Zobrazeno 1 - 10
of 382
pro vyhledávání: '"Guenther, U."'
Autor:
Beyer, L. P., Gathen, L. von zur, Rayah, B. El, Dewald, O., Zieschang, T., Diers, A., Ely, E. Wesley, Guenther, U.
Publikováno v:
BMC Anesthesiology; 12/13/2024, Vol. 24 Issue 1, p1-10, 10p
Autor:
Bittner, S., Dietz, B., Guenther, U., Harney, H. L., Miski-Oglu, M., Richter, A., Schaefer, F.
Publikováno v:
Phys. Rev. Lett. 108: 024101, 2012
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). The shape of the billiard depends on two parameters. The Hamiltonia
Externí odkaz:
http://arxiv.org/abs/1107.4256
Publikováno v:
J. Phys. A: Math. Theor. 42, (2009), 105205
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-Hermitian Hamiltonians with point-interaction potentials. Here we resha
Externí odkaz:
http://arxiv.org/abs/0811.0365
Publikováno v:
J. Phys. A: Math. Theor. 41 (2008) 255206
We study a non-Hermitian $PT-$symmetric generalization of an $N$-particle, two-mode Bose-Hubbard system, modeling for example a Bose-Einstein condensate in a double well potential coupled to a continuum via a sink in one of the wells and a source in
Externí odkaz:
http://arxiv.org/abs/0802.3164
Publikováno v:
Magnetohydrodynamics 42 (2006) 123-130
The irregular polarity reversals of the Earth's magnetic field have attracted much interest during the last decades. Despite the fact that recent numerical simulations of the geodynamo have shown nice polarity transitions, the very reason and the bas
Externí odkaz:
http://arxiv.org/abs/physics/0601011
Publikováno v:
Czech.J.Phys. 54 (2004) 1075-1089
The spectral branching behavior of the 2x2 operator matrix of the magneto-hydrodynamic alpha^2-dynamo is analyzed numerically. Some qualitative aspects of level crossings are briefly discussed with the help of a simple toy model which is based on a Z
Externí odkaz:
http://arxiv.org/abs/math-ph/0407015
Publikováno v:
Phys.Rev. D69 (2004) 044003
We investigate four-dimensional effective theories which are obtained by dimensional reduction of multidimensional cosmological models with factorizable geometry and consider the interaction between conformal excitations of the internal space (geomet
Externí odkaz:
http://arxiv.org/abs/hep-ph/0306191
Publikováno v:
Phys.Rev. D68 (2003) 044010
We consider multidimensional gravitational models with a nonlinear scalar curvature term and form fields in the action functional. In our scenario it is assumed that the higher dimensional spacetime undergoes a spontaneous compactification to a warpe
Externí odkaz:
http://arxiv.org/abs/hep-th/0303023
Publikováno v:
Astrophys.Space Sci. 283 (2003) 679-684
A non-linear gravitational model with a multidimensional geometry and quadratic scalar curvature is considered. For certain parameter ranges, the extra dimensions are stabilized if the internal spaces have negative curvature. As a consequence, the 4-
Externí odkaz:
http://arxiv.org/abs/gr-qc/0209045
Autor:
Guenther, U., Stefani, F.
Publikováno v:
J. Math. Phys. 44 (2003) 3097-3111
The isospectrality problem is studied for the operator of the spherical hydromagnetic alpha^2-dynamo. It is shown that this operator is formally pseudo-Hermitian (J-symmetric) and lives in a Krein space. Based on the J-symmetry, an operator intertwin
Externí odkaz:
http://arxiv.org/abs/math-ph/0208012