arXivDaily arXiv每日学术速递 周一至周五更新
arXiv 1708.09381cond-mat.quant-gasnlin.PSphysics.optics
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具有立方自吸引的二维和一维线性耦合势阱中基态、涡旋和偶极子的自发对称性破缺

Spontaneous symmetry breaking of fundamental states, vortices, and dipoles in two- and one-dimensional linearly coupled traps with cubic self-attraction

Zhaopin Chen, Yongyao Li, Boris A. Malomed, Luca Salasnich

摘要:

我们介绍了二维和一维(2D和1D)系统的两个线性耦合的Gross-Pitaevskii方程(GPE)与立方自吸引和谐振子(HO)的捕获势在每个GPE。该系统模拟了一个负散射长度的玻色-爱因斯坦凝聚体,加载在一个双饼阱中,结合面内HO势。除此之外,1D版本还适用于具有克尔非线性和由HO势表示的芯内限制的双芯波导中的光传输。分析的主题是在二维和一维基态(GS,别名基本)模式,以及在二维涡旋和一维偶极模式(后者不存在没有HO电位)的自发对称性破缺。通过变分近似和数值分析,发现二维和一维系统都产生了超临界型的破缺分岔。通过计算微扰模式的本征值,分析了SBB产生的对称态和非对称态的稳定性,并通过直接模拟进行了验证。非对称高斯系统总是稳定的,而涡的稳定区域随着线性耦合常数$ κ$的增加而缩小并最终消失。如果$κ$太大(在$κ>κ_{\max }$),2D系统中的SBB不会发生;在这种情况下,双组分系统的行为基本上与单组分系统相同。在一维系统中,对称和非对称偶极模都具有额外的振荡不稳定性,与对称破缺无关。这种不稳定性发生在几个区域,这些区域随着$κ$的增加而扩大。

英文摘要:

We introduce two- and one-dimensional (2D and 1D) systems of two linearly-coupled Gross-Pitaevskii equations (GPEs) with the cubic self-attraction and harmonic-oscillator (HO) trapping potential in each GPE. The system models a Bose-Einstein condensate with a negative scattering length, loaded in a double-pancake trap, combined with the in-plane HO potential. In addition to that, the 1D version applies to the light transmission in a dual-core waveguide with the Kerr nonlinearity and in-core confinement represented by the HO potential. The subject of the analysis is spontaneous symmetry breaking in 2D and 1D ground-state (GS, alias fundamental) modes, as well as in 2D vortices and 1D dipole modes (the latter ones do not exist without the HO potential). By means of the variational approximation and numerical analysis, it is found that both the 2D and 1D systems give rise to a symmetry-breaking bifurcation (SBB) of the supercrtical type. Stability of symmetric states and asymmetric ones, produced by the SBB, is analyzed through the computation of eigenvalues for perturbation modes, and verified by direct simulations. The asymmetric GSs are always stable, while the stability region for vortices shrinks and eventually disappears with the increase of the linear-coupling constant, $ κ$. The SBB in the 2D system does not occur if $κ$ is too large (at $κ>κ_{\max }$); in that case, the two-component system behaves, essentially, as its single-component counterpart. In the 1D system, both asymmetric and symmetric dipole modes feature an additional oscillatory instability, unrelated to the symmetry breaking. This instability occurs in several regions, which expand with the increase of $κ$.

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