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General formulas of the two-electron operator representing either atomic or effective interactions are given in a coupled tensorial form in relativistic approximation. The alternatives of using uncoupled, coupled and antisymmetric…

Atomic Physics · Physics 2010-04-30 Rytis Jursenas , Gintaras Merkelis

This paper deals with a method for the approximation of a spectral density function among the solutions of a generalized moment problem a` la Byrnes/Georgiou/Lindquist. The approximation is pursued with respect to the Kullback-Leibler…

Optimization and Control · Mathematics 2009-11-04 Augusto Ferrante , Federico Ramponi , Francesco Ticozzi

Under which conditions do outcome probabilities of measurements possess a quantum-mechanical model? This kind of problem is solved here for the case of two dichotomic von Neumann measurements which can be applied repeatedly to a quantum…

Quantum Physics · Physics 2010-08-27 Tobias Fritz

In this paper we present a solution of the Einstein's boxes paradox by modern Quantum Mechanics in which a notion of density matrix is equivalent to a notion of a quantum state of a system. We use a secondary quantization formalism in the…

Quantum Physics · Physics 2007-05-23 E. Yu. Bunkova , O. A. Khrustalev , O. D. Timofeevskaya

The idea that symmetries simplify or reduce the complexity of a system has been remarkably fruitful in physics, and especially in quantum mechanics. On a mathematical level, symmetry groups single out a certain structure in the Hilbert…

Quantum Physics · Physics 2021-03-16 Oleg Kabernik

Entanglement transformation of composite quantum systems is investigated in the context of group representation theory. Representation of the direct product group $SL(2,C)\otimes SL(2,C)$, composed of local operators acting on the binary…

Quantum Physics · Physics 2009-11-07 Li-Xiang Cen , Xin-Qi Li , YiJing Yan

In this article, we study a direct and an inverse problem for the bi-wave operator $(\Box^2)$ along with second and lower order time-dependent perturbations. In the direct problem, we prove that the operator is well-posed, given initial and…

Analysis of PDEs · Mathematics 2026-05-28 Sombuddha Bhattacharyya , Pranav Kumar

In this paper we treat the Jaynes-Cummings model with dissipation and give an approximate solution to the master equation for the density operator {\bf under the general setting} by making use of the Zassenhaus expansion.

Quantum Physics · Physics 2015-05-27 Kazuyuki Fujii , Tatsuo Suzuki

This paper addresses a construction of new $q-$Hermite polynomials with a full characterization of their main properties and corresponding raising and lowering operator algebra. The three-term recursive relation as well as the second-order…

Mathematical Physics · Physics 2013-10-07 Won Sang Chung , Mahouton Norbert Hounkonnou , Arjika Sama

We provide a constructive algorithm to find the best separable approximation to an arbitrary density matrix of a composite quantum system of finite dimensions. The method leads to a condition of separability and to a measure of…

Quantum Physics · Physics 2009-10-30 Maciej Lewenstein , Anna Sanpera

We revisit the problem of computing (robust) controlled invariant sets for discrete-time linear systems. Departing from previous approaches, we consider implicit, rather than explicit, representations for controlled invariant sets.…

Optimization and Control · Mathematics 2022-08-10 Tzanis Anevlavis , Zexiang Liu , Necmiye Ozay , Paulo Tabuada

A general classification of linear differential and finite-difference operators possessing a finite-dimensional invariant subspace with a polynomial basis is given. The main result is that any operator with the above property must have a…

High Energy Physics - Theory · Physics 2008-02-03 Alexander Turbiner

Given the algebra of observables of a quantum system subject to selection rules, a state can be represented by different density matrices. As a result, different von Neumann entropies can be associated with the same state. Motivated by a…

Quantum Physics · Physics 2021-05-25 Paolo Facchi , Giovanni Gramegna , Arturo Konderak

Recent advancements in photon induced near-field electron microscopy (PINEM) enable the preparation, coherent manipulation and characterization of free-electron quantum states. The available measurement consists of electron energy…

Numerical Analysis · Mathematics 2026-03-17 Florian Oberender

The introduction of operator states and of observables in various fields of quantum physics has raised questions about the mathematical structures of the corresponding spaces. In the framework of third quantization it had been conjectured…

Mathematical Physics · Physics 2015-03-02 T. Prosen , L. Martignon , T. H. Seligman

An efficient procedure for constructing quasi-exactly solvable matrix models is suggested. It is based on the fact that the representation spaces of representations of the algebra sl(2,R) within the class of first-order matrix differential…

High Energy Physics - Theory · Physics 2009-10-30 Renat Zhdanov

A problem of a wave identification is formulated. An example is considered in conditions of one-dimensional Cauchy problem for conventional string equation in matrix form and its inhomogeneous two-component version. The acoustic and…

Mathematical Physics · Physics 2014-12-30 Sergey Leble , Irina Vereshchagina

In this paper we consider nonlinear problems with an operator depending only on the deformation tensor. We consider the class of operators derived from a potential and with $(p,\delta)$ structure, for $1<p\leq 2$ and for all $\delta\geq0$.…

Analysis of PDEs · Mathematics 2021-12-24 Luigi C. Berselli , Michael Růžička

We introduce a general random model of a combinatorial optimization problem with geometric structure that encapsulates both linear programming and integer linear programming. Let $Q$ be a bounded set called the feasible set, $E$ be an…

Probability · Mathematics 2024-07-25 Dylan J. Altschuler

A model operator approach to calculations of the QED corrections to energy levels in relativistic many-electron atomic systems is developed. The model Lamb shift operator is represented by a sum of local and nonlocal potentials which are…

Atomic Physics · Physics 2013-07-26 V. M. Shabaev , I. I. Tupitsyn , V. A. Yerokhin