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Bera J, Batin AQ, Ghosh S, Malomed B, Roy U. Generation of higher harmonics in dipolar Bose-Einstein condensates trapped in periodically modulated potentials. PHILOSOPHICAL TRANSACTIONS. SERIES A, MATHEMATICAL, PHYSICAL, AND ENGINEERING SCIENCES 2023; 381:20220075. [PMID: 36842989 DOI: 10.1098/rsta.2022.0075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2022] [Accepted: 09/26/2022] [Indexed: 06/18/2023]
Abstract
We consider a quasi-one-dimensional Bose-Einstein condensate with contact and long-range dipolar interactions, under the action of the time-periodic modulation applied to the harmonic-oscillator and optical-lattice trapping potentials. The modulation results in generation of a variety of harmonics in oscillations of the condensate's width and centre-of-mass coordinate. These include multiple and combinational harmonics, represented by sharp peaks in the system's spectra. Approximate analytical results are produced by the variational method, which are verified by systematic simulations of the underlying Gross-Pitaevskii equation. This article is part of the theme issue 'New trends in pattern formation and nonlinear dynamics of extended systems'.
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Affiliation(s)
- Jayanta Bera
- Department of Physics, C. V. Raman Global University, Bhubaneswar 752054, Odisha, India
| | - Abdul Q Batin
- Department of Physics, Indian Institute of Technology Patna,Patna 801106, Bihar, India
| | - Suranjana Ghosh
- Department of Physics, Indian Institute of Science Education and Research Kolkata, Mohanpur 741246, West Bengal, India
| | - Boris Malomed
- Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, and Center for Light-Matter Interaction, Tel Aviv University, P.O.B. 39040, Ramat Aviv, Tel Aviv, Israel
- Instituto de Alta Investigación, Universidad de Tarapacá, Casilla 7D, Arica, Chile
| | - Utpal Roy
- Department of Physics, Indian Institute of Technology Patna,Patna 801106, Bihar, India
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2
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Dong B, Zhang Y. Raman laser induced self-organization with topology in a dipolar condensate. OPTICS EXPRESS 2023; 31:7523-7534. [PMID: 36859881 DOI: 10.1364/oe.479091] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/24/2022] [Accepted: 12/12/2022] [Indexed: 06/18/2023]
Abstract
We investigate the ground states of a dipolar Bose-Einstein condensate (BEC) subject to Raman laser induced spin-orbit coupling with mean-field theory. Owing to the interplay between spin-orbit coupling and atom-atom interactions, the BEC presents remarkable self-organization behavior and thus hosts various exotic phases including vortex with discrete rotational symmetry, stripe with spin helix, and chiral lattices with C4 symmetry. The peculiar chiral self-organized array of square lattice, which spontaneously breaks both U(1) and rotational symmetries, is observed when the contact interaction is considerable in comparison with the spin-orbit coupling. Moreover, we show that the Raman-induced spin-orbit coupling plays a crucial role in forming rich topological spin textures of the chiral self-organized phases by introducing a channel for atoms to turn on spin flipping between two components. The self-organization phenomena predicted here feature topology owing to spin-orbit coupling. In addition, we find long-lived metastable self-organized arrays with C6 symmetry in the case of strong spin-orbit coupling. We also present a proposal to observe these predicted phases in ultracold atomic dipolar gases with laser-induced spin-orbit coupling, which may stimulate broad theoretical as well as experimental interest.
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Kopyciński J, Łebek M, Górecki W, Pawłowski K. Ultrawide Dark Solitons and Droplet-Soliton Coexistence in a Dipolar Bose Gas with Strong Contact Interactions. PHYSICAL REVIEW LETTERS 2023; 130:043401. [PMID: 36763437 DOI: 10.1103/physrevlett.130.043401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/14/2022] [Revised: 11/10/2022] [Accepted: 12/19/2022] [Indexed: 06/18/2023]
Abstract
We look into dark solitons in a quasi-1D dipolar Bose gas and in a quantum droplet. We derive the analytical solitonic solution of a Gross-Pitaevskii-like equation accounting for beyond mean-field effects. The results show there is a certain critical value of the dipolar interactions, for which the width of a motionless soliton diverges. Moreover, there is a peculiar solution of the motionless soliton with a nonzero density minimum. We also present the energy spectrum of these solitons with an additional excitation subbranch appearing. Finally, we perform a series of numerical experiments revealing the coexistence of a dark soliton inside a quantum droplet.
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Affiliation(s)
- Jakub Kopyciński
- Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Maciej Łebek
- Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
| | - Wojciech Górecki
- Faculty of Physics, University of Warsaw, Pasteura 5, 02-093 Warsaw, Poland
| | - Krzysztof Pawłowski
- Center for Theoretical Physics, Polish Academy of Sciences, Al. Lotników 32/46, 02-668 Warsaw, Poland
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4
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Chomaz L, Ferrier-Barbut I, Ferlaino F, Laburthe-Tolra B, Lev BL, Pfau T. Dipolar physics: a review of experiments with magnetic quantum gases. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2022; 86:026401. [PMID: 36583342 DOI: 10.1088/1361-6633/aca814] [Citation(s) in RCA: 20] [Impact Index Per Article: 10.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/13/2022] [Accepted: 12/02/2022] [Indexed: 06/17/2023]
Abstract
Since the achievement of quantum degeneracy in gases of chromium atoms in 2004, the experimental investigation of ultracold gases made of highly magnetic atoms has blossomed. The field has yielded the observation of many unprecedented phenomena, in particular those in which long-range and anisotropic dipole-dipole interactions (DDIs) play a crucial role. In this review, we aim to present the aspects of the magnetic quantum-gas platform that make it unique for exploring ultracold and quantum physics as well as to give a thorough overview of experimental achievements. Highly magnetic atoms distinguish themselves by the fact that their electronic ground-state configuration possesses a large electronic total angular momentum. This results in a large magnetic moment and a rich electronic transition spectrum. Such transitions are useful for cooling, trapping, and manipulating these atoms. The complex atomic structure and large dipolar moments of these atoms also lead to a dense spectrum of resonances in their two-body scattering behaviour. These resonances can be used to control the interatomic interactions and, in particular, the relative importance of contact over dipolar interactions. These features provide exquisite control knobs for exploring the few- and many-body physics of dipolar quantum gases. The study of dipolar effects in magnetic quantum gases has covered various few-body phenomena that are based on elastic and inelastic anisotropic scattering. Various many-body effects have also been demonstrated. These affect both the shape, stability, dynamics, and excitations of fully polarised repulsive Bose or Fermi gases. Beyond the mean-field instability, strong dipolar interactions competing with slightly weaker contact interactions between magnetic bosons yield new quantum-stabilised states, among which are self-bound droplets, droplet assemblies, and supersolids. Dipolar interactions also deeply affect the physics of atomic gases with an internal degree of freedom as these interactions intrinsically couple spin and atomic motion. Finally, long-range dipolar interactions can stabilise strongly correlated excited states of 1D gases and also impact the physics of lattice-confined systems, both at the spin-polarised level (Hubbard models with off-site interactions) and at the spinful level (XYZ models). In the present manuscript, we aim to provide an extensive overview of the various related experimental achievements up to the present.
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Affiliation(s)
- Lauriane Chomaz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Physikalisches Institut der Universität Heidelberg, Im Neuenheimer Feld 226, 69120 Heidelberg, Germany
| | - Igor Ferrier-Barbut
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
- Université Paris-Saclay, Institut d'Optique Graduate School, CNRS, Laboratoire Charles Fabry, 91127 Palaiseau, France
| | - Francesca Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstrasse 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - Bruno Laburthe-Tolra
- Université Sorbonne Paris Nord, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France
- CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - Benjamin L Lev
- Departments of Physics and Applied Physics and Ginzton Laboratory, Stanford University, Stanford, CA 94305, United States of America
| | - Tilman Pfau
- Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70550 Stuttgart, Germany
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Miyazawa Y, Inoue R, Matsui H, Nomura G, Kozuma M. Bose-Einstein Condensation of Europium. PHYSICAL REVIEW LETTERS 2022; 129:223401. [PMID: 36493443 DOI: 10.1103/physrevlett.129.223401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/24/2022] [Revised: 09/23/2022] [Accepted: 10/12/2022] [Indexed: 06/17/2023]
Abstract
We report the realization of a Bose-Einstein condensate of europium atoms, which is a strongly dipolar species with unique properties, a highly symmetric [Xe]4f^{7}6s^{2} ^{8}S_{7/2} electronic ground state and a hyperfine structure. By means of evaporative cooling in a crossed optical dipole trap, we produce a condensate of ^{151}Eu containing up to 5×10^{4} atoms. We estimate the scattering length of ^{151}Eu to be a_{s}=110(4) a_{B} after comparing the velocities of expansion of condensates to different orientations of the atomic magnetic moments, where a_{B} is the Bohr radius. We observe deformation of the condensate in the vicinity of the Feshbach resonance at 1.32 G with a width of 10 mG.
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Affiliation(s)
- Yuki Miyazawa
- Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama, Kanagawa 226-8503, Japan
| | - Ryotaro Inoue
- Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama, Kanagawa 226-8503, Japan
| | - Hiroki Matsui
- Department of Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8550, Japan
| | - Gyohei Nomura
- Department of Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8550, Japan
| | - Mikio Kozuma
- Institute of Innovative Research, Tokyo Institute of Technology, 4259 Nagatsuta, Midori, Yokohama, Kanagawa 226-8503, Japan
- Department of Physics, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro, Tokyo 152-8550, Japan
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6
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Zhao ZB, Chen GH, Liu B, Li YY. Discrete vortex quantum droplets. CHAOS, SOLITONS & FRACTALS 2022; 162:112481. [DOI: 10.1016/j.chaos.2022.112481] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 09/01/2023]
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7
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Interplay between Binary and Three-Body Interactions and Enhancement of Stability in Trapless Dipolar Bose–Einstein Condensates. APPLIED SCIENCES-BASEL 2022. [DOI: 10.3390/app12031135] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
We investigate the nonlocal Gross–Pitaevskii (GP) equation with long-range dipole-dipole and contact interactions (including binary and three-body collisions). We address the impact of the three-body interaction on stabilizing trapless dipolar Bose–Einstein condensates (BECs). It is found that the dipolar BECs exhibit stability not only for the usual combination of attractive binary and repulsive three-body interactions, but also for the case when these terms have opposite signs. The trapless stability of the dipolar BECs may be further enhanced by time-periodic modulation of the three-body interaction imposed by means of Feshbach resonance. The results are produced analytically using the variational approach and confirmed by numerical simulations.
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8
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Thomas R, Kjærgaard N. A digital feedback controller for stabilizing large electric currents to the ppm level for Feshbach resonance studies. THE REVIEW OF SCIENTIFIC INSTRUMENTS 2020; 91:034705. [PMID: 32260003 DOI: 10.1063/1.5128935] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 09/23/2019] [Accepted: 02/23/2020] [Indexed: 06/11/2023]
Abstract
Magnetic Feshbach resonances are a key tool in the field of ultracold quantum gases, but their full exploitation requires the generation of large, stable magnetic fields up to 1000 G with fractional stabilities of better than 10-4. Design considerations for electromagnets producing these fields, such as optical access and fast dynamical response, mean that electric currents in excess of 100 A are often needed to obtain the requisite field strengths. We describe a simple digital proportional-integral-derivative current controller constructed using a field-programmable gate array and off-the-shelf evaluation boards that allows for gain scheduling, enabling optimal control of current sources with non-linear actuators. Our controller can stabilize an electric current of 337.5 A to the level of 7.5 × 10-7 in an averaging time of 10 min and with a control bandwidth of 2 kHz.
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Affiliation(s)
- R Thomas
- Department of Physics, QSO-Centre for Quantum Science, and Dodd-Walls Centre, University of Otago, Dunedin 9016, New Zealand
| | - N Kjærgaard
- Department of Physics, QSO-Centre for Quantum Science, and Dodd-Walls Centre, University of Otago, Dunedin 9016, New Zealand
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9
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Petter D, Natale G, van Bijnen RMW, Patscheider A, Mark MJ, Chomaz L, Ferlaino F. Probing the Roton Excitation Spectrum of a Stable Dipolar Bose Gas. PHYSICAL REVIEW LETTERS 2019; 122:183401. [PMID: 31144863 DOI: 10.1103/physrevlett.122.183401] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/29/2018] [Indexed: 06/09/2023]
Abstract
We measure the excitation spectrum of a stable dipolar Bose-Einstein condensate over a wide momentum range via Bragg spectroscopy. We precisely control the relative strength ε_{dd} of the dipolar to the contact interactions and observe that the spectrum increasingly deviates from the linear phononic behavior for increasing ε_{dd}. Reaching the dipolar-dominated regime ε_{dd}>1, we observe the emergence of a roton minimum in the spectrum and its softening towards instability. We characterize how the excitation energy and the strength of the density-density correlations at the roton momentum vary with ε_{dd}. Our findings are in excellent agreement with numerical calculations based on mean-field Bogoliubov theory. When including beyond-mean-field corrections, in the form of a Lee-Huang-Yang potential, we observe a quantitative deviation from the experiment, questioning the validity of such a description in the roton regime.
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Affiliation(s)
- D Petter
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - G Natale
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - R M W van Bijnen
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
| | - A Patscheider
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M J Mark
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
| | - L Chomaz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - F Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, Technikerstraße 21a, 6020 Innsbruck, Austria
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10
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Prasad SB, Bland T, Mulkerin BC, Parker NG, Martin AM. Instability of Rotationally Tuned Dipolar Bose-Einstein Condensates. PHYSICAL REVIEW LETTERS 2019; 122:050401. [PMID: 30821994 DOI: 10.1103/physrevlett.122.050401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2018] [Revised: 12/04/2018] [Indexed: 06/09/2023]
Abstract
The possibility of effectively inverting the sign of the dipole-dipole interaction, by fast rotation of the dipole polarization, is examined within a harmonically trapped dipolar Bose-Einstein condensate. Our analysis is based on the stationary states in the Thomas-Fermi limit, in the corotating frame, as well as direct numerical simulations in the Thomas-Fermi regime, explicitly accounting for the rotating polarization. The condensate is found to be inherently unstable due to the dynamical instability of collective modes. This ultimately prevents the realization of robust and long-lived rotationally tuned states. Our findings have major implications for experimentally accessing this regime.
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Affiliation(s)
- S B Prasad
- School of Physics, University of Melbourne, Melbourne 3010, Australia
| | - T Bland
- Joint Quantum Centre Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - B C Mulkerin
- Centre for Quantum and Optical Science, Swinburne University of Technology, Melbourne 3122, Australia
| | - N G Parker
- School of Physics, University of Melbourne, Melbourne 3010, Australia
- Joint Quantum Centre Durham-Newcastle, School of Mathematics, Statistics and Physics, Newcastle University, Newcastle upon Tyne, NE1 7RU, United Kingdom
| | - A M Martin
- School of Physics, University of Melbourne, Melbourne 3010, Australia
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11
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Baier S, Petter D, Becher JH, Patscheider A, Natale G, Chomaz L, Mark MJ, Ferlaino F. Realization of a Strongly Interacting Fermi Gas of Dipolar Atoms. PHYSICAL REVIEW LETTERS 2018; 121:093602. [PMID: 30230905 DOI: 10.1103/physrevlett.121.093602] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/30/2018] [Indexed: 06/08/2023]
Abstract
We realize a two-component dipolar Fermi gas with tunable interactions, using erbium atoms. Employing a lattice-protection technique, we selectively prepare deeply degenerate mixtures of the two lowest spin states and perform high-resolution Feshbach spectroscopy in an optical dipole trap. We identify a comparatively broad Feshbach resonance and map the interspin scattering length in its vicinity. The Fermi mixture shows a remarkable collisional stability in the strongly interacting regime, providing a first step towards studies of superfluid pairing, crossing from Cooper pairs to bound molecules, in presence of dipole-dipole interactions.
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Affiliation(s)
- S Baier
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - D Petter
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - J H Becher
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - A Patscheider
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - G Natale
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - L Chomaz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M J Mark
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - F Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
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12
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Lepoutre S, Gabardos L, Kechadi K, Pedri P, Gorceix O, Maréchal E, Vernac L, Laburthe-Tolra B. Collective Spin Modes of a Trapped Quantum Ferrofluid. PHYSICAL REVIEW LETTERS 2018; 121:013201. [PMID: 30028151 DOI: 10.1103/physrevlett.121.013201] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/26/2018] [Indexed: 06/08/2023]
Abstract
We report on the observation of a collective spin mode in a spinor Bose-Einstein condensate. Initially, all spins point perpendicular to the external magnetic field. The lowest energy mode consists of a sinusoidal oscillation of the local spin around its original axis, with an oscillation amplitude that linearly depends on the spatial coordinates. The frequency of the oscillation is set by the zero-point kinetic energy of the BEC. The observations are in excellent agreement with hydrodynamic equations. The observed spin mode has a universal character, independent of the atomic spin and spin-dependent contact interactions.
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Affiliation(s)
- S Lepoutre
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - L Gabardos
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - K Kechadi
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - P Pedri
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - O Gorceix
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - E Maréchal
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - L Vernac
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
| | - B Laburthe-Tolra
- Université Paris 13, Sorbonne Paris Cité, Laboratoire de Physique des Lasers, F-93430 Villetaneuse, France and CNRS, UMR 7538, LPL, F-93430 Villetaneuse, France
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13
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Plestid R, Mahon P, O'Dell DHJ. Violent relaxation in quantum fluids with long-range interactions. Phys Rev E 2018; 98:012112. [PMID: 30110820 DOI: 10.1103/physreve.98.012112] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/20/2017] [Indexed: 06/08/2023]
Abstract
Violent relaxation is a process that occurs in systems with long-range interactions. It has the peculiar feature of dramatically amplifying small perturbations, and rather than driving the system to equilibrium, it instead leads to slowly evolving configurations known as quasistationary states that fall outside the standard paradigm of statistical mechanics. Violent relaxation was originally identified in gravity-driven stellar dynamics; here, we extend the theory into the quantum regime by developing a quantum version of the Hamiltonian mean field (HMF) model which exemplifies many of the generic properties of long-range interacting systems. The HMF model can either be viewed as describing particles interacting via a cosine potential, or equivalently as the kinetic XY model with infinite-range interactions, and its quantum fluid dynamics can be obtained from a generalized Gross-Pitaevskii equation. We show that singular caustics that form during violent relaxation are regulated by interference effects in a universal way described by Thom's catastrophe theory applied to waves and this leads to emergent length scales and timescales not present in the classical problem. In the deep quantum regime we find that violent relaxation is suppressed altogether by quantum zero-point motion. Our results are relevant to laboratory studies of self-organization in cold atomic gases with long-range interactions.
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Affiliation(s)
- Ryan Plestid
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W. Hamilton, Ontario, Canada L8S 4M1
- Perimeter Institute for Theoretical Physics, 31 Caroline St. N., Waterloo, Ontario, Canada N2L 2Y5
| | - Perry Mahon
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W. Hamilton, Ontario, Canada L8S 4M1
- Department of Physics, University of Toronto, 60 St. George St., Toronto, Ontario, Canada M5S 1A7
| | - D H J O'Dell
- Department of Physics and Astronomy, McMaster University, 1280 Main St. W. Hamilton, Ontario, Canada L8S 4M1
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14
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Chomaz L, van Bijnen RMW, Petter D, Faraoni G, Baier S, Becher JH, Mark MJ, Wächtler F, Santos L, Ferlaino F. Observation of Roton Mode Population in a Dipolar Quantum Gas. NATURE PHYSICS 2018; 14:442-446. [PMID: 29861780 PMCID: PMC5972007 DOI: 10.1038/s41567-018-0054-7] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2017] [Accepted: 01/22/2018] [Indexed: 05/26/2023]
Abstract
The concept of a roton, a special kind of elementary excitation, forming a minimum of energy at finite momentum, has been essential to understand the properties of superfluid 4He 1. In quantum liquids, rotons arise from the strong interparticle interactions, whose microscopic description remains debated 2. In the realm of highly-controllable quantum gases, a roton mode has been predicted to emerge due to magnetic dipole-dipole interactions despite of their weakly-interacting character 3. This prospect has raised considerable interest 4-12; yet roton modes in dipolar quantum gases have remained elusive to observations. Here we report experimental and theoretical studies of the momentum distribution in Bose-Einstein condensates of highly-magnetic erbium atoms, revealing the existence of the long-sought roton mode. Following an interaction quench, the roton mode manifests itself with the appearance of symmetric peaks at well-defined finite momentum. The roton momentum follows the predicted geometrical scaling with the inverse of the confinement length along the magnetisation axis. From the growth of the roton population, we probe the roton softening of the excitation spectrum in time and extract the corresponding imaginary roton gap. Our results provide a further step in the quest towards supersolidity in dipolar quantum gases 13.
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Affiliation(s)
- L. Chomaz
- Institut für Experimentalphysik,Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - R. M. W. van Bijnen
- Institut für Quantenoptik und Quanteninformation,Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - D. Petter
- Institut für Experimentalphysik,Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - G. Faraoni
- Institut für Experimentalphysik,Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Dipartimento di Fisica e Astronomia, Università di Firenze, Via Sansone 1, 50019 Sesto Fiorentino, Italy
| | - S. Baier
- Institut für Experimentalphysik,Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - J. H. Becher
- Institut für Experimentalphysik,Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M. J. Mark
- Institut für Experimentalphysik,Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation,Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - F. Wächtler
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover, Germany
| | - L. Santos
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstr. 2, 30167 Hannover, Germany
| | - F. Ferlaino
- Institut für Experimentalphysik,Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation,Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
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15
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Abolins BP, Zillich RE, Whaley KB. Quantum phases of dipolar rotors on two-dimensional lattices. J Chem Phys 2018; 148:102338. [DOI: 10.1063/1.5005522] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Affiliation(s)
- B. P. Abolins
- Department of Chemistry, University of California, Berkeley, California 94720, USA
| | - R. E. Zillich
- Institut für Theoretische Physik, Johannes Kepler Universität Linz, Altenbergerstraße 69, 4040 Linz, Austria
| | - K. B. Whaley
- Department of Chemistry, University of California, Berkeley, California 94720, USA
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16
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Yu ZF, Xue JK. The phase diagram and stability of trapped D-dimensional spin-orbit coupled Bose-Einstein condensate. Sci Rep 2017; 7:15635. [PMID: 29142281 PMCID: PMC5688179 DOI: 10.1038/s41598-017-15900-w] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/20/2017] [Accepted: 11/05/2017] [Indexed: 11/08/2022] Open
Abstract
By variational analysis and direct numerical simulation, we study the phase transition and stability of a trapped D-dimensional Bose-Einstein condensate with spin-orbit coupling. The complete phase and stability diagrams of the system are presented in full parameter space, while the collapse dynamics induced by the mean-filed attraction and the mechanism for stabilizing the collapse by spin-orbit coupling are illustrated explicitly. Particularly, a full and deep understanding of the dependence of phase transition and stability mechanism on geometric dimensionality and external trap potential is revealed. It is shown that the spin-orbit coupling can modify the dispersion relations, which can balance the mean-filed attractive interaction and result in a spin polarized or overlapped state to stabilize the collapse, then changes the collapsing threshold dependent on the geometric dimensionality and external trap potential. Moreover, from 2D to 3D system, the mean-field attraction for inducing the collapse is reduced and the collapse speed is enhanced, namely, the collapse can be more easily stabilized in 2D system. That is, the collapse can be manipulated by adjusting the spin-orbit coupling, Raman coupling, geometric dimensionality and the external trap potential, which can provide a possible way for elaborating the collapse dynamics experimentally.
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Affiliation(s)
- Zi-Fa Yu
- College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070, China
| | - Ju-Kui Xue
- College of Physics and Electronic Engineering, Northwest Normal University, Lanzhou, 730070, China.
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17
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Fan Z, Shi Y, Liu Y, Pang W, Li Y, Malomed BA. Cross-symmetric dipolar-matter-wave solitons in double-well chains. Phys Rev E 2017; 95:032226. [PMID: 28415205 DOI: 10.1103/physreve.95.032226] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/24/2016] [Indexed: 11/07/2022]
Abstract
We consider a dipolar Bose-Einstein condensate trapped in an array of two-well systems with an arbitrary orientation of the dipoles relative to the system's axis. The system can be built as a chain of local traps sliced into two parallel lattices by a repelling laser sheet. It is modeled by a pair of coupled discrete Gross-Pitaevskii equations, with dipole-dipole self-interactions and cross interactions. When the dipoles are not polarized perpendicular or parallel to the lattice, the cross interaction is asymmetric, replacing the familiar symmetric two-component discrete solitons by two new species of cross-symmetric ones, viz., on-site- and off-site-centered solitons, which are strongly affected by the orientation of the dipoles and separation between the parallel lattices. A very narrow region of intermediate asymmetric discrete solitons is found at the boundary between the on- and off-site families. Two different types of solitons in the PT-symmetric version of the system are constructed too, and stability areas are identified for them.
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Affiliation(s)
- Zhiwei Fan
- Department of Applied Physics, South China Agricultural University, Guangzhou 510642, China
| | - Yuhan Shi
- Department of Applied Physics, South China Agricultural University, Guangzhou 510642, China
| | - Yan Liu
- Department of Applied Physics, South China Agricultural University, Guangzhou 510642, China
| | - Wei Pang
- Department of Experiment Teaching, Guangdong University of Technology, Guangzhou 510006, China
| | - Yongyao Li
- Department of Applied Physics, South China Agricultural University, Guangzhou 510642, China.,School of Physics and Optoelectronic Engineering, Foshan University, Foshan 528000, China
| | - Boris A Malomed
- Department of Applied Physics, South China Agricultural University, Guangzhou 510642, China.,Department of Physical Electronics, School of Electrical Engineering, Faculty of Engineering, Tel Aviv University, Tel Aviv 69978, Israel.,Laboratory of Nonlinear-Optical Informatics, ITMO University, St. Petersburg 197101, Russia
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18
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Yang BC, Pérez-Ríos J, Robicheaux F. Classical Fractals and Quantum Chaos in Ultracold Dipolar Collisions. PHYSICAL REVIEW LETTERS 2017; 118:154101. [PMID: 28452515 DOI: 10.1103/physrevlett.118.154101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/12/2016] [Indexed: 06/07/2023]
Abstract
We examine a dipolar-gas model to address fundamental issues regarding the correspondence between classical chaos and quantum observations in ultracold dipolar collisions. The theoretical model consists of a short-range Lennard-Jones potential well with an anisotropic, long-range dipole-dipole interaction between two atoms. Both the classical and quantum dynamics are explored for the same Hamiltonian of the system. The classical chaotic scattering is revealed by the fractals developed in the scattering function (defined as the final atom separation as a function of initial conditions), while the quantum chaotic features lead to the repulsion of the eigenphases from the corresponding quantum S matrix. The nearest-eigenphase-spacing statistics have an intermediate behavior between the Poisson and the Wigner-Dyson distributions. The character of the distribution can be controlled by changing an effective Planck constant or the dipole moment. The degree of quantum chaos shows a good correspondence with the overall average of the classical scattering function. The results presented here also provide helpful insights for understanding the role of the inherent dipole-dipole interaction in the currently ongoing experiments on ultracold collisions of highly magnetic atoms.
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Affiliation(s)
- B C Yang
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| | - Jesús Pérez-Ríos
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
| | - F Robicheaux
- Department of Physics and Astronomy, Purdue University, West Lafayette, Indiana 47907, USA
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19
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Martin AM, Marchant NG, O'Dell DHJ, Parker NG. Vortices and vortex lattices in quantum ferrofluids. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2017; 29:103004. [PMID: 28145899 DOI: 10.1088/1361-648x/aa53a6] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/06/2023]
Abstract
The experimental realization of quantum-degenerate Bose gases made of atoms with sizeable magnetic dipole moments has created a new type of fluid, known as a quantum ferrofluid, which combines the extraordinary properties of superfluidity and ferrofluidity. A hallmark of superfluids is that they are constrained to rotate through vortices with quantized circulation. In quantum ferrofluids the long-range dipolar interactions add new ingredients by inducing magnetostriction and instabilities, and also affect the structural properties of vortices and vortex lattices. Here we give a review of the theory of vortices in dipolar Bose-Einstein condensates, exploring the interplay of magnetism with vorticity and contrasting this with the established behaviour in non-dipolar condensates. We cover single vortex solutions, including structure, energy and stability, vortex pairs, including interactions and dynamics, and also vortex lattices. Our discussion is founded on the mean-field theory provided by the dipolar Gross-Pitaevskii equation, ranging from analytic treatments based on the Thomas-Fermi (hydrodynamic) and variational approaches to full numerical simulations. Routes for generating vortices in dipolar condensates are discussed, with particular attention paid to rotating condensates, where surface instabilities drive the nucleation of vortices, and lead to the emergence of rich and varied vortex lattice structures. We also present an outlook, including potential extensions to degenerate Fermi gases, quantum Hall physics, toroidal systems and the Berezinskii-Kosterlitz-Thouless transition.
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Affiliation(s)
- A M Martin
- School of Physics, University of Melbourne, Victoria 3010, Australia
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20
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Macia A, Sánchez-Baena J, Boronat J, Mazzanti F. Droplets of Trapped Quantum Dipolar Bosons. PHYSICAL REVIEW LETTERS 2016; 117:205301. [PMID: 27886489 DOI: 10.1103/physrevlett.117.205301] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/21/2016] [Indexed: 06/06/2023]
Abstract
Strongly interacting systems of dipolar bosons in three dimensions confined by harmonic traps are analyzed using the exact path integral ground-state Monte Carlo method. By adding a repulsive two-body potential, we find a narrow window of interaction parameters leading to stable ground-state configurations of droplets in a crystalline arrangement. We find that this effect is entirely due to the interaction present in the Hamiltonian without resorting to additional stabilizing mechanisms or specific three-body forces. We analyze the number of droplets formed in terms of the Hamiltonian parameters, relate them to the corresponding s-wave scattering length, and discuss a simple scaling model for the density profiles. Our results are in qualitative agreement with recent experiments showing a quantum Rosensweig instability in trapped Dy atoms.
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Affiliation(s)
- A Macia
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain
| | - J Sánchez-Baena
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain
| | - J Boronat
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain
| | - F Mazzanti
- Departament de Física, Universitat Politècnica de Catalunya, Campus Nord B4-B5, E-08034 Barcelona, Spain
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21
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Wood AA, McKellar BHJ, Martin AM. Persistent Superfluid Flow Arising from the He-McKellar-Wilkens Effect in Molecular Dipolar Condensates. PHYSICAL REVIEW LETTERS 2016; 116:250403. [PMID: 27391706 DOI: 10.1103/physrevlett.116.250403] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/21/2016] [Indexed: 06/06/2023]
Abstract
We show that the He-McKellar-Wilkens effect can induce a persistent flow in a Bose-Einstein condensate of polar molecules confined in a toroidal trap, with the dipolar interaction mediated via an electric dipole moment. For Bose-Einstein condensates of atoms with a magnetic dipole moment, we show that although it is theoretically possible to induce persistent flow via the Aharonov-Casher effect, the strength of the electric field required is prohibitive. We also outline an experimental geometry tailored specifically for observing the He-McKellar-Wilkens effect in toroidally trapped condensates.
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Affiliation(s)
- A A Wood
- School of Physics, University of Melbourne, Victoria 3010, Australia
| | - B H J McKellar
- ARC Centre of Excellence for Particle Physics at the Terascale, School of Physics, University of Melbourne, Victoria 3010, Australia
| | - A M Martin
- School of Physics, University of Melbourne, Victoria 3010, Australia
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22
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Thaicharoen N, Gonçalves LF, Raithel G. Atom-Pair Kinetics with Strong Electric-Dipole Interactions. PHYSICAL REVIEW LETTERS 2016; 116:213002. [PMID: 27284655 DOI: 10.1103/physrevlett.116.213002] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/31/2015] [Indexed: 06/06/2023]
Abstract
Rydberg-atom ensembles are switched from a weakly to a strongly interacting regime via adiabatic transformation of the atoms from an approximately nonpolar into a highly dipolar quantum state. The resultant electric dipole-dipole forces are probed using a device akin to a field ion microscope. Ion imaging and pair-correlation analysis reveal the kinetics of the interacting atoms. Dumbbell-shaped pair-correlation images demonstrate the anisotropy of the binary dipolar force. The dipolar C_{3} coefficient, derived from the time dependence of the images, agrees with the value calculated from the permanent electric-dipole moment of the atoms. The results indicate many-body dynamics akin to disorder-induced heating in strongly coupled particle systems.
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Affiliation(s)
- N Thaicharoen
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
| | - L F Gonçalves
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
- Instituto de Física de São Carlos, Universidade de São Paulo, Caixa Postal 369, 13560-970 São Carlos, São Paulo, Brasil
| | - G Raithel
- Department of Physics, University of Michigan, Ann Arbor, Michigan 48109, USA
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23
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Zhang XF, Wen L, Dai CQ, Dong RF, Jiang HF, Chang H, Zhang SG. Exotic vortex lattices in a rotating binary dipolar Bose-Einstein condensate. Sci Rep 2016; 6:19380. [PMID: 26778736 PMCID: PMC4726089 DOI: 10.1038/srep19380] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2015] [Accepted: 12/08/2015] [Indexed: 11/29/2022] Open
Abstract
In the last decade, considerable advances have been made in the investigation of dipolar quantum gases. Previous theoretical investigations of a rotating binary dipolar Bose-Einstein condensate, where only one component possesses dipole moment, were mainly focused on two special orientations of the dipoles: perpendicular or parallel to the plane of motion. Here we study the ground-state and rotational properties of such a system for an arbitrary orientation of the dipoles. We demonstrate the ground-state vortex structures depend strongly on the relative strength between dipolar and contact interactions and the rotation frequency, as well as on the orientation of the dipoles. In the absence of rotation, the tunable dipolar interaction can be used to induce the squeezing or expansion of the cloud, and to derive the phase transition between phase coexistence and separation. Under finite rotation, the system is found to exhibit exotic ground-state vortex configurations, such as kernel-shell, vortex necklace, and compensating stripe vortex structures. We also check the validity of the Feynman relation, and find no significant deviations from it. The obtained results open up alternate ways for the quantum control of dipolar quantum gases.
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Affiliation(s)
- Xiao-Fei Zhang
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, People’s Republic of China
| | - Lin Wen
- College of Physics and Electronic Engineering, Chongqing Normal University, Chongqing 400047, People’s Republic of China
| | - Cai-Qing Dai
- School of Science, Zhejiang Agriculture and Forestry University, Lin’an, Zhejiang 311300, People’s Republic of China
| | - Rui-Fang Dong
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, People’s Republic of China
| | - Hai-Feng Jiang
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, People’s Republic of China
| | - Hong Chang
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, People’s Republic of China
| | - Shou-Gang Zhang
- Key Laboratory of Time and Frequency Primary Standards, National Time Service Center, Chinese Academy of Sciences, Xi’an 710600, People’s Republic of China
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24
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Sabari S, Jisha CP, Porsezian K, Brazhnyi VA. Dynamical stability of dipolar Bose-Einstein condensates with temporal modulation of the s-wave scattering length. Phys Rev E 2015; 92:032905. [PMID: 26465538 DOI: 10.1103/physreve.92.032905] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/20/2015] [Indexed: 11/07/2022]
Abstract
We study the stabilization properties of dipolar Bose-Einstein condensate by temporal modulation of short-range two-body interaction. Through both analytical and numerical methods, we analyze the mean-field Gross-Pitaevskii equation with short-range two-body and long-range, nonlocal, dipolar interaction terms. We derive the equation of motion and effective potential of the dipolar condensate by variational method. We show that there is an enhancement of the condensate stability due to the inclusion of dipolar interaction in addition to the two-body contact interaction. We also show that the stability of the dipolar condensate increases in the presence of time varying two-body contact interaction; the temporal modification of the contact interaction prevents the collapse of dipolar Bose-Einstein condensate. Finally we confirm the semi-analytical prediction through the direct numerical simulations of the governing equation.
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Affiliation(s)
- S Sabari
- Department of Physics, University of Pune, Pune 411007, Maharashtra, India.,Department of Physics, Pondicherry University, Puducherry 605014, Puducherry, India
| | - Chandroth P Jisha
- Centro de Física do Porto, Faculdade de Ciências, Universidade do Porto, R. Campo Alegre 687, Porto 4169-007, Portugal
| | - K Porsezian
- Department of Physics, Pondicherry University, Puducherry 605014, Puducherry, India
| | - Valeriy A Brazhnyi
- Centro de Física do Porto, Faculdade de Ciências, Universidade do Porto, R. Campo Alegre 687, Porto 4169-007, Portugal
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25
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Maier T, Kadau H, Schmitt M, Wenzel M, Ferrier-Barbut I, Pfau T, Frisch A, Baier S, Aikawa K, Chomaz L, Mark MJ, Ferlaino F, Makrides C, Tiesinga E, Petrov A, Kotochigova S. Emergence of Chaotic Scattering in Ultracold Er and Dy. PHYSICAL REVIEW. X 2015; 5:041029. [PMID: 29876143 PMCID: PMC5986194 DOI: 10.1103/physrevx.5.041029] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
We show that for ultracold magnetic lanthanide atoms chaotic scattering emerges due to a combination of anisotropic interaction potentials and Zeeman coupling under an external magnetic field. This scattering is studied in a collaborative experimental and theoretical effort for both dysprosium and erbium. We present extensive atom-loss measurements of their dense magnetic Feshbach-resonance spectra, analyze their statistical properties, and compare to predictions from a random-matrix-theory-inspired model. Furthermore, theoretical coupled-channels simulations of the anisotropic molecular Hamiltonian at zero magnetic field show that weakly bound, near threshold diatomic levels form overlapping, uncoupled chaotic series that when combined are randomly distributed. The Zeeman interaction shifts and couples these levels, leading to a Feshbach spectrum of zero-energy bound states with nearest-neighbor spacings that changes from randomly to chaotically distributed for increasing magnetic field. Finally, we show that the extreme temperature sensitivity of a small, but sizable fraction of the resonances in the Dy and Er atom-loss spectra is due to resonant nonzero partial-wave collisions. Our threshold analysis for these resonances indicates a large collision-energy dependence of the three-body recombination rate.
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Affiliation(s)
- T. Maier
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - H. Kadau
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - M. Schmitt
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - M. Wenzel
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - I. Ferrier-Barbut
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - T. Pfau
- 5. Physikalisches Institut and Center for Integrated Quantum Science and Technology, Universität Stuttgart, Pfaffenwaldring 57, 70569 Stuttgart, Germany
| | - A. Frisch
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - S. Baier
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - K. Aikawa
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - L. Chomaz
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - M. J. Mark
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - F. Ferlaino
- Institut für Experimentalphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
- Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - C. Makrides
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - E. Tiesinga
- Joint Quantum Institute and Center for Quantum Information and Computer Science, National Institute of Standards and Technology and the University of Maryland, 100 Bureau Drive, Stop 8423, Gaithersburg, Maryland 20899, USA
| | - A. Petrov
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
| | - S. Kotochigova
- Department of Physics, Temple University, Philadelphia, Pennsylvania 19122, USA
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26
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Two-component dipolar Bose-Einstein condensate in concentrically coupled annular traps. Sci Rep 2015; 5:8684. [PMID: 25731962 PMCID: PMC4346789 DOI: 10.1038/srep08684] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/11/2014] [Accepted: 01/29/2015] [Indexed: 11/30/2022] Open
Abstract
Dipolar Bosonic atoms confined in external potentials open up new avenues for quantum-state manipulation and will contribute to the design and exploration of novel functional materials. Here we investigate the ground-state and rotational properties of a rotating two-component dipolar Bose-Einstein condensate, which consists of both dipolar bosonic atoms with magnetic dipole moments aligned vertically to the condensate and one without dipole moments, confined in concentrically coupled annular traps. For the nonrotational case, it is found that the tunable dipolar interaction can be used to control the location of each component between the inner and outer rings, and to induce the desired ground-state phase. Under finite rotation, it is shown that there exists a critical value of rotational frequency for the nondipolar case, above which vortex state can form at the trap center, and the related vortex structures depend strongly on the rotational frequency. For the dipolar case, it is found that various ground-state phases and the related vortex structures, such as polygonal vortex clusters and vortex necklaces, can be obtained via a proper choice of the dipolar interaction and rotational frequency. Finally, we also study and discuss the formation process of such vortex structures.
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27
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Baillie D, Bisset RN, Ticknor C, Blakie PB. Number fluctuations of a dipolar condensate: anisotropy and slow approach to the thermodynamic regime. PHYSICAL REVIEW LETTERS 2014; 113:265301. [PMID: 25615347 DOI: 10.1103/physrevlett.113.265301] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/13/2014] [Indexed: 06/04/2023]
Abstract
We present a theory for the number fluctuations of a quasi-two-dimensional (quasi-2D) dipolar Bose-Einstein condensate measured with finite resolution cells. We show that when the dipoles are tilted to have a component parallel to the plane of the trap, the number fluctuations become anisotropic, i.e., depend on the in-plane orientation of the measurement cell. We develop analytic results for the quantum and thermal fluctuations applicable to the cell sizes accessible in experiments. We show that as cell size is increased the thermodynamic fluctuation result is approached much more slowly than in condensates with short range interactions, so experiments would not require high numerical aperture imaging to observe the predicted effect.
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Affiliation(s)
- D Baillie
- Jack Dodd Centre for Quantum Technology, Department of Physics, University of Otago, Dunedin 9016, New Zealand
| | - R N Bisset
- Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - C Ticknor
- Center for Nonlinear Studies and Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
| | - P B Blakie
- Jack Dodd Centre for Quantum Technology, Department of Physics, University of Otago, Dunedin 9016, New Zealand
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28
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Aikawa K, Frisch A, Mark M, Baier S, Grimm R, Bohn JL, Jin DS, Bruun GM, Ferlaino F. Anisotropic relaxation dynamics in a dipolar Fermi gas driven out of equilibrium. PHYSICAL REVIEW LETTERS 2014; 113:263201. [PMID: 25615326 DOI: 10.1103/physrevlett.113.263201] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/06/2014] [Indexed: 06/04/2023]
Abstract
We report on the observation of a large anisotropy in the rethermalization dynamics of an ultracold dipolar Fermi gas driven out of equilibrium. Our system consists of an ultracold sample of strongly magnetic 167Er fermions, spin polarized in the lowest Zeeman sublevel. In this system, elastic collisions arise purely from universal dipolar scattering. Based on cross-dimensional rethermalization experiments, we observe a strong anisotropy of the scattering, which manifests itself in a large angular dependence of the thermal relaxation dynamics. Our result is in good agreement with recent theoretical predictions. Furthermore, we measure the rethermalization rate as a function of temperature for different angles and find that the suppression of collisions by Pauli blocking is not influenced by the dipole orientation.
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Affiliation(s)
- K Aikawa
- Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - A Frisch
- Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - M Mark
- Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - S Baier
- Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria
| | - R Grimm
- Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria and Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
| | - J L Bohn
- JILA, NIST, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - D S Jin
- JILA, NIST, and Department of Physics, University of Colorado, Boulder, Colorado 80309, USA
| | - G M Bruun
- Department of Physics and Astronomy, University of Aarhus, Ny Munkegade, DK-8000 Aarhus C, Denmark
| | - F Ferlaino
- Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, Technikerstraße 25, 6020 Innsbruck, Austria and Institut für Quantenoptik und Quanteninformation, Österreichische Akademie der Wissenschaften, 6020 Innsbruck, Austria
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29
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Li Y, Wu C. Unconventional symmetries of Fermi liquid and Cooper pairing properties with electric and magnetic dipolar fermions. JOURNAL OF PHYSICS. CONDENSED MATTER : AN INSTITUTE OF PHYSICS JOURNAL 2014; 26:493203. [PMID: 25401291 DOI: 10.1088/0953-8984/26/49/493203] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The rapid experimental progress of ultra-cold dipolar fermions opens up a whole new opportunity to investigate novel many-body physics of fermions. In this article, we review theoretical studies of the Fermi liquid theory and Cooper pairing instabilities of both electric and magnetic dipolar fermionic systems from the perspective of unconventional symmetries. When the electric dipole moments are aligned by the external electric field, their interactions exhibit the explicit d(r(2)-3z(2)) anisotropy. The Fermi liquid properties, including the single-particle spectra, thermodynamic susceptibilities and collective excitations, are all affected by this anisotropy. The electric dipolar interaction provides a mechanism for the unconventional spin triplet Cooper pairing, which is different from the usual spin-fluctuation mechanism in solids and the superfluid (3)He. Furthermore, the competition between pairing instabilities in the singlet and triplet channels gives rise to a novel time-reversal symmetry breaking superfluid state. Unlike electric dipole moments which are induced by electric fields and unquantized, magnetic dipole moments are intrinsic proportional to the hyperfine-spin operators with a Lande factor. Its effects even manifest in unpolarized systems exhibiting an isotropic but spin-orbit coupled nature. The resultant spin-orbit coupled Fermi liquid theory supports a collective sound mode exhibiting a topologically non-trivial spin distribution over the Fermi surface. It also leads to a novel p-wave spin triplet Cooper pairing state whose spin and orbital angular momentum are entangled to the total angular momentum J = 1 dubbed the J-triplet pairing. This J-triplet pairing phase is different from both the spin-orbit coupled (3)He-B phase with J = 0 and the spin-orbit decoupled (3)He-A phase.
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Affiliation(s)
- Yi Li
- Princeton Center for Theoretical Science, Princeton University, Princeton, NJ 08544, USA
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30
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Wave instabilities in the presence of non vanishing background in nonlinear Schrödinger systems. Sci Rep 2014; 4:7285. [PMID: 25468032 PMCID: PMC4252897 DOI: 10.1038/srep07285] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2014] [Accepted: 11/14/2014] [Indexed: 11/30/2022] Open
Abstract
We investigate wave collapse ruled by the generalized nonlinear Schrödinger (NLS) equation in 1+1 dimensions, for localized excitations with non-zero background, establishing through virial identities a new criterion for blow-up. When collapse is arrested, a semiclassical approach allows us to show that the system can favor the formation of dispersive shock waves. The general findings are illustrated with a model of interest to both classical and quantum physics (cubic-quintic NLS equation), demonstrating a radically novel scenario of instability, where solitons identify a marginal condition between blow-up and occurrence of shock waves, triggered by arbitrarily small mass perturbations of different sign.
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31
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Kotochigova S. Controlling interactions between highly magnetic atoms with Feshbach resonances. REPORTS ON PROGRESS IN PHYSICS. PHYSICAL SOCIETY (GREAT BRITAIN) 2014; 77:093901. [PMID: 25221938 DOI: 10.1088/0034-4885/77/9/093901] [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
This paper reviews current experimental and theoretical progress in the study of dipolar quantum gases of ground and meta-stable atoms with a large magnetic moment. We emphasize the anisotropic nature of Feshbach resonances due to coupling to fast-rotating resonant molecular states in ultracold s-wave collisions between magnetic atoms in external magnetic fields. The dramatic differences in the distribution of resonances of magnetic (7)S3 chromium and magnetic lanthanide atoms with a submerged 4f shell and non-zero electron angular momentum is analyzed. We focus on dysprosium and erbium as important experimental advances have been recently made to cool and create quantum-degenerate gases for these atoms. Finally, we describe progress in locating resonances in collisions of meta-stable magnetic atoms in electronic P-states with ground-state atoms, where an interplay between collisional anisotropies and spin-orbit coupling exists.
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32
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Eto Y, Saito H, Hirano T. Observation of dipole-induced spin texture in an 87Rb Bose-Einstein condensate. PHYSICAL REVIEW LETTERS 2014; 112:185301. [PMID: 24856705 DOI: 10.1103/physrevlett.112.185301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/26/2014] [Indexed: 06/03/2023]
Abstract
We report the formation of spin texture resulting from the magnetic dipole-dipole interaction in a spin-2 87Rb Bose-Einstein condensate. The spinor condensate is prepared in the transversely polarized spin state and the time evolution is observed under a magnetic field of 90 mG with a gradient of 3 mG/cm using Stern-Gerlach imaging. The experimental results are compared with numerical simulations of the Gross-Pitaevskii equation, which reveals that the observed spatial modulation of the longitudinal magnetization is due to the spin precession in an effective magnetic field produced by the dipole-dipole interaction. These results show that the dipole-dipole interaction has considerable effects even on spinor condensates of alkali metal atoms.
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Affiliation(s)
- Yujiro Eto
- Department of Physics, Gakushuin University, Toshima, Tokyo 171-8588, Japan
| | - Hiroki Saito
- Department of Engineering Science, University of Electro-Communications, Chofu, Tokyo 182-8585, Japan
| | - Takuya Hirano
- Department of Physics, Gakushuin University, Toshima, Tokyo 171-8588, Japan
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33
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Gopalakrishnan S, Martin I, Demler EA. Quantum quasicrystals of spin-orbit-coupled dipolar bosons. PHYSICAL REVIEW LETTERS 2013; 111:185304. [PMID: 24237533 DOI: 10.1103/physrevlett.111.185304] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/10/2013] [Indexed: 06/02/2023]
Abstract
We study quasi-two-dimensional dipolar Bose gases in which the bosons experience a Rashba spin-orbit coupling. We show that the degenerate dispersion minimum due to the spin-orbit coupling, combined with the long-range dipolar interaction, can stabilize a number of quantum crystalline and quasicrystalline ground states. Coupling the bosons to a fermionic species can further stabilize these phases. We estimate that the crystalline and quasicrystalline phases should be detectable in realistic dipolar condensates, e.g., dysprosium, and discuss their symmetries and excitations.
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34
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Mulkerin BC, van Bijnen RMW, O'Dell DHJ, Martin AM, Parker NG. Anisotropic and long-range vortex interactions in two-dimensional dipolar Bose gases. PHYSICAL REVIEW LETTERS 2013; 111:170402. [PMID: 24206463 DOI: 10.1103/physrevlett.111.170402] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/13/2013] [Indexed: 06/02/2023]
Abstract
We perform a theoretical study into how dipole-dipole interactions modify the properties of superfluid vortices within the context of a two-dimensional atomic Bose gas of co-oriented dipoles. The reduced density at a vortex acts like a giant antidipole, changing the density profile and generating an effective dipolar potential centred at the vortex core whose most slowly decaying terms go as 1/ρ(2) and ln(ρ)/ρ(3). These effects modify the vortex-vortex interaction which, in particular, becomes anisotropic for dipoles polarized in the plane. Striking modifications to vortex-vortex dynamics are demonstrated, i.e., anisotropic corotation dynamics and the suppression of vortex annihilation.
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Affiliation(s)
- B C Mulkerin
- School of Physics, University of Melbourne, Victoria 3010, Australia
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35
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Bismut G, Laburthe-Tolra B, Maréchal E, Pedri P, Gorceix O, Vernac L. Anisotropic excitation spectrum of a dipolar quantum Bose gas. PHYSICAL REVIEW LETTERS 2012; 109:155302. [PMID: 23102324 DOI: 10.1103/physrevlett.109.155302] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/25/2012] [Indexed: 06/01/2023]
Abstract
We measure the excitation spectrum of a dipolar chromium Bose-Einstein condensate with Raman-Bragg spectroscopy. The energy spectrum depends on the orientation of the dipoles with respect to the excitation momentum, demonstrating an anisotropy that originates from the dipole-dipole interactions between the atoms. We compare our results with the Bogoliubov theory based on the local density approximation and, at large excitation wavelengths, with the numerical simulations of the time-dependent Gross-Pitaevskii equation. Our results show an anisotropy of the speed of sound.
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Affiliation(s)
- G Bismut
- Laboratoire de Physique des Lasers, UMR 7538 CNRS, Université Paris 13, Villetaneuse, France
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36
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Baranov MA, Dalmonte M, Pupillo G, Zoller P. Condensed Matter Theory of Dipolar Quantum Gases. Chem Rev 2012; 112:5012-61. [DOI: 10.1021/cr2003568] [Citation(s) in RCA: 480] [Impact Index Per Article: 40.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- M. A. Baranov
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
- RRC “Kurchatov Institute”,
Kurchatov Square 1, 123182, Moscow, Russia
| | - M. Dalmonte
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Dipartimento di Fisica dell’Università
di Bologna, via Irnerio 46, 40126 Bologna, Italy
| | - G. Pupillo
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
- ISIS (UMR 7006) and IPCMS (UMR
7504), Université de Strasbourg and CNRS, Strasbourg, France
| | - P. Zoller
- Institute for Quantum Optics and Quantum Information of the Austrian Academy of Sciences, A-6020 Innsbruck, Austria
- Institute for Theoretical Physics, University of Innsbruck, A-6020 Innsbruck, Austria
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37
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Aikawa K, Frisch A, Mark M, Baier S, Rietzler A, Grimm R, Ferlaino F. Bose-Einstein condensation of erbium. PHYSICAL REVIEW LETTERS 2012; 108:210401. [PMID: 23003221 DOI: 10.1103/physrevlett.108.210401] [Citation(s) in RCA: 113] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/06/2012] [Indexed: 06/01/2023]
Abstract
We report on the achievement of Bose-Einstein condensation of erbium atoms and on the observation of magnetic Feshbach resonances at low magnetic fields. By means of evaporative cooling in an optical dipole trap, we produce pure condensates of 168Er, containing up to 7×10(4) atoms. Feshbach spectroscopy reveals an extraordinary rich loss spectrum with six loss resonances already in a narrow magnetic-field range up to 3 G. Finally, we demonstrate the application of a low-field Feshbach resonance to produce a tunable dipolar Bose-Einstein condensate and we observe its characteristic d-wave collapse.
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Affiliation(s)
- K Aikawa
- Institut für Experimentalphysik and Zentrum für Quantenphysik, Universität Innsbruck, Innsbruck, Austria
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38
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39
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Maucher F, Henkel N, Saffman M, Królikowski W, Skupin S, Pohl T. Rydberg-induced solitons: three-dimensional self-trapping of matter waves. PHYSICAL REVIEW LETTERS 2011; 106:170401. [PMID: 21635018 DOI: 10.1103/physrevlett.106.170401] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/11/2011] [Indexed: 05/30/2023]
Abstract
We propose a scheme for the creation of stable three-dimensional bright solitons in Bose-Einstein condensates, i.e., the matter-wave analog of so-called spatiotemporal "light bullets." Off-resonant dressing to Rydberg nD states is shown to provide nonlocal attractive interactions, leading to self-trapping of mesoscopic atomic clouds by a collective excitation of a Rydberg atom pair. We present detailed potential calculations and demonstrate the existence of stable solitons under realistic experimental conditions by means of numerical simulations.
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Affiliation(s)
- F Maucher
- Max Planck Institute for the Physics of Complex Systems, 01187 Dresden, Germany
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40
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Gawryluk K, Bongs K, Brewczyk M. How to observe dipolar effects in spinor Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2011; 106:140403. [PMID: 21561171 DOI: 10.1103/physrevlett.106.140403] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/01/2010] [Indexed: 05/30/2023]
Abstract
We propose an experiment which proves the possibility of spinning gaseous media via dipolar interactions in the spirit of the famous Einstein-de Haas effect for ferromagnets. The main idea is to utilize resonances that we find in spinor condensates of alkali atoms while these systems are placed in an oscillating magnetic field. A significant transfer of angular momentum from spin to motional degrees of freedom observed on resonance is a spectacular manifestation of dipolar effects in spinor condensates.
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Affiliation(s)
- Krzysztof Gawryluk
- Wydział Fizyki, Uniwersytet w Białymstoku, ul. Lipowa 41, 15-424 Białystok, Poland
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41
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Ticknor C, Wilson RM, Bohn JL. Anisotropic superfluidity in a dipolar Bose gas. PHYSICAL REVIEW LETTERS 2011; 106:065301. [PMID: 21405474 DOI: 10.1103/physrevlett.106.065301] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/12/2010] [Revised: 12/13/2010] [Indexed: 05/30/2023]
Abstract
We study the superfluid character of a dipolar Bose-Einstein condensate (DBEC) in a quasi-two dimensional geometry. We consider the dipole polarization to have some nonzero projection into the plane of the condensate so that the effective interaction is anisotropic in this plane, yielding an anisotropic dispersion relation. By performing direct numerical simulations of a probe moving through the DBEC, we observe the sudden onset of drag or creation of vortex-antivortex pairs at critical velocities that depend strongly on the direction of the probe's motion. This anisotropy emerges because of the anisotropic manifestation of a rotonlike mode in the system.
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Affiliation(s)
- Christopher Ticknor
- Theoretical Division, Los Alamos National Laboratory, Los Alamos, New Mexico 87545, USA
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42
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Pasquiou B, Bismut G, Maréchal E, Pedri P, Vernac L, Gorceix O, Laburthe-Tolra B. Spin relaxation and band excitation of a dipolar Bose-Einstein condensate in 2D optical lattices. PHYSICAL REVIEW LETTERS 2011; 106:015301. [PMID: 21231749 DOI: 10.1103/physrevlett.106.015301] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/15/2010] [Revised: 11/25/2010] [Indexed: 05/30/2023]
Abstract
We observe interband transitions mediated by dipole-dipole interactions for an array of 1D quantum gases of chromium atoms, trapped in a 2D optical lattice. Interband transitions occur when dipolar relaxation releases an energy larger than the lattice band gap. For symmetric lattice sites, and a magnetic field parallel to the lattice axis, we compare the measured dipolar relaxation rate with a Fermi golden rule calculation. Below a magnetic field threshold, we obtain an almost complete suppression of dipolar relaxation, leading to metastable 1D gases in the highest Zeeman state.
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Affiliation(s)
- B Pasquiou
- Laboratoire de Physique des Lasers, CNRS UMR 7538, Université Paris 13, 99 Avenue J.-B. Clément, 93430 Villetaneuse, France
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43
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Pikovski A, Klawunn M, Shlyapnikov GV, Santos L. Interlayer superfluidity in bilayer systems of fermionic polar molecules. PHYSICAL REVIEW LETTERS 2010; 105:215302. [PMID: 21231317 DOI: 10.1103/physrevlett.105.215302] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 08/24/2010] [Revised: 10/12/2010] [Indexed: 05/30/2023]
Abstract
We consider fermionic polar molecules in a bilayer geometry where they are oriented perpendicularly to the layers, which permits both low inelastic losses and superfluid pairing. The dipole-dipole interaction between molecules of different layers leads to the emergence of interlayer superfluids. The superfluid regimes range from BCS-like fermionic superfluidity with a high Tc to Bose-Einstein (quasi-)condensation of interlayer dimers, thus exhibiting a peculiar BCS-Bose-Einstein condensation crossover. We show that one can cover the entire crossover regime under current experimental conditions.
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Affiliation(s)
- A Pikovski
- Institut für Theoretische Physik, Leibniz Universität Hannover, Appelstrasse 2, 30169, Hannover, Germany
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44
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Bismut G, Pasquiou B, Maréchal E, Pedri P, Vernac L, Gorceix O, Laburthe-Tolra B. Collective excitations of a dipolar Bose-Einstein condensate. PHYSICAL REVIEW LETTERS 2010; 105:040404. [PMID: 20867824 DOI: 10.1103/physrevlett.105.040404] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/14/2010] [Indexed: 05/29/2023]
Abstract
We have measured the effect of dipole-dipole interactions on the frequency of a collective mode of a Bose-Einstein condensate. At relatively large numbers of atoms, the experimental measurements are in good agreement with zero temperature theoretical predictions based on the Thomas-Fermi approach. Experimental results obtained for the dipolar shift of a collective mode show a larger dependency to both the trap geometry and the atom number than the ones obtained when measuring the modification of the condensate aspect ratio due to dipolar forces. These findings are in good agreement with simulations based on a Gaussian ansatz.
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Affiliation(s)
- G Bismut
- Laboratoire de Physique des Lasers, CNRS UMR 7538, Université Paris 13, 99 Avenue J.-B. Clément, 93430 Villetaneuse, France
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45
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Lahaye T, Pfau T, Santos L. Mesoscopic ensembles of polar bosons in triple-well potentials. PHYSICAL REVIEW LETTERS 2010; 104:170404. [PMID: 20482095 DOI: 10.1103/physrevlett.104.170404] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/27/2009] [Revised: 02/25/2010] [Indexed: 05/29/2023]
Abstract
Mesoscopic dipolar Bose gases in triple-well potentials offer a minimal system for the analysis of the nonlocal character of the dipolar interaction. We show that this nonlocal character may be clearly revealed by a variety of possible ground-state phases. In addition, an appropriate control of short-range and dipolar interactions may lead to novel scenarios for the dynamics of polar bosons in lattices, including the dynamical creation of mesoscopic quantum superpositions, which may be employed in the design of Heisenberg-limited atom interferometers.
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Affiliation(s)
- T Lahaye
- Université de Toulouse, UPS, Laboratoire Collisions Agrégats Réactivité, IRSAMC; F-31062 Toulouse, France
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46
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Rutkowska KA, Malomed BA, Morandotti R. Control of the collapse of bimodal light beams by magnetically tunable birefringences. OPTICS EXPRESS 2010; 18:8879-8895. [PMID: 20588733 DOI: 10.1364/oe.18.008879] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/29/2023]
Abstract
Using a system of coupled nonlinear Schrödinger equations (CNLSEs), we show that nonlinear light propagation in self-focusing Kerr media can be controlled via a suitable combination of linear and circular birefringences. In particular, magneto-optical effects are taken as a specific physical example, which enables the introduction of both types of birefringences simultaneously via the joint action of the Cotton-Mouton and the Faraday effect. We demonstrate the efficient management of the collapse of (2 + 1)D beams in magneto-optic dielectric media, which may result in either the acceleration or the suppression of the collapse. However, our study also shows that a complete stabilization of the bimodal beams (i.e., the propagation of two-dimensional solitary waves) is not possible under the proposed conditions. The analysis is performed by directly numerically solving the CNLSEs, as well as by using the variational approximation, both showing consistent results. The investigated method allows high-power beam propagation in Kerr media while avoiding collapse, thus offering a viable alternative to the techniques applied in non-instantaneous and/or non-local nonlinear media.
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47
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Wang Y, D'Incao JP, Nägerl HC, Esry BD. Colliding Bose-Einstein condensates to observe Efimov physics. PHYSICAL REVIEW LETTERS 2010; 104:113201. [PMID: 20366473 DOI: 10.1103/physrevlett.104.113201] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/30/2009] [Indexed: 05/29/2023]
Abstract
We explore the manifestation of Efimov physics through the collision energy dependence of the three-body scattering observables and propose that it can be measured by observing atom loss in collisions of Bose-Einstein condensates. Our study shows that log-periodic Efimov features in the scattering observables extend beyond the usual threshold regime to nonzero collision energies and result from two interfering pathways. Further, these oscillations have a one-to-one connection with the scattering length oscillations at zero energy and thus to Efimov states themselves.
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Affiliation(s)
- Yujun Wang
- Department of Physics, Kansas State University, Manhattan, Kansas 66506, USA
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48
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Wilson RM, Ronen S, Bohn JL. Critical superfluid velocity in a trapped dipolar gas. PHYSICAL REVIEW LETTERS 2010; 104:094501. [PMID: 20366986 DOI: 10.1103/physrevlett.104.094501] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/29/2009] [Revised: 01/28/2010] [Indexed: 05/29/2023]
Abstract
We investigate the superfluid properties of a dipolar Bose-Einstein condensate (BEC) in a fully three-dimensional trap. Specifically, we estimate a superfluid critical velocity for this system by applying the Landau criterion to its discrete quasiparticle spectrum. We test this critical velocity by direct numerical simulation of condensate depletion as a blue-detuned laser moves through the condensate. In both cases, the presence of the roton in the spectrum serves to lower the critical velocity beyond a critical particle number. Since the shape of the dispersion, and hence the roton minimum, is tunable as a function of particle number, we thereby propose an experiment that can simultaneously measure the Landau critical velocity of a dipolar BEC and demonstrate the presence of the roton in this system.
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Affiliation(s)
- Ryan M Wilson
- JILA and Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA.
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49
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Cherng RW, Demler E. Magnetoroton softening in Rb spinor condensates with dipolar interactions. PHYSICAL REVIEW LETTERS 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] [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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50
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Linzon Y, Rutkowska KA, Malomed BA, Morandotti R. Magneto-optical control of light collapse in bulk Kerr media. PHYSICAL REVIEW LETTERS 2009; 103:053902. [PMID: 19792500 DOI: 10.1103/physrevlett.103.053902] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/18/2009] [Indexed: 05/28/2023]
Abstract
The Cotton-Mouton (Voigt) and Faraday effects induce adjustable linear and circular birefringence in optical media with external magnetic fields. We consider these effects as a technique for magneto-optical control of the transmission of bimodal light beams through Kerr-nonlinear crystals. Numerical analysis suggests that a properly applied magnetic field may accelerate, delay, or arrest the collapse of (2+1)D beams. Experimentally, the magnetic collapse acceleration is demonstrated in a bulk yttrium iron garnet (YIG) crystal.
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Affiliation(s)
- Y Linzon
- Université du Quebec, Institute National de la Recherche Scientifique, Varennes, Quebec J3X 1S2, Canada
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