineer binary collisions between solitons of either the same or opposite magnetization and map out their trajectories.
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Affiliation(s)
- A Farolfi
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - D Trypogeorgos
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - C Mordini
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - G Lamporesi
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - G Ferrari
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, and Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
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8
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Effective p-wave Fermi-Fermi Interaction Induced by Bosonic Superfluids. Sci Rep 2020; 10:10822. [PMID: 32616717 PMCID: PMC7331653 DOI: 10.1038/s41598-020-67020-7] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/10/2020] [Accepted: 05/26/2020] [Indexed: 11/17/2022] Open
Abstract
We study the two-dimensional Bose-Fermi mixture on square lattice at finite temperature by using the determinant quantum Monte Carlo method within the weakly interacting regime. Here we consider the attractive Bose-Hubbard model and free spinless fermions. In the absence of boson-fermion interactions, we obtain the boundary of the collapsed state of the attractive bosons. In the presence of boson-fermion interactions, an effective p-wave interaction between fermions will be induced as far as the bosons are in a superfluid state. Moreover, we find the emergence of the composite fermion pairs at low temperatures.
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9
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A Dual-Species Bose-Einstein Condensate with Attractive Interspecies Interactions. CONDENSED MATTER 2020. [DOI: 10.3390/condmat5010021] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
We report on the production of a 41 K- 87 Rb dual-species Bose–Einstein condensate with tunable interspecies interaction and we study the mixture in the attractive regime; i.e., for negative values of the interspecies scattering length a 12 . The binary condensate is prepared in the ground state and confined in a pure optical trap. We exploit Feshbach resonances for tuning the value of a 12 . After compensating the gravitational sag between the two species with a magnetic field gradient, we drive the mixture into the attractive regime. We let the system evolve both in free space and in an optical waveguide. In both geometries, for strong attractive interactions, we observe the formation of self-bound states, recognizable as quantum droplets. Our findings prove that robust, long-lived droplet states can be realized in attractive two-species mixtures, despite the two atomic components possibly experiencing different potentials.
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10
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Liu Y, Qi F, Zhang Y, Chen S. Mass-Imbalanced Atoms in a Hard-Wall Trap: An Exactly Solvable Model Associated with D 6 Symmetry. iScience 2019; 22:181-194. [PMID: 31785556 PMCID: PMC6911986 DOI: 10.1016/j.isci.2019.11.018] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2019] [Revised: 08/16/2019] [Accepted: 11/09/2019] [Indexed: 11/13/2022] Open
Abstract
We show that a system consisting of two interacting particles with mass ratio 3 or 1/3 in a hard-wall box can be exactly solved by using Bethe-type ansatz. The ansatz is based on a finite superposition of plane waves associated with a dihedral group D6, which enforces the momentums after a series of scattering and reflection processes to fulfill the D6 symmetry. Starting from a two-body elastic collision model in a hard-wall box, we demonstrate how a finite momentum distribution is related to the D2n symmetry for permitted mass ratios. For a quantum system with mass ratio 3, we obtain exact eigenenergies and eigenstates by solving Bethe-type-ansatz equations for arbitrary interaction strength. A many-body excited state of the system is found to be independent of the interaction strength, i.e., the wave function looks exactly the same for non-interacting two particles or in the hard-core limit. At nonergodicity points, the permitted momentums fulfill the D2n symmetry The Bethe Ansatz method is extended to solve the mass-imbalanced quantum system We exactly solve the interacting two-particle system in a hard-wall with mass ratio 3
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Affiliation(s)
- Yanxia Liu
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, P. R. China
| | - Fan Qi
- Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, P. R. China
| | - Yunbo Zhang
- Institute of Theoretical Physics, Shanxi University, Taiyuan 030006, P. R. China.
| | - Shu Chen
- Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190, China; School of Physical Sciences, University of Chinese Academy of Sciences, Beijing 100049, China; The Yangtze River Delta Physics Research Center, Liyang, Jiangsu 213300, China.
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11
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Pierce M, Leyronas X, Chevy F. Few Versus Many-Body Physics of an Impurity Immersed in a Superfluid of Spin 1/2 Attractive Fermions. PHYSICAL REVIEW LETTERS 2019; 123:080403. [PMID: 31491212 DOI: 10.1103/physrevlett.123.080403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/11/2019] [Revised: 06/12/2019] [Indexed: 06/10/2023]
Abstract
In this Letter we investigate the properties of an impurity immersed in a superfluid of strongly correlated spin 1/2 fermions and we calculate the beyond-mean-field corrections to the energy of a weakly interacting impurity. We show that these corrections are divergent and have to be regularized by properly accounting for three-body physics in the problem and that our approach naturally provides a unifying framework for Bose and Fermi polaron physics.
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Affiliation(s)
- M Pierce
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 75005 Paris France
| | - X Leyronas
- Laboratoire de physique de l'Ecole normale supérieure, ENS, Université PSL, CNRS, Sorbonne Université, Université Paris-Diderot, Sorbonne Paris Cité, 75005 Paris France
| | - F Chevy
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 75005 Paris France
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12
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Observation of fermion-mediated interactions between bosonic atoms. Nature 2019; 568:61-64. [DOI: 10.1038/s41586-019-1055-0] [Citation(s) in RCA: 57] [Impact Index Per Article: 11.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2018] [Accepted: 01/30/2019] [Indexed: 11/08/2022]
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13
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Chen Y, Horikoshi M, Yoshioka K, Kuwata-Gonokami M. Dynamical Critical Behavior of an Attractive Bose-Einstein Condensate Phase Transition. PHYSICAL REVIEW LETTERS 2019; 122:040406. [PMID: 30768305 DOI: 10.1103/physrevlett.122.040406] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Indexed: 06/09/2023]
Abstract
When matter undergoes a continuous phase transition on a finite timescale, the Kibble-Zurek mechanism predicts universal scaling behavior with respect to structure formation. The scaling is dependent on the universality class and is irrelevant to the details of the system. Here, we examine this phenomenon by controlling the timescale of the phase transition to a Bose-Einstein condensate using sympathetic cooling of an ultracold Bose thermal cloud with tunable interactions in an elongated trap. The phase transition results in a diverse number of bright solitons and gray solitons in the condensate that undergo attractive and repulsive interactions, respectively. The power law dependence of the average soliton number on the timescale of the phase transition is measured for each interaction and compared. The results support the Kibble-Zurek mechanism, in that the scaling behavior is determined by universality and does not rely on the interaction properties.
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Affiliation(s)
- Yiping Chen
- Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
| | - Munekazu Horikoshi
- Institute of Photon Science and Technology, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
- Photon Science Center, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Kosuke Yoshioka
- Photon Science Center, Graduate School of Engineering, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - Makoto Kuwata-Gonokami
- Department of Physics, Graduate School of Science, The University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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14
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Affiliation(s)
- Mati Aharonyan
- Department of Physics and Center for Quantum Entanglement Science and Technology (QUEST), Bar-Ilan University, Ramat Gan, Israel
| | - Emanuele G. Dalla Torre
- Department of Physics and Center for Quantum Entanglement Science and Technology (QUEST), Bar-Ilan University, Ramat Gan, Israel
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15
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Kinnunen JJ, Wu Z, Bruun GM. Induced p-Wave Pairing in Bose-Fermi Mixtures. PHYSICAL REVIEW LETTERS 2018; 121:253402. [PMID: 30608823 DOI: 10.1103/physrevlett.121.253402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/13/2018] [Indexed: 06/09/2023]
Abstract
Cooper pairing caused by an induced interaction represents a paradigm in our description of fermionic superfluidity. Here, we present a strong coupling theory for the critical temperature of p-wave pairing between spin polarized fermions immersed in a Bose-Einstein condensate. The fermions interact via the exchange of phonons in the condensate, and our self-consistent theory takes into account the full frequency and momentum dependence of the resulting induced interaction. We demonstrate that both retardation and self-energy effects are important for obtaining a reliable value of the critical temperature. Focusing on experimentally relevant systems, we perform a systematic analysis varying the boson-boson and boson-fermion interaction strength as well as their masses, and identify the most suitable system for realizing a p-wave superfluid. Our results show that such a superfluid indeed is experimentally within reach using light bosons mixed with heavy fermions.
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Affiliation(s)
- Jami J Kinnunen
- Department of Applied Physics, Aalto University, FI-00076 Aalto, Finland
| | - Zhigang Wu
- Shenzhen Institute for Quantum Science and Engineering and Department of Physics, Southern University of Science and Technology, Shenzhen 518055, China
| | - Georg M Bruun
- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C, Denmark
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16
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Luan T, Li Y, Zhang X, Chen X. Realization of two-stage crossed beam cooling and the comparison with Delta-kick cooling in experiment. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2018; 89:123110. [PMID: 30599612 DOI: 10.1063/1.5046815] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/02/2018] [Accepted: 11/24/2018] [Indexed: 06/09/2023]
Abstract
We report the first experimental realization of the two-stage crossed beam cooling (TSCBC) method that we proposed in 2013 [L. Wang et al., J. Phys. B: At., Mol. Opt. Phys. 46, 195302 (2013)]. With the 87Rb Bose-Einstein condensation apparatus and electromagnet coils providing the magnetic levitation to counteract the gravitation, we simulated the micro-gravity environment and realized the TSCBC with 4 × 104 87Rb atoms. We estimated that the lowest temperature of atoms can be at 3.56 nK with a new method and verified that the cooling process is adiabatic enough with time-of-flight images. According to analysis, we believed that the noise of magnetic field was the main obstacle that hinders the further cooling of the atomic ensemble. Under the same experimental conditions, we carried out the Delta-kick cooling method and got a lowest temperature of 23.3 nK also with 4 × 104 87Rb atoms. According to the results of comparing experiments, we can see that the TSCBC method is more effective.
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Affiliation(s)
- Tian Luan
- China Academy of Electronics and Information Technology, Beijing 100041, People's Republic of China
| | - Yufan Li
- School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, People's Republic of China
| | - Xuesong Zhang
- China Academy of Electronics and Information Technology, Beijing 100041, People's Republic of China
| | - Xuzong Chen
- School of Electronics Engineering and Computer Science, Peking University, Beijing 100871, People's Republic of China
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17
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Rossi R, Ohgoe T, Van Houcke K, Werner F. Resummation of Diagrammatic Series with Zero Convergence Radius for Strongly Correlated Fermions. PHYSICAL REVIEW LETTERS 2018; 121:130405. [PMID: 30312043 DOI: 10.1103/physrevlett.121.130405] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/21/2018] [Revised: 07/26/2018] [Indexed: 06/08/2023]
Abstract
We demonstrate that a summing up series of Feynman diagrams can yield unbiased accurate results for strongly correlated fermions even when the convergence radius vanishes. We consider the unitary Fermi gas, a model of nonrelativistic fermions in three-dimensional continuous space. Diagrams are built from partially dressed or fully dressed propagators of single particles and pairs. The series is resummed by a conformal-Borel transformation that incorporates the large-order behavior and the analytic structure in the Borel plane, which are found by the instanton approach. We report highly accurate numerical results for the equation of state in the normal unpolarized regime, and reconcile experimental data with the theoretically conjectured fourth virial coefficient.
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Affiliation(s)
- R Rossi
- Laboratoire de Physique Statistique, Ecole Normale Supérieure-Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, 75005 Paris, France
| | - T Ohgoe
- Department of Applied Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-8656, Japan
| | - K Van Houcke
- Laboratoire de Physique Statistique, Ecole Normale Supérieure-Université PSL, CNRS, Sorbonne Université, Université Paris Diderot, 75005 Paris, France
| | - F Werner
- Laboratoire Kastler Brossel, Ecole Normale Supérieure-Université PSL, CNRS, Sorbonne Université, Collège de France, 75005 Paris, France
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18
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Absence of Landau damping in driven three-component Bose-Einstein condensate in optical lattices. Sci Rep 2018; 8:11523. [PMID: 30069027 PMCID: PMC6070551 DOI: 10.1038/s41598-018-29454-y] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Accepted: 07/10/2018] [Indexed: 11/25/2022] Open
Abstract
We explore the quantum many-body physics of a three-component Bose-Einstein condensate in an optical lattice driven by laser fields in V and Λ configurations. We obtain exact analytical expressions for the energy spectrum and amplitudes of elementary excitations, and discover symmetries among them. We demonstrate that the applied laser fields induce a gap in the otherwise gapless Bogoliubov spectrum. We find that Landau damping of the collective modes above the energy of the gap is carried by laser-induced roton modes and is considerably suppressed compared to the phonon-mediated damping endemic to undriven scalar condensates
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19
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Fava E, Bienaimé T, Mordini C, Colzi G, Qu C, Stringari S, Lamporesi G, Ferrari G. Observation of Spin Superfluidity in a Bose Gas Mixture. PHYSICAL REVIEW LETTERS 2018; 120:170401. [PMID: 29756820 DOI: 10.1103/physrevlett.120.170401] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/13/2017] [Indexed: 06/08/2023]
Abstract
The spin dynamics of a harmonically trapped Bose-Einstein condensed binary mixture of sodium atoms is experimentally investigated at finite temperature. In the collisional regime the motion of the thermal component is shown to be damped because of spin drag, while the two condensates exhibit a counterflow oscillation without friction, thereby providing direct evidence for spin superfluidity. Results are also reported in the collisionless regime where the spin components of both the condensate and thermal part oscillate without damping, their relative motion being driven by a mean-field effect. We also measure the static polarizability of the condensed and thermal parts and we find a large increase of the condensate polarizability with respect to the T=0 value, in agreement with the predictions of theory.
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Affiliation(s)
- Eleonora Fava
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
| | - Tom Bienaimé
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
| | - Carmelo Mordini
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
- Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - Giacomo Colzi
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
- Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - Chunlei Qu
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
| | - Sandro Stringari
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
- Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - Giacomo Lamporesi
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
- Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
| | - Gabriele Ferrari
- INO-CNR BEC Center and Dipartimento di Fisica, Università di Trento, 38123 Povo, Italy
- Trento Institute for Fundamental Physics and Applications, INFN, 38123 Povo, Italy
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20
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DeSalvo BJ, Patel K, Johansen J, Chin C. Observation of a Degenerate Fermi Gas Trapped by a Bose-Einstein Condensate. PHYSICAL REVIEW LETTERS 2017; 119:233401. [PMID: 29286694 DOI: 10.1103/physrevlett.119.233401] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/19/2017] [Indexed: 06/07/2023]
Abstract
We report on the formation of a stable quantum degenerate mixture of fermionic ^{6}Li and bosonic ^{133}Cs in an optical trap by sympathetic cooling near an interspecies Feshbach resonance. New regimes of quantum degenerate Bose-Fermi mixtures are identified. With moderate attractive interspecies interactions, we show that a degenerate Fermi gas of Li can be fully confined in a Cs Bose-Einstein condensate without external potentials. For stronger attraction where mean-field collapse is expected, no such instability is observed. Potential mechanisms to explain this phenomenon are discussed.
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Affiliation(s)
- B J DeSalvo
- James Franck Institute, Enrico Fermi Institute, and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Krutik Patel
- James Franck Institute, Enrico Fermi Institute, and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Jacob Johansen
- James Franck Institute, Enrico Fermi Institute, and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA
| | - Cheng Chin
- James Franck Institute, Enrico Fermi Institute, and Department of Physics, The University of Chicago, Chicago, Illinois 60637, USA
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21
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Matzliah N, Edri H, Sinay A, Ozeri R, Davidson N. Observation of Optomechanical Strain in a Cold Atomic Cloud. PHYSICAL REVIEW LETTERS 2017; 119:163201. [PMID: 29099207 DOI: 10.1103/physrevlett.119.163201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/15/2017] [Indexed: 06/07/2023]
Abstract
We report the observation of optomechanical strain applied to thermal and quantum degenerate ^{87}Rb atomic clouds when illuminated by an intense, far detuned homogeneous laser beam. In this regime the atomic cloud acts as a lens that focuses the laser beam. As a backaction, the atoms experience a force opposite to the beam deflection, which depends on the atomic cloud density profile. We experimentally demonstrate the basic features of this force, distinguishing it from the well-established scattering and dipole forces. The observed strain saturates, ultimately limiting the momentum impulse that can be transferred to the atoms. This optomechanical force may effectively induce interparticle interactions, which can be optically tuned.
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Affiliation(s)
- Noam Matzliah
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Hagai Edri
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Asif Sinay
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Roee Ozeri
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel
| | - Nir Davidson
- Department of Physics of Complex Systems, Weizmann Institute of Science, Rehovot 7610001, Israel
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22
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Laurent S, Pierce M, Delehaye M, Yefsah T, Chevy F, Salomon C. Connecting Few-Body Inelastic Decay to Quantum Correlations in a Many-Body System: A Weakly Coupled Impurity in a Resonant Fermi Gas. PHYSICAL REVIEW LETTERS 2017; 118:103403. [PMID: 28339272 DOI: 10.1103/physrevlett.118.103403] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/22/2016] [Indexed: 06/06/2023]
Abstract
We study three-body recombination in an ultracold Bose-Fermi mixture. We first show theoretically that, for weak interspecies coupling, the loss rate is proportional to Tan's contact. Second, using a ^{7}Li/^{6}Li mixture we probe the recombination rate in both the thermal and dual superfluid regimes. We find excellent agreement with our model in the BEC-BCS crossover. At unitarity where the fermion-fermion scattering length diverges, we show that the loss rate is proportional to n_{f}^{4/3}, where n_{f} is the fermionic density. This unusual exponent signals nontrivial two-body correlations in the system. Our results demonstrate that few-body losses can be used as a quantitative probe of quantum correlations in many-body ensembles.
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Affiliation(s)
- Sébastien Laurent
- Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, 75005 Paris, France
| | - Matthieu Pierce
- Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, 75005 Paris, France
| | - Marion Delehaye
- Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, 75005 Paris, France
| | - Tarik Yefsah
- Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, 75005 Paris, France
| | - Frédéric Chevy
- Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, 75005 Paris, France
| | - Christophe Salomon
- Laboratoire Kastler Brossel, ENS-PSL Research University, CNRS, UPMC-Sorbonne Universités, Collège de France, 24 rue Lhomond, 75005 Paris, France
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23
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Jiang Y, Qi R, Shi ZY, Zhai H. Vortex Lattices in the Bose-Fermi Superfluid Mixture. PHYSICAL REVIEW LETTERS 2017; 118:080403. [PMID: 28282164 DOI: 10.1103/physrevlett.118.080403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/05/2016] [Indexed: 06/06/2023]
Abstract
In this Letter we show that the vortex lattice structure in the Bose-Fermi superfluid mixture can undergo a sequence of structure transitions when the Fermi superfluid is tuned from the BCS regime to the BEC regime. This is due to the difference in the vortex core structure of a Fermi superfluid in the BCS regime and in the BEC regime. In the BCS regime the vortex core is nearly filled, while the density at the vortex core gradually decreases until it empties out in the BEC regime. Therefore, with the density-density interaction between the Bose and the Fermi superfluids, interaction between the two sets of vortex lattices gets stronger in the BEC regime, which yields the structure transition of vortex lattices. In view of the recent realization of this superfluid mixture and vortices therein, our theoretical predication can be verified experimentally in the near future.
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Affiliation(s)
- Yuzhu Jiang
- State Key Laboratory of Magnetic Resonance and Atomic and Molecular Physics, Wuhan Institute of Physics and Mathematics, Chinese Academy of Sciences, Wuhan 430071, China
| | - Ran Qi
- Department of Physics, Renmin University of China, Beijing, 100872, China
| | - Zhe-Yu Shi
- Institute for Advanced Study, Tsinghua University, Beijing, 100084, China
| | - Hui Zhai
- Institute for Advanced Study, Tsinghua University, Beijing, 100084, China
- Collaborative Innovation Center of Quantum Matter, Beijing, 100084, China
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24
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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: 5] [Impact Index Per Article: 0.7] [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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25
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Yao XC, Chen HZ, Wu YP, Liu XP, Wang XQ, Jiang X, Deng Y, Chen YA, Pan JW. Observation of Coupled Vortex Lattices in a Mass-Imbalance Bose and Fermi Superfluid Mixture. PHYSICAL REVIEW LETTERS 2016; 117:145301. [PMID: 27740822 DOI: 10.1103/physrevlett.117.145301] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2016] [Indexed: 06/06/2023]
Abstract
Quantized vortices play an essential role in diverse superfluid phenomena. In a Bose-Fermi superfluid mixture, especially of two mass-imbalance species, such macroscopic quantum phenomena are particularly rich due to the interplay between the Bose and Fermi superfluidity. However, generating a Bose-Fermi two-species superfluid, producing coupled vortex lattices within, and further probing interspecies interaction effects remain challenging. Here, we experimentally realize a two-species superfluid with dilute gases of lithium-6 and potassium-41, having a mass ratio of about seven. By rotating the superfluid mixture, we simultaneously produce coupled vortex lattices of the two species and thus present a definitive visual evidence for the double superfluidity. Moreover, we report several unconventional behaviors, due to the Bose-Fermi interaction, on the formation and decay of two-species vortices.
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Affiliation(s)
- Xing-Can Yao
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - Hao-Ze Chen
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Yu-Ping Wu
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Xiang-Pei Liu
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Xiao-Qiong Wang
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Xiao Jiang
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Youjin Deng
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Yu-Ao Chen
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
| | - Jian-Wei Pan
- Shanghai Branch, National Laboratory for Physical Sciences at Microscale and Department of Modern Physics, University of Science and Technology of China, Hefei, Anhui 230026, China
- CAS Center for Excellence and Synergetic Innovation Center in Quantum Information and Quantum Physics, University of Science and Technology of China, Shanghai 201315, China
- CAS-Alibaba Quantum Computing Laboratory, Shanghai 201315, China
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26
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Grusdt F, Fleischhauer M. Tunable Polarons of Slow-Light Polaritons in a Two-Dimensional Bose-Einstein Condensate. PHYSICAL REVIEW LETTERS 2016; 116:053602. [PMID: 26894712 DOI: 10.1103/physrevlett.116.053602] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2015] [Indexed: 06/05/2023]
Abstract
When an impurity interacts with a bath of phonons it forms a polaron. For increasing interaction strengths the mass of the polaron increases and it can become self-trapped. For impurity atoms inside an atomic Bose-Einstein condensate (BEC) the nature of this transition is not understood. While Feynman's variational approach to the Fröhlich model predicts a sharp transition for light impurities, renormalization group studies always predict an extended intermediate-coupling region characterized by large phonon correlations. To investigate this intricate regime and to test polaron physics beyond the validity of the Fröhlich model we suggest a versatile experimental setup that allows us to tune both the mass of the impurity and its interactions with the BEC. The impurity is realized as a dark-state polariton (DSP) inside a quasi-two-dimensional BEC. We show that its interactions with the Bogoliubov phonons lead to photonic polarons, described by the Bogoliubov-Fröhlich Hamiltonian, and make theoretical predictions using an extension of a recently introduced renormalization group approach to Fröhlich polarons.
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Affiliation(s)
- Fabian Grusdt
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Germany
- Graduate School Materials Science in Mainz, Gottlieb-Daimler-Strasse 47, 67663 Kaiserslautern, Germany
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Michael Fleischhauer
- Department of Physics and Research Center OPTIMAS, University of Kaiserslautern, Germany
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27
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Delehaye M, Laurent S, Ferrier-Barbut I, Jin S, Chevy F, Salomon C. Critical Velocity and Dissipation of an Ultracold Bose-Fermi Counterflow. PHYSICAL REVIEW LETTERS 2015; 115:265303. [PMID: 26765001 DOI: 10.1103/physrevlett.115.265303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/10/2015] [Indexed: 06/05/2023]
Abstract
We study the dynamics of counterflowing bosonic and fermionic lithium atoms. First, by tuning the interaction strength we measure the critical velocity v(c) of the system in the BEC-BCS crossover in the low temperature regime and we compare it to the recent prediction of Castin et al., C. R. Phys. 16, 241 (2015). Second, raising the temperature of the mixture slightly above the superfluid transitions reveals an unexpected phase locking of the oscillations of the clouds induced by dissipation.
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Affiliation(s)
- Marion Delehaye
- Laboratoire Kastler Brossel, ENS-PSL, CNRS, UPMC-Sorbonne Universités, and Collège de France, 75005 Paris, France
| | - Sébastien Laurent
- Laboratoire Kastler Brossel, ENS-PSL, CNRS, UPMC-Sorbonne Universités, and Collège de France, 75005 Paris, France
| | - Igor Ferrier-Barbut
- Laboratoire Kastler Brossel, ENS-PSL, CNRS, UPMC-Sorbonne Universités, and Collège de France, 75005 Paris, France
| | - Shuwei Jin
- Laboratoire Kastler Brossel, ENS-PSL, CNRS, UPMC-Sorbonne Universités, and Collège de France, 75005 Paris, France
| | - Frédéric Chevy
- Laboratoire Kastler Brossel, ENS-PSL, CNRS, UPMC-Sorbonne Universités, and Collège de France, 75005 Paris, France
| | - Christophe Salomon
- Laboratoire Kastler Brossel, ENS-PSL, CNRS, UPMC-Sorbonne Universités, and Collège de France, 75005 Paris, France
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28
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Luan T, Yao H, Wang L, Li C, Yang S, Chen X, Ma Z. Two-stage crossed beam cooling with ⁶Li and ¹³³Cs atoms in microgravity. OPTICS EXPRESS 2015; 23:11378-11387. [PMID: 25969232 DOI: 10.1364/oe.23.011378] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
Applying the direct simulation Monte Carlo (DSMC) method developed for ultracold Bose-Fermi mixture gases research, we study the sympathetic cooling process of 6Li and 133Cs atoms in a crossed optical dipole trap. The obstacles to producing 6Li Fermi degenerate gas via direct sympathetic cooling with 133Cs are also analyzed, by which we find that the side-effect of the gravity is one of the main obstacles. Based on the dynamic nature of 6Li and 133Cs atoms, we suggest a two-stage cooling process with two pairs of crossed beams in microgravity environment. According to our simulations, the temperature of 6Li atoms can be cooled to T = 29.5 pK and T/TF = 0.59 with several thousand atoms, which propose a novel way to get ultracold fermion atoms with quantum degeneracy near pico-Kelvin.
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29
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Nishida Y. Polaronic atom-trimer continuity in three-component Fermi gases. PHYSICAL REVIEW LETTERS 2015; 114:115302. [PMID: 25839286 DOI: 10.1103/physrevlett.114.115302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/17/2014] [Indexed: 06/04/2023]
Abstract
Recently it has been proposed that three-component Fermi gases may exhibit a new type of crossover physics in which an unpaired Fermi sea of atoms smoothly evolves into that of trimers in addition to the ordinary BCS-BEC crossover of condensed pairs. Here we study its corresponding polaron problem in which a single impurity atom of one component interacts with condensed pairs of the other two components with equal populations. By developing a variational approach in the vicinity of a narrow Feshbach resonance, we show that the impurity atom smoothly changes its character from atom to trimer with increasing the attraction and eventually there is a sharp transition to dimer. The emergent polaronic atom-trimer continuity can be probed in ultracold atoms experiments by measuring the impurity spectral function. Our novel crossover wave function properly incorporating the polaronic atom-trimer continuity will provide a useful basis to further investigate the phase diagram of three-component Fermi gases in more general situations.
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Affiliation(s)
- Yusuke Nishida
- Department of Physics, Tokyo Institute of Technology, Ookayama, Meguro, Tokyo 152-8551, Japan
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30
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Weimer W, Morgener K, Singh VP, Siegl J, Hueck K, Luick N, Mathey L, Moritz H. Critical velocity in the BEC-BCS crossover. PHYSICAL REVIEW LETTERS 2015; 114:095301. [PMID: 25793823 DOI: 10.1103/physrevlett.114.095301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/22/2014] [Indexed: 06/04/2023]
Abstract
We map out the critical velocity in the crossover from Bose-Einstein condensation to Bardeen-Cooper-Schrieffer superfluidity with ultracold ^{6}Li gases. A small attractive potential is dragged along lines of constant column density. The rate of the induced heating increases steeply above a critical velocity v_{c}. In the same samples, we measure the speed of sound v_{s} by exciting density waves and compare the results to the measured values of v_{c}. We perform numerical simulations in the Bose-Einstein condensation regime and find very good agreement, validating the approach. In the strongly correlated regime our measurements of v_{c} provide a testing ground for theoretical approaches.
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Affiliation(s)
- Wolf Weimer
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Kai Morgener
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Vijay Pal Singh
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Jonas Siegl
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Klaus Hueck
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Niclas Luick
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Ludwig Mathey
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- The Hamburg Centre for Ultrafast Imaging, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - Henning Moritz
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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31
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Observation of coherent quench dynamics in a metallic many-body state of fermionic atoms. Nat Commun 2015; 6:6009. [DOI: 10.1038/ncomms7009] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2014] [Accepted: 12/01/2014] [Indexed: 11/09/2022] Open
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32
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Zheng W, Zhai H. Quasiparticle lifetime in a mixture of Bose and Fermi superfluids. PHYSICAL REVIEW LETTERS 2014; 113:265304. [PMID: 25615350 DOI: 10.1103/physrevlett.113.265304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/05/2014] [Indexed: 06/04/2023]
Abstract
In this Letter, we study the effect of quasiparticle interactions in a Bose-Fermi superfluid mixture. We consider the lifetime of a quasiparticle of the Bose superfluid due to its interaction with quasiparticles in the Fermi superfluid. We find that this damping rate, i.e., the inverse of the lifetime, has quite a different threshold behavior at the BCS and the BEC side of the Fermi superfluid. The damping rate is a constant near the threshold momentum in the BCS side, while it increases rapidly in the BEC side. This is because, in the BCS side, the decay process is restricted by the constraint that the fermion quasiparticle is located near the Fermi surface, while such a restriction does not exist in the BEC side where the damping process is dominated by bosonic quasiparticles of the Fermi superfluid. Our results are related to the collective mode experiment in the recently realized Bose-Fermi superfluid mixture.
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Affiliation(s)
- Wei Zheng
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
| | - Hui Zhai
- Institute for Advanced Study, Tsinghua University, Beijing 100084, China
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