共查询到20条相似文献,搜索用时 15 毫秒
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We study properties of a particle moving in a double-well potential in the two-level approximation placed in an additional
external time-dependent field. Using previously established property (J. Phys. A 41, 244023 (2008)) that any two-level system possesses a pseudo-supersymmetry we introduce the notion of pseudo-supersymmetric
field. It is shown that these fields, even if their time dependence is not periodical, may produce the effect of localization
of the particle in one of the wells of the double-well potential. 相似文献
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Ditlevsen PD 《Physical review. E, Statistical physics, plasmas, fluids, and related interdisciplinary topics》1999,60(1):172-179
Noise-induced jumping between metastable states in a potential depends on the structure of the noise. For an alpha-stable noise, jumping triggered by single extreme events contributes to the transition probability. This is also called Levy flights and might be of importance in triggering sudden changes in geophysical flow and perhaps even climatic changes. The steady-state statistics is also influenced by the noise structure leading to a non-Gibbs distribution for an alpha-stable noise. 相似文献
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The density distribution of ultracold two-component fermionic gases 6Li, which are confined in a gradient magnetic field and a symmetrical double-well potential, is investigated by employing local-density approximation. It is found that three different regimes including quasi-molecular Bose-Einstein condensation (BECm), the dimers in the unitarity limit (ULd), and Bardeen-Cooper-Schrieffer superfluid (BCS) can coexist at the same time. Furthermore, the ranges of these regimes can be controlled to some extent by tuning the gradient of the magnetic field and the parameters characterizing the properties of the double-well potential. This study is of guidance and significance for experimentally realizing the coexistence of BECm, ULd, and BCS in the double-well potential. 相似文献
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The purpose of this paper is to investigate the effect of a twist on the losses of leaky modes in microstructured optical fibers (MOF). A helicoidal system of coordinates is introduced to define the structure and to set up the problem. These coordinates, albeit non-orthogonal, preserve the translational invariance in a way that allows a two-dimensional finite element model similar to that of classical straight waveguides. The Perfectly Matched Layer (PML) technique is used to compute the leaky modes in the fibers. Helicoidal coordinates and PML are unified under the point of view of geometrical transformations which allows the design of 'twisted PML' that provides the right tool to determine the leaky modes in the twisted structures. 相似文献
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Acoustic metamaterials constructed by resonant microelements in subwavelength scale were generally characterized by the effective medium approximation theory, which neglects the interaction between adjacent elements. In this paper, we show that twisting the orientation of resonators in acoustic metamaterials produces secondary coupled resonant modes by introducing internal vibration interaction. Metamaterials composed of a single-slit Helmholtz resonator arranged in two-dimensional square lattice are investigated. We rotate a portion of the resonator so that the adjacent resonators in a ??X direction have a twist angle of ??. For the system with ??=180°, the coupling interaction produces the symmetric coupled mode in in-phase oscillation and the antisymmetric coupled mode in out-of-phase oscillation. This acoustic analog of ??hybridization effect?? leads to a sharp transparency window in the extended locally-resonant forbidden gap, which is analogous to the phenomenon of electromagnetically induced transparency. Such coupled resonant modes may have potential applications in sound wave manipulations such as acoustic filtering and imaging. 相似文献
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Shin Y Saba M Schirotzek A Pasquini TA Leanhardt AE Pritchard DE Ketterle W 《Physical review letters》2004,92(15):150401
Bose-Einstein condensates of sodium atoms, prepared in an optical dipole trap, were distilled into a second empty dipole trap adjacent to the first one. The distillation was driven by thermal atoms spilling over the potential barrier separating the two wells and then forming a new condensate. This process serves as a model system for metastability in condensates, provides a test for quantum kinetic theories of condensate formation, and also represents a novel technique for creating or replenishing condensates in new locations. 相似文献
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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. 相似文献
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We investigate the stability of the first excited state, the so-called “π-state,” of Bose-Einstein condensates in a double-well potential. From the condition of complex excitation energies, we determine the critical barrier height, above which the π-state is dynamically unstable. We find that the critical barrier height decreases monotonically as the number of condensate atoms increases. We also simulate the dynamics of the π-state by solving the time-dependent Gross-Pitaevskii equation. Our simulation results show that the π-state in the dynamically unstable region exhibits distinctively different behavior from that in the dynamically stable region. 相似文献
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B.U. Felderhof 《Physica A》2008,387(23):5752-5760
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S. A. Nazarov 《Acoustical Physics》2010,56(6):1004-1015
We study the discrete spectrum of the Laplace operator with the Dirichlet boundary conditions in a plane waveguide made of
a band of unit width and half-band of width h perpendicular to it. The existence of critical width h
* ∈ (1,2] is established: in the case of h ∈ (0, h*), the discrete spectrum σ
d
h
of the problem contains only one eigenvalur λ1
h
, but σ
d
h
= ⊘ at h ≥ h
*. The asymptotics of the eigenvalue λ1
h
at h → + 0 is found. 相似文献
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Lluí as Torner Concepci an Santos Juan P. Torres Dumitru Mihalache 《Fiber and Integrated Optics》1994,13(3):271-280
The existence of new hybrid waveguide modes of properly tailored integrated optical waveguides consisting of ultrathin films clad by positive birefringent media is pointed out. 相似文献
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D.J. Robbins 《Optics Communications》1983,47(5):309-312
A theory is presented of guided TE modes in a one-dimensional slabe waveguide bounded by nonlinear media with intensity dependent refractive indices. It is shown that this is a straightforward generalisation of linear slab waveguide theory with the modes parametrised by the power flow down the guide. Illustrative dispersion curves and mode shapes are discussed. 相似文献
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交叉电场和磁场中的氢原子具有双阱势能结构。本文基于量子力学模拟,采用半周期脉冲(HCP)序列开展电子波包的非绝热操控。详细研究了HCP的电场幅度、数量和时间间隔对电子波包的空间和能量分布的影响,实现了将初始电子波包非绝热转移到远离库伦中心的外势阱中的低能态,这些低能态较为稳定且显示出很大的电偶极矩。相比光激发和绝热操控,本文的方法更为快速、高效,可以应用于更为复杂的外场或分子体系。 相似文献
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We study the inelastic scattering of a probe particle on a Bose-Einstein condensate
confined in a double-well potential. We identify prominent signatures of the underlying
mean-field phase space in the scattering signal and derive an analytical expression for
the inelastic scattering cross section. 相似文献