1
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Aydin A, Keski-Rahkonen J, Heller EJ. Quantum acoustics unravels Planckian resistivity. Proc Natl Acad Sci U S A 2024; 121:e2404853121. [PMID: 38968118 DOI: 10.1073/pnas.2404853121] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/12/2024] [Accepted: 06/05/2024] [Indexed: 07/07/2024] Open
Abstract
Strange metals exhibit universal linear-in-temperature resistivity described by a Planckian scattering rate, the origin of which remains elusive. By employing an approach inspired by quantum optics, we arrive at the coherent state representation of lattice vibrations: quantum acoustics. Utilizing this nonperturbative framework, we demonstrate that lattice vibrations could serve as active drivers in the Planckian resistivity phenomenon, challenging prevailing theories. By treating charge carriers as quantum wave packets negotiating the dynamic acoustic field, we find that a competition ensues between localization and delocalization giving rise to the previously conjectured universal quantum bound of diffusion, [Formula: see text], independent of temperature or any other material parameters. This leads to the enigmatic T-linear resistivity over hundreds of degrees, except at very low temperatures. Quantum diffusion also explains why strange metals have much higher electrical resistivity than typical metals. Our work elucidates the critical role of phonons in Planckian resistivity from a unique perspective and reconsiders their significance in the transport properties of strange metals.
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Affiliation(s)
- Alhun Aydin
- Department of Physics, Harvard University, 02138 Cambridge, MA
- Faculty of Engineering and Natural Sciences, Sabanci University, 34956 Tuzla, Istanbul, Türkiye
| | - Joonas Keski-Rahkonen
- Department of Physics, Harvard University, 02138 Cambridge, MA
- Computational Physics Laboratory, Tampere University, FI-33101 Tampere, Finland
| | - Eric J Heller
- Department of Physics, Harvard University, 02138 Cambridge, MA
- Department of Chemistry and Chemical Biology, Harvard University, 02138 Cambridge, MA
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2
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Das P, Leeb V, Knolle J, Knap M. Realizing Altermagnetism in Fermi-Hubbard Models with Ultracold Atoms. PHYSICAL REVIEW LETTERS 2024; 132:263402. [PMID: 38996311 DOI: 10.1103/physrevlett.132.263402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/23/2023] [Accepted: 05/17/2024] [Indexed: 07/14/2024]
Abstract
Altermagnetism represents a type of collinear magnetism, that is in some aspects distinct from ferromagnetism and from conventional antiferromagnetism. In contrast to the latter, sublattices of opposite spin are related by spatial rotations and not only by translations and inversions. As a result, altermagnets have spin-split bands leading to unique experimental signatures. Here, we show theoretically how a d-wave altermagnetic phase can be realized with ultracold fermionic atoms in optical lattices. We propose an altermagnetic Hubbard model with anisotropic next-nearest neighbor hopping and obtain the Hartree-Fock phase diagram. The altermagnetic phase separates in a metallic and an insulating phase and is robust over a large parameter regime. We show that one of the defining characteristics of altermagnetism, the anisotropic spin transport, can be probed with trap-expansion experiments.
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Affiliation(s)
| | | | - Johannes Knolle
- Technical University of Munich, TUM School of Natural Sciences, Physics Department, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, 80799 München, Germany
- Blackett Laboratory, Imperial College London, London SW7 2AZ, United Kingdom
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3
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Rosenberg E, Andersen TI, Samajdar R, Petukhov A, Hoke JC, Abanin D, Bengtsson A, Drozdov IK, Erickson C, Klimov PV, Mi X, Morvan A, Neeley M, Neill C, Acharya R, Allen R, Anderson K, Ansmann M, Arute F, Arya K, Asfaw A, Atalaya J, Bardin JC, Bilmes A, Bortoli G, Bourassa A, Bovaird J, Brill L, Broughton M, Buckley BB, Buell DA, Burger T, Burkett B, Bushnell N, Campero J, Chang HS, Chen Z, Chiaro B, Chik D, Cogan J, Collins R, Conner P, Courtney W, Crook AL, Curtin B, Debroy DM, Barba ADT, Demura S, Di Paolo A, Dunsworth A, Earle C, Faoro L, Farhi E, Fatemi R, Ferreira VS, Burgos LF, Forati E, Fowler AG, Foxen B, Garcia G, Genois É, Giang W, Gidney C, Gilboa D, Giustina M, Gosula R, Dau AG, Gross JA, Habegger S, Hamilton MC, Hansen M, Harrigan MP, Harrington SD, Heu P, Hill G, Hoffmann MR, Hong S, Huang T, Huff A, Huggins WJ, Ioffe LB, Isakov SV, Iveland J, Jeffrey E, Jiang Z, Jones C, Juhas P, Kafri D, Khattar T, Khezri M, Kieferová M, Kim S, Kitaev A, Klots AR, Korotkov AN, Kostritsa F, Kreikebaum JM, Landhuis D, Laptev P, Lau KM, Laws L, Lee J, Lee KW, Lensky YD, Lester BJ, Lill AT, Liu W, Locharla A, Mandrà S, Martin O, Martin S, McClean JR, McEwen M, Meeks S, Miao KC, Mieszala A, Montazeri S, Movassagh R, Mruczkiewicz W, Nersisyan A, Newman M, Ng JH, Nguyen A, Nguyen M, Niu MY, O'Brien TE, Omonije S, Opremcak A, Potter R, Pryadko LP, Quintana C, Rhodes DM, Rocque C, Rubin NC, Saei N, Sank D, Sankaragomathi K, Satzinger KJ, Schurkus HF, Schuster C, Shearn MJ, Shorter A, Shutty N, Shvarts V, Sivak V, Skruzny J, Smith WC, Somma RD, Sterling G, Strain D, Szalay M, Thor D, Torres A, Vidal G, Villalonga B, Heidweiller CV, White T, Woo BWK, Xing C, Yao ZJ, Yeh P, Yoo J, Young G, Zalcman A, Zhang Y, Zhu N, Zobrist N, Neven H, Babbush R, Bacon D, Boixo S, Hilton J, Lucero E, Megrant A, Kelly J, Chen Y, Smelyanskiy V, Khemani V, Gopalakrishnan S, Prosen T, Roushan P. Dynamics of magnetization at infinite temperature in a Heisenberg spin chain. Science 2024; 384:48-53. [PMID: 38574139 DOI: 10.1126/science.adi7877] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2023] [Accepted: 03/01/2024] [Indexed: 04/06/2024]
Abstract
Understanding universal aspects of quantum dynamics is an unresolved problem in statistical mechanics. In particular, the spin dynamics of the one-dimensional Heisenberg model were conjectured as to belong to the Kardar-Parisi-Zhang (KPZ) universality class based on the scaling of the infinite-temperature spin-spin correlation function. In a chain of 46 superconducting qubits, we studied the probability distribution of the magnetization transferred across the chain's center, [Formula: see text]. The first two moments of [Formula: see text] show superdiffusive behavior, a hallmark of KPZ universality. However, the third and fourth moments ruled out the KPZ conjecture and allow for evaluating other theories. Our results highlight the importance of studying higher moments in determining dynamic universality classes and provide insights into universal behavior in quantum systems.
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Affiliation(s)
- E Rosenberg
- Google Research, Mountain View, CA, USA
- Department of Physics, Cornell University, Ithaca, NY, USA
| | | | - R Samajdar
- Department of Physics, Princeton University, Princeton, NJ, USA
- Princeton Center for Theoretical Science, Princeton University, Princeton, NJ, USA
| | | | - J C Hoke
- Department of Physics, Stanford University, Stanford, CA, USA
| | - D Abanin
- Google Research, Mountain View, CA, USA
| | | | - I K Drozdov
- Google Research, Mountain View, CA, USA
- Department of Physics, University of Connecticut, Storrs, CT, USA
| | | | | | - X Mi
- Google Research, Mountain View, CA, USA
| | - A Morvan
- Google Research, Mountain View, CA, USA
| | - M Neeley
- Google Research, Mountain View, CA, USA
| | - C Neill
- Google Research, Mountain View, CA, USA
| | - R Acharya
- Google Research, Mountain View, CA, USA
| | - R Allen
- Google Research, Mountain View, CA, USA
| | | | - M Ansmann
- Google Research, Mountain View, CA, USA
| | - F Arute
- Google Research, Mountain View, CA, USA
| | - K Arya
- Google Research, Mountain View, CA, USA
| | - A Asfaw
- Google Research, Mountain View, CA, USA
| | - J Atalaya
- Google Research, Mountain View, CA, USA
| | - J C Bardin
- Google Research, Mountain View, CA, USA
- Department of Electrical and Computer Engineering, University of Massachusetts, Amherst, MA, USA
| | - A Bilmes
- Google Research, Mountain View, CA, USA
| | - G Bortoli
- Google Research, Mountain View, CA, USA
| | | | - J Bovaird
- Google Research, Mountain View, CA, USA
| | - L Brill
- Google Research, Mountain View, CA, USA
| | | | | | - D A Buell
- Google Research, Mountain View, CA, USA
| | - T Burger
- Google Research, Mountain View, CA, USA
| | - B Burkett
- Google Research, Mountain View, CA, USA
| | | | - J Campero
- Google Research, Mountain View, CA, USA
| | - H-S Chang
- Google Research, Mountain View, CA, USA
| | - Z Chen
- Google Research, Mountain View, CA, USA
| | - B Chiaro
- Google Research, Mountain View, CA, USA
| | - D Chik
- Google Research, Mountain View, CA, USA
| | - J Cogan
- Google Research, Mountain View, CA, USA
| | - R Collins
- Google Research, Mountain View, CA, USA
| | - P Conner
- Google Research, Mountain View, CA, USA
| | | | - A L Crook
- Google Research, Mountain View, CA, USA
| | - B Curtin
- Google Research, Mountain View, CA, USA
| | | | | | - S Demura
- Google Research, Mountain View, CA, USA
| | | | | | - C Earle
- Google Research, Mountain View, CA, USA
| | - L Faoro
- Google Research, Mountain View, CA, USA
| | - E Farhi
- Google Research, Mountain View, CA, USA
| | - R Fatemi
- Google Research, Mountain View, CA, USA
| | | | | | - E Forati
- Google Research, Mountain View, CA, USA
| | | | - B Foxen
- Google Research, Mountain View, CA, USA
| | - G Garcia
- Google Research, Mountain View, CA, USA
| | - É Genois
- Google Research, Mountain View, CA, USA
| | - W Giang
- Google Research, Mountain View, CA, USA
| | - C Gidney
- Google Research, Mountain View, CA, USA
| | - D Gilboa
- Google Research, Mountain View, CA, USA
| | | | - R Gosula
- Google Research, Mountain View, CA, USA
| | | | - J A Gross
- Google Research, Mountain View, CA, USA
| | | | - M C Hamilton
- Google Research, Mountain View, CA, USA
- Department of Electrical and Computer Engineering, Auburn University, Auburn, AL, USA
| | - M Hansen
- Google Research, Mountain View, CA, USA
| | | | | | - P Heu
- Google Research, Mountain View, CA, USA
| | - G Hill
- Google Research, Mountain View, CA, USA
| | | | - S Hong
- Google Research, Mountain View, CA, USA
| | - T Huang
- Google Research, Mountain View, CA, USA
| | - A Huff
- Google Research, Mountain View, CA, USA
| | | | - L B Ioffe
- Google Research, Mountain View, CA, USA
| | | | - J Iveland
- Google Research, Mountain View, CA, USA
| | - E Jeffrey
- Google Research, Mountain View, CA, USA
| | - Z Jiang
- Google Research, Mountain View, CA, USA
| | - C Jones
- Google Research, Mountain View, CA, USA
| | - P Juhas
- Google Research, Mountain View, CA, USA
| | - D Kafri
- Google Research, Mountain View, CA, USA
| | - T Khattar
- Google Research, Mountain View, CA, USA
| | - M Khezri
- Google Research, Mountain View, CA, USA
| | - M Kieferová
- Google Research, Mountain View, CA, USA
- QSI, Faculty of Engineering & Information Technology, University of Technology Sydney, Ultimo, NSW, Australia
| | - S Kim
- Google Research, Mountain View, CA, USA
| | - A Kitaev
- Google Research, Mountain View, CA, USA
| | - A R Klots
- Google Research, Mountain View, CA, USA
| | - A N Korotkov
- Google Research, Mountain View, CA, USA
- Department of Electrical and Computer Engineering, University of California, Riverside, CA, USA
| | | | | | | | - P Laptev
- Google Research, Mountain View, CA, USA
| | - K-M Lau
- Google Research, Mountain View, CA, USA
| | - L Laws
- Google Research, Mountain View, CA, USA
| | - J Lee
- Google Research, Mountain View, CA, USA
- Department of Chemistry, Columbia University, New York, NY, USA
| | - K W Lee
- Google Research, Mountain View, CA, USA
| | | | | | - A T Lill
- Google Research, Mountain View, CA, USA
| | - W Liu
- Google Research, Mountain View, CA, USA
| | | | - S Mandrà
- Google Research, Mountain View, CA, USA
| | - O Martin
- Google Research, Mountain View, CA, USA
| | - S Martin
- Google Research, Mountain View, CA, USA
| | | | - M McEwen
- Google Research, Mountain View, CA, USA
| | - S Meeks
- Google Research, Mountain View, CA, USA
| | - K C Miao
- Google Research, Mountain View, CA, USA
| | | | | | | | | | | | - M Newman
- Google Research, Mountain View, CA, USA
| | - J H Ng
- Google Research, Mountain View, CA, USA
| | - A Nguyen
- Google Research, Mountain View, CA, USA
| | - M Nguyen
- Google Research, Mountain View, CA, USA
| | - M Y Niu
- Google Research, Mountain View, CA, USA
| | | | - S Omonije
- Google Research, Mountain View, CA, USA
| | | | - R Potter
- Google Research, Mountain View, CA, USA
| | - L P Pryadko
- Department of Physics and Astronomy, University of California, Riverside, CA, USA
| | | | | | - C Rocque
- Google Research, Mountain View, CA, USA
| | - N C Rubin
- Google Research, Mountain View, CA, USA
| | - N Saei
- Google Research, Mountain View, CA, USA
| | - D Sank
- Google Research, Mountain View, CA, USA
| | | | | | | | | | | | - A Shorter
- Google Research, Mountain View, CA, USA
| | - N Shutty
- Google Research, Mountain View, CA, USA
| | - V Shvarts
- Google Research, Mountain View, CA, USA
| | - V Sivak
- Google Research, Mountain View, CA, USA
| | - J Skruzny
- Google Research, Mountain View, CA, USA
| | | | - R D Somma
- Google Research, Mountain View, CA, USA
| | | | - D Strain
- Google Research, Mountain View, CA, USA
| | - M Szalay
- Google Research, Mountain View, CA, USA
| | - D Thor
- Google Research, Mountain View, CA, USA
| | - A Torres
- Google Research, Mountain View, CA, USA
| | - G Vidal
- Google Research, Mountain View, CA, USA
| | | | | | - T White
- Google Research, Mountain View, CA, USA
| | - B W K Woo
- Google Research, Mountain View, CA, USA
| | - C Xing
- Google Research, Mountain View, CA, USA
| | | | - P Yeh
- Google Research, Mountain View, CA, USA
| | - J Yoo
- Google Research, Mountain View, CA, USA
| | - G Young
- Google Research, Mountain View, CA, USA
| | - A Zalcman
- Google Research, Mountain View, CA, USA
| | - Y Zhang
- Google Research, Mountain View, CA, USA
| | - N Zhu
- Google Research, Mountain View, CA, USA
| | - N Zobrist
- Google Research, Mountain View, CA, USA
| | - H Neven
- Google Research, Mountain View, CA, USA
| | - R Babbush
- Google Research, Mountain View, CA, USA
| | - D Bacon
- Google Research, Mountain View, CA, USA
| | - S Boixo
- Google Research, Mountain View, CA, USA
| | - J Hilton
- Google Research, Mountain View, CA, USA
| | - E Lucero
- Google Research, Mountain View, CA, USA
| | - A Megrant
- Google Research, Mountain View, CA, USA
| | - J Kelly
- Google Research, Mountain View, CA, USA
| | - Y Chen
- Google Research, Mountain View, CA, USA
| | | | - V Khemani
- Department of Physics, Stanford University, Stanford, CA, USA
| | | | - T Prosen
- Faculty of Mathematics and Physics, University of Ljubljana, Ljubljana, Slovenia
| | - P Roushan
- Google Research, Mountain View, CA, USA
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4
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Yan Z, Patel PB, Mukherjee B, Vale CJ, Fletcher RJ, Zwierlein MW. Thermography of the superfluid transition in a strongly interacting Fermi gas. Science 2024; 383:629-633. [PMID: 38330124 DOI: 10.1126/science.adg3430] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/28/2022] [Accepted: 01/10/2024] [Indexed: 02/10/2024]
Abstract
Heat transport can serve as a fingerprint identifying different states of matter. In a normal liquid, a hotspot diffuses, whereas in a superfluid, heat propagates as a wave called "second sound." Direct imaging of heat transport is challenging, and one usually resorts to detecting secondary effects. In this study, we establish thermography of a strongly interacting atomic Fermi gas, whose radio-frequency spectrum provides spatially resolved thermometry with subnanokelvin resolution. The superfluid phase transition was directly observed as the sudden change from thermal diffusion to second-sound propagation and is accompanied by a peak in the second-sound diffusivity. This method yields the full heat and density response of the strongly interacting Fermi gas and therefore all defining properties of Landau's two-fluid hydrodynamics.
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Affiliation(s)
- Zhenjie Yan
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Parth B Patel
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Biswaroop Mukherjee
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Chris J Vale
- Optical Science Centre and ARC Centre of Excellence in Future Low-Energy Electronics Technologies, Swinburne University of Technology, Melbourne 3122, Australia
| | - Richard J Fletcher
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Martin W Zwierlein
- MIT-Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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5
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Classical theory of universal quantum work distribution in chaotic and disordered non-interacting Fermi systems. Sci Rep 2022; 12:15017. [PMID: 36056116 PMCID: PMC9440039 DOI: 10.1038/s41598-022-18796-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/28/2022] [Accepted: 08/19/2022] [Indexed: 11/24/2022] Open
Abstract
We present a universal theory of quantum work statistics in generic disordered non-interacting Fermi systems, displaying a chaotic single-particle spectrum captured by random matrix theory. We consider quantum quenches both within a driven random matrix formalism and in an experimentally accessible microscopic model, describing a two-dimensional disordered quantum dot. By extending Anderson’s orthogonality determinant formula to compute quantum work distribution, we demonstrate that work statistics is non-Gaussian and is characterized by a few dimensionless parameters. At longer times, quantum interference effects become irrelevant and the quantum work distribution is well-described in terms of a purely classical ladder model with a symmetric exclusion process in energy space, while bosonization and mean field methods provide accurate analytical expressions for the work statistics. Our results demonstrate the universality of work distribution in generic chaotic Fermi systems, captured by the analytical predictions of a mean field theory, and can be verified by calorimetric measurements on nanoscale circuits.
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6
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Joshi MK, Kranzl F, Schuckert A, Lovas I, Maier C, Blatt R, Knap M, Roos CF. Observing emergent hydrodynamics in a long-range quantum magnet. Science 2022; 376:720-724. [PMID: 35549407 DOI: 10.1126/science.abk2400] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
Identifying universal properties of nonequilibrium quantum states is a major challenge in modern physics. A fascinating prediction is that classical hydrodynamics emerges universally in the evolution of any interacting quantum system. We experimentally probed the quantum dynamics of 51 individually controlled ions, realizing a long-range interacting spin chain. By measuring space-time-resolved correlation functions in an infinite temperature state, we observed a whole family of hydrodynamic universality classes, ranging from normal diffusion to anomalous superdiffusion, that are described by Lévy flights. We extracted the transport coefficients of the hydrodynamic theory, reflecting the microscopic properties of the system. Our observations demonstrate the potential for engineered quantum systems to provide key insights into universal properties of nonequilibrium states of quantum matter.
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Affiliation(s)
- M K Joshi
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstraße 21a, 6020 Innsbruck, Austria
| | - F Kranzl
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstraße 21a, 6020 Innsbruck, Austria.,Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - A Schuckert
- 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, 80799 München, Germany
| | - I Lovas
- 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, 80799 München, Germany
| | - C Maier
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstraße 21a, 6020 Innsbruck, Austria.,AQT, Technikerstraße 17, 6020 Innsbruck, Austria
| | - R Blatt
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstraße 21a, 6020 Innsbruck, Austria.,Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M 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, 80799 München, Germany
| | - C F Roos
- Institute for Quantum Optics and Quantum Information, Austrian Academy of Sciences, Technikerstraße 21a, 6020 Innsbruck, Austria.,Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
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7
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Observation of spin-space quantum transport induced by an atomic quantum point contact. Nat Commun 2021; 12:6724. [PMID: 34795240 PMCID: PMC8602744 DOI: 10.1038/s41467-021-27011-2] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2021] [Accepted: 11/01/2021] [Indexed: 11/08/2022] Open
Abstract
Quantum transport is ubiquitous in physics. So far, quantum transport between terminals has been extensively studied in solid state systems from the fundamental point of views such as the quantized conductance to the applications to quantum devices. Recent works have demonstrated a cold-atom analog of a mesoscopic conductor by engineering a narrow conducting channel with optical potentials, which opens the door for a wealth of research of atomtronics emulating mesoscopic electronic devices and beyond. Here we realize an alternative scheme of the quantum transport experiment with ytterbium atoms in a two-orbital optical lattice system. Our system consists of a multi-component Fermi gas and a localized impurity, where the current can be created in the spin space by introducing the spin-dependent interaction with the impurity. We demonstrate a rich variety of localized-impurity-induced quantum transports, which paves the way for atomtronics exploiting spin degrees of freedom.
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8
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Marquardt R. Mean square displacement of a free quantum particle in a thermal state. Mol Phys 2021. [DOI: 10.1080/00268976.2021.1971315] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/20/2022]
Affiliation(s)
- Roberto Marquardt
- Laboratoire de Chimie Quantique – Institut de Chimie – UMR 7177 CNRS/Unistra, Université de Strasbourg, Strasbourg Cedex, France
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9
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Emergent hydrodynamics in a strongly interacting dipolar spin ensemble. Nature 2021; 597:45-50. [PMID: 34471276 DOI: 10.1038/s41586-021-03763-1] [Citation(s) in RCA: 13] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/22/2020] [Accepted: 06/23/2021] [Indexed: 11/08/2022]
Abstract
Conventional wisdom holds that macroscopic classical phenomena naturally emerge from microscopic quantum laws1-7. However, despite this mantra, building direct connections between these two descriptions has remained an enduring scientific challenge. In particular, it is difficult to quantitatively predict the emergent 'classical' properties of a system (for example, diffusivity, viscosity and compressibility) from a generic microscopic quantum Hamiltonian7-14. Here we introduce a hybrid solid-state spin platform, where the underlying disordered, dipolar quantum Hamiltonian gives rise to the emergence of unconventional spin diffusion at nanometre length scales. In particular, the combination of positional disorder and on-site random fields leads to diffusive dynamics that are Fickian yet non-Gaussian15-20. Finally, by tuning the underlying parameters within the spin Hamiltonian via a combination of static and driven fields, we demonstrate direct control over the emergent spin diffusion coefficient. Our work enables the investigation of hydrodynamics in many-body quantum spin systems.
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10
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Long Y, Xiong F, Parker CV. Spin Susceptibility above the Superfluid Onset in Ultracold Fermi Gases. PHYSICAL REVIEW LETTERS 2021; 126:153402. [PMID: 33929234 DOI: 10.1103/physrevlett.126.153402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2020] [Revised: 10/01/2020] [Accepted: 03/02/2021] [Indexed: 06/12/2023]
Abstract
Ultracold atomic Fermi gases can be tuned to interact strongly, which produces a display of spectroscopic signatures above the superfluid transition reminiscent of the pseudogap in cuprates. However, the extent of the analogy can be questioned since many thermodynamic quantities in the low temperature spin-imbalanced normal state can be described successfully using Fermi liquid theory. Here we present spin susceptibility measurements across the interaction strength-temperature phase diagram using a novel radio frequency technique with ultracold ^{6}Li gases. For all significant interaction strengths and at all temperatures we find the spin susceptibility is reduced compared to the equivalent value for a noninteracting Fermi gas. At unitarity, we can use the local density approximation to extract the integrated spin susceptibility for the uniform gas as a function of temperature, which at high temperatures is generally less than theoretically predicted. At low temperatures, our data lie within the range of theoretical predictions, although we can also describe the entire curve using a very simple one-parameter mean field model with monotonically increasing spin susceptibility.
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Affiliation(s)
- Yun Long
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Feng Xiong
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | - Colin V Parker
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
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11
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Patel PB, Yan Z, Mukherjee B, Fletcher RJ, Struck J, Zwierlein MW. Universal sound diffusion in a strongly interacting Fermi gas. Science 2021; 370:1222-1226. [PMID: 33273102 DOI: 10.1126/science.aaz5756] [Citation(s) in RCA: 26] [Impact Index Per Article: 8.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/20/2019] [Accepted: 10/24/2020] [Indexed: 11/02/2022]
Abstract
Transport of strongly interacting fermions is crucial for the properties of modern materials, nuclear fission, the merging of neutron stars, and the expansion of the early Universe. Here, we observe a universal quantum limit of diffusivity in a homogeneous, strongly interacting atomic Fermi gas by studying sound propagation and its attenuation through the coupled transport of momentum and heat. In the normal state, the sound diffusivity D monotonically decreases upon lowering the temperature, in contrast to the diverging behavior of weakly interacting Fermi liquids. Below the superfluid transition temperature, D attains a universal value set by the ratio of Planck's constant and the particle mass. Our findings inform theories of fermion transport, with relevance for hydrodynamic flow of electrons, neutrons, and quarks.
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Affiliation(s)
- Parth B Patel
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Zhenjie Yan
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Biswaroop Mukherjee
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Richard J Fletcher
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Julian Struck
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA.,Département de Physique, Ecole Normale Supérieure/PSL Research University, CNRS, 24 rue Lhomond, 75005 Paris, France
| | - Martin W Zwierlein
- Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA. .,MIT-Harvard Center for Ultracold Atoms, Cambridge, MA 02139, USA.,Research Laboratory of Electronics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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12
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Spin transport in a tunable Heisenberg model realized with ultracold atoms. Nature 2020; 588:403-407. [DOI: 10.1038/s41586-020-3033-y] [Citation(s) in RCA: 82] [Impact Index Per Article: 20.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2020] [Accepted: 09/25/2020] [Indexed: 11/08/2022]
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13
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Grochowski PT, Karpiuk T, Brewczyk M, Rzążewski K. Breathing Mode of a Bose-Einstein Condensate Immersed in a Fermi Sea. PHYSICAL REVIEW LETTERS 2020; 125:103401. [PMID: 32955322 DOI: 10.1103/physrevlett.125.103401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/28/2019] [Revised: 03/06/2020] [Accepted: 08/06/2020] [Indexed: 06/11/2023]
Abstract
By analyzing the breathing mode of a Bose-Einstein condensate repulsively interacting with a polarized fermionic cloud, we further the understanding of a Bose-Fermi mixture recently realized by Lous et al. [Phys. Rev. Lett. 120, 243403 (2018)PRLTAO0031-900710.1103/PhysRevLett.120.243403]. We show that a hydrodynamic description of a domain wall between bosonic and fermionic atoms reproduces the experimental data of Huang et al. [Phys. Rev. A 99, 041602(R) (2019)PLRAAN2469-992610.1103/PhysRevA.99.041602]. Two different types of interaction renormalization are explored, based on lowest-order constrained variational and perturbation techniques. In order to replicate nonmonotonic behavior of the oscillation frequency observed in the experiment, temperature effects have to be included. We find that the frequency down-shift is caused by the fermion-induced compression and rethermalization of the bosonic species as the system is quenched into the strongly interacting regime.
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Affiliation(s)
- Piotr T Grochowski
- Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Tomasz Karpiuk
- Wydział Fizyki, Uniwersytet w Białymstoku, ul. K. Ciołkowskiego 1L, 15-245 Białystok, Poland
| | - Mirosław Brewczyk
- Wydział Fizyki, Uniwersytet w Białymstoku, ul. K. Ciołkowskiego 1L, 15-245 Białystok, Poland
| | - Kazimierz Rzążewski
- Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
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14
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Bohlen M, Sobirey L, Luick N, Biss H, Enss T, Lompe T, Moritz H. Sound Propagation and Quantum-Limited Damping in a Two-Dimensional Fermi Gas. PHYSICAL REVIEW LETTERS 2020; 124:240403. [PMID: 32639806 DOI: 10.1103/physrevlett.124.240403] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/09/2020] [Revised: 04/26/2020] [Accepted: 05/22/2020] [Indexed: 06/11/2023]
Abstract
Strongly interacting two-dimensional Fermi systems are one of the great remaining challenges in many-body physics due to the interplay of strong local correlations and enhanced long-range fluctuations. Here, we probe the thermodynamic and transport properties of a 2D Fermi gas across the BEC-BCS crossover by studying the propagation and damping of sound modes. We excite particle currents by imprinting a phase step onto homogeneous Fermi gases trapped in a box potential and extract the speed of sound from the frequency of the resulting density oscillations. We measure the speed of sound across the BEC-BCS crossover and compare the resulting dynamic measurement of the equation of state both to a static measurement based on recording density profiles and to quantum Monte Carlo calculations and find reasonable agreement between all three. We also measure the damping of the sound mode, which is determined by the shear and bulk viscosities as well as the thermal conductivity of the gas. We find that the damping is minimal in the strongly interacting regime and the diffusivity approaches the universal quantum bound ℏ/m of a perfect fluid.
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Affiliation(s)
- Markus Bohlen
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
- Laboratoire Kastler Brossel, ENS-Université PSL, CNRS, Sorbonne Université, Collège de France, 24 rue Lhomond, Paris 75005, France
| | - Lennart Sobirey
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Niclas Luick
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Hauke Biss
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Tilman Enss
- Intitut für Theoretische Physik, Universität Heidelberg, Philosophenweg 19, Heidelberg 69120, Germany
| | - Thomas Lompe
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
| | - Henning Moritz
- Institut für Laserphysik, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
- The Hamburg Centre for Ultrafast Imaging, Universität Hamburg, Luruper Chaussee 149, Hamburg 22761, Germany
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15
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Yan ZZ, Ni Y, Robens C, Zwierlein MW. Bose polarons near quantum criticality. Science 2020; 368:190-194. [DOI: 10.1126/science.aax5850] [Citation(s) in RCA: 85] [Impact Index Per Article: 21.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/04/2019] [Accepted: 03/13/2020] [Indexed: 11/02/2022]
Affiliation(s)
- Zoe Z. Yan
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Yiqi Ni
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Carsten Robens
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
| | - Martin W. Zwierlein
- MIT–Harvard Center for Ultracold Atoms, Research Laboratory of Electronics, and Department of Physics, Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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16
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Jensen S, Gilbreth CN, Alhassid Y. Pairing Correlations across the Superfluid Phase Transition in the Unitary Fermi Gas. PHYSICAL REVIEW LETTERS 2020; 124:090604. [PMID: 32202890 DOI: 10.1103/physrevlett.124.090604] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2018] [Revised: 06/17/2019] [Accepted: 01/17/2020] [Indexed: 06/10/2023]
Abstract
In the two-component Fermi gas with a contact interaction, a pseudogap regime can exist at temperatures between the superfluid critical temperature T_{c} and a temperature T^{*}>T_{c}. This regime is characterized by pairing correlations without superfluidity. However, in the unitary limit of infinite scattering length, the existence of this regime is still debated. To help address this, we have applied finite-temperature auxiliary-field quantum Monte Carlo (AFMC) methods to study the thermodynamics of the superfluid phase transition and signatures of the pseudogap in the spin-balanced homogeneous unitary Fermi gas. We present results at finite filling factor ν≃0.06 for the condensate fraction, an energy-staggering pairing gap, the spin susceptibility, and the heat capacity, and compare them to experimental data when available. In contrast to previous AFMC simulations, our model space consists of the complete first Brillouin zone of the lattice, and our calculations are performed in the canonical ensemble of fixed particle number. The canonical ensemble AFMC framework enables the calculation of a model-independent gap, providing direct information on pairing correlations without the need for numerical analytic continuation. We use finite-size scaling to estimate T_{c} at the corresponding filling factor. We find that the energy-staggering pairing gap vanishes above T_{c}, showing no pseudogap effects, and that the spin susceptibility shows a substantially reduced signature of a spin gap compared to previously reported AFMC simulations.
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Affiliation(s)
- S Jensen
- Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520, USA
| | - C N Gilbreth
- Institute for Nuclear Theory, Box 351550, University of Washington, Seattle, Washington 98195, USA
| | - Y Alhassid
- Center for Theoretical Physics, Sloane Physics Laboratory, Yale University, New Haven, Connecticut 06520, USA
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17
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Abstract
Electrical current in conventional metals is carried by electrons that retain their individual character. Bad metals, such as the normal state of some high-temperature superconductors, violate this scenario, and the complete picture for their behavior remains unresolved. Here, we report phenomena consistent with bad-metal behaviour in an optical-lattice Hubbard model by measuring the transport lifetime for a mass current excited by stimulated Raman transitions. We demonstrate incompatibility with weak-scattering theory and key characteristics of bad metals: anomalous resistivity scaling consistent with T-linear behavior, the onset of incoherent transport, and the approach to the Mott–Ioffe–Regel limit. Our work demonstrates a direct method for determining the transport lifetime, which is critical to theory but difficult to measure in materials, and exposes minimal ingredients for bad-metal behavior. The origin of bad-metal resistivity is a long-standing problem for condensed matter physics. Here the authors show anomalous resistivity, transport lifetime, and relaxation dynamics consistent with bad-metal behavior over a wide range of temperature for fermionic potassium atoms in optical lattices.
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18
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Spin current generation and relaxation in a quenched spin-orbit-coupled Bose-Einstein condensate. Nat Commun 2019; 10:375. [PMID: 30670693 PMCID: PMC6343014 DOI: 10.1038/s41467-018-08119-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/21/2018] [Accepted: 12/14/2018] [Indexed: 11/27/2022] Open
Abstract
Understanding the effects of spin-orbit coupling (SOC) and many-body interactions on spin transport is important in condensed matter physics and spintronics. This topic has been intensively studied for spin carriers such as electrons but barely explored for charge-neutral bosonic quasiparticles (including their condensates), which hold promises for coherent spin transport over macroscopic distances. Here, we explore the effects of synthetic SOC (induced by optical Raman coupling) and atomic interactions on the spin transport in an atomic Bose-Einstein condensate (BEC), where the spin-dipole mode (SDM, actuated by quenching the Raman coupling) of two interacting spin components constitutes an alternating spin current. We experimentally observe that SOC significantly enhances the SDM damping while reducing the thermalization (the reduction of the condensate fraction). We also observe generation of BEC collective excitations such as shape oscillations. Our theory reveals that the SOC-modified interference, immiscibility, and interaction between the spin components can play crucial roles in spin transport. Spin-orbit coupling is interesting for fundamental understanding of spin transport and quench dynamics. Here the authors demonstrate spin-current generation and its relaxation in spin-orbit-coupled Bose-Einstein condensates of Rb atoms in different spin states.
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19
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Nichols MA, Cheuk LW, Okan M, Hartke TR, Mendez E, Senthil T, Khatami E, Zhang H, Zwierlein MW. Spin transport in a Mott insulator of ultracold fermions. Science 2018; 363:383-387. [DOI: 10.1126/science.aat4387] [Citation(s) in RCA: 80] [Impact Index Per Article: 13.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2018] [Accepted: 11/20/2018] [Indexed: 11/02/2022]
Abstract
Strongly correlated materials are expected to feature unconventional transport properties, such that charge, spin, and heat conduction are potentially independent probes of the dynamics. In contrast to charge transport, the measurement of spin transport in such materials is highly challenging. We observed spin conduction and diffusion in a system of ultracold fermionic atoms that realizes the half-filled Fermi-Hubbard model. For strong interactions, spin diffusion is driven by super-exchange and doublon-hole–assisted tunneling, and strongly violates the quantum limit of charge diffusion. The technique developed in this work can be extended to finite doping, which can shed light on the complex interplay between spin and charge in the Hubbard model.
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20
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Rammelmüller L, Loheac AC, Drut JE, Braun J. Finite-Temperature Equation of State of Polarized Fermions at Unitarity. PHYSICAL REVIEW LETTERS 2018; 121:173001. [PMID: 30411942 DOI: 10.1103/physrevlett.121.173001] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/20/2018] [Indexed: 06/08/2023]
Abstract
We study in a nonperturbative fashion the thermodynamics of a unitary Fermi gas over a wide range of temperatures and spin polarizations. To this end, we use the complex Langevin method, a first principles approach for strongly coupled systems. Specifically, we show results for the density equation of state, the magnetization, and the magnetic susceptibility. At zero polarization, our results agree well with state-of-the-art results for the density equation of state and with experimental data. At finite polarization and low fugacity, our results are in excellent agreement with the third-order virial expansion. In the fully quantum mechanical regime close to the balanced limit, the critical temperature for superfluidity appears to depend only weakly on the spin polarization.
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Affiliation(s)
- Lukas Rammelmüller
- Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- GSI Helmholtzzentrum für Schwerionenforschung GmbH, Planckstraße 1, D-64291 Darmstadt, Germany
| | - Andrew C Loheac
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Joaquín E Drut
- Department of Physics and Astronomy, University of North Carolina, Chapel Hill, North Carolina 27599, USA
| | - Jens Braun
- Institut für Kernphysik (Theoriezentrum), Technische Universität Darmstadt, D-64289 Darmstadt, Germany
- FAIR, Facility for Antiproton and Ion Research in Europe GmbH, Planckstraße 1, D-64291 Darmstadt, Germany
- ExtreMe Matter Institute EMMI, GSI, Planckstraße 1, D-64291 Darmstadt, Germany
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21
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Parisi L, Astrakharchik GE, Giorgini S. Spin Dynamics and Andreev-Bashkin Effect in Mixtures of One-Dimensional Bose Gases. PHYSICAL REVIEW LETTERS 2018; 121:025302. [PMID: 30085725 DOI: 10.1103/physrevlett.121.025302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/11/2018] [Revised: 03/01/2018] [Indexed: 06/08/2023]
Abstract
We investigate the propagation of spin waves in two-component mixtures of one-dimensional Bose gases interacting through repulsive contact potentials. By using quantum Monte Carlo methods we calculate static ground-state properties, such as the spin susceptibility and the spin structure factor, as a function of the coupling strengths and we determine the critical parameters for phase separation. In homogeneous mixtures, results of the velocity of spin waves and of its softening close to the critical point of phase separation are obtained by means of hydrodynamic theory and a sum-rule approach. We quantify the nondissipative drag effect, resulting from the Andreev-Bashkin current-current interaction between the two components of the gas, and we show that in the regime of strong coupling it causes a significant suppression of the spin-wave velocity.
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Affiliation(s)
- L Parisi
- Dipartimento di Fisica, Università di Trento and CNR-INO BEC Center, I-38050 Povo, Trento, Italy
| | - G E Astrakharchik
- Departament de Física i Enginyeria Nuclear, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain
| | - S Giorgini
- Dipartimento di Fisica, Università di Trento and CNR-INO BEC Center, I-38050 Povo, Trento, Italy
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22
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Wlazłowski G, Sekizawa K, Marchwiany M, Magierski P. Suppressed Solitonic Cascade in Spin-Imbalanced Superfluid Fermi Gas. PHYSICAL REVIEW LETTERS 2018; 120:253002. [PMID: 29979062 DOI: 10.1103/physrevlett.120.253002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2017] [Indexed: 06/08/2023]
Abstract
Cold atoms experiments offer invaluable information on superfluid dynamics, including decay cascades of topological defects. While the cascade properties are well established for Bose systems, our understanding of their behavior in Fermi counterparts is very limited, in particular in spin-imbalanced systems, where superfluid (paired) and normal (unpaired) particles naturally coexist giving rise to complex spatial structure of the atomic cloud. Here we show, based on a newly developed microscopic approach, that the decay cascades of topological defects are dramatically modified by the spin polarization. We demonstrate that decay cascades end up at different stages: "dark soliton," "vortex ring," or "vortex line," depending on the polarization. We reveal that it is caused by sucking of unpaired particles into the soliton's internal structure. As a consequence vortex reconnections are hindered and we anticipate that quantum turbulence phenomenon can be significantly affected, indicating new physics induced by polarization effects.
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Affiliation(s)
- Gabriel Wlazłowski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, Warsaw 00-662, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Kazuyuki Sekizawa
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, Warsaw 00-662, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
| | - Maciej Marchwiany
- Interdisciplinary Centre for Mathematical and Computational Modelling (ICM), University of Warsaw, A. Pawińskiego 5a, Warsaw 02-106, Poland
| | - Piotr Magierski
- Faculty of Physics, Warsaw University of Technology, Ulica Koszykowa 75, Warsaw 00-662, Poland
- Department of Physics, University of Washington, Seattle, Washington 98195-1560, USA
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23
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Emergent symmetry at superradiance transition of a Bose condensate in two crossed beam cavities. Sci Bull (Beijing) 2018; 63:542-547. [PMID: 36658840 DOI: 10.1016/j.scib.2018.04.008] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/20/2018] [Revised: 04/03/2018] [Accepted: 04/04/2018] [Indexed: 01/21/2023]
Abstract
Recently an experiment on superradiant transition of a Bose condensate in two crossed beam cavities has been reported by Léonard et al. in Nature 543, 87 (2017). The surprise is they find that across the superradiant transition, the cavity light can be emitted in any superposition of these two cavity modes. This indicates an additional U(1) symmetry that does not exist in the full Hamiltonian. In this paper we show that this symmetry is an emergent symmetry in the vicinity of the phase transition. We identify all the necessary conditions that are required for this emergent U(1) symmetry and show that this experiment is a special case that satisfies these conditions. We further show that the superradiant transition in this system can also be driven to a first order one when the system is tuned away from the point having the emergent symmetry.
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24
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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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25
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Cai W, Guo H, He Y, Chien CC. Shear Viscosity of Uniform Fermi Gases with Population Imbalance. Sci Rep 2018; 8:3981. [PMID: 29507313 PMCID: PMC5838242 DOI: 10.1038/s41598-018-22273-1] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2017] [Accepted: 02/19/2018] [Indexed: 11/15/2022] Open
Abstract
The shear viscosity has been an important topic in ultracold Fermi gases, and it has served as a diagnostic of various theories. Due to the complicated phase structures of population-imbalanced (polarized) Fermi gases with tunable attraction, past works on the shear viscosity mainly focused on unpolarized Fermi gases. Here we investigate the shear viscosity of homogeneous, population-imbalanced Fermi superfluid at finite temperatures by a pairing fluctuation theory for thermodynamical quantities and a gauge-invariant linear response theory for transport coefficients. The Cooper pairs lead to the anomalous shear viscosity analogous to the shear viscosity. We derive an exact relation connecting certain thermodynamic quantities and transport coefficients at the mean-field level for polarized unitary Fermi superfluids. An approximate relation beyond mean-field is proposed and only exhibits mild deviations from our numerical results. In the unitary and Bose-Einstein condensation (BEC) regimes, the total shear viscosity increases with the polarization because the excess majority fermions cause gapless excitations acting like a normal fluid. Moreover, competition among the excess fermions, noncondensed pairs, and fermionic quasiparticles may lead to non-monotonic behavior of the ratio between the shear viscosity and relaxation time as the polarization increases.
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Affiliation(s)
- Weimin Cai
- Department of Physics, Southeast University, Nanjing, 211189, China
| | - Hao Guo
- Department of Physics, Southeast University, Nanjing, 211189, China.
| | - Yan He
- College of Physical Science and Technology, Sichuan University, Chengdu, Sichuan, 610064, China
| | - Chih-Chun Chien
- School of Natural Sciences, University of California, Merced, CA, 95343, USA.
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26
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Du C, van der Sar T, Zhou TX, Upadhyaya P, Casola F, Zhang H, Onbasli MC, Ross CA, Walsworth RL, Tserkovnyak Y, Yacoby A. Control and local measurement of the spin chemical potential in a magnetic insulator. Science 2018; 357:195-198. [PMID: 28706070 DOI: 10.1126/science.aak9611] [Citation(s) in RCA: 55] [Impact Index Per Article: 9.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2016] [Accepted: 06/09/2017] [Indexed: 12/20/2022]
Abstract
The spin chemical potential characterizes the tendency of spins to diffuse. Probing this quantity could provide insight into materials such as magnetic insulators and spin liquids and aid optimization of spintronic devices. Here we introduce single-spin magnetometry as a generic platform for nonperturbative, nanoscale characterization of spin chemical potentials. We experimentally realize this platform using diamond nitrogen-vacancy centers and use it to investigate magnons in a magnetic insulator, finding that the magnon chemical potential can be controlled by driving the system's ferromagnetic resonance. We introduce a symmetry-based two-fluid theory describing the underlying magnon processes, measure the local thermomagnonic torque, and illustrate the detection sensitivity using electrically controlled spin injection. Our results pave the way for nanoscale control and imaging of spin transport in mesoscopic systems.
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Affiliation(s)
- Chunhui Du
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA
| | - Toeno van der Sar
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA
| | - Tony X Zhou
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
| | - Pramey Upadhyaya
- Department of Physics and Astronomy, University of California, Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USA
| | - Francesco Casola
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
| | - Huiliang Zhang
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
| | - Mehmet C Onbasli
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.,Koç University, Department of Electrical and Electronics Engineering, Sarıyer, 34450 Istanbul, Turkey
| | - Caroline A Ross
- Department of Materials Science and Engineering, Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA
| | - Ronald L Walsworth
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA.,Harvard-Smithsonian Center for Astrophysics, 60 Garden Street, Cambridge, MA 02138, USA
| | - Yaroslav Tserkovnyak
- Department of Physics and Astronomy, University of California, Los Angeles, 475 Portola Plaza, Los Angeles, CA 90095, USA
| | - Amir Yacoby
- Department of Physics, Harvard University, 17 Oxford Street, Cambridge, MA 02138, USA. .,John A. Paulson School of Engineering and Applied Sciences, Harvard University, Cambridge, MA 02138, USA
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Grochowski PT, Karpiuk T, Brewczyk M, Rzążewski K. Unified Description of Dynamics of a Repulsive Two-Component Fermi Gas. PHYSICAL REVIEW LETTERS 2017; 119:215303. [PMID: 29219395 DOI: 10.1103/physrevlett.119.215303] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/28/2017] [Indexed: 06/07/2023]
Abstract
We study a binary spin mixture of a zero-temperature repulsively interacting ^{6}Li atoms using both the atomic-orbital and density-functional approaches. The gas is initially prepared in a configuration of two magnetic domains and we determine the frequency of the spin-dipole oscillations which are emerging after the repulsive barrier, initially separating the domains, is removed. We find, in agreement with recent experiment [G. Valtolina et al., Nat. Phys. 13, 704 (2017)NPAHAX1745-247310.1038/nphys4108], the occurrence of a ferromagnetic instability in an atomic gas while the interaction strength between different spin states is increased, after which the system becomes ferromagnetic. The ferromagnetic instability is preceded by the softening of the spin-dipole mode.
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Affiliation(s)
- Piotr T Grochowski
- Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
| | - Tomasz Karpiuk
- Wydział Fizyki, Uniwersytet w Białymstoku, ul. K. Ciołkowskiego 1L, 15-245 Białystok, Poland
| | - Mirosław Brewczyk
- Wydział Fizyki, Uniwersytet w Białymstoku, ul. K. Ciołkowskiego 1L, 15-245 Białystok, Poland
| | - Kazimierz Rzążewski
- Center for Theoretical Physics, Polish Academy of Sciences, Aleja Lotników 32/46, 02-668 Warsaw, Poland
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28
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Hartman T, Hartnoll SA, Mahajan R. Upper Bound on Diffusivity. PHYSICAL REVIEW LETTERS 2017; 119:141601. [PMID: 29053285 DOI: 10.1103/physrevlett.119.141601] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/27/2017] [Indexed: 06/07/2023]
Abstract
The linear growth of operators in local quantum systems leads to an effective light cone even if the system is nonrelativistic. We show that the consistency of diffusive transport with this light cone places an upper bound on the diffusivity: D≲v^{2}τ_{eq}. The operator growth velocity v defines the light cone, and τ_{eq} is the local equilibration time scale, beyond which the dynamics of conserved densities is diffusive. We verify that the bound is obeyed in various weakly and strongly interacting theories. In holographic models, this bound establishes a relation between the hydrodynamic and leading nonhydrodynamic quasinormal modes of planar black holes. Our bound relates transport data-including the electrical resistivity and the shear viscosity-to the local equilibration time, even in the absence of a quasiparticle description. In this way, the bound sheds light on the observed T-linear resistivity of many unconventional metals, the shear viscosity of the quark-gluon plasma, and the spin transport of unitary fermions.
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Affiliation(s)
- Thomas Hartman
- Department of Physics, Cornell University, Ithaca, New York 14850, USA
| | - Sean A Hartnoll
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - Raghu Mahajan
- Department of Physics, Stanford University, Stanford, California 94305, USA
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29
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Mueller EJ. Review of pseudogaps in strongly interacting Fermi gases. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2017; 80:104401. [PMID: 28686169 DOI: 10.1088/1361-6633/aa7e53] [Citation(s) in RCA: 15] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
A central challenge in modern condensed matter physics is developing the tools for understanding nontrivial yet unordered states of matter. One important idea to emerge in this context is that of a 'pseudogap': the fact that under appropriate circumstances the normal state displays a suppression of the single particle spectral density near the Fermi level, reminiscent of the gaps seen in ordered states of matter. While these concepts arose in a solid state context, they are now being explored in cold gases. This article reviews the current experimental and theoretical understanding of the normal state of strongly interacting Fermi gases, with particular focus on the phenomonology which is traditionally associated with the pseudogap.
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Affiliation(s)
- Erich J Mueller
- Laboratory of Atomic and Solid State Physics, Cornell University, Ithaca NY 14853, United States of America
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30
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Krinner S, Esslinger T, Brantut JP. Two-terminal transport measurements with cold atoms. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:343003. [PMID: 28749788 DOI: 10.1088/1361-648x/aa74a1] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/07/2023]
Abstract
In recent years, the ability of cold atom experiments to explore condensed-matter-related questions has dramatically progressed. Transport experiments, in particular, have expanded to the point in which conductance and other transport coefficients can now be measured in a way that is directly analogous to solid-state physics, extending cold-atom-based quantum simulations into the domain of quantum electronic devices. In this topical review, we describe the transport experiments performed with cold gases in the two-terminal configuration, with an emphasis on the specific features of cold atomic gases compared to solid-state physics. We present the experimental techniques and the main experimental findings, focusing on-but not restricted to-the recent experiments performed by our group. We finally discuss the perspectives opened up by this approach, the main technical and conceptual challenges for future developments, and potential applications in quantum simulation for transport phenomena and mesoscopic physics problems.
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Affiliation(s)
- Sebastian Krinner
- Institute for Quantum Electronics, ETH Zurich, 8093 Zurich, Switzerland
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31
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Universal linear-temperature resistivity: possible quantum diffusion transport in strongly correlated superconductors. Sci Rep 2017; 7:9469. [PMID: 28842685 PMCID: PMC5573385 DOI: 10.1038/s41598-017-09792-z] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2017] [Accepted: 07/28/2017] [Indexed: 11/09/2022] Open
Abstract
The strongly correlated electron fluids in high temperature cuprate superconductors demonstrate an anomalous linear temperature (T) dependent resistivity behavior, which persists to a wide temperature range without exhibiting saturation. As cooling down, those electron fluids lose the resistivity and condense into the superfluid. However, the origin of the linear-T resistivity behavior and its relationship to the strongly correlated superconductivity remain a mystery. Here we report a universal relation \documentclass[12pt]{minimal}
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\begin{document}$$d{\boldsymbol{\rho }}/{\boldsymbol{dT}}=({{\boldsymbol{\mu }}}_{{\bf{0}}}{{\boldsymbol{k}}}_{{\boldsymbol{B}}}/{\boldsymbol{\hslash }})\,{{\boldsymbol{\lambda }}}_{{\boldsymbol{L}}}^{{\bf{2}}}$$\end{document}dρ/dT=(μ0kB/ℏ)λL2, which bridges the slope of the linear-T-dependent resistivity (dρ/dT) to the London penetration depth λL at zero temperature among cuprate superconductor Bi2Sr2CaCu2O8+δ and heavy fermion superconductors CeCoIn5, where μ0 is vacuum permeability, kB is the Boltzmann constant and ħ is the reduced Planck constant. We extend this scaling relation to different systems and found that it holds for other cuprate, pnictide and heavy fermion superconductors as well, regardless of the significant differences in the strength of electronic correlations, transport directions, and doping levels. Our analysis suggests that the scaling relation in strongly correlated superconductors could be described as a hydrodynamic diffusive transport, with the diffusion coefficient (D) approaching the quantum limit D ~ ħ/m*, where m* is the quasi-particle effective mass.
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Krauser JS, Heinze J, Götze S, Langbecker M, Fläschner N, Cook L, Hanna TM, Tiesinga E, Sengstock K, Becker C. Investigation of Feshbach resonances in ultracold 40K spin mixtures. PHYSICAL REVIEW. A 2017; 95:042701. [PMID: 29876533 PMCID: PMC5986192 DOI: 10.1103/physreva.95.042701] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/08/2023]
Abstract
Magnetically tunable Feshbach resonances are an indispensable tool for experiments with atomic quantum gases. We report on 37 thus far unpublished Feshbach resonances and four further probable Feshbach resonances in spin mixtures of ultracold fermionic 40K with temperatures well below 100 nK. In particular, we locate a broad resonance at B = 389.7G with a magnetic width of 26.7 G. Here 1 G = 10-4 T. Furthermore, by exciting low-energy spin waves, we demonstrate a means to precisely determine the zero crossing of the scattering length for this broad Feshbach resonance. Our findings allow for further tunability in experiments with ultracold 40K quantum gases.
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Affiliation(s)
- J. S. Krauser
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - J. Heinze
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - S. Götze
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - M. Langbecker
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Institut für Physik, Johannes Gutenberg Universität Mainz, Staudingerweg 7, 55128 Mainz, Germany
| | - N. Fläschner
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - L. Cook
- Department of Physics and Astronomy, University College London, Gower Street, London WC1E 6BT, United Kingdom
| | - T. M. Hanna
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA
| | - E. Tiesinga
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, Gaithersburg, Maryland 20899, USA
| | - K. Sengstock
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - C. Becker
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- Zentrum für Optische Quantentechnologien, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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33
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Luciuk C, Smale S, Böttcher F, Sharum H, Olsen BA, Trotzky S, Enss T, Thywissen JH. Observation of Quantum-Limited Spin Transport in Strongly Interacting Two-Dimensional Fermi Gases. PHYSICAL REVIEW LETTERS 2017; 118:130405. [PMID: 28409948 DOI: 10.1103/physrevlett.118.130405] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/20/2016] [Indexed: 06/07/2023]
Abstract
We measure the transport properties of two-dimensional ultracold Fermi gases during transverse demagnetization in a magnetic field gradient. Using a phase-coherent spin-echo sequence, we are able to distinguish bare spin diffusion from the Leggett-Rice effect, in which demagnetization is slowed by the precession of a spin current around the local magnetization. When the two-dimensional scattering length is tuned to be comparable to the inverse Fermi wave vector k_{F}^{-1}, we find that the bare transverse spin diffusivity reaches a minimum of 1.7(6)ℏ/m, where m is the bare particle mass. The rate of demagnetization is also reflected in the growth rate of the s-wave contact, observed using time-resolved spectroscopy. The contact rises to 0.28(3)k_{F}^{2} per particle, which quantifies how scaling symmetry is broken by near-resonant interactions, unlike in unitary three-dimensional systems. Our observations support the conjecture that, in systems with strong scattering, the local relaxation rate is bounded from above by k_{B}T/ℏ.
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Affiliation(s)
- C Luciuk
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - S Smale
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - F Böttcher
- 5. Physikalisches Institut and Centre for Integrated Quantum Science and Technology, Universität Stuttgart, D-70569 Stuttgart, Germany
| | - H Sharum
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - B A Olsen
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - S Trotzky
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - T Enss
- Institut für Theoretische Physik, Universität Heidelberg, D-69120 Heidelberg, Germany
| | - J H Thywissen
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
- Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
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34
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Uchino S, Ueda M. Anomalous Transport in the Superfluid Fluctuation Regime. PHYSICAL REVIEW LETTERS 2017; 118:105303. [PMID: 28339264 DOI: 10.1103/physrevlett.118.105303] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/03/2016] [Indexed: 06/06/2023]
Abstract
Motivated by a recent experiment in ultracold atoms [S. Krinner et al., Proc. Natl. Acad. Sci. U.S.A. 113, 8144 (2016)PNASA60027-842410.1073/pnas.1601812113], we analyze transport of attractively interacting fermions through a one-dimensional wire near the superfluid transition. We show that in a ballistic regime where the conductance is quantized in the absence of interaction, the conductance is renormalized by superfluid fluctuations in reservoirs. In particular, the particle conductance is strongly enhanced, and the conductance plateau is blurred by emergent bosonic pair transport. For spin transport, in addition to the contact resistance, the wire itself is resistive, leading to a suppression of the measured spin conductance. Our results are qualitatively consistent with the experimental observations.
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Affiliation(s)
- Shun Uchino
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
| | - Masahito Ueda
- RIKEN Center for Emergent Matter Science, Wako, Saitama 351-0198, Japan
- Department of Physics, University of Tokyo, 7-3-1 Hongo, Bunkyo-ku, Tokyo 113-0033, Japan
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35
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Koller AP, Wall ML, Mundinger J, Rey AM. Dynamics of Interacting Fermions in Spin-Dependent Potentials. PHYSICAL REVIEW LETTERS 2016; 117:195302. [PMID: 27858432 DOI: 10.1103/physrevlett.117.195302] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Indexed: 06/06/2023]
Abstract
Recent experiments with dilute trapped Fermi gases observed that weak interactions can drastically modify spin transport dynamics and give rise to robust collective effects including global demagnetization, macroscopic spin waves, spin segregation, and spin self-rephasing. In this Letter, we develop a framework for studying the dynamics of weakly interacting fermionic gases following a spin-dependent change of the trapping potential which illuminates the interplay between spin, motion, Fermi statistics, and interactions. The key idea is the projection of the state of the system onto a set of lattice spin models defined on the single-particle mode space. Collective phenomena, including the global spreading of quantum correlations in real space, arise as a consequence of the long-ranged character of the spin model couplings. This approach achieves good agreement with prior measurements and suggests a number of directions for future experiments.
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Affiliation(s)
- Andrew P Koller
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- JILA, NIST, Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Michael L Wall
- JILA, NIST, Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Josh Mundinger
- Department of Mathematics and Statistics, Swarthmore College, 500 College Avenue, Swarthmore, Pennsylvania 19081, USA
| | - Ana Maria Rey
- Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- JILA, NIST, Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
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36
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Deng S, Shi ZY, Diao P, Yu Q, Zhai H, Qi R, Wu H. Observation of the Efimovian expansion in scale-invariant Fermi gases. Science 2016; 353:371-4. [DOI: 10.1126/science.aaf0666] [Citation(s) in RCA: 56] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/13/2015] [Accepted: 06/21/2016] [Indexed: 11/02/2022]
Affiliation(s)
- Shujin Deng
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Zhe-Yu Shi
- Institute for Advanced Study, Tsinghua University, Beijing 100084, P. R. China
| | - Pengpeng Diao
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Qianli Yu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
| | - Hui Zhai
- Institute for Advanced Study, Tsinghua University, Beijing 100084, P. R. China
| | - Ran Qi
- Department of Physics, Renmin University of China, Beijing 100872, P. R. China
| | - Haibin Wu
- State Key Laboratory of Precision Spectroscopy, East China Normal University, Shanghai 200062, P. R. China
- Collaborative Innovation Center of Extreme Optics, Shanxi University, Taiyuan 030006, China
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37
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Abstract
We study particle and spin transport in a single-mode quantum point contact, using a charge neutral, quantum degenerate Fermi gas with tunable, attractive interactions. This yields the spin and particle conductance of the point contact as a function of chemical potential or confinement. The measurements cover a regime from weak attraction, where quantized conductance is observed, to the resonantly interacting superfluid. Spin conductance exhibits a broad maximum when varying the chemical potential at moderate interactions, which signals the emergence of Cooper pairing. In contrast, the particle conductance is unexpectedly enhanced even before the gas is expected to turn into a superfluid, continuously rising from the plateau at [Formula: see text] for weak interactions to plateau-like features at nonuniversal values as high as [Formula: see text] for intermediate interactions. For strong interactions, the particle conductance plateaus disappear and the spin conductance gets suppressed, confirming the spin-insulating character of a superfluid. Our observations document the breakdown of universal conductance quantization as many-body correlations appear. The observed anomalous quantization challenges a Fermi liquid description of the normal phase, shedding new light on the nature of the strongly attractive Fermi gas.
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38
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Bluhm M, Schäfer T. Model-Independent Determination of the Shear Viscosity of a Trapped Unitary Fermi gas: Application to High-Temperature Data. PHYSICAL REVIEW LETTERS 2016; 116:115301. [PMID: 27035308 DOI: 10.1103/physrevlett.116.115301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/04/2015] [Indexed: 06/05/2023]
Abstract
Determinations of the shear viscosity of trapped ultracold gases suffer from systematic, uncontrolled uncertainties related to the treatment of the dilute part of the gas cloud. In this work we present an analysis of expansion experiments based on a new method, anisotropic fluid dynamics, that interpolates between Navier-Stokes fluid dynamics at the center of the cloud and ballistic behavior in the dilute corona. We validate the method using a comparison between anisotropic fluid dynamics and numerical solutions of the Boltzmann equation. We then apply anisotropic fluid dynamics to the expansion data reported by Cao et al. In the high-temperature limit we find η=0.282(mT)^{3/2}, which agrees within about 5% with the theoretical prediction η=0.269(mT)^{3/2}.
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Affiliation(s)
- M Bluhm
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - T Schäfer
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
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39
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Beverland ME, Alagic G, Martin MJ, Koller AP, Rey AM, Gorshkov AV. Realizing exactly solvable SU( N) magnets with thermal atoms. PHYSICAL REVIEW. A 2016; 93:10.1103/PhysRevA.93.051601. [PMID: 31276073 PMCID: PMC6604830 DOI: 10.1103/physreva.93.051601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/26/2023]
Abstract
We show that n thermal fermionic alkaline-earth-metal atoms in a flat-bottom trap allow one to robustly implement a spin model displaying two symmetries: the S n symmetry that permutes atoms occupying different vibrational levels of the trap and the SU(N) symmetry associated with N nuclear spin states. The symmetries make the model exactly solvable, which, in turn, enables the analytic study of dynamical processes such as spin diffusion in this SU(N) system. We also show how to use this system to generate entangled states that allow for Heisenberg-limited metrology. This highly symmetric spin model should be experimentally realizable even when the vibrational levels are occupied according to a high-temperature thermal or an arbitrary nonthermal distribution.
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Affiliation(s)
- Michael E Beverland
- Institute for Quantum Information & Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - Gorjan Alagic
- Department of Mathematical Sciences, University of Copenhagen, Copenhagen, Denmark
| | - Michael J Martin
- Institute for Quantum Information & Matter, California Institute of Technology, Pasadena, California 91125, USA
| | - Andrew P Koller
- JILA, NIST, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ana M Rey
- JILA, NIST, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Alexey V Gorshkov
- Joint Quantum Institute and Joint Center for Quantum Information and Computer Science, NIST/University of Maryland, College Park, Maryland 20742, USA
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40
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Guimarães PRC, Plascak JA, de Alcantara Bonfim OF, Florencio J. Dynamics of the transverse Ising model with next-nearest-neighbor interactions. PHYSICAL REVIEW. E, STATISTICAL, NONLINEAR, AND SOFT MATTER PHYSICS 2015; 92:042115. [PMID: 26565176 DOI: 10.1103/physreve.92.042115] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2015] [Indexed: 06/05/2023]
Abstract
We study the effects of next-nearest-neighbor (NNN) interactions on the dynamics of the one-dimensional spin-1/2 transverse Ising model in the high-temperature limit. We use exact diagonalization to obtain the time-dependent transverse correlation function and the corresponding spectral density for a tagged spin. Our results for chains of 13 spins with periodic boundary conditions produce results which are valid in the infinite-size limit. In general we find that the NNN coupling produces slower dynamics accompanied by an enhancement of the central mode behavior. Even in the case of a strong transverse field, if the NNN coupling is sufficiently large, then there is a crossover from collective mode to central mode behavior. We also obtain several recurrants for the continued fraction representation of the relaxation function.
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Affiliation(s)
- P R C Guimarães
- Departamento de Física, Universidade Federal de Viçosa, 36571-000 Viçosa, Minas Gerais, Brazil
| | - J A Plascak
- Universidade Federal da Paraíba, Centro de Ciências Exatas e da Natureza-Campus I, Departamento de Física, CCEN Cidade Universitária-João Pessoa, PB, Brazil and Department of Physics and Astronomy, University of Georgia, 30602 Athens, Georgia, USA
| | | | - J Florencio
- Departamento de Física, Universidade Federal Fluminense, Av. Litorânea s/n, Niterói, 24210-340, RJ, Brazil
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41
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Niroomand D, Graham SD, McGuirk JM. Longitudinal Spin Diffusion in a Nondegenerate Trapped ^{87}Rb Gas. PHYSICAL REVIEW LETTERS 2015; 115:075302. [PMID: 26317727 DOI: 10.1103/physrevlett.115.075302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Indexed: 06/04/2023]
Abstract
Longitudinal spin diffusion of two pseudospin domains is studied in a trapped ^{87}Rb sample above quantum degeneracy, and the effect of coherence in the domain wall on the dynamics of the system is investigated. Coherence in a domain wall leads to transverse-spin-mediated longitudinal spin diffusion that is slower than classical predictions, as well as altering the domains' oscillation frequency. The system also shows an instability in the longitudinal spin dynamics as longitudinal and transverse spin components couple, and a conversion of longitudinal spin to transverse spin is observed, resulting in an increase in the total amount of coherence in the system.
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Affiliation(s)
- D Niroomand
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - S D Graham
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
| | - J M McGuirk
- Department of Physics, Simon Fraser University, Burnaby, British Columbia V5A 1S6, Canada
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42
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Sagi Y, Drake TE, Paudel R, Chapurin R, Jin DS. Breakdown of the fermi liquid description for strongly interacting fermions. PHYSICAL REVIEW LETTERS 2015; 114:075301. [PMID: 25763961 DOI: 10.1103/physrevlett.114.075301] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2014] [Indexed: 06/04/2023]
Abstract
The nature of the normal state of an ultracold Fermi gas in the BCS-BEC crossover regime is an intriguing and controversial topic. While the many-body ground state remains a condensate of paired fermions, the normal state must evolve from a Fermi liquid to a Bose gas of molecules as a function of the interaction strength. How this occurs is still largely unknown. We explore this question with measurements of the distribution of single-particle energies and momenta in a nearly homogeneous gas above T(c). The data fit well to a function that includes a narrow, positively dispersing peak that corresponds to quasiparticles and an "incoherent background" that can accommodate broad, asymmetric line shapes. We find that the quasiparticle's spectral weight vanishes abruptly as the strength of interactions is modified, which signals the breakdown of a Fermi liquid description. Such a sharp feature is surprising in a crossover.
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Affiliation(s)
- Yoav Sagi
- JILA, National Institute of Standards and Technology and the University of Colorado, and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - Tara E Drake
- JILA, National Institute of Standards and Technology and the University of Colorado, and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - Rabin Paudel
- JILA, National Institute of Standards and Technology and the University of Colorado, and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - Roman Chapurin
- JILA, National Institute of Standards and Technology and the University of Colorado, and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | - Deborah S Jin
- JILA, National Institute of Standards and Technology and the University of Colorado, and the Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
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Dynamical phases in quenched spin-orbit-coupled degenerate Fermi gas. Nat Commun 2015; 6:6103. [PMID: 25600665 DOI: 10.1038/ncomms7103] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/23/2014] [Accepted: 12/12/2014] [Indexed: 11/08/2022] Open
Abstract
The spin-orbit-coupled degenerate Fermi gas provides a new platform for realizing topological superfluids and related topological excitations. However, previous studies have been mainly focused on the topological properties of the stationary ground state. Here, we investigate the quench dynamics of a spin-orbit-coupled two-dimensional Fermi gas in which the Zeeman field serves as the major quench parameter. Three post-quench dynamical phases are identified according to the asymptotic behaviour of the order parameter. In the undamped phase, a persistent oscillation of the order parameter may support a topological Floquet state with multiple edge states. In the damped phase, the magnitude of the order parameter approaches a constant via a power-law decay, which may support a dynamical topological phase with one edge state at the boundary. In the overdamped phase, the order parameter decays to zero exponentially although the condensate fraction remains finite. These predictions can be observed in the strong-coupling regime.
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Trotzky S, Beattie S, Luciuk C, Smale S, Bardon AB, Enss T, Taylor E, Zhang S, Thywissen JH. Observation of the Leggett-Rice effect in a unitary Fermi gas. PHYSICAL REVIEW LETTERS 2015; 114:015301. [PMID: 25615476 DOI: 10.1103/physrevlett.114.015301] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/05/2014] [Indexed: 06/04/2023]
Abstract
We observe that the diffusive spin current in a strongly interacting degenerate Fermi gas of (40)K precesses about the local magnetization. As predicted by Leggett and Rice, precession is observed both in the Ramsey phase of a spin-echo sequence, and in the nonlinearity of the magnetization decay. At unitarity, we measure a Leggett-Rice parameter γ=1.08(9) and a bare transverse spin diffusivity D(0)(⊥)=2.3(4)ℏ/m for a normal-state gas initialized with full polarization and at one-fifth of the Fermi temperature, where m is the atomic mass. One might expect γ=0 at unitarity, where two-body scattering is purely dissipative. We observe γ→0 as temperature is increased towards the Fermi temperature, consistent with calculations that show the degenerate Fermi sea restores a nonzero γ. Tuning the scattering length a, we find that a sign change in γ occurs in the range 0<(k(F)a)(-1)≲1.3, where k(F) is the Fermi momentum. We discuss how γ reveals the effective interaction strength of the gas, such that the sign change in γ indicates a switching of branch between a repulsive and an attractive Fermi gas.
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Affiliation(s)
- S Trotzky
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - S Beattie
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - C Luciuk
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - S Smale
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - A B Bardon
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada
| | - T Enss
- Institut für Theoretische Physik, Universität Heidelberg, 69120 Heidelberg, Germany
| | - E Taylor
- Department of Physics and Astronomy, McMaster University, Hamilton, Ontario L8S 4M1, Canada
| | - S Zhang
- Department of Physics, Center of Theoretical and Computational Physics, University of Hong Kong, Hong Kong, China
| | - J H Thywissen
- Department of Physics, University of Toronto, Ontario M5S 1A7, Canada and Canadian Institute for Advanced Research, Toronto, Ontario M5G 1Z8, Canada
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45
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Hild S, Fukuhara T, Schauß P, Zeiher J, Knap M, Demler E, Bloch I, Gross C. Far-from-equilibrium spin transport in Heisenberg quantum magnets. PHYSICAL REVIEW LETTERS 2014; 113:147205. [PMID: 25325657 DOI: 10.1103/physrevlett.113.147205] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/25/2014] [Indexed: 06/04/2023]
Abstract
We study experimentally the far-from-equilibrium dynamics in ferromagnetic Heisenberg quantum magnets realized with ultracold atoms in an optical lattice. After controlled imprinting of a spin spiral pattern with an adjustable wave vector, we measure the decay of the initial spin correlations through single-site resolved detection. On the experimentally accessible time scale of several exchange times, we find a profound dependence of the decay rate on the wave vector. In one-dimensional systems, we observe diffusionlike spin transport with a dimensionless diffusion coefficient of 0.22(1). We show how this behavior emerges from the microscopic properties of the closed quantum system. In contrast to the one-dimensional case, our transport measurements for two-dimensional Heisenberg systems indicate anomalous superdiffusion.
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Affiliation(s)
- Sebastian Hild
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | | | - Peter Schauß
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - Johannes Zeiher
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - Michael Knap
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA and ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | - Eugene Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Immanuel Bloch
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany and Ludwig-Maximilians-Universität, Fakultät für Physik, 80799 München, Germany
| | - Christian Gross
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
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46
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Ferrier-Barbut I, Delehaye M, Laurent S, Grier AT, Pierce M, Rem BS, Chevy F, Salomon C. A mixture of Bose and Fermi superfluids. Science 2014; 345:1035-8. [DOI: 10.1126/science.1255380] [Citation(s) in RCA: 195] [Impact Index Per Article: 19.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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47
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Bardon AB, Beattie S, Luciuk C, Cairncross W, Fine D, Cheng NS, Edge GJA, Taylor E, Zhang S, Trotzky S, Thywissen JH. Transverse Demagnetization Dynamics of a Unitary Fermi Gas. Science 2014; 344:722-4. [DOI: 10.1126/science.1247425] [Citation(s) in RCA: 73] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- A. B. Bardon
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - S. Beattie
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - C. Luciuk
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - W. Cairncross
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - D. Fine
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - N. S. Cheng
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - G. J. A. Edge
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - E. Taylor
- Department of Physics and Astronomy, McMaster University, L8S 4M1 Canada
| | - S. Zhang
- Department of Physics, Center of Theoretical and Computational Physics, University of Hong Kong, China
| | - S. Trotzky
- Department of Physics, University of Toronto, M5S 1A7 Canada
| | - J. H. Thywissen
- Department of Physics, University of Toronto, M5S 1A7 Canada
- Canadian Institute for Advanced Research, Toronto, Ontario, M5G 1Z8 Canada
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48
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Cini M, Bellucci S. Quantum rings in magnetic fields and spin current generation. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:145301. [PMID: 24637301 DOI: 10.1088/0953-8984/26/14/145301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
We propose three different mechanisms for pumping spin-polarized currents in a ballistic circuit using a time-dependent magnetic field acting on an asymmetrically connected quantum ring at half filling. The first mechanism works thanks to a rotating magnetic field and produces an alternating current with a partial spin polarization. The second mechanism works by rotating the ring in a constant field; like the former case, it produces an alternating charge current, but the spin current is dc. Both methods do not require a spin-orbit interaction to achieve the polarized current, but the rotating ring could be used to measure the spin-orbit interaction in the ring using characteristic oscillations. On the other hand, the last mechanism that we propose depends on the spin-orbit interaction in an essential way, and requires a time-dependent magnetic field in the plane of the ring. This arrangement can be designed to pump a purely spin current. The absence of a charge current is demonstrated analytically. Moreover, a simple formula for the current is derived and compared with the numerical results.
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Affiliation(s)
- Michele Cini
- Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Rome, Italy. Istituto Nazionale di Fisica Nucleare-Laboratori Nazionali di Frascati, Via E. Fermi 40, I-00044 Frascati, Italy
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Krauser JS, Ebling U, Fläschner N, Heinze J, Sengstock K, Lewenstein M, Eckardt A, Becker C. Giant Spin Oscillations in an Ultracold Fermi Sea. Science 2014; 343:157-60. [DOI: 10.1126/science.1244059] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Affiliation(s)
- J. S. Krauser
- ILP (Institut für Laserphysik), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - U. Ebling
- ICFO (Institut de Ciències Fotòniques), Avenida Carl Friedrich Gauss 3, 08860 Castelldefels, Spain
| | - N. Fläschner
- ILP (Institut für Laserphysik), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - J. Heinze
- ILP (Institut für Laserphysik), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - K. Sengstock
- ILP (Institut für Laserphysik), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- ZOQ (Zentrum für Optische Quantentechnologien), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
| | - M. Lewenstein
- ICFO (Institut de Ciències Fotòniques), Avenida Carl Friedrich Gauss 3, 08860 Castelldefels, Spain
- ICREA (Institució Catalana de Recerca i Estudis Avançats), Lluís Companys 23, 08010 Barcelona, Spain
| | - A. Eckardt
- MPI-PKS (Max-Planck-Institut für Physik komplexer Systeme), Nöthnitzer Straße 38, 01187 Dresden, Germany
| | - C. Becker
- ILP (Institut für Laserphysik), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
- ZOQ (Zentrum für Optische Quantentechnologien), Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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50
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Goulko O, Chevy F, Lobo C. Spin drag of a Fermi gas in a harmonic trap. PHYSICAL REVIEW LETTERS 2013; 111:190402. [PMID: 24266462 DOI: 10.1103/physrevlett.111.190402] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/23/2013] [Indexed: 06/02/2023]
Abstract
Using a Boltzmann equation approach, we analyze how the spin drag of a trapped interacting fermionic mixture is influenced by the nonhomogeneity of the system in a classical regime where the temperature is much larger than the Fermi temperature. We show that for very elongated geometries, the spin damping rate can be related to the spin conductance of an infinitely long cylinder. We characterize analytically the spin conductance both in the hydrodynamic and collisionless limits and discuss the influence of the velocity profile. Our results are in good agreement with recent experiments and provide a quantitative benchmark for further studies of spin drag in ultracold gases.
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Affiliation(s)
- O Goulko
- Physics Department, Arnold Sommerfeld Center for Theoretical Physics, and Center for NanoScience, Ludwig-Maximilians-Universität, Theresienstraße 37, 80333 Munich, Germany
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