arXiv 0912.32092009-12-16cond-mat.quant-gasquant-ph

玻色-爱因斯坦凝聚体流过弱环时的电流-相位关系

Current-Phase Relation of a Bose-Einstein Condensate Flowing Through a Weak Link

F. Piazza, L. A. Collins, A. Smerzi

备注：: 6 pages, 5 figures
DOI：: 10.1103/PhysRevA.81.033613

摘要：

通过解析求解一维Gross-Pitaevskii方程，研究了玻色-爱因斯坦凝聚体流过排斥方势垒时的电流-相位关系。势垒高度和宽度固定电流-相位关系$j(δϕ)$，对于弱势垒，其倾向于$j\sim\cos(δϕ/2)$，对于强势垒，其倾向于约瑟夫森正弦关系$j\sim\sin(δϕ)$。在这两个极限之间，电流-相位关系取决于势垒宽度。特别是，足够宽的障碍，我们观察到两个家庭的多值电流相位关系。在文献中已知的属于第一类的图可以在相同的相位差处具有两个不同的电流正值。第二族，我们所知的新的，可以代替地允许三个不同的正电流仍然对应于相同的相位差。最后，我们表明，多值的行为产生的流体动力学和非线性色散分量的流之间的竞争，后者是由于在障碍区域内的孤子的存在。

英文摘要：

We study the current-phase relation of a Bose-Einstein condensate flowing through a repulsive square barrier by solving analytically the one dimensional Gross-Pitaevskii equation. The barrier height and width fix the current-phase relation $j(δϕ)$, which tends to $j\sim\cos(δϕ/2)$ for weak barriers and to the Josephson sinusoidal relation $j\sim\sin(δϕ)$ for strong barriers. Between these two limits, the current-phase relation depends on the barrier width. In particular, for wide enough barriers, we observe two families of multivalued current-phase relations. Diagrams belonging to the first family, already known in the literature, can have two different positive values of the current at the same phase difference. The second family, new to our knowledge, can instead allow for three different positive currents still corresponding to the same phase difference. Finally, we show that the multivalued behavior arises from the competition between hydrodynamic and nonlinear-dispersive components of the flow, the latter due to the presence of a soliton inside the barrier region.

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摘要：

英文摘要：

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