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… (More)

In a recent paper [F. Stefani, G. Gerbeth. Asymmetric polarity reversals, bimodal field distribution, and coherence resonance in a spherically symmetric mean-field dynamo model. Phys. Rev. Lett. 94… (More)

Effective 4-dimensional theories are investigated which were obtained under dimensional reduction of multidimensional cosmological models with a minimal coupled scalar field as a matter source.… (More)

A non-Hermitian complex symmetric 2 × 2-matrix toy model is used to study projective Hilbert space structures in the vicinity of exceptional points (EPs). The bi-orthogonal eigenvectors of a… (More)

We study a non-Hermitian PT −symmetric generalization of an Nparticle, two-mode Bose-Hubbard system, modeling for example a Bose-Einstein condensate in a double well potential coupled to a continuum… (More)

We study inhomogeneous multidimensional cosmological models with a higher dimensional space-time manifold M = M 0 × n i=1 M i (n ≥ 1) under dimensional reduction to D 0-dimensional effective models.… (More)

The quantum mechanical brachistochrone system with a PT-symmetric Hamiltonian is Naimark-dilated and reinterpreted as a subsystem of a Hermitian system in a higher-dimensional Hilbert space. This… (More)

The PT −symmetric (PTS) quantum brachistochrone problem is re-analyzed as quantum system consisting of a non-Hermitian PTS component and a purely Hermitian component simultaneously. Interpreting this… (More)

The isospectrality problem is studied for the operator of the spherical hydromagnetic α−dynamo. It is shown that this operator is formally pseudo-Hermitian (J−symmetric) and lives in a Krein space.… (More)

The beat time τfpt associated with the energy transfer between two coupled oscillators is dictated by the bandwidth theorem which sets a lower bound τfpt ∼ 1/δω. We show, both experimentally and… (More)