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Optimal Topological Test for Degeneracies of Real Hamiltonians

Niklas Johansson·Erik Sjöqvist
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Abstract

We consider adiabatic transport of eigenstates of real Hamiltonians around loops in parameter space. It is demonstrated that loops that map to nontrivial loops in the space of eigenbases must encircle degeneracies. Examples from Jahn-Teller theory are presented to illustrate the test. We show furthermore that the proposed test is optimal.

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Niklas Johansson, Erik Sjöqvist. 2004-01-09. Optimal Topological Test for Degeneracies of Real Hamiltonians. https://doi.org/10.1103/physrevlett.92.060406

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