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arXiv 0904.4417cond-mat.quant-gascond-mat.other
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非线性周期系统中的间隙孤子和Bloch波

Gap Solitons and Bloch Waves in Nonlinear Periodic Systems

Yongping Zhang, Zhaoxin Liang, Biao Wu

摘要:

本文全面研究了一维非线性周期系统中的间隙孤子和布洛赫波。结果表明,它们之间存在一种组合关系:在布里渊区中心或边缘的布洛赫波是由基本带隙孤子(FGS)组成的无限长链。我们认为这种关系与非线性Bloch波和非线性Wannier函数之间的精确关系有关。利用这种复合关系,可以不经计算而得到许多关于间隙孤子的结论。例如,对于散焦非线性,在$n$阶线性Bloch带隙中存在$n$族FGS;对于聚焦情况,在半无限带隙和其它带隙中存在无限个FGS族。此外,还分析了带隙孤子的稳定性。在文献中,有数值结果表明,一些FGS具有传播常数(或化学势)的截止值,即这些FGS并不存在于线性带隙中的所有传播常数(或化学势)值。我们对这种中断提供了一种解释。

英文摘要:

We comprehensively investigate gap solitons and Bloch waves in one-dimensional nonlinear periodic systems. Our results show that there exists a composition relation between them: Bloch waves at either the center or edge of the Brillouin zone are infinite chains composed of fundamental gap solitons(FGSs). We argue that such a relation is related to the exact relation between nonlinear Bloch waves and nonlinear Wannier functions. With this composition relation, many conclusions can be drawn for gap solitons without any computation. For example, for the defocusing nonlinearity, there are $n$ families of FGS in the $n$th linear Bloch band gap; for the focusing case, there are infinite number of families of FGSs in the semi-infinite gap and other gaps. In addition, the stability of gap solitons is analyzed. In literature there are numerical results showing that some FGSs have cutoffs on propagation constant (or chemical potential), i.e. these FGSs do not exist for all values of propagation constant (or chemical potential) in the linear band gap. We offer an explanation for this cutoff.

机构、总结、中文摘要均由AI分析而来,可能存在错误,请以论文正文为准。

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