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arXiv 1012.0194quant-phmath-phmath.MP
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非厄米特二次su(2)Hamilton算子的度量算子

Metric operators for non-Hermitian quadratic su(2) Hamiltonians

Paulo E. G. Assis

摘要:

构造了一类具有反线性对称性的非厄米二次su(2)Hamilton算子.这是通过分析这种系统在代数自同构方面可能的对称性来实现的。事实上,这种对称性的不同实现方式,包括自然发生的电荷共轭与宇称和时间反转。一旦指定的基本反线性对称的哈密顿量,前者,如果不破,导致一个纯粹的实谱和后者可以映射到一个埃尔米特对应,除其他可能性,一个相似性变换。在这里,李代数的方法被用来调查广义斯旺森哈密顿识别类的二次哈密顿,允许这样的映射到厄米对应。然而对于线性su(2)系统,这种类型的每个哈密顿量都可以通过变换映射到厄米特对应物,该变换本身是su(2)生成元的线性组合的指数,对于二次哈密顿量,情况更加复杂。因此,更精细的相似性变换,包括二次指数的可能性,也详细探讨。与以前研究的su(1,1)相反,su(2)哈密顿量的有限维表示的存在允许与有限矩阵的显式对角化结果进行比较。最后,构造的相似变换进行了比较,与类似的斯旺森的方法精确diagonalsation的问题,建立一个简单的两种方法之间的关系。

英文摘要:

A class of non-Hermitian quadratic su(2) Hamiltonians having an anti-linear symmetry is constructed. This is achieved by analysing the possible symmetries of such systems in terms of automorphisms of the algebra. In fact, different realisations for this type of symmetry are obtained, including the natural occurrence of charge conjugation together with parity and time reversal. Once specified the underlying anti-linear symmetry of the Hamiltonian, the former, if unbroken, leads to a purely real spectrum and the latter can be mapped to a Hermitian counterpart by, amongst other possibilities, a similarity transformation. Here, Lie-algebraic methods which were used to investigate the generalised Swanson Hamiltonian are employed to identify the class of quadratic Hamiltonians that allow for such a mapping to the Hermitian counterpart. Whereas for the linear su(2) system every Hamiltonian of this type can be mapped to a Hermitian counterpart by a transformation which is itself an exponential of a linear combination of su(2) generators, the situation is more complicated for quadratic Hamiltonians. Therefore, the possibility of more elaborate similarity transformations, including quadratic exponents, is also explored in detail. The existence of finite dimensional representations for the su(2) Hamiltonian, as opposed to the su(1,1) studied before, allows for comparison with explicit diagonalisation results for finite matrices. Finally, the similarity transformations constructed are compared with the analogue of Swanson's method for exact diagonalsation of the problem, establishing a simple relation between both approaches.

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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