The Experts below are selected from a list of 63486 Experts worldwide ranked by ideXlab platform
Shiliang Zhu - One of the best experts on this subject based on the ideXlab platform.
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energy levels of a spin orbit coupled bose einstein condensate in a Double Well Potential
Laser Physics, 2015Co-Authors: Wenyuan Wang, Shiliang Zhu, Hui Cao, Jie LiuAbstract:We investigate the energy levels of a spin–orbit-coupled Bose–Einstein condensate in a Double-Well Potential under the mean-field approximation. We find that the energy levels of the system can be significantly influenced by the atomic interactions. Without atomic interaction, four energy levels change linearly with the tunneling amplitude, the Raman coupling, and the spin–orbit coupling. However, whenever atomic interaction is considered, three more energy levels will appear, which have a nonlinear dependence on those parameters above. These three energy levels are multi-degenerate and related to the macro-symmetry of the system.
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josephson dynamics of a spin orbit coupled bose einstein condensate in a Double Well Potential
Physical Review A, 2012Co-Authors: Danwei Zhang, Z D Wang, Shiliang ZhuAbstract:We investigate the quantum dynamics of an experimentally realized spin-orbit-coupled Bose-Einstein condensate in a Double-Well Potential. The spin-orbit coupling can significantly enhance the atomic interWell tunneling. We find the coexistence of internal and external Josephson effects in the system, which are moreover inherently coupled in a complicated form even in the absence of interatomic interactions. Moreover, we show that the spin-dependent tunneling between two Wells can induce a net atomic spin current referred as spin Josephson effects. Such spin Josephson effects can be observable under realistic conditions.
Gunter Wunner - One of the best experts on this subject based on the ideXlab platform.
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dipolar bose einstein condensates in a pt symmetric Double Well Potential
Physical Review A, 2014Co-Authors: Rudiger Fortanier, Dennis Dast, Daniel Haag, Holger Cartarius, Jorg Main, Gunter Wunner, Robin GutohrleinAbstract:We investigate dipolar Bose-Einstein condensates in a complex external Double-Well Potential that features a combined parity and time-reversal symmetry. On the basis of the Gross-Pitaevskii equation we study the effects of the long-ranged anisotropic dipole-dipole interaction on ground and excited states by the use of a time-dependent variational approach. We show that the property of a similar non-dipolar condensate to possess real energy eigenvalues in certain parameter ranges is preserved despite the inclusion of this nonlinear interaction. Furthermore, we present states that break the PT symmetry and investigate the stability of the distinct stationary solutions. In our dynamical simulations we reveal a complex stabilization mechanism for PT-symmetric, as Well as for PT-broken states which are, in principle, unstable with respect to small perturbations.
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model of a pt symmetric bose einstein condensate in a δ function Double Well Potential
Physical Review A, 2012Co-Authors: Holger Cartarius, Gunter WunnerAbstract:The observation of $\mathcal{PT}$ symmetry in a coupled optical waveguide system that involves a complex refractive index has been demonstrated impressively in the experiment by R\"uter et al. [Nat. Phys. 6, 192 (2010)]. This is, however, only an optical analog of a quantum system, and it would be highly desirable to observe the manifestation of $\mathcal{PT}$ symmetry and the resulting properties also in a real, experimentally accessible, quantum system. Following a suggestion by Klaiman et al. [Phys. Rev. Lett. 101, 080402 (2008)], we investigate a $\mathcal{PT}$-symmetric arrangement of a Bose-Einstein condensate in a Double-Well Potential, where in one Well cold atoms are injected while in the other particles are extracted from the condensate. We investigate, in particular, the effects of the nonlinearity in the Gross-Pitaevskii equation on the $\mathcal{PT}$ properties of the condensate. To study these effects we analyze a simple one-dimensional model system in which the condensate is placed into two $\mathcal{PT}$-symmetric $\ensuremath{\delta}$-function traps. The analysis will serve as a useful guide for studies of the behavior of Bose-Einstein condensates in realistic $\mathcal{PT}$-symmetric Double Wells.
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model of a pt symmetric bose einstein condensate in a delta function Double Well Potential
Physical Review A, 2012Co-Authors: Holger Cartarius, Gunter WunnerAbstract:The observation of PT symmetry in a coupled optical wave guide system that involves a complex refractive index has been demonstrated impressively in the experiment by R\"uter el al. (Nat. Phys. 6, 192, 2010). This is, however, only an optical analogue of a quantum system, and it would be highly desirable to observe the manifestation of PT symmetry and the resulting properties also in a real, experimentally accessible, quantum system. Following a suggestion by Klaiman et al. (Phys. Rev. Lett. 101, 080402, 2008), we investigate a PT symmetric arrangement of a Bose-Einstein condensate in a Double Well Potential, where in one Well cold atoms are injected while in the other particles are extracted from the condensate. We investigate, in particular, the effects of the nonlinearity in the Gross-Pitaevskii equation on the PT properties of the condensate. To study these effects we analyze a simple one-dimensional model system in which the condensate is placed into two PT symmetric delta-function traps. The analysis will serve as a useful guide for studies of the behaviour of Bose-Einstein condensates in realistic PT symmetric Double Wells.
Lincoln D Carr - One of the best experts on this subject based on the ideXlab platform.
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vortex macroscopic superpositions in ultracold bosons in a Double Well Potential
Physical Review A, 2015Co-Authors: Miguel Angel Garciamarch, Lincoln D CarrAbstract:We study macroscopic superpositions in the orbital rather than the spatial degrees of freedom, in a three-dimensional, Double-Well system. We show that the ensuing dynamics of $N$ interacting excited ultracold bosons, which, in general, requires at least eight single-particle modes and $(\genfrac{}{}{0pt}{}{N+7}{N})$ Fock vectors, is described by a surprisingly small set of many-body states. An initial state with half the atoms in each Well, and purposely excited in one of them, gives rise to the tunneling of axisymmetric and transverse vortex structures. We show that transverse vortices tunnel orders of magnitude faster than axisymmetric ones and are therefore more experimentally accessible. The tunneling process generates macroscopic superpositions only distinguishable by their orbital properties and within experimentally realistic times.
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macroscopic superposition states of ultracold bosons in a Double Well Potential
Frontiers of Physics in China, 2012Co-Authors: Dimitri R Dounasfrazer, Lincoln D Carr, Miguel Angel GarciamarchAbstract:We present a thorough description of the physical regimes for ultracold bosons in Double Wells, with special attention paid to macroscopic superpositions (MSs). We use a generalization of the Lipkin-Meshkov-Glick Hamiltonian of up to eight single particle modes to study these MSs, solving the Hamiltonian with a combination of numerical exact diagonalization and high-order perturbation theory. The MS is between left and right Potential Wells; the extreme case with all atoms simultaneously located in both Wells and in only two modes is the famous NOON state, but our approach encompasses much more general MSs. Use of more single particle modes brings dimensionality into the problem, allows us to set hard limits on the use of the original two-mode LMG model commonly treated in the literature, and also introduces a mixed Josephson-Fock regime. Higher modes introduce angular degrees of freedom and MS states with different angular properties.
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macroscopic superposition states of ultracold bosons in a Double Well Potential
arXiv: Quantum Gases, 2011Co-Authors: Dimitri R Dounasfrazer, Lincoln D Carr, Miguel Angel GarciamarchAbstract:We present a thorough description of the physical regimes for ultracold bosons in Double Wells, with special attention paid to macroscopic superpositions (MSs). We use a generalization of the Lipkin-Meshkov-Glick Hamiltonian of up to eight single particle modes to study these MSs, solving the Hamiltonian with a combination of numerical exact diagonalization and high-order perturbation theory. The MS is between left and right Potential Wells; the extreme case with all atoms simultaneously located in both Wells and in only two modes is the famous NOON state, but our approach encompasses much more general MSs. Use of more single particle modes brings dimensionality into the problem, allows us to set hard limits on the use of the original two-mode LMG model commonly treated in the literature, and also introduces a new mixed Josephson-Fock regime. Higher modes introduce angular degrees of freedom and MS states with different angular properties.
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ultracold bosons in a tilted multilevel Double Well Potential
Physical Review Letters, 2007Co-Authors: Dimitri R Dounasfrazer, Ann M Hermundstad, Lincoln D CarrAbstract:The N-body problem in a tilted Double Well requires new features for macroscopic quantum superposition in ultracold atoms. In particular, one needs to go beyond the single-particle ground state in each Well. We provide explicit criteria for when two energy levels are needed to describe the state space. For typical experimental parameters, two levels are indeed required for the creation of macroscopic superposition states. Furthermore, we show that a small tilt causes the collapse of such states. However, partial macroscopic superposition states reappear when the tilt can be compensated by atom-atom interactions.
Holger Cartarius - One of the best experts on this subject based on the ideXlab platform.
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dipolar bose einstein condensates in a pt symmetric Double Well Potential
Physical Review A, 2014Co-Authors: Rudiger Fortanier, Dennis Dast, Daniel Haag, Holger Cartarius, Jorg Main, Gunter Wunner, Robin GutohrleinAbstract:We investigate dipolar Bose-Einstein condensates in a complex external Double-Well Potential that features a combined parity and time-reversal symmetry. On the basis of the Gross-Pitaevskii equation we study the effects of the long-ranged anisotropic dipole-dipole interaction on ground and excited states by the use of a time-dependent variational approach. We show that the property of a similar non-dipolar condensate to possess real energy eigenvalues in certain parameter ranges is preserved despite the inclusion of this nonlinear interaction. Furthermore, we present states that break the PT symmetry and investigate the stability of the distinct stationary solutions. In our dynamical simulations we reveal a complex stabilization mechanism for PT-symmetric, as Well as for PT-broken states which are, in principle, unstable with respect to small perturbations.
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model of a pt symmetric bose einstein condensate in a δ function Double Well Potential
Physical Review A, 2012Co-Authors: Holger Cartarius, Gunter WunnerAbstract:The observation of $\mathcal{PT}$ symmetry in a coupled optical waveguide system that involves a complex refractive index has been demonstrated impressively in the experiment by R\"uter et al. [Nat. Phys. 6, 192 (2010)]. This is, however, only an optical analog of a quantum system, and it would be highly desirable to observe the manifestation of $\mathcal{PT}$ symmetry and the resulting properties also in a real, experimentally accessible, quantum system. Following a suggestion by Klaiman et al. [Phys. Rev. Lett. 101, 080402 (2008)], we investigate a $\mathcal{PT}$-symmetric arrangement of a Bose-Einstein condensate in a Double-Well Potential, where in one Well cold atoms are injected while in the other particles are extracted from the condensate. We investigate, in particular, the effects of the nonlinearity in the Gross-Pitaevskii equation on the $\mathcal{PT}$ properties of the condensate. To study these effects we analyze a simple one-dimensional model system in which the condensate is placed into two $\mathcal{PT}$-symmetric $\ensuremath{\delta}$-function traps. The analysis will serve as a useful guide for studies of the behavior of Bose-Einstein condensates in realistic $\mathcal{PT}$-symmetric Double Wells.
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model of a pt symmetric bose einstein condensate in a delta function Double Well Potential
Physical Review A, 2012Co-Authors: Holger Cartarius, Gunter WunnerAbstract:The observation of PT symmetry in a coupled optical wave guide system that involves a complex refractive index has been demonstrated impressively in the experiment by R\"uter el al. (Nat. Phys. 6, 192, 2010). This is, however, only an optical analogue of a quantum system, and it would be highly desirable to observe the manifestation of PT symmetry and the resulting properties also in a real, experimentally accessible, quantum system. Following a suggestion by Klaiman et al. (Phys. Rev. Lett. 101, 080402, 2008), we investigate a PT symmetric arrangement of a Bose-Einstein condensate in a Double Well Potential, where in one Well cold atoms are injected while in the other particles are extracted from the condensate. We investigate, in particular, the effects of the nonlinearity in the Gross-Pitaevskii equation on the PT properties of the condensate. To study these effects we analyze a simple one-dimensional model system in which the condensate is placed into two PT symmetric delta-function traps. The analysis will serve as a useful guide for studies of the behaviour of Bose-Einstein condensates in realistic PT symmetric Double Wells.
Jie Liu - One of the best experts on this subject based on the ideXlab platform.
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spin orbit coupled bec in a Double Well Potential quantum energy spectrum and flat band
Physics Letters A, 2015Co-Authors: Wenyuan Wang, Hui Cao, Jie LiuAbstract:Abstract Spin–orbit-coupled Bose–Einstein condensates (BECs) provide a powerful platform for studies on physical problems in various fields. Here we study the energy spectrum of a tunable spin–orbit-coupled BEC in a Double-Well Potential with adjustable Raman laser intensity. We find in the single-particle spectrum there is a highly degenerate flat band in the ground state of the BEC, which remains stable against changes of the Raman strength. Many-body interactions between atoms remove this high degeneracy. Analytical results for particular cases are obtained by using the perturbation theory, which are in good agreement with the numerical results.
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energy levels of a spin orbit coupled bose einstein condensate in a Double Well Potential
Laser Physics, 2015Co-Authors: Wenyuan Wang, Shiliang Zhu, Hui Cao, Jie LiuAbstract:We investigate the energy levels of a spin–orbit-coupled Bose–Einstein condensate in a Double-Well Potential under the mean-field approximation. We find that the energy levels of the system can be significantly influenced by the atomic interactions. Without atomic interaction, four energy levels change linearly with the tunneling amplitude, the Raman coupling, and the spin–orbit coupling. However, whenever atomic interaction is considered, three more energy levels will appear, which have a nonlinear dependence on those parameters above. These three energy levels are multi-degenerate and related to the macro-symmetry of the system.
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the effects of the beyond mean field corrections of fermi superfluid gas in a Double Well Potential
International Journal of Modern Physics C, 2012Co-Authors: Wenyuan Wang, Wenshan Duan, Jie LiuAbstract:By considering the contribution of the higher-order term representing the lowest approximation of beyond mean field corrections, we investigate a superfluid Fermi gas confined in a Double-Well Potential in Bose–Einstein Condensation (BEC) side of the Bardeen–Cooper–Schrieffer (BCS) to BEC crossover. Two limited cases of deep BEC regime and BEC regime of BCS–BEC crossover, corresponding to the two-body scattering length asc is small enough and large enough, respectively. We derive a simple two-mode model that could depict the dynamics effectively. With making thorough analysis on the two-mode model and its corresponding classical Hamiltonian, we find that the Josephson oscillation or self-trapping phenomenon could emerge at certain parameters. We find three kinds of the phase states: Josephson oscillation (JO), oscillating-phase-type self-trapping (OPTST) and running-phase-type self-trapping (RPTST). The dependence of these three phase states on the dimensionless interaction parameter y = 1/(kFasc) and the initial system energy are given in this paper.
