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Visualization of branch points in PT-symmetric waveguides.

Research paper by Shachar S Klaiman, Uwe U Günther, Nimrod N Moiseyev

Indexed on: 04 Sep '08Published on: 04 Sep '08Published in: Physical review letters



Abstract

The visualization of an exceptional point in a PT-symmetric directional coupler (DC) is demonstrated. In such a system the exceptional point can be probed by varying only a single parameter. Using the Rayleigh-Schrödinger perturbation theory we prove that the spectrum of a PT-symmetric Hamiltonian is real as long as the radius of convergence has not been reached. We also show how one can use a PT-symmetric directional coupler to measure the radius of convergence for non-PT-symmetric structures. For such systems the physical meaning of the rather mathematical term radius of convergence is exemplified.