336 citations · 858 across the 16 of their papers we have counts for
16 papers
Bypassing the bandwidth theorem with PT symmetry
Hamidreza Ramezani, J. Schindler, F. M. Ellis +2
The beat time τ_{fpt} associated with the energy transfer between two coupled oscillators is dictated by the bandwidth theorem which sets a lower bound τ_{fpt}\sim 1/δω. We show, b…
Nonlinear PT-symmetric plaquettes
Kai Li, P. G. Kevrekidis, Boris A. Malomed +1
We introduce four basic two-dimensional (2D) plaquette configurations with onsite cubic nonlinearities, which may be used as building blocks for 2D PT -symmetric lattices. For each…
PT symmetry and spontaneous symmetry breaking in a microwave billiard
S. Bittner, B. Dietz, U. Guenther +4
We demonstrate the presence of parity-time (PT) symmetry for the non-Hermitian two-state Hamiltonian of a dissipative microwave billiard in the vicinity of an exceptional point (EP…
PT-symmetric quantum state discrimination
Carl M. Bender, Dorje C. Brody, Joao Caldeira +1
Suppose that a system is known to be in one of two quantum states, or . If these states are not orthogonal, then in conventional quantum mechanics it is impossibl…
PT symmetry, Cartan decompositions, Lie triple systems and Krein space related Clifford algebras
Uwe Guenther, Sergii Kuzhel
Gauged PT quantum mechanics (PTQM) and corresponding Krein space setups are studied. For models with constant non-Abelian gauge potentials and extended parity inversions compact an…
On the spectrum of the magnetohydrodynamic mean-field alpha^2-dynamo operator
Uwe Guenther, Heinz Langer, Christiane Tretter
The existence of magnetohydrodynamic mean-field alpha^2-dynamos with spherically symmetric, isotropic helical turbulence function alpha is related to a non-self-adjoint spectral pr…
-self-adjoint operators with -symmetries: extension theory approach
S. Albeverio, U. Guenther, S. Kuzhel
A well known tool in conventional (von Neumann) quantum mechanics is the self-adjoint extension technique for symmetric operators. It is used, e.g., for the construction of Dirac-H…
Projective Hilbert space structures at exceptional points
Uwe Guenther, Ingrid Rotter, Boris F. Samsonov
A non-Hermitian complex symmetric 2x2 matrix toy model is used to study projective Hilbert space structures in the vicinity of exceptional points (EPs). The bi-orthogonal eigenvect…
Reversals in nature and the nature of reversals
Frank Stefani, Mingtian Xu, Luca Sorriso-Valvo +2
The asymmetric shape of reversals of the Earth's magnetic field indicates a possible connection with relaxation oscillations as they were early discussed by van der Pol. A simple m…
A globally diagonalizable alpha^2-dynamo operator, SUSY QM and the Dirac equation
Uwe Guenther, Boris F. Samsonov, Frank Stefani
A new class of semi-analytically solvable MHD alpha^2-dynamos is found based on a global diagonalization of the matrix part of the dynamo differential operator. Close parallels to…
Third order spectral branch points in Krein space related setups: PT-symmetric matrix toy model, MHD alpha^2-dynamo, and extended Squire equation
Uwe Guenther, Frank Stefani
The spectra of self-adjoint operators in Krein spaces are known to possess real sectors as well as sectors of pair-wise complex conjugate eigenvalues. Transitions from one spectral…
Phenomenology of brane-world cosmological models
Uwe Guenther, Alexander Zhuk
We present a brief review of brane-world models - models in which our observable Universe with its standard matter fields is assumed as localized on a domain wall (three-brane) in…
Remarks on dimensional reduction of multidimensional cosmological models
Uwe Guenther, Alexander Zhuk
Multidimensional cosmological models with factorizable geometry and their dimensional reduction to effective four-dimensional theories are analyzed on sensitivity to different scal…
Gravitational Excitons as Dark Matter
U. Guenther, A. Zhuk
In earlier work it was pointed out that for warped product spacetimes the conformal (geometrical moduli) excitations of the internal compactified factor spaces should be observable…
A note on dynamical stabilization of internal spaces in multidimensional cosmology
U. Guenther, A. Zhuk
The possibility of dynamical stabilization of an internal space is investigated for a multidimensional cosmological model with minimal coupled scalar field as inflaton. It is shown…
Gravitational excitons from extra dimensions
U. Guenther, A. Zhuk
Inhomogeneous multidimensional cosmological models with a higher dimensional space-time manifold are investigated under dimensional reduction. In the Einstein conformal frame, smal…