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Jordan blocks and generalized bi-orthogonal bases: realizations in open wave systems

Alec Maassen van den Brink·K. Young
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Abstract

Dissipative systems can be described in terms of non-hermitian hamiltonians H, whose left eigenvectors f^j and right eigenvectors f_j form a bi-orthogonal system. Bi-orthogonal systems could suffer from two difficulties. (a) If the eigenvectors do not span the whole space, then H can only be diagonalized to blocks (the Jordan-block problem). (b) Normalization would not be possible and many familiar-looking formulas would fail if (f^j,f_j) = 0 for some j (the orthonormalization problem). Waves in open systems provide a well-founded realization of a bi-orthogonal system, and it is shown that these two problems can indeed occur and are both related to higher-order poles in the frequency-domain Green's function. The resolution is then given by introducing a generalized duality transformation involving extra basis vectors, whose time evolution is modified by polynomials in the time t. One thus obtains a nontrivial extension of the bi-orthogonal formalism for dissipative systems.

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Alec Maassen van den Brink, K. Young. 1999-05-25. Jordan blocks and generalized bi-orthogonal bases: realizations in open wave systems. https://doi.org/10.1088/0305-4470%2F34%2F12%2F308

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