1
|
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'.
Collapse
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
| |
Collapse
|
2
|
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.
Collapse
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
| |
Collapse
|
3
|
The Irreversible Quantum Dynamics of the Three-Level su(1, 1) Bosonic Model. Symmetry (Basel) 2022. [DOI: 10.3390/sym14122542] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/03/2022] Open
Abstract
We study the quantum dynamics of the opened three-level su(1, 1) bosonic model. The effective non-Hermitian Hamiltonians describing the system of the Lindblad equation in the short time limit are constructed. The obtained non-Hermitian Hamiltonians are exactly solvable by the Algebraic Bethe Ansatz. This approach allows representing biorthogonal and nonorthogonal bases of the system. We analyze the biorthogonal expectation values of a number of particles in the zero mode and represent it in the determinantal form. The time-dependent density matrix satisfying the Lindblad master equation is found in terms of the nonorthogonal basis.
Collapse
|
4
|
Zou YQ, Bakkali-Hassani B, Maury C, Le Cerf É, Nascimbene S, Dalibard J, Beugnon J. Magnetic Dipolar Interaction between Hyperfine Clock States in a Planar Alkali Bose Gas. PHYSICAL REVIEW LETTERS 2020; 125:233604. [PMID: 33337228 DOI: 10.1103/physrevlett.125.233604] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 07/28/2020] [Accepted: 11/04/2020] [Indexed: 06/12/2023]
Abstract
In atomic systems, clock states feature a zero projection of the total angular momentum and thus a low sensitivity to magnetic fields. This makes them widely used for metrological applications like atomic fountains or gravimeters. Here, we show that a mixture of two such nonmagnetic states still displays magnetic dipole-dipole interactions comparable to the one expected for the other Zeeman states of the same atomic species. Using high-resolution spectroscopy of a planar gas of ^{87}Rb atoms with a controlled in plane shape, we explore the effective isotropic and extensive character of these interactions and demonstrate their tunability. Our measurements set strong constraints on the relative values of the s-wave scattering lengths a_{ij} involving the two clock states.
Collapse
Affiliation(s)
- Y-Q Zou
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - B Bakkali-Hassani
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - C Maury
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - É Le Cerf
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - S Nascimbene
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - J Dalibard
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| | - J Beugnon
- Laboratoire Kastler Brossel, Collège de France, CNRS, ENS-PSL University, Sorbonne Université, 11 Place Marcelin Berthelot, 75005 Paris, France
| |
Collapse
|
5
|
Effects of dipolar interactions on the sensitivity of nonlinear spinor-BEC interterometry. Sci Rep 2018; 8:3218. [PMID: 29459778 PMCID: PMC5818612 DOI: 10.1038/s41598-018-21566-9] [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: 10/12/2017] [Accepted: 01/25/2018] [Indexed: 11/09/2022] Open
Abstract
We consider the effects of dipole-dipole interactions on a nonlinear interferometer with spin-1 Bose-Einstein condensates. Compared with the traditional atomic SU(1,1) interferometer, the shot-noise phase sensitivity can be beaten with respect to the input total average number of particles; and the improved sensitivity depends on the effective strength of the dipolar interaction via modifying the trapping geometry. It indicates that the best performance of the interferometer is achieved with highly oblate trap potential. The Bayesian phase estimation strategy is explored to extract the phase information. We show that the Cramér-Rao phase uncertainly bound can saturate, when the ideal dis-entangle scheme is applied. The phase average of the phase sensitivity is also discussed.
Collapse
|
6
|
Xu P, Sun H, Yi S, Zhang W. Rebuilding of destroyed spin squeezing in noisy environments. Sci Rep 2017; 7:14102. [PMID: 29074937 PMCID: PMC5658406 DOI: 10.1038/s41598-017-14442-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Accepted: 10/10/2017] [Indexed: 11/09/2022] Open
Abstract
We investigate the process of spin squeezing in a ferromagnetic dipolar spin-1 Bose-Einstein condensate under the driven one-axis twisting scheme, with emphasis on the detrimental effect of noisy environments (stray magnetic fields) which completely destroy the spin squeezing. By applying concatenated dynamical decoupling pulse sequences with a moderate bias magnetic field to suppress the effect of the noisy environments, we faithfully reconstruct the spin squeezing process under realistic experimental conditions. Our noise-resistant method is ready to be employed to generate the spin squeezed state in a dipolar spin-1 Bose-Einstein condensate and paves a feasible way to the Heisenberg-limit quantum metrology.
Collapse
Affiliation(s)
- Peng Xu
- School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, China
| | - Huanying Sun
- School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, China
| | - S Yi
- CAS Key Laboratory of Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing, 100190, China
| | - Wenxian Zhang
- School of Physics and Technology, Wuhan University, Wuhan, Hubei, 430072, China.
| |
Collapse
|
7
|
Huang Y, Xiong HN, Yang Y, Hu ZD, Xi Z. Quantum control of spin-nematic squeezing in a dipolar spin-1 condensate. Sci Rep 2017; 7:43159. [PMID: 28233786 PMCID: PMC5324127 DOI: 10.1038/srep43159] [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: 10/04/2016] [Accepted: 01/20/2017] [Indexed: 11/09/2022] Open
Abstract
Versatile controllability of interactions and magnetic field in ultracold atomic gases ha now reached an era where spin mixing dynamics and spin-nematic squeezing can be studied. Recent experiments have realized spin-nematic squeezed vacuum and dynamic stabilization following a quench through a quantum phase transition. Here we propose a scheme for storage of maximal spin-nematic squeezing, with its squeezing angle maintained in a fixed direction, in a dipolar spin-1 condensate by applying a microwave pulse at a time that maximal squeezing occurs. The dynamic stabilization of the system is achieved by manipulating the external periodic microwave pulses. The stability diagram for the range of pulse periods and phase shifts that stabilize the dynamics is numerical simulated and agrees with a stability analysis. Moreover, the stability range coincides well with the spin-nematic vacuum squeezed region which indicates that the spin-nematic squeezed vacuum will never disappear as long as the spin dynamics are stabilized.
Collapse
Affiliation(s)
- Yixiao Huang
- School of Science, Zhejiang University of Science and Technology, Hangzhou, Zhejiang, 310023, China.,College of Computer Science, Shaanxi Normal University, Xi'an 710062, China
| | - Heng-Na Xiong
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
| | - Yang Yang
- Department of Applied Physics, Zhejiang University of Technology, Hangzhou 310023, China
| | - Zheng-Da Hu
- Jiangsu Provincial Research Center of Light Industrial Optoelectronic Engineering and Technology, School of Science, Jiangnan University, Wuxi 214122, China
| | - Zhengjun Xi
- College of Computer Science, Shaanxi Normal University, Xi'an 710062, China
| |
Collapse
|
8
|
Phase diagram and spin mixing dynamics in spinor condensates with a microwave dressing field. Sci Rep 2015; 5:14464. [PMID: 26403676 PMCID: PMC4585920 DOI: 10.1038/srep14464] [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: 03/27/2015] [Accepted: 07/21/2015] [Indexed: 11/10/2022] Open
Abstract
Spinor condensates immersed in a microwave dressing field, which access both negative and positive values of the net quadratic Zeeman effect, have been realized in a recent experiment. In this report, we study the ground state properties of a spinor condensate with a microwave dressing field which enables us to access both negative and positive values of quadratic Zeeman energy. The ground state exhibits three different phases by varying the magnetization and the net quadratic Zeeman energy for both cases of ferromagnetic and antiferromagnetic interactions. We investigate the atomic-number fluctuations of the ground state and show that the hyperfine state displays super-Poissonian and sub-Poissonian distributions in the different phases. We also discuss the dynamical properties and show that the separatrix has a remarkable relation to the magnetization.
Collapse
|
9
|
Armaitis J, Duine RA, Stoof HTC. Quantum rotor model for a Bose-Einstein condensate of dipolar molecules. PHYSICAL REVIEW LETTERS 2013; 111:215301. [PMID: 24313496 DOI: 10.1103/physrevlett.111.215301] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2013] [Revised: 09/02/2013] [Indexed: 06/02/2023]
Abstract
We show that a Bose-Einstein condensate of heteronuclear molecules in the regime of small and static electric fields is described by a quantum rotor model for the macroscopic electric dipole moment of the molecular gas cloud. We solve this model exactly and find the symmetric, i.e., rotationally invariant, and dipolar phases expected from the single-molecule problem, but also an axial and planar nematic phase due to many-body effects. Investigation of the wave function of the macroscopic dipole moment also reveals squeezing of the probability distribution for the angular momentum of the molecules.
Collapse
Affiliation(s)
- J Armaitis
- Institute for Theoretical Physics, Utrecht University, Leuvenlaan 4, 3584 CE Utrecht, The Netherlands
| | | | | |
Collapse
|
10
|
Maluckov A, Gligorić G, Hadžievski L, Malomed BA, Pfau T. Stable periodic density waves in dipolar Bose-Einstein condensates trapped in optical lattices. PHYSICAL REVIEW LETTERS 2012; 108:140402. [PMID: 22540773 DOI: 10.1103/physrevlett.108.140402] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/07/2011] [Indexed: 05/31/2023]
Abstract
Density-wave patterns in discrete media with local interactions are known to be unstable. We demonstrate that stable double- and triple-period patterns (DPPs and TPPs), with respect to the period of the underlying lattice, exist in media with nonlocal nonlinearity. This is shown in detail for dipolar Bose-Einstein condensates, loaded into a deep one-dimensional optical lattice. The DPP and TPP emerge via phase transitions of the second and first kind, respectively. The emerging patterns may be stable if the dipole-dipole interactions are repulsive and sufficiently strong, in comparison with the local repulsive nonlinearity. Within the set of the considered states, the TPPs realize a minimum of the free energy. A vast stability region for the TPPs is found in the parameter space, while the DPP stability region is relatively narrow. The same mechanism may create stable density-wave patterns in other physical media featuring nonlocal interactions.
Collapse
Affiliation(s)
- Aleksandra Maluckov
- Faculty of Sciences and Mathematics, University of Niš, Post Office Box 224, 18000 Niš, Serbia
| | | | | | | | | |
Collapse
|
11
|
Yasunaga M, Tsubota M. Spin echo in spinor dipolar Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2008; 101:220401. [PMID: 19113463 DOI: 10.1103/physrevlett.101.220401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/03/2008] [Indexed: 05/27/2023]
Abstract
We theoretically propose and numerically realize spin echo in a spinor Bose-Einstein condensate (BEC). We investigate the influence on the spin echo of phase separation of the condensate. The equation of motion of the spin density exhibits two relaxation times. We use two methods to separate the relaxation times and hence demonstrate a technique to reveal magnetic dipole-dipole interactions in spinor BECs.
Collapse
Affiliation(s)
- Masashi Yasunaga
- Department of Physics, Osaka City University, Osaka 558-8585, Japan
| | | |
Collapse
|
12
|
Sawyer BC, Stuhl BK, Wang D, Yeo M, Ye J. Molecular beam collisions with a magnetically trapped target. PHYSICAL REVIEW LETTERS 2008; 101:203203. [PMID: 19113337 DOI: 10.1103/physrevlett.101.203203] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/16/2008] [Indexed: 05/27/2023]
Abstract
Cold, neutral hydroxyl radicals are Stark decelerated and efficiently loaded into a permanent magnetic trap. The OH molecules are trapped in the rovibrational ground state at a density of approximately 10;{6} cm;{-3} and temperature of 70 mK. Collision studies between the trapped OH sample and supersonic beams of atomic He and molecular D2 determine absolute collision cross sections. The He-OH and D2-OH center-of-mass collision energies are tuned from 60 cm;{-1} to 230 cm;{-1} and 145 cm;{-1} to 510 cm;{-1}, respectively, yielding evidence of quantum threshold scattering and resonant energy transfer between colliding particles.
Collapse
Affiliation(s)
- Brian C Sawyer
- JILA, National Institute of Standards and Technology and the University of Colorado Department of Physics, University of Colorado, Boulder, Colorado 80309-0440, USA
| | | | | | | | | |
Collapse
|
13
|
Cherng RW, Gritsev V, Stamper-Kurn DM, Demler E. Dynamical instability of the XY spiral state of ferromagnetic condensates. PHYSICAL REVIEW LETTERS 2008; 100:180404. [PMID: 18518354 DOI: 10.1103/physrevlett.100.180404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/22/2007] [Revised: 01/09/2008] [Indexed: 05/26/2023]
Abstract
We calculate the spectrum of collective excitations of the XY spiral state prepared adiabatically or suddenly from a uniform ferromagnetic F=1 condensate. For spiral wave vectors past a critical value, spin wave excitation energies become imaginary indicating a dynamical instability. We construct phase diagrams as functions of spiral wave vector and quadratic Zeeman energy.
Collapse
Affiliation(s)
- R W Cherng
- Physics Department, Harvard University, Cambridge, Massachusetts 02138, USA
| | | | | | | |
Collapse
|
14
|
Yi S, Li T, Sun CP. Novel quantum phases of dipolar bose gases in optical lattices. PHYSICAL REVIEW LETTERS 2007; 98:260405. [PMID: 17678073 DOI: 10.1103/physrevlett.98.260405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/01/2007] [Indexed: 05/16/2023]
Abstract
We investigate the quantum phases of polarized dipolar bosons loaded into a two-dimensional square and three-dimensional cubic optical lattices. We show that the long-range and anisotropic nature of the dipole-dipole interaction induces a rich variety of quantum phases, including the supersolid and striped supersolid phases in two-dimensional lattices, and the layered supersolid phase in three-dimensional lattices.
Collapse
Affiliation(s)
- S Yi
- Institute of Theoretical Physics, Chinese Academy of Sciences, Beijing, 100080, People's Republic of China
| | | | | |
Collapse
|
15
|
Bortolotti DCE, Ronen S, Bohn JL, Blume D. Scattering length instability in dipolar Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2006; 97:160402. [PMID: 17155376 DOI: 10.1103/physrevlett.97.160402] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/18/2006] [Indexed: 05/12/2023]
Abstract
We predict a new kind of instability in a Bose-Einstein condensate composed of dipolar particles. Namely, a comparatively weak dipole moment can produce a large, negative two-body scattering length that can collapse the Bose-Einstein condensate. To verify this effect, we validate mean-field solutions to this problem using exact, diffusion Monte Carlo methods. We show that the diffusion Monte Carlo energies are reproduced accurately within a mean-field framework if the variation of the s-wave scattering length with the dipole strength is accounted for properly.
Collapse
Affiliation(s)
- D C E Bortolotti
- JILA, NIST and Department of Physics, University of Colorado, Boulder, CO 80309-0440, USA
| | | | | | | |
Collapse
|
16
|
Bhattacharya M, Raman C. Detecting level crossings without looking at the spectrum. PHYSICAL REVIEW LETTERS 2006; 97:140405. [PMID: 17155226 DOI: 10.1103/physrevlett.97.140405] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/31/2006] [Indexed: 05/12/2023]
Abstract
In many physical systems it is important to be aware of the crossings and avoided crossings which occur when eigenvalues of a physical observable are varied using an external parameter. We have discovered a powerful algebraic method of finding such crossings via a mapping to the problem of locating the roots of a polynomial in that parameter. We demonstrate our method on atoms and molecules in a magnetic field, where it has implications in the search for Feshbach resonances. In the atomic case our method allows us to point out a new class of invariants of the Breit-Rabi Hamiltonian of magnetic resonance. In the case of molecules, it enables us to find curve crossings with practically no knowledge of the corresponding Born-Oppenheimer potentials.
Collapse
Affiliation(s)
- M Bhattacharya
- School of Physics, Georgia Institute of Technology, Atlanta, Georgia 30332, USA
| | | |
Collapse
|
17
|
Kawaguchi Y, Saito H, Ueda M. Spontaneous circulation in ground-state spinor dipolar Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2006; 97:130404. [PMID: 17026015 DOI: 10.1103/physrevlett.97.130404] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 06/12/2006] [Indexed: 05/12/2023]
Abstract
We report on a study of the spin-1 ferromagnetic Bose-Einstein condensate with magnetic dipole-dipole interactions. By solving the nonlocal Gross-Pitaevskii equations for this system, we find three ground-state phases. Moreover, we show that a substantial orbital angular momentum accompanied by chiral symmetry breaking emerges spontaneously in a certain parameter regime. We predict that all these phases can be observed in the spin-1 87Rb condensate by changing the number of atoms or the trap frequency.
Collapse
Affiliation(s)
- Yuki Kawaguchi
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| | | | | |
Collapse
|
18
|
Sun B, Zhang WX, Yi S, Chapman MS, You L. Dipolar effect in coherent spin mixing of two atoms in a single optical lattice site. PHYSICAL REVIEW LETTERS 2006; 97:123201. [PMID: 17025962 DOI: 10.1103/physrevlett.97.123201] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/08/2006] [Indexed: 05/12/2023]
Abstract
We show that atomic dipolar effects are detectable in the system that recently demonstrated two-atom coherent spin dynamics within individual lattice sites of a Mott state. Based on a two-state approximation for the two-atom internal states and relying on a variational approach, we have estimated the spin dipolar effect. Despite the absolute weakness of the dipole-dipole interaction, it is shown that it leads to experimentally observable effects in the spin mixing dynamics.
Collapse
Affiliation(s)
- B Sun
- School of Physics, Georgia Institute of Technology, Atlanta, GA 30332, USA
| | | | | | | | | |
Collapse
|
19
|
Yi S, Pu H. Spontaneous spin textures in dipolar spinor condensates. PHYSICAL REVIEW LETTERS 2006; 97:020401. [PMID: 16907420 DOI: 10.1103/physrevlett.97.020401] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/07/2006] [Indexed: 05/11/2023]
Abstract
We have mapped out a detailed phase diagram that shows the ground state structure of a spin-1 condensate with magnetic dipole-dipole interactions. We show that the interplay between the dipolar and the spin-exchange interactions induces a rich variety of quantum phases that exhibit spontaneous magnetic ordering in the form of intricate spin textures.
Collapse
Affiliation(s)
- S Yi
- Department of Physics and Astronomy, and Rice Quantum Institute, Rice University, Houston, Texas 77251-1892, USA
| | | |
Collapse
|
20
|
Santos L, Pfau T. Spin-3 chromium Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2006; 96:190404. [PMID: 16803090 DOI: 10.1103/physrevlett.96.190404] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/28/2005] [Revised: 12/15/2005] [Indexed: 05/10/2023]
Abstract
We analyze the physics of spin-3 Bose-Einstein condensates, and, in particular, the new physics expected in ongoing experiments with condensates of chromium atoms. We first discuss the ground-state properties, which, depending on still unknown chromium parameters, and for low magnetic fields, can present various types of phases. We also discuss the spinor dynamics in chromium spinor condensates, which present significant qualitative differences when compared to other spinor condensates. In particular, dipole-induced spin relaxation may lead for low magnetic fields to transfer of spin into angular momentum similar to the well-known Einstein-de Haas effect. Additionally, a rapid large transference of population between distant magnetic states also becomes possible.
Collapse
Affiliation(s)
- L Santos
- Institut für Theoretische Physik III, Universität Stuttgart, Germany
| | | |
Collapse
|
21
|
Kawaguchi Y, Saito H, Ueda M. Einstein-de Haas effect in dipolar Bose-Einstein condensates. PHYSICAL REVIEW LETTERS 2006; 96:080405. [PMID: 16606159 DOI: 10.1103/physrevlett.96.080405] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/02/2005] [Indexed: 05/08/2023]
Abstract
The general properties of the order parameter for a dipolar spinor Bose-Einstein condensate are discussed based on symmetries of interactions. An initially spin-polarized dipolar condensate is shown to dynamically generate a nonsingular vortex via spin-orbit interactions--a phenomenon reminiscent of the Einstein-de Haas effect in ferromagnets.
Collapse
Affiliation(s)
- Yuki Kawaguchi
- Department of Physics, Tokyo Institute of Technology, 2-12-1 Ookayama, Meguro-ku, Tokyo 152-8551, Japan
| | | | | |
Collapse
|
22
|
Griesmaier A, Werner J, Hensler S, Stuhler J, Pfau T. Bose-Einstein condensation of chromium. PHYSICAL REVIEW LETTERS 2005; 94:160401. [PMID: 15904199 DOI: 10.1103/physrevlett.94.160401] [Citation(s) in RCA: 34] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 03/01/2005] [Indexed: 05/02/2023]
Abstract
We report on the generation of a Bose-Einstein condensate in a gas of chromium atoms, which have an exceptionally large magnetic dipole moment and therefore underlie anisotropic long-range interactions. The preparation of the chromium condensate requires novel cooling strategies that are adapted to its special electronic and magnetic properties. The final step to reach quantum degeneracy is forced evaporative cooling of 52Cr atoms within a crossed optical dipole trap. At a critical temperature of T(c) approximately 700 nK, we observe Bose-Einstein condensation by the appearance of a two-component velocity distribution. We are able to produce almost pure condensates with more than 50,000 condensed 52Cr atoms.
Collapse
Affiliation(s)
- Axel Griesmaier
- 5. Physikalisches Institut, Universität Stuttgart, 70550 Stuttgart, Germany.
| | | | | | | | | |
Collapse
|