Visualization of branch points in PT-symmetric waveguides.
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.
Klaiman
Shachar
S
Shulich Department of Chemistry, Technion-Israel Institute of Technology, Haifa 32000, Israel.
Günther
Uwe
U
Moiseyev
Nimrod
N