Articolele autorului Nicolae Cotfas
Link la profilul stiintific al lui Nicolae Cotfas

Properties of finite Gaussians and the discrete-continuous transition

Weyl’s formulation of quantum mechanics opened the possibility of studying the dynamics of quantum systems both in infinite-dimensional and finite-dimensional systems. Based on Weyl’s approach, generalized by Schwinger, a self-consistent theoretical framework describing physical systems characterized by a finite-dimensional space of states has been created. The used mathematical formalism is further developed by adding finite-dimensional versions

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Hypergeometric type operators and their supersymmetric partners

The generalization of the factorization method performed by Mielnik [J. Math. Phys. 25, 3387 (1984)] opened new ways to generate exactly solvable potentials in quantum mechanics. We present an application of Mielnik's method to hypergeometric type operators. It is based on some solvable Riccati equations and leads to a unitary description of the quantum systems exactly solvable in terms of orthogonal polynomials or associated special functions.

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Finite-dimensional Hilbert space and frame quantization

The quantum observables used in the case of quantum systems with finite-dimensional Hilbert space are defined either algebraically in terms of an orthonormal basis and discrete Fourier transformation or by using a continuous system of coherent states. We present an alternative approach to these important quantum systems based on the finite frame quantization. Finite systems of coherent states, usually called finite tight frames, can be defined in

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Complex and real Hermite polynomials and related quantizations

It is known that the anti-Wick (or standard coherent state) quantization of the complex plane produces both canonical commutation rule and quantum spectrum of the harmonic oscillator (up to the addition of a constant). In this work, we show that these two issues are not necessarily coupled: there exists a family of separable Hilbert spaces, including the usual Fock–Bargmann space, and in each element in this family there exists an overcomplete

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Finite tight frames and some applications

A finite-dimensional Hilbert space is usually described in terms of an orthonormal basis, but in certain approaches or applications a description in terms of a finite overcomplete system of vectors, called a finite tight frame, may offer some advantages. The use of a finite tight frame may lead to a simpler description of the symmetry transformations, to a simpler and more symmetric form of invariants or to the possibility to define new mathematical

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Gazeau-Klauder type coherent states for hypergeometric type operators
Symmetry properties of Penrose type tilings
Aperiodic packings of clusters obtained by projection
Penrose-type patterns obtained by projection from a 12D lattice
Shape invariance, raising and lowering operators in hypergeometric type equations