Comment on 'Experimental observation of the topological structure of exceptional points' [Phys.Rev.Lett. 86, 787 (2001]

摘要

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 orderbranch point in the complex plane.