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Bohrdt A, Demler E, Grusdt F. Dichotomy of heavy and light pairs of holes in the t-J model. Nat Commun 2023; 14:8017. [PMID: 38049409 PMCID: PMC10695955 DOI: 10.1038/s41467-023-43453-2] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2023] [Accepted: 11/09/2023] [Indexed: 12/06/2023] Open
Abstract
A key step in unraveling the mysteries of materials exhibiting unconventional superconductivity is to understand the underlying pairing mechanism. While it is widely agreed upon that the pairing glue in many of these systems originates from antiferromagnetic spin correlations, a microscopic description of pairs of charge carriers remains lacking. Here we use state-of-the art numerical methods to probe the internal structure and dynamical properties of pairs of charge carriers in quantum antiferromagnets in four-legged cylinders. Exploiting the full momentum resolution in our simulations, we are able to distinguish two qualitatively different types of bound states: a highly mobile, meta-stable pair, which has a dispersion proportional to the hole hopping t, and a heavy pair, which can only move due to spin exchange processes and turns into a flat band in the Ising limit of the model. Understanding the pairing mechanism can on the one hand pave the way to boosting binding energies in related models, and on the other hand enable insights into the intricate competition of various phases of matter in strongly correlated electron systems.
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Affiliation(s)
- A Bohrdt
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, MA, 02138, USA
- Department of Physics, Harvard University, Cambridge, MA, 02138, USA
| | - E Demler
- Institut für Theoretische Physik, ETH Zurich, 8093, Zurich, Switzerland
| | - F Grusdt
- Department of Physics and Arnold Sommerfeld Center for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, München, D-80333, Germany.
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, D-80799, München, Germany.
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2
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Ciorciaro L, Smoleński T, Morera I, Kiper N, Hiestand S, Kroner M, Zhang Y, Watanabe K, Taniguchi T, Demler E, İmamoğlu A. Kinetic magnetism in triangular moiré materials. Nature 2023; 623:509-513. [PMID: 37968525 PMCID: PMC10651480 DOI: 10.1038/s41586-023-06633-0] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/03/2023] [Accepted: 09/12/2023] [Indexed: 11/17/2023]
Abstract
Magnetic properties of materials ranging from conventional ferromagnetic metals to strongly correlated materials such as cuprates originate from Coulomb exchange interactions. The existence of alternate mechanisms for magnetism that could naturally facilitate electrical control has been discussed theoretically1-7, but an experimental demonstration8 in an extended system has been missing. Here we investigate MoSe2/WS2 van der Waals heterostructures in the vicinity of Mott insulator states of electrons forming a frustrated triangular lattice and observe direct evidence of magnetic correlations originating from a kinetic mechanism. By directly measuring electronic magnetization through the strength of the polarization-selective attractive polaron resonance9,10, we find that when the Mott state is electron-doped, the system exhibits ferromagnetic correlations in agreement with the Nagaoka mechanism.
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Affiliation(s)
- L Ciorciaro
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - T Smoleński
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - I Morera
- Departament de Física Quàntica i Astrofísica, Facultat de Física, Universitat de Barcelona, Barcelona, Spain
- Institut de Ciències del Cosmos, Universitat de Barcelona, Barcelona, Spain
| | - N Kiper
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - S Hiestand
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - M Kroner
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland
| | - Y Zhang
- Department of Physics and Astronomy, University of Tennessee, Knoxville, TN, USA
- Min H. Kao Department of Electrical Engineering and Computer Science, University of Tennessee, Knoxville, TN, USA
| | - K Watanabe
- Research Center for Electronic and Optical Materials, National Institute for Materials Science, Tsukuba, Japan
| | - T Taniguchi
- Research Center for Materials Nanoarchitectonics, National Institute for Materials Science, Tsukuba, Japan
| | - E Demler
- Institute for Theoretical Physics, ETH Zürich, Zürich, Switzerland
| | - A İmamoğlu
- Institute for Quantum Electronics, ETH Zürich, Zürich, Switzerland.
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3
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Knörzer J, Shi T, Demler E, Cirac JI. Spin-Holstein Models in Trapped-Ion Systems. Phys Rev Lett 2022; 128:120404. [PMID: 35394310 DOI: 10.1103/physrevlett.128.120404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/16/2021] [Revised: 12/29/2021] [Accepted: 03/07/2022] [Indexed: 06/14/2023]
Abstract
In this work, we highlight how trapped-ion quantum systems can be used to study generalized Holstein models, and benchmark expensive numerical calculations. We study a particular spin-Holstein model that can be implemented with arrays of ions confined by individual microtraps, and that is closely related to the Holstein model of condensed matter physics, used to describe electron-phonon interactions. In contrast to earlier proposals, we focus on simulating many-electron systems and inspect the competition between charge-density wave order, fermion pairing, and phase separation. In our numerical study, we employ a combination of complementary approaches, based on non-Gaussian variational ansatz states and matrix product states, respectively. We demonstrate that this hybrid approach outperforms standard density-matrix renormalization group calculations.
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Affiliation(s)
- J Knörzer
- Max-Planck-Institute of Quantum Optics, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
| | - T Shi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190, China
- CAS Center for Excellence in Topological Quantum Computation, University of Chinese Academy of Sciences, Beijing 100049, China
| | - E Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Institute for Theoretical Physics, ETH Zurich, 8093 Zurich, Switzerland
| | - J I Cirac
- Max-Planck-Institute of Quantum Optics, Hans-Kopfermann-Straße 1, D-85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstraße 4, D-80799 München, Germany
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4
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Bohrdt A, Demler E, Grusdt F. Rotational Resonances and Regge-like Trajectories in Lightly Doped Antiferromagnets. Phys Rev Lett 2021; 127:197004. [PMID: 34797143 DOI: 10.1103/physrevlett.127.197004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/02/2021] [Accepted: 10/13/2021] [Indexed: 06/13/2023]
Abstract
Understanding the nature of charge carriers in doped Mott insulators holds the key to unravelling puzzling properties of strongly correlated electron systems, including cuprate superconductors. Several theoretical models suggested that dopants can be understood as bound states of partons, the analogues of quarks in high-energy physics. However, direct signatures of spinon-chargon bound states are lacking, both in experiment and theory. Here we propose a rotational variant of angle-resolved photo-emission spectroscopy (ARPES) and calculate rotational spectra numerically using the density-matrix renormalization group. We identify long-lived rotational resonances for an individual dopant, which we interpret as a direct indicator of the microscopic structure of spinon-chargon bound states. Similar to Regge trajectories reflecting the quark structure of mesons, we establish a linear dependence of the rotational energy on the superexchange coupling. The rotational peaks we find are strongly suppressed in standard ARPES spectra, but we suggest a multiphoton extension of ARPES which allows us to access rotational spectra. Our findings suggest that multiphoton spectroscopy experiments should provide new insights into emergent universal features of strongly correlated electron systems.
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Affiliation(s)
- A Bohrdt
- Department of Physics and Institute for Advanced Study, Technical University of Munich, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, D-80799 München, Germany
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - E Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - F Grusdt
- Munich Center for Quantum Science and Technology (MCQST), Schellingstr. 4, D-80799 München, Germany
- Department of Physics and Arnold Sommerfeld Center for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstr. 37, München D-80333, Germany
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5
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Bohrdt A, Wang Y, Koepsell J, Kánasz-Nagy M, Demler E, Grusdt F. Dominant Fifth-Order Correlations in Doped Quantum Antiferromagnets. Phys Rev Lett 2021; 126:026401. [PMID: 33512175 DOI: 10.1103/physrevlett.126.026401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/11/2020] [Accepted: 12/11/2020] [Indexed: 06/12/2023]
Abstract
Traditionally, one- and two-point correlation functions are used to characterize many-body systems. In strongly correlated quantum materials, such as the doped 2D Fermi-Hubbard system, these may no longer be sufficient, because higher-order correlations are crucial to understanding the character of the many-body system and can be numerically dominant. Experimentally, such higher-order correlations have recently become accessible in ultracold atom systems. Here, we reveal strong non-Gaussian correlations in doped quantum antiferromagnets and show that higher-order correlations dominate over lower-order terms. We study a single mobile hole in the t-J model using the density matrix renormalization group and reveal genuine fifth-order correlations which are directly related to the mobility of the dopant. We contrast our results to predictions using models based on doped quantum spin liquids which feature significantly reduced higher-order correlations. Our predictions can be tested at the lowest currently accessible temperatures in quantum simulators of the 2D Fermi-Hubbard model. Finally, we propose to experimentally study the same fifth-order spin-charge correlations as a function of doping. This will help to reveal the microscopic nature of charge carriers in the most debated regime of the Hubbard model, relevant for understanding high-T_{c} superconductivity.
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Affiliation(s)
- A Bohrdt
- Department of Physics and Institute for Advanced Study, Technical University of Munich, 85748 Garching, Germany
- Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, D-80799 München, Germany
| | - Y Wang
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- Department of Physics and Astronomy, Clemson University, Clemson, South Carolina 29631, USA
| | - J Koepsell
- Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, D-80799 München, Germany
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - M Kánasz-Nagy
- Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
| | - E Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - F Grusdt
- Munich Center for Quantum Science and Technology (MCQST), Schellingstrasse 4, D-80799 München, Germany
- Department of Physics and Arnold Sommerfeld Center for Theoretical Physics (ASC), Ludwig-Maximilians-Universität München, Theresienstrasse 37, München D-80333, Germany
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6
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Dehollain JP, Mukhopadhyay U, Michal VP, Wang Y, Wunsch B, Reichl C, Wegscheider W, Rudner MS, Demler E, Vandersypen LMK. Nagaoka ferromagnetism observed in a quantum dot plaquette. Nature 2020; 579:528-533. [PMID: 32123352 DOI: 10.1038/s41586-020-2051-0] [Citation(s) in RCA: 23] [Impact Index Per Article: 5.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 01/08/2020] [Indexed: 11/09/2022]
Abstract
Engineered, highly controllable quantum systems are promising simulators of emergent physics beyond the simulation capabilities of classical computers1. An important problem in many-body physics is itinerant magnetism, which originates purely from long-range interactions of free electrons and whose existence in real systems has been debated for decades2,3. Here we use a quantum simulator consisting of a four-electron-site square plaquette of quantum dots4 to demonstrate Nagaoka ferromagnetism5. This form of itinerant magnetism has been rigorously studied theoretically6-9 but has remained unattainable in experiments. We load the plaquette with three electrons and demonstrate the predicted emergence of spontaneous ferromagnetic correlations through pairwise measurements of spin. We find that the ferromagnetic ground state is remarkably robust to engineered disorder in the on-site potentials and we can induce a transition to the low-spin state by changing the plaquette topology to an open chain. This demonstration of Nagaoka ferromagnetism highlights that quantum simulators can be used to study physical phenomena that have not yet been observed in any experimental system. The work also constitutes an important step towards large-scale quantum dot simulators of correlated electron systems.
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Affiliation(s)
- J P Dehollain
- QuTech, TU Delft, Delft, The Netherlands.,Kavli Institute of Nanoscience, TU Delft, Delft, The Netherlands.,School of Mathematical and Physical Sciences, University of Technology Sydney, Sydney, New South Wales, Australia
| | - U Mukhopadhyay
- QuTech, TU Delft, Delft, The Netherlands.,Kavli Institute of Nanoscience, TU Delft, Delft, The Netherlands
| | - V P Michal
- QuTech, TU Delft, Delft, The Netherlands.,Kavli Institute of Nanoscience, TU Delft, Delft, The Netherlands
| | - Y Wang
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - B Wunsch
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - C Reichl
- Solid State Physics Laboratory, ETH Zürich, Zürich, Switzerland
| | - W Wegscheider
- Solid State Physics Laboratory, ETH Zürich, Zürich, Switzerland
| | - M S Rudner
- Center for Quantum Devices, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark.,Niels Bohr International Academy, Niels Bohr Institute, University of Copenhagen, Copenhagen, Denmark
| | - E Demler
- Department of Physics, Harvard University, Cambridge, MA, USA
| | - L M K Vandersypen
- QuTech, TU Delft, Delft, The Netherlands. .,Kavli Institute of Nanoscience, TU Delft, Delft, The Netherlands.
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7
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Boulier T, Maslek J, Bukov M, Bracamontes C, Magnan E, Lellouch S, Demler E, Goldman N, Porto JV. Parametric heating in a 2D periodically-driven bosonic system: Beyond the weakly-interacting regime. Phys Rev X 2019; 9:10.1103/physrevx.9.011047. [PMID: 32117577 PMCID: PMC7047775 DOI: 10.1103/physrevx.9.011047] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/09/2023]
Abstract
We experimentally investigate the effects of parametric instabilities on the short-time heating process of periodically-driven bosons in 2D optical lattices with a continuous transverse (tube) degree of freedom. We analyze three types of periodic drives: (i) linear along the x-lattice direction only, (ii) linear along the lattice diagonal, and (iii) circular in the lattice plane. In all cases, we demonstrate that the BEC decay is dominated by the emergence of unstable Bogoliubov modes, rather than scattering in higher Floquet bands, in agreement with recent theoretical predictions. The observed BEC depletion rates are much higher when shaking both along x and y directions, as opposed to only x or only y. We also report an explosion of the decay rates at large drive amplitudes, and suggest a phenomenological description beyond Bogoliubov theory. In this strongly-coupled regime, circular drives heat faster than diagonal drives, which illustrates the non-trivial dependence of the heating on the choice of drive.
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Affiliation(s)
- T. Boulier
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742 USA
- Laboratoire Charles Fabry, Institut dOptique Graduate School, CNRS, Université Paris-Saclay, 91127 Palaiseau cedex, France
| | - J. Maslek
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742 USA
| | - M. Bukov
- Department of Physics, University of California Berkeley, CA 94720, USA
| | - C. Bracamontes
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742 USA
| | - E. Magnan
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742 USA
- Laboratoire Charles Fabry, Institut dOptique Graduate School, CNRS, Université Paris-Saclay, 91127 Palaiseau cedex, France
| | - S. Lellouch
- Laboratoire de Physique des Lasers, Atomes et Molcules, Université Lille 1 Sciences et Technologies, CNRS; F-59655 Villeneuve d’Ascq Cedex, France
| | - E. Demler
- Department of Physics, Harvard University, Cambridge, MA 02138, USA
| | - N. Goldman
- Center for Nonlinear Phenomena and Complex Systems, Université Libre de Bruxelles, CP 231, Campus Plaine, B-1050 Brussels, Belgium
| | - J. V. Porto
- Joint Quantum Institute, National Institute of Standards and Technology and the University of Maryland, College Park, Maryland 20742 USA
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8
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Kucsko G, Choi S, Choi J, Maurer PC, Zhou H, Landig R, Sumiya H, Onoda S, Isoya J, Jelezko F, Demler E, Yao NY, Lukin MD. Critical Thermalization of a Disordered Dipolar Spin System in Diamond. Phys Rev Lett 2018; 121:023601. [PMID: 30085738 DOI: 10.1103/physrevlett.121.023601] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/03/2018] [Indexed: 06/08/2023]
Abstract
Statistical mechanics underlies our understanding of macroscopic quantum systems. It is based on the assumption that out-of-equilibrium systems rapidly approach their equilibrium states, forgetting any information about their microscopic initial conditions. This fundamental paradigm is challenged by disordered systems, in which a slowdown or even absence of thermalization is expected. We report the observation of critical thermalization in a three dimensional ensemble of ∼10^{6} electronic spins coupled via dipolar interactions. By controlling the spin states of nitrogen vacancy color centers in diamond, we observe slow, subexponential relaxation dynamics and identify a regime of power-law decay with disorder-dependent exponents; this behavior is modified at late times owing to many-body interactions. These observations are quantitatively explained by a resonance counting theory that incorporates the effects of both disorder and interactions.
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Affiliation(s)
- G Kucsko
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - S Choi
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - J Choi
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
- School of Engineering and Applied Sciences, Harvard University, Cambridge, Massachusetts 02138, USA
| | - P C Maurer
- Department of Physics, Stanford University, Stanford, California 94305, USA
| | - H Zhou
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - R Landig
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - H Sumiya
- Sumitomo Electric Industries Ltd., Itami, Hyougo, 664-0016, Japan
| | - S Onoda
- Takasaki Advanced Radiation Research Institute, National Institutes for Quantum and Radiological Science and Technology, Takasaki, Gunma 370-1292, Japan
| | - J Isoya
- Research Centre for Knowledge Communities, University of Tsukuba, Tsukuba, Ibaraki 305-8550, Japan
| | - F Jelezko
- Institut für Quantenoptik, Universität Ulm, 89081 Ulm, Germany
| | - E Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - N Y Yao
- Department of Physics, University of California Berkeley, Berkeley, California 94720, USA
| | - M D Lukin
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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9
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Abstract
Giant impurity excitations are powerful probes for exploring new regimes of far out of equilibrium dynamics in few- and many-body quantum systems, and in situ observations of correlations. Motivated by recent experimental progress in spectroscopic studies of Rydberg excitations in ultracold atoms, we develop a new theoretical approach for describing multiscale dynamics of Rydberg excitations in quantum Bose gases. We find that the crossover from few- to many-body dynamics manifests in a dramatic change in spectral profile from resolved molecular lines to broad Gaussian distributions representing a superpolaronic state in which many atoms bind to the Rydberg impurity. We discuss signatures of this crossover in the temperature and density dependence of the spectra.
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Affiliation(s)
- Richard Schmidt
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - H R Sadeghpour
- ITAMP, Harvard-Smithsonian Center for Astrophysics, Cambridge, Massachusetts 02138, USA
| | - E Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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10
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Fogarty T, Cormick C, Landa H, Stojanović VM, Demler E, Morigi G. Nanofriction in Cavity Quantum Electrodynamics. Phys Rev Lett 2015; 115:233602. [PMID: 26684118 DOI: 10.1103/physrevlett.115.233602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/02/2015] [Indexed: 06/05/2023]
Abstract
The dynamics of cold trapped ions in a high-finesse resonator results from the interplay between the long-range Coulomb repulsion and the cavity-induced interactions. The latter are due to multiple scatterings of laser photons inside the cavity and become relevant when the laser pump is sufficiently strong to overcome photon decay. We study the stationary states of ions coupled with a mode of a standing-wave cavity as a function of the cavity and laser parameters, when the typical length scales of the two self-organizing processes, Coulomb crystallization and photon-mediated interactions, are incommensurate. The dynamics are frustrated and in specific limiting cases can be cast in terms of the Frenkel-Kontorova model, which reproduces features of friction in one dimension. We numerically recover the sliding and pinned phases. For strong cavity nonlinearities, they are in general separated by bistable regions where superlubric and stick-slip dynamics coexist. The cavity, moreover, acts as a thermal reservoir and can cool the chain vibrations to temperatures controlled by the cavity parameters and by the ions' phase. These features are imprinted in the radiation emitted by the cavity, which is readily measurable in state-of-the-art setups of cavity quantum electrodynamics.
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Affiliation(s)
- T Fogarty
- Theoretische Physik, Universität des Saarlandes, D-66123 Saarbrücken, Germany
| | - C Cormick
- IFEG, CONICET and Universidad Nacional de Córdoba, Ciudad Universitaria, X5016LAE Córdoba, Argentina
| | - H Landa
- LPTMS, CNRS, Univ. Paris-Sud, Université Paris-Saclay, 91405 Orsay, France
| | | | - E Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
| | - Giovanna Morigi
- Theoretische Physik, Universität des Saarlandes, D-66123 Saarbrücken, Germany
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11
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Kuhnert M, Geiger R, Langen T, Gring M, Rauer B, Kitagawa T, Demler E, Adu Smith D, Schmiedmayer J. Multimode dynamics and emergence of a characteristic length scale in a one-dimensional quantum system. Phys Rev Lett 2013; 110:090405. [PMID: 23496695 DOI: 10.1103/physrevlett.110.090405] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/22/2012] [Indexed: 06/01/2023]
Abstract
We study the nonequilibrium dynamics of a coherently split one-dimensional Bose gas by measuring the full probability distribution functions of matter-wave interference. Observing the system on different length scales allows us to probe the dynamics of excitations on different energy scales, revealing two distinct length-scale-dependent regimes of relaxation. We measure the crossover length scale separating these two regimes and identify it with the prethermalized phase-correlation length of the system. Our approach enables a direct observation of the multimode dynamics characterizing one-dimensional quantum systems.
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Affiliation(s)
- M Kuhnert
- Vienna Center for Quantum Science and Technology, Atominstitut, TU Wien, Stadionallee 2, 1020 Vienna, Austria
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12
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Yao NY, Laumann CR, Gorshkov AV, Bennett SD, Demler E, Zoller P, Lukin MD. Topological flat bands from dipolar spin systems. Phys Rev Lett 2012; 109:266804. [PMID: 23368600 DOI: 10.1103/physrevlett.109.266804] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/18/2012] [Indexed: 06/01/2023]
Abstract
We propose and analyze a physical system that naturally admits two-dimensional topological nearly flat bands. Our approach utilizes an array of three-level dipoles (effective S=1 spins) driven by inhomogeneous electromagnetic fields. The dipolar interactions produce arbitrary uniform background gauge fields for an effective collection of conserved hard-core bosons, namely, the dressed spin flips. These gauge fields result in topological band structures, whose band gap can be larger than the corresponding bandwidth. Exact diagonalization of the full interacting Hamiltonian at half-filling reveals the existence of superfluid, crystalline, and supersolid phases. An experimental realization using either ultracold polar molecules or spins in the solid state is considered.
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Affiliation(s)
- N Y Yao
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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13
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Zapata I, Sols F, Demler E. Triplet pair correlations in s-wave superfluids as a signature of the Fulde-Ferrell-Larkin-Ovchinnikov state. Phys Rev Lett 2012; 109:155304. [PMID: 23102326 DOI: 10.1103/physrevlett.109.155304] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/08/2011] [Indexed: 06/01/2023]
Abstract
We show that antiparallel triplet pairing correlations are generated in superfluids with purely s-wave interactions whenever population imbalance enforces anisotropic Fulde-Ferrell (FF) or inhomogeneous Larkin-Ovchinikov (LO) states. These triplet correlations appear in the Cooper pair wave function, while the triplet part of the gap remains zero. The same set of quasiparticle states contributes to the triplet component and to the polarization, thus spatially correlating them. In the LO case, this set forms a narrow band of Andreev states centered on the nodes of the s-wave order parameter. This picture naturally provides a unifying explanation of previous findings that attractive p-wave interaction stabilizes FFLO states. We also study a similar triplet mixing which occurs when a balanced two-component system displays FFLO-type oscillations due to a spin-dependent optical lattice. We discuss how this triplet component can be measured in systems of ultracold atoms using a rapid ramp across a p-wave Feshbach resonance. This should provide a smoking gun signature of FFLO states.
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Affiliation(s)
- I Zapata
- Departamento de Física de Materiales, Universidad Complutense de Madrid, Madrid, Spain
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14
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Gring M, Kuhnert M, Langen T, Kitagawa T, Rauer B, Schreitl M, Mazets I, Smith DA, Demler E, Schmiedmayer J. Relaxation and Prethermalization in an Isolated Quantum System. Science 2012; 337:1318-22. [DOI: 10.1126/science.1224953] [Citation(s) in RCA: 701] [Impact Index Per Article: 58.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
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15
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Wunsch B, Zinner NT, Mekhov IB, Huang SJ, Wang DW, Demler E. Few-body bound states in dipolar gases and their detection. Phys Rev Lett 2011; 107:073201. [PMID: 21902390 DOI: 10.1103/physrevlett.107.073201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/22/2011] [Indexed: 05/31/2023]
Abstract
We consider dipolar interactions between heteronuclear molecules in a low-dimensional setup consisting of two one-dimensional tubes. We demonstrate that attraction between molecules in different tubes can overcome intratube repulsion and complexes with several molecules in the same tube are stable. In situ detection schemes of the few-body complexes are proposed. We discuss extensions to many tubes and layers, and outline the implications on many-body physics.
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Affiliation(s)
- B Wunsch
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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16
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Zapata I, Wunsch B, Zinner NT, Demler E. π phases in balanced fermionic superfluids on spin-dependent optical lattices. Phys Rev Lett 2010; 105:095301. [PMID: 20868172 DOI: 10.1103/physrevlett.105.095301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/09/2009] [Revised: 06/18/2010] [Indexed: 05/29/2023]
Abstract
We study a balanced two-component system of ultracold fermions in one dimension with attractive interactions and subject to a spin-dependent optical lattice potential of opposite sign for the two components. We find states with different types of modulated pairing order parameters which are conceptually similar to π phases discussed for superconductor-ferromagnet heterostructures. Increasing the lattice depth induces sharp transitions between states of different parity. While the origin of the order parameter oscillations is similar to the Fulde-Ferrel-Larkin-Ovchinnikov phase for paired states with spin imbalance, the current system is intrinsically stable to phase separation. We discuss experimental requirements for creating and probing these novel phases.
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Affiliation(s)
- I Zapata
- Departamento de Física de Materiales, Universidad Complutense de Madrid, E-28040 Madrid, Spain
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17
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Pohl T, Demler E, Lukin MD. Dynamical crystallization in the dipole blockade of ultracold atoms. Phys Rev Lett 2010; 104:043002. [PMID: 20366704 DOI: 10.1103/physrevlett.104.043002] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/26/2009] [Revised: 10/23/2009] [Indexed: 05/29/2023]
Abstract
We describe a method for controlling many-body states in extended ensembles of Rydberg atoms, forming crystalline structures during laser excitation of a frozen atomic gas. Specifically, we predict the existence of an excitation-number staircase in laser excitation of atomic ensembles into Rydberg states. It is shown that such ordered states can be selectively excited by chirped laser pulses, and, via quantum state transfer from atoms to light, be used to create crystalline photonic states.
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Affiliation(s)
- T Pohl
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
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18
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Cherng RW, Demler E. Magnetoroton softening in Rb spinor condensates with dipolar interactions. Phys Rev Lett 2009; 103:185301. [PMID: 19905809 DOI: 10.1103/physrevlett.103.185301] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/03/2009] [Revised: 10/09/2009] [Indexed: 05/28/2023]
Abstract
Superfluids with a tendency towards periodic order have both phonon- and rotonlike spectra. We show that magnetoroton softening occurs in 87Rb spinor condensates. A rich variety of dynamical instabilities emerges as a function of the magnetic field orientation and strength of the quadratic Zeeman shift. These instabilities are driven by an effective dipolar interaction modified dramatically by quasi-two-dimensionality and rapid Larmor precession.
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Affiliation(s)
- R W Cherng
- Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA
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19
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Cherng RW, Gritsev V, Stamper-Kurn DM, Demler E. Dynamical instability of the XY spiral state of ferromagnetic condensates. Phys Rev Lett 2008; 100:180404. [PMID: 18518354 DOI: 10.1103/physrevlett.100.180404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 01/09/2008] [Indexed: 05/26/2023]
Abstract
We calculate the spectrum of collective excitations of the XY spiral state prepared adiabatically or suddenly from a uniform ferromagnetic F=1 condensate. For spiral wave vectors past a critical value, spin wave excitation energies become imaginary indicating a dynamical instability. We construct phase diagrams as functions of spiral wave vector and quadratic Zeeman energy.
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Affiliation(s)
- R W Cherng
- Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA
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20
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Rey AM, Gritsev V, Bloch I, Demler E, Lukin MD. Preparation and detection of magnetic quantum phases in optical superlattices. Phys Rev Lett 2007; 99:140601. [PMID: 17930655 DOI: 10.1103/physrevlett.99.140601] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/11/2007] [Revised: 07/31/2007] [Indexed: 05/25/2023]
Abstract
We describe a novel approach to prepare, detect, and characterize magnetic quantum phases in ultracold spinor atoms loaded in optical superlattices. Our technique makes use of singlet-triplet spin manipulations in an array of isolated double-well potentials in analogy to recently demonstrated control in quantum dots. We also discuss the many-body singlet-triplet spin dynamics arising from coherent coupling between nearest neighbor double wells and derive an effective description for such systems. We use it to study the generation of complex magnetic states by adiabatic and nonequilibrium dynamics.
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Affiliation(s)
- A M Rey
- Institute for Theoretical Atomic, Molecular and Optical Physics, Harvard-Smithsonian Center of Astrophysics, Cambridge, MA 02138, USA
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21
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Abstract
We study the interplay between superfluidity and magnetism in a multicomponent gas of ultracold fermions. Ward-Takahashi identities constrain possible mean-field states describing order parameters for both pairing and magnetization. The structure of global phase diagrams arises from competition among these states as functions of anisotropies in chemical potential, density, or interactions. They exhibit first and second order phase transition as well as multicritical points, metastability regions, and phase separation. We comment on experimental signatures in ultracold atoms.
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Affiliation(s)
- R W Cherng
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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22
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Büchler HP, Demler E, Lukin M, Micheli A, Prokof'ev N, Pupillo G, Zoller P. Strongly correlated 2D quantum phases with cold polar molecules: controlling the shape of the interaction potential. Phys Rev Lett 2007; 98:060404. [PMID: 17358920 DOI: 10.1103/physrevlett.98.060404] [Citation(s) in RCA: 143] [Impact Index Per Article: 8.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/11/2006] [Indexed: 05/14/2023]
Abstract
We discuss techniques to tune and shape the long-range part of the interaction potentials in quantum gases of bosonic polar molecules by dressing rotational excitations with static and microwave fields. This provides a novel tool towards engineering strongly correlated quantum phases in combination with low-dimensional trapping geometries. As an illustration, we discuss the 2D superfluid-crystal quantum phase transition for polar molecules interacting via an electric-field-induced dipole-dipole potential.
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Affiliation(s)
- H P Büchler
- Institute for Theoretical Physics, University of Innsbruck, 6020 Innsbruck, Austria
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23
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Wang DW, Mishchenko EG, Demler E. Pseudospin ferromagnetism in double-quantum-wire systems. Phys Rev Lett 2005; 95:086802. [PMID: 16196890 DOI: 10.1103/physrevlett.95.086802] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/28/2005] [Indexed: 05/04/2023]
Abstract
We propose that a pseudospin ferromagnetic (i.e., interwire coherent) state can exist in a system of two parallel wires of finite width in the presence of a perpendicular magnetic field. This novel quantum many-body state appears when the interwire distance decreases below a certain critical value which depends on the magnetic field. We determine the phase boundary of the ferromagnetic phase by analyzing the softening of the spin-mode velocity using the bosonization approach. We also discuss the signatures of this state in tunneling and Coulomb drag experiments.
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Affiliation(s)
- D-W Wang
- Department of Physics, National Tsing-Hua University, Hsinchu, Taiwan 300, Republic of China
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24
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Altman E, Polkovnikov A, Demler E, Halperin BI, Lukin MD. Superfluid-insulator transition in a moving system of interacting bosons. Phys Rev Lett 2005; 95:020402. [PMID: 16090666 DOI: 10.1103/physrevlett.95.020402] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2004] [Indexed: 05/03/2023]
Abstract
We analyze the stability of superfluid currents in a system of strongly interacting ultracold atoms in an optical lattice. We show that such a system undergoes a dynamic, irreversible phase transition at a critical phase gradient that depends on the interaction strength between atoms. At commensurate filling, the phase boundary continuously interpolates between the classical modulation instability of a weakly interacting condensate and the equilibrium quantum phase transition into a Mott insulator state at which the critical current vanishes. We argue that quantum fluctuations smear the transition boundary in low dimensional systems. Finally we discuss the implications to realistic experiments.
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Affiliation(s)
- E Altman
- Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA
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25
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Duan LM, Demler E, Lukin MD. Controlling spin exchange interactions of ultracold atoms in optical lattices. Phys Rev Lett 2003; 91:090402. [PMID: 14525163 DOI: 10.1103/physrevlett.91.090402] [Citation(s) in RCA: 212] [Impact Index Per Article: 10.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/25/2002] [Indexed: 05/24/2023]
Abstract
We describe a general technique that allows one to induce and control strong interaction between spin states of neighboring atoms in an optical lattice. We show that the properties of spin exchange interactions, such as magnitude, sign, and anisotropy, can be designed by adjusting the optical potentials. We illustrate how this technique can be used to efficiently "engineer" quantum spin systems with desired properties, for specific examples ranging from scalable quantum computation to probing a model with complex topological order that supports exotic anyonic excitations.
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Affiliation(s)
- L-M Duan
- Institute for Quantum Information, California Institute of Technology, mc 107-81, Pasadena, CA 91125, USA
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26
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Hofstetter W, Cirac JI, Zoller P, Demler E, Lukin MD. High-temperature superfluidity of fermionic atoms in optical lattices. Phys Rev Lett 2002; 89:220407. [PMID: 12485058 DOI: 10.1103/physrevlett.89.220407] [Citation(s) in RCA: 92] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2002] [Indexed: 05/24/2023]
Abstract
Fermionic atoms confined in a potential created by standing wave light can undergo a phase transition to a superfluid state at a dramatically increased transition temperature. Depending upon carefully controlled parameters, a transition to a superfluid state of Cooper pairs, antiferromagnetic states or d-wave pairing states can be induced and probed under realistic experimental conditions. We describe an atomic physics experiment that can provide critical insight into the origin of high-temperature superconductivity in cuprates.
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Affiliation(s)
- W Hofstetter
- Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA
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27
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Demler E, Sachdev S, Zhang Y. Spin-ordering quantum transitions of superconductors in a magnetic field. Phys Rev Lett 2001; 87:067202. [PMID: 11497851 DOI: 10.1103/physrevlett.87.067202] [Citation(s) in RCA: 21] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/20/2001] [Indexed: 05/23/2023]
Abstract
We argue that recent neutron scattering measurements by Lake et al. [Science 291, 1759 (2001)] of the spin excitation spectrum of La(2-delta)Sr(delta)CuO4 in a magnetic field can be understood in terms of proximity to a phase with co-existing superconductivity and spin density wave order. We present a general theory for such quantum transitions, and argue that their low energy spin fluctuations are controlled by a singular correction from the superflow kinetic energy, acting in the region outside the vortex cores. We propose numerous experimental tests of our theory.
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Affiliation(s)
- E Demler
- Department of Physics, Harvard University, Cambridge, Massachusetts 02138, USA
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28
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Demler E, Nayak C, Das Sarma S. Bilayer coherent and quantum Hall phases: duality and quantum disorder. Phys Rev Lett 2001; 86:1853-1856. [PMID: 11290265 DOI: 10.1103/physrevlett.86.1853] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/09/2000] [Indexed: 05/23/2023]
Abstract
We consider a fully spin-polarized quantum Hall system with no interlayer tunneling at total filling factor nu = 1/k (where k is an odd integer) using the Chern-Simons-Ginzburg-Landau theory. Exploiting particle-vortex duality and the concept of quantum disordering, we find a large number of possible compressible and incompressible ground states, some of which may have relevance to recent experiments of Spielman et al. [Phys. Rev. Lett. 84, 5808 (2000)]. We find interlayer coherent compressible states without Hall quantization and interlayer incoherent incompressible states with Hall quantization in addition to the usual (k,k,k) Halperin states, which are both interlayer coherent and incompressible.
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Affiliation(s)
- E Demler
- Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA
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29
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