Comment on "Experimental observation of the topological structure of exceptional points" [Phys.Rev.Lett. 86, 787 (2001]
arXiv:quant-ph/0107105
Abstract
It is shown that the two experiments Dembowski et al., PRL 86, 787 (2001), and Lauber et al., PRL 72, 1004 (1994), prove the same topological singularity. The phase changes found in both experiments are related to a second order branch point in the complex plane.
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