1
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Spierings DC, Thywissen JH, Steinberg AM. Spin Rotations in a Bose-Einstein Condensate Driven by Counterflow and Spin-Independent Interactions. PHYSICAL REVIEW LETTERS 2024; 132:173401. [PMID: 38728731 DOI: 10.1103/physrevlett.132.173401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/31/2023] [Accepted: 03/13/2024] [Indexed: 05/12/2024]
Abstract
We observe spin rotations caused by atomic collisions in a nonequilibrium Bose-condensed gas of ^{87}Rb. Reflection from a pseudomagnetic barrier creates counterflow in which forward- and backward-propagating matter waves have partly transverse spin directions. Even though inter-atomic interaction strengths are state independent, the indistinguishability of parallel spins leads to spin dynamics. A local magnetodynamic model, which captures the salient features of the observed spin textures, highlights an essential connection between four-wave mixing and collisional spin rotation. The observed phenomenon is commonly thought not to occur in Bose condensates; our observations and model clarify the nature of these effective-magnetic spin rotations.
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Affiliation(s)
- David C Spierings
- Department of Physics and CQIQC, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Joseph H Thywissen
- Department of Physics and CQIQC, University of Toronto, Toronto, Ontario M5S 1A7, Canada
| | - Aephraim M Steinberg
- Department of Physics and CQIQC, University of Toronto, Toronto, Ontario M5S 1A7, Canada
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2
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Lewis-Swan RJ, Barberena D, Cline JRK, Young DJ, Thompson JK, Rey AM. Cavity-QED Quantum Simulator of Dynamical Phases of a Bardeen-Cooper-Schrieffer Superconductor. PHYSICAL REVIEW LETTERS 2021; 126:173601. [PMID: 33988424 DOI: 10.1103/physrevlett.126.173601] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/02/2020] [Accepted: 03/22/2021] [Indexed: 05/12/2023]
Abstract
We propose to simulate dynamical phases of a BCS superconductor using an ensemble of cold atoms trapped in an optical cavity. Effective Cooper pairs are encoded via the internal states of the atoms, and attractive interactions are realized via the exchange of virtual photons between atoms coupled to a common cavity mode. Control of the interaction strength combined with a tunable dispersion relation of the effective Cooper pairs allows exploration of the full dynamical phase diagram of the BCS model as a function of system parameters and the prepared initial state. Our proposal paves the way for the study of the nonequilibrium features of quantum magnetism and superconductivity by harnessing atom-light interactions in cold atomic gases.
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Affiliation(s)
- Robert J Lewis-Swan
- Homer L. Dodge Department of Physics and Astronomy, The University of Oklahoma, Norman, Oklahoma 73019, USA
- Center for Quantum Research and Technology, The University of Oklahoma, Norman, Oklahoma 73019, USA
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Diego Barberena
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
| | - Julia R K Cline
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Dylan J Young
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - James K Thompson
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - Ana Maria Rey
- JILA, NIST, Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, Colorado 80309, USA
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3
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Pegahan S, Arakelyan I, Thomas JE. Energy-Resolved Information Scrambling in Energy-Space Lattices. PHYSICAL REVIEW LETTERS 2021; 126:070601. [PMID: 33666450 DOI: 10.1103/physrevlett.126.070601] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/04/2020] [Revised: 12/10/2020] [Accepted: 01/28/2021] [Indexed: 06/12/2023]
Abstract
Weakly interacting Fermi gases simulate spin lattices in energy space, offering a rich platform for investigating information spreading and spin coherence in a large many-body quantum system. We show that the collective spin vector can be determined as a function of energy from the measured spin density, enabling general energy-space resolved protocols. We measure an out-of-time-order correlation function in this system and observe the energy dependence of the many-body coherence.
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Affiliation(s)
- S Pegahan
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - I Arakelyan
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
| | - J E Thomas
- Department of Physics, North Carolina State University, Raleigh, North Carolina 27695, USA
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4
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Tang WH, Zhang S. Quantum Spin Dynamics in a Normal Bose Gas with Spin-Orbit Coupling. PHYSICAL REVIEW LETTERS 2018; 121:120403. [PMID: 30296115 DOI: 10.1103/physrevlett.121.120403] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/02/2018] [Indexed: 06/08/2023]
Abstract
In this Letter, we investigate spin dynamics of a two-component Bose gas with spin-orbit coupling realized in cold atom experiments. We derive coupled hydrodynamic equations for number and spin densities as well as their associated currents. Specializing to the quasi-one-dimensional situation, we obtain analytic solutions of the spin helix structure and its dynamics in both adiabatic and diabatic regimes. In the adiabatic regime, the transverse spin decays parabolically in the short-time limit and exponentially in the long-time limit, depending on initial polarization. In contrast, in the diabatic regime, transverse spin density and current oscillate in a way similar to the charge-current oscillation in an undamped LC circuit. The effects of Rabi coupling on the short-time spin dynamics is also discussed. Finally, using realistic experimental parameters for ^{87}Rb, we show that the timescales for spin dynamics is of the order of milliseconds to a few seconds and can be observed experimentally.
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Affiliation(s)
- Wai Ho Tang
- Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Hong Kong, China
| | - Shizhong Zhang
- Department of Physics and Center of Theoretical and Computational Physics, The University of Hong Kong, Hong Kong, China
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5
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Norcia MA, Lewis-Swan RJ, Cline JRK, Zhu B, Rey AM, Thompson JK. Cavity-mediated collective spin-exchange interactions in a strontium superradiant laser. Science 2018; 361:259-262. [DOI: 10.1126/science.aar3102] [Citation(s) in RCA: 86] [Impact Index Per Article: 14.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/25/2017] [Accepted: 05/25/2018] [Indexed: 11/02/2022]
Affiliation(s)
- Matthew A. Norcia
- JILA, NIST, and Department of Physics, University of Colorado, 440 UCB, Boulder, CO 80309, USA
| | - Robert J. Lewis-Swan
- JILA, NIST, and Department of Physics, University of Colorado, 440 UCB, Boulder, CO 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA
| | - Julia R. K. Cline
- JILA, NIST, and Department of Physics, University of Colorado, 440 UCB, Boulder, CO 80309, USA
| | - Bihui Zhu
- JILA, NIST, and Department of Physics, University of Colorado, 440 UCB, Boulder, CO 80309, USA
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA 02138, USA
| | - Ana M. Rey
- JILA, NIST, and Department of Physics, University of Colorado, 440 UCB, Boulder, CO 80309, USA
- Center for Theory of Quantum Matter, University of Colorado, Boulder, CO 80309, USA
| | - James K. Thompson
- JILA, NIST, and Department of Physics, University of Colorado, 440 UCB, Boulder, CO 80309, USA
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6
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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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7
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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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8
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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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9
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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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10
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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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11
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Koller AP, Beverland M, Gorshkov AV, Rey AM. Beyond the spin model approximation for Ramsey spectroscopy. PHYSICAL REVIEW LETTERS 2014; 112:123001. [PMID: 24724647 DOI: 10.1103/physrevlett.112.123001] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/03/2013] [Indexed: 06/03/2023]
Abstract
Ramsey spectroscopy has become a powerful technique for probing nonequilibrium dynamics of internal (pseudospin) degrees of freedom of interacting systems. In many theoretical treatments, the key to understanding the dynamics has been to assume the external (motional) degrees of freedom are decoupled from the pseudospin degrees of freedom. Determining the validity of this approximation-known as the spin model approximation-has not been addressed in detail. Here we shed light in this direction by calculating Ramsey dynamics exactly for two interacting spin-1/2 particles in a harmonic trap. We focus on s-wave-interacting fermions in quasi one- and two-dimensional geometries. We find that in one dimension the spin model assumption works well over a wide range of experimentally relevant conditions, but can fail at time scales longer than those set by the mean interaction energy. Surprisingly, in two dimensions a modified version of the spin model is exact to first order in the interaction strength. This analysis is important for a correct interpretation of Ramsey spectroscopy and has broad applications ranging from precision measurements to quantum information and to fundamental probes of many-body systems.
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Affiliation(s)
- A P Koller
- JILA, NIST, and Department of Physics, University of Colorado Boulder, Colorado 80309, USA
| | - M Beverland
- Institute for Quantum Information and Matter, California Institute of Technology, MC 305-16, Pasadena, California 91125, USA
| | - A V Gorshkov
- Joint Quantum Institute, NIST, and University of Maryland, College Park, Maryland 20742, USA
| | - A M Rey
- JILA, NIST, and Department of Physics, University of Colorado Boulder, Colorado 80309, USA
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12
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Radić J, Natu SS, Galitski V. Interaction-tuned dynamical transitions in a Rashba spin-orbit-coupled Fermi gas. PHYSICAL REVIEW LETTERS 2014; 112:095302. [PMID: 24655264 DOI: 10.1103/physrevlett.112.095302] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2013] [Indexed: 06/03/2023]
Abstract
We consider the time evolution of the magnetization in a Rashba spin-orbit coupled Fermi gas, starting from a fully polarized initial state. We model the dynamics using a Boltzmann equation, which we solve in the Hartree-Fock approximation. The resulting nonlinear system of equations gives rise to three distinct dynamical regimes with qualitatively different asymptotic behaviors of the magnetization at long times. The distinct regimes and the transitions between them are controlled by the ratio of interaction and spin-orbit coupling strength λ: for small λ, the magnetization decays to zero. For intermediate λ, it displays undamped oscillations about zero, and for large λ, a partially magnetized state is dynamically stabilized. The dynamics we find is a spin analog of interaction induced self-trapping in double-well Bose Einstein condensates. The predicted phenomena can be realized in trapped Fermi gases with synthetic spin-orbit interactions.
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Affiliation(s)
- Juraj Radić
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Stefan S Natu
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
| | - Victor Galitski
- Joint Quantum Institute and Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA and Condensed Matter Theory Center, Department of Physics, University of Maryland, College Park, Maryland 20742-4111, USA
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13
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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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14
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Pechkis HK, Wrubel JP, Schwettmann A, Griffin PF, Barnett R, Tiesinga E, Lett PD. Spinor dynamics in an antiferromagnetic spin-1 thermal Bose gas. PHYSICAL REVIEW LETTERS 2013; 111:025301. [PMID: 23889412 DOI: 10.1103/physrevlett.111.025301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/13/2013] [Indexed: 06/02/2023]
Abstract
We present experimental observations of coherent spin-population oscillations in a cold thermal, Bose gas of spin-1 23Na atoms. The population oscillations in a multi-spatial-mode thermal gas have the same behavior as those observed in a single-spatial-mode antiferromagnetic spinor Bose-Einstein condensate. We demonstrate this by showing that the two situations are described by the same dynamical equations, with a factor of 2 change in the spin-dependent interaction coefficient, which results from the change to particles with distinguishable momentum states in the thermal gas. We compare this theory to the measured spin population evolution after times up to a few hundreds of ms, finding quantitative agreement with the amplitude and period. We also measure the damping time of the oscillations as a function of magnetic field.
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Affiliation(s)
- H K Pechkis
- Quantum Measurement Division, National Institute of Standards and Technology, 100 Bureau Drive, Gaithersburg, Maryland 20899-8424, USA
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15
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Heinze J, Krauser JS, Fläschner N, Sengstock K, Becker C, Ebling U, Eckardt A, Lewenstein M. Engineering spin waves in a high-spin ultracold Fermi gas. PHYSICAL REVIEW LETTERS 2013; 110:250402. [PMID: 23829716 DOI: 10.1103/physrevlett.110.250402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2013] [Indexed: 06/02/2023]
Abstract
We report on the detailed study of multicomponent spin waves in an s=3/2 Fermi gas where the high spin leads to novel tensorial degrees of freedom compared to s=1/2 systems. The excitations of a spin-nematic state are investigated from the linear to the nonlinear regime, where the tensorial character is particularly pronounced. By tuning the initial state we engineer the tensorial spin-wave character, such that the magnitude and the sign of the counterflow spin currents are effectively controlled. A comparison of our data with numerical and analytical results shows good agreement.
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Affiliation(s)
- J Heinze
- Institut für Laser-Physik, Universität Hamburg, Luruper Chaussee 149, 22761 Hamburg, Germany
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16
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Hazlett EL, Zhang Y, Stites RW, Gibble K, O'Hara KM. s-Wave collisional frequency shift of a fermion clock. PHYSICAL REVIEW LETTERS 2013; 110:160801. [PMID: 23679589 DOI: 10.1103/physrevlett.110.160801] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/08/2012] [Indexed: 06/02/2023]
Abstract
We report an s-wave collisional frequency shift of an atomic clock based on fermions. In contrast to bosons, the fermion clock shift is insensitive to the population difference of the clock states, set by the first pulse area in Ramsey spectroscopy, θ(1). The fermion shift instead depends strongly on the second pulse area θ(2). It allows the shift to be canceled, nominally at θ(2)=π/2, but correlations perturb the null to slightly larger θ(2). The frequency shift is relevant for optical lattice clocks and increases with the spatial inhomogeneity of the clock excitation field, naturally larger at optical frequencies.
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Affiliation(s)
- Eric L Hazlett
- Department of Physics, The Pennsylvania State University, University Park, Pennsylvania 16802, USA
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Zürn G, Lompe T, Wenz AN, Jochim S, Julienne PS, Hutson JM. Precise characterization of 6Li Feshbach resonances using trap-sideband-resolved RF spectroscopy of weakly bound molecules. PHYSICAL REVIEW LETTERS 2013; 110:135301. [PMID: 23581332 DOI: 10.1103/physrevlett.110.135301] [Citation(s) in RCA: 76] [Impact Index Per Article: 6.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/06/2012] [Indexed: 06/02/2023]
Abstract
We perform radio-frequency dissociation spectroscopy of weakly bound 6Li2 Feshbach molecules using low-density samples of about 30 molecules in an optical dipole trap. Combined with a high magnetic field stability, this allows us to resolve the discrete trap levels in the radio-frequency dissociation spectra. This novel technique allows the binding energy of Feshbach molecules to be determined with unprecedented precision. We use these measurements as an input for a fit to the 6Li scattering potential using coupled-channel calculations. From this new potential, we determine the pole positions of the broad 6Li Feshbach resonances with an accuracy better than 7×10(-4) of the resonance widths. This eliminates the dominant uncertainty for current precision measurements of the equation of state of strongly interacting Fermi gases. As an important consequence, our results imply a corrected value for the Bertsch parameter ξ measured by Ku et al. [Science 335, 563 (2012)], which is ξ=0.370(5)(8).
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Affiliation(s)
- G Zürn
- Physikalisches Institut, Ruprecht-Karls-Universität Heidelberg, 69120 Heidelberg, Germany
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Sommer A, Ku M, Roati G, Zwierlein MW. Universal spin transport in a strongly interacting Fermi gas. Nature 2011; 472:201-4. [DOI: 10.1038/nature09989] [Citation(s) in RCA: 220] [Impact Index Per Article: 16.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2011] [Accepted: 03/04/2011] [Indexed: 11/09/2022]
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Deutsch C, Ramirez-Martinez F, Lacroûte C, Reinhard F, Schneider T, Fuchs JN, Piéchon F, Laloë F, Reichel J, Rosenbusch P. Spin self-rephasing and very long coherence times in a trapped atomic ensemble. PHYSICAL REVIEW LETTERS 2010; 105:020401. [PMID: 20867686 DOI: 10.1103/physrevlett.105.020401] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/24/2010] [Revised: 05/28/2010] [Indexed: 05/29/2023]
Abstract
We perform Ramsey spectroscopy on the ground state of ultracold 87Rb atoms magnetically trapped on a chip in the Knudsen regime. Field inhomogeneities over the sample should limit the 1/e contrast decay time to about 3 s, while decay times of 58 ± 12 s are actually observed. We explain this surprising result by a spin self-rephasing mechanism induced by the identical spin rotation effect originating from particle indistinguishability. We propose a theory of this synchronization mechanism and obtain good agreement with the experimental observations. The effect is general and may appear in other physical systems.
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Affiliation(s)
- C Deutsch
- Laboratoire Kastler Brossel, ENS, UPMC, CNRS, 24 rue Lhomond, 75005 Paris, France
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Yu Z, Pethick CJ. Clock shifts of optical transitions in ultracold atomic gases. PHYSICAL REVIEW LETTERS 2010; 104:010801. [PMID: 20366356 DOI: 10.1103/physrevlett.104.010801] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/24/2009] [Indexed: 05/29/2023]
Abstract
We calculate the shift, due to interatomic interactions, of an optical transition in an atomic Fermi gas trapped in an optical lattice, as in recent experiments of Campbell et al. [Science 324, 360 (2009)]. Using a pseudospin formalism to describe the density matrix of atoms, we derive a Bloch equation which incorporates both spatial inhomogeneity of the probe laser field and interatomic interactions. Expressions are given for the frequency shift as a function of pulse duration, detuning of the probe laser, and the spatial dependence of the electric field of the probe beam. In the low temperature semiclassical regime, we find that the magnitude of the shift is proportional to the temperature.
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Affiliation(s)
- Zhenhua Yu
- The Niels Bohr International Academy, The Niels Bohr Institute, University of Copenhagen, Blegdamsvej 17, DK-2100 Copenhagen Ø, Denmark
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Du X, Zhang Y, Petricka J, Thomas JE. Controlling spin current in a trapped Fermi gas. PHYSICAL REVIEW LETTERS 2009; 103:010401. [PMID: 19659125 DOI: 10.1103/physrevlett.103.010401] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/29/2009] [Revised: 06/05/2009] [Indexed: 05/28/2023]
Abstract
We study fundamental features of spin current in a very weakly interacting Fermi gas of 6Li. By creating a spin current and then reversing its flow, we demonstrate control of the spin current. This reversal is predicted by a spin vector evolution equation in energy representation, which shows how the spin and energy of individual atoms become correlated in the nearly undamped regime of the experiments. The theory provides a simple physical description of the spin current and explains both the large amplitude and the slow temporal evolution of the data. Our results have applications in studying and controlling fundamental spin interactions and spin currents in ultracold gases.
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Affiliation(s)
- X Du
- Department of Physics, Duke University, Durham, North Carolina 27708, USA
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Piéchon F, Fuchs JN, Laloë F. Cumulative identical spin rotation effects in collisionless trapped atomic gases. PHYSICAL REVIEW LETTERS 2009; 102:215301. [PMID: 19519112 DOI: 10.1103/physrevlett.102.215301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/26/2009] [Revised: 04/21/2009] [Indexed: 05/27/2023]
Abstract
We discuss the strong spin segregation in a dilute trapped Fermi gas recently observed by Du et al. with an "anomalous" large time scale and amplitude. In a collisionless regime, the atoms oscillate rapidly in the trap and average the inhomogeneous external field in an energy dependent way, which controls their transverse spin precession frequency. During interactions between atoms with different spin directions, the identical spin rotation effect transfers atoms to the up or down spin state, depending on their motional energy. Since low energy atoms are closer to the center of the trap than high energy atoms, the final outcome is a strong correlation between spins and positions.
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Affiliation(s)
- F Piéchon
- Laboratoire de Physique des Solides, CNRS UMR 8502, Université Paris-Sud, F-91405 Orsay, France
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23
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Gangardt DM, Kamenev A. Bloch oscillations in a one-dimensional spinor gas. PHYSICAL REVIEW LETTERS 2009; 102:070402. [PMID: 19257649 DOI: 10.1103/physrevlett.102.070402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/21/2008] [Revised: 01/19/2009] [Indexed: 05/27/2023]
Abstract
A force applied to a spin-flipped particle in a one-dimensional spinor gas may lead to Bloch oscillations of the particle's position and velocity. The existence of Bloch oscillations crucially depends on the viscous friction force exerted by the rest of the gas on the spin excitation. We evaluate the friction in terms of the quantum fluid parameters. In particular, we show that the friction is absent for integrable cases, such as an SU(2) symmetric gas of bosons or fermions. For small deviations from the exact integrability the friction is very weak, opening the possibility to observe Bloch oscillations.
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Affiliation(s)
- D M Gangardt
- School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham, B15 2TT, United Kingdom.
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