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Title: Multicomponent gap solitons in spinor Bose-Einstein condensates

Abstract

We model the nonlinear behavior of spin-1 Bose-Einstein condensates (BECs) with repulsive spin-independent interactions and either ferromagnetic or antiferromagnetic (polar) spin-dependent interactions, loaded into a one-dimensional optical lattice potential. We show that both types of BECs exhibit dynamical instabilities and may form spatially localized multicomponent structures. The localized states of the spinor matter waves take the form of vector gap solitons and self-trapped waves that exist only within gaps of the linear Bloch-wave band-gap spectrum. Of special interest are the nonlinear localized states that do not exhibit a common spatial density profile shared by all condensate components, and consequently cannot be described by the single mode approximation (SMA) frequently employed within the framework of the mean-field treatment. We show that the non-SMA states can exhibits Josephson-like internal oscillations and self-magnetization, i.e., intrinsic precession of the local spin. Finally, we demonstrate that nonstationary states of a spinor BEC in a lattice exhibit coherent undamped spin-mixing dynamics, and that their controlled conversion into a stationary state can be achieved by the application of an external magnetic field.

Authors:
; ; ;  [1]
  1. ARC Centre of Excellence for Quantum-Atom Optics and Nonlinear Physics Centre, Research School of Physical Sciences and Engineering, The Australian National University, Canberra ACT 0200 (Australia)
Publication Date:
OSTI Identifier:
20982168
Resource Type:
Journal Article
Resource Relation:
Journal Name: Physical Review. A; Journal Volume: 75; Journal Issue: 2; Other Information: DOI: 10.1103/PhysRevA.75.023617; (c) 2007 The American Physical Society; Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND SUPERFLUIDITY; ANTIFERROMAGNETISM; APPROXIMATIONS; BOSE-EINSTEIN CONDENSATION; CONDENSATES; DENSITY; INSTABILITY; INTERACTIONS; JOSEPHSON EFFECT; MAGNETIC FIELDS; MAGNETIZATION; MEAN-FIELD THEORY; MIXING; NONLINEAR PROBLEMS; ONE-DIMENSIONAL CALCULATIONS; OPTICAL MODELS; OSCILLATIONS; POTENTIALS; SOLITONS; SPIN; TRAPPING

Citation Formats

DaPbrowska-Wuester, Beata J., Ostrovskaya, Elena A., Alexander, Tristram J., and Kivshar, Yuri S.. Multicomponent gap solitons in spinor Bose-Einstein condensates. United States: N. p., 2007. Web. doi:10.1103/PHYSREVA.75.023617.
DaPbrowska-Wuester, Beata J., Ostrovskaya, Elena A., Alexander, Tristram J., & Kivshar, Yuri S.. Multicomponent gap solitons in spinor Bose-Einstein condensates. United States. doi:10.1103/PHYSREVA.75.023617.
DaPbrowska-Wuester, Beata J., Ostrovskaya, Elena A., Alexander, Tristram J., and Kivshar, Yuri S.. Thu . "Multicomponent gap solitons in spinor Bose-Einstein condensates". United States. doi:10.1103/PHYSREVA.75.023617.
@article{osti_20982168,
title = {Multicomponent gap solitons in spinor Bose-Einstein condensates},
author = {DaPbrowska-Wuester, Beata J. and Ostrovskaya, Elena A. and Alexander, Tristram J. and Kivshar, Yuri S.},
abstractNote = {We model the nonlinear behavior of spin-1 Bose-Einstein condensates (BECs) with repulsive spin-independent interactions and either ferromagnetic or antiferromagnetic (polar) spin-dependent interactions, loaded into a one-dimensional optical lattice potential. We show that both types of BECs exhibit dynamical instabilities and may form spatially localized multicomponent structures. The localized states of the spinor matter waves take the form of vector gap solitons and self-trapped waves that exist only within gaps of the linear Bloch-wave band-gap spectrum. Of special interest are the nonlinear localized states that do not exhibit a common spatial density profile shared by all condensate components, and consequently cannot be described by the single mode approximation (SMA) frequently employed within the framework of the mean-field treatment. We show that the non-SMA states can exhibits Josephson-like internal oscillations and self-magnetization, i.e., intrinsic precession of the local spin. Finally, we demonstrate that nonstationary states of a spinor BEC in a lattice exhibit coherent undamped spin-mixing dynamics, and that their controlled conversion into a stationary state can be achieved by the application of an external magnetic field.},
doi = {10.1103/PHYSREVA.75.023617},
journal = {Physical Review. A},
number = 2,
volume = 75,
place = {United States},
year = {Thu Feb 15 00:00:00 EST 2007},
month = {Thu Feb 15 00:00:00 EST 2007}
}
  • Magnetic solitons in spinor Bose-Einstein condensates confined in a one-dimensional optical lattice are studied by the Holstein-Primakoff transformation method. It is shown that due to the long-range light-induced and static magnetic dipole-dipole interactions, there exist different types of magnetic solitary excitations in different parameter regions. Compared to conventional solid-state materials, the parameters of this type of magnetic solitons in an optical lattice can be easily tuned by the above dipole-dipole interactions, which are highly controllable in experiments.
  • By numerical simulations of the Gross-Pitaevskii mean-field equations, we show that the dynamical creation of stable complex vector solitons in a homogeneous spin-1 Bose-Einstein condensate can be achieved by applying a localized magnetic field for a certain duration, with the initial uniform density prepared differently for the formation of different vector solitons. In particular, it is shown that stable dark-bright-dark vector solitons, dark-bright-bright vector solitons, and other analogous solutions can be dynamically created. It is also found that the peak intensity and the group velocity of the vector solitons thus generated can be tuned by adjusting the applied magnetic field.more » Extensions of our approach also allow for the creation of vector-soliton chains or the pumping of many vector solitons. The results can be useful for possible vector-soliton-based applications of dilute Bose-Einstein condensates.« less
  • We show that bright solitons exist in quasi-one-dimensional heteronuclear multicomponent Bose-Einstein condensates with repulsive self-interaction and attractive interspecies interaction. They are remarkably robust to perturbations of initial data and collisions and can be generated by the mechanism of modulational instability. Some possibilities for control and the behavior of the system in fully three-dimensional scenarios are also discussed.
  • We analyze the existence and stability of spatially extended (Bloch-type) and localized states of a Bose-Einstein condensate loaded into an optical lattice. In the framework of the Gross-Pitaevskii equation with a periodic potential, we study the band-gap structure of the matter-wave spectrum in both the linear and nonlinear regimes. We demonstrate the existence of families of spatially localized matter-wave gap solitons, and analyze their stability in different band gaps, for both repulsive and attractive atomic interactions.
  • We discuss localized ground states of Bose-Einstein condensates (BEC's) in optical lattices with attractive and repulsive three-body interactions in the framework of a quintic nonlinear Schroedinger equation which extends the Gross-Pitaevskii equation to the one-dimensional case. We use both a variational method and a self-consistent approach to show the existence of unstable localized excitations which are similar to Townes solitons of the cubic nonlinear Schroedinger equation in two dimensions. These solutions are shown to be located in the forbidden zones of the band structure, very close to the band edges, separating decaying states from stable localized ones (gap solitons) fullymore » characterizing their delocalizing transition. In this context the usual gap solitons appear as a mechanism for arresting the collapse in low-dimensional BEC's in optical lattices with an attractive real three-body interaction. The influence of the imaginary part of the three-body interaction, leading to dissipative effects in gap solitons, and the effect of atoms feeding from the thermal cloud are also discussed. These results may be of interest for both BEC's in atomic chips and Tonks-Girardeau gas in optical lattices.« less