Results 41 to 50 of about 138,468 (211)

The density matrix in the non-Hermitian approach to open quantum system dynamics

Atti della Accademia Peloritana dei Pericolanti : Classe di Scienze Fisiche, Matematiche e Naturali, 2019
In this paper we review an approach to the dynamics of open quantum systems based of non-Hermitian Hamiltonians. Non-Hermitian Hamiltonians arise naturally when one wish to study a subsystem interacting with a continuum of states.
Alessandro Sergi
doaj   +1 more source

On unitary/Hermitian duality in matrix models [PDF]

Nuclear Physics B, 2005
Unitary 1-matrix models are shown to be exactly equivalent to hermitian 1-matrix models coupled to 2N vectors with appropriate potentials, to all orders in the 1/N expansion. This fact allows us to use all the techniques developed and results obtained in hermitian 1-matrix models to investigate unitary as well as other 1-matrix models with the Haar ...
openaire   +2 more sources

Butson-type complex Hadamard matrices and association schemes on Galois rings of characteristic 4

Special Matrices, 2018
We consider nonsymmetric hermitian complex Hadamard matrices belonging to the Bose-Mesner algebra of commutative nonsymmetric association schemes. First, we give a characterization of the eigenmatrix of a commutative nonsymmetric association scheme of ...
Ikuta Takuya, Munemasa Akihiro
doaj   +1 more source

Numerical Optimization of Eigenvalues of Hermitian Matrix Functions [PDF]

SIAM Journal on Matrix Analysis and Applications, 2014
This work concerns the global minimization of a prescribed eigenvalue or a weighted sum of prescribed eigenvalues of a Hermitian matrix-valued function depending on its parameters analytically in a box. We describe how the analytical properties of eigenvalue functions can be put into use to derive piece-wise quadratic functions that underestimate the ...
Emre Mengi, E. Alper Yildirim, Mustafa Kiliç   +2 more
openaire   +5 more sources

Cubic Idempotence Preserver Problem in Hermitian Matrix Space

Journal of Harbin University of Science and Technology
Preserver problems are the study of preserving maps of certain invariants on a given mathematical structure. In order to preserve the cubic idempotent of Hermitian matrix space, we study the image from the basis of 2 × 2-dimensional Hermitian matrix ...
ZHANG Haoran, XU Jinli
doaj   +1 more source

Scattering cross section resonance originating from a spectral singularity

, 2011
Using techniques of supersymmetric quantum mechanics, scattering properties of Hermitian Hamiltonians, which are related to non-Hermitian ones by similarity transformations, are studied.
Samsonov, Boris F.
core   +1 more source

Hermitian Adjacency Matrix of Digraphs and Mixed Graphs [PDF]

Journal of Graph Theory, 2016
AbstractThe article gives a thorough introduction to spectra of digraphs via its Hermitian adjacency matrix. This matrix is indexed by the vertices of the digraph, and the entry corresponding to an arc from x to y is equal to the complex unity i (and its symmetric entry is ) if the reverse arc is not present.
Krystal Guo, Bojan Mohar
openaire   +2 more sources

Transport and spectral features in non-Hermitian open systems

Physical Review Research, 2021
We study the transport and spectral properties of a non-Hermitian one-dimensional disordered lattice, the diagonal matrix elements of which are random complex variables taking both positive (loss) and negative (gain) imaginary values: Their distribution ...
A. F. Tzortzakakis, K. G. Makris, A. Szameit, E. N. Economou   +3 more
doaj   +1 more source

Relativistic Non-Hermitian Quantum Mechanics

, 2014
We develop relativistic wave equations in the framework of the new non-hermitian ${\cal PT}$ quantum mechanics. The familiar Hermitian Dirac equation emerges as an exact result of imposing the Dirac algebra, the criteria of ${\cal PT}$-symmetric quantum ...
Jones-Smith, Katherine, Mathur, Harsh
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Optimization Problems of Hermitian Quadratic Matrix-Valued Functions and Applications

Axioms
In this paper, we investigate optimization problems for a Hermitian quadratic matrix-valued function involving two variable matrices. We derive algebraic formulas for the maximal and minimal ranks and partial inertias of this function based on a ...
Sihem Guerarra
doaj   +1 more source