Informacja

Drogi użytkowniku, aplikacja do prawidłowego działania wymaga obsługi JavaScript. Proszę włącz obsługę JavaScript w Twojej przeglądarce.

Wyszukujesz frazę "continuous spectrum" wg kryterium: Temat


Wyświetlanie 1-6 z 6
Tytuł:
Singular continuous spectrum of half-line Schrodinger operators with point interactions on a sparse set
Autorzy:
Lotoreichik, V.
Powiązania:
https://bibliotekanauki.pl/articles/254871.pdf
Data publikacji:
2011
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
half-line Schrodinger operators
delta-interactions
singular continuous spectrum
Opis:
We say that a discrete set X = {xn}n ∈ N0 on the half-line 0 = x0 < x1 < x2 < x3 < ⋅ ⋅ ⋅< xn < ⋅ ⋅ ⋅,< +∞ is sparse if the distances Δxn = xn+1-xn between neighbouring points satisfy the condition [formula]. In this paper half-line Schrödinger operators with point δ- and δ'- interactions on a sparse set are considered. Assuming that strengths of point interactions tend to ∞ we give simple sufficient conditions for such Schrödinger operators to have non-empty singular continuous spectrum and to have purely singular continuous spectrum, which coincides with R+.
Źródło:
Opuscula Mathematica; 2011, 31, 4; 615-628
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Weyl-Titchmarsh type formula for Hermite operator with small perturbation
Autorzy:
Simonov, S.
Powiązania:
https://bibliotekanauki.pl/articles/255278.pdf
Data publikacji:
2009
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Jacobi matrices
absolutely continuous spectrum
subordinacy theory
Weyl-Titchmarsh theory
Opis:
Small perturbations of the Jacobi matrix with weights √n and zero diagonal are considered. A formula relating the asymptotics of polynomials of the first kind to the spectral density is obtained, which is an analogue of the classical Weyl-Titchmarsh formula for the Schr ödinger operator on the half-line with summable potential. Additionally, a base of generalized eigenvectors for "free" Hermite operator is studied and asymptotics of Plancherel-Rotach type are obtained.
Źródło:
Opuscula Mathematica; 2009, 29, 2; 187-207
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spectra of some selfadjoint Jacobi operators in the double root case
Autorzy:
Motyka, W.
Powiązania:
https://bibliotekanauki.pl/articles/254745.pdf
Data publikacji:
2015
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Jacobi matrices
double root case
asymptotic behavior
subordination theory
absolutely continuous spectrum
discrete spectrum
Opis:
In this paper we prove a mixed spectrum of Jacobi operators defined by λn = s(n)(1 + x(n)) and qn = — 2s(n)(l+y/(n)), where (s(n)) is a real unbounded sequence, (x(n)) and (y(n)) are some perturbations.
Źródło:
Opuscula Mathematica; 2015, 35, 3; 353-370
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
On one condition of absolutely continuous spectrum for self-adjoint operators and its applications
Autorzy:
Ianovich, E.
Powiązania:
https://bibliotekanauki.pl/articles/254841.pdf
Data publikacji:
2018
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
self-adjoint operators absolutely continuous spectrum
equi-absolute continuity
spectral density
Jacobi matrices
Opis:
In this work the method of analyzing of the absolutely continuous spectrum for self-adjoint operators is considered. For the analysis it is used an approximation of a self-adjoint operator A by a sequence of operators An with absolutely continuous spectrum on a given interval [a, b] which converges to A in a strong sense on a dense set. The notion of equi-absolute continuity is also used. It was found a sufficient condition of absolute continuity of the operator A spectrum on the finite interval [a, b] and the condition for that the corresponding spectral density belongs to the class Lp[a,b] (p ≥ 1). The application of this method to Jacobi matrices is considered. As one of the results we obtain the following assertion: Under some mild assumptions, suppose that there exist a constant C > 0 and a positive function g(x) ∈ Lp[a, b] (p ≥ 1).such that for all n sufficiently large and almost all [formula] the estimate [formula] holds, where Pn(x) are 1st type polynomials associated with Jacobi matrix (in the sense of Akhiezer) and bn is a second diagonal sequence of Jacobi matrix. Then the spectrum of Jacobi matrix operator is purely absolutely continuous on [a, b] and for the corresponding spectral density ƒ (x) we have ƒ (x) ∈ Lp[a,b].
Źródło:
Opuscula Mathematica; 2018, 38, 5; 699-718
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
Spontaneous decay of level from spectral theory point of view
Autorzy:
Ianovich, Eduard
Powiązania:
https://bibliotekanauki.pl/articles/2048989.pdf
Data publikacji:
2021
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
spectral theory
quantum field theory
self-adjoint operators
absolutely continuous spectrum
spontaneous decay
Opis:
In quantum field theory it is believed that the spontaneous decay of excited atomic or molecular level is due to the interaction with continuum of field modes. Besides, the atom makes a transition from upper level to lower one so that the probability to find the atom in the excited state tends to zero. In this paper it will be shown that the mathematical model in single-photon approximation may predict another behavior of this probability generally. Namely, the probability to find the atom in the excited state may tend to a nonzero constant so that the atom is not in the pure state finally. This effect is due to that the spectrum of the complete Hamiltonian is not purely absolutely continuous and has a discrete level outside the continuous part. Namely, we state that in the corresponding invariant subspace, determining the time evolution, the spectrum of the complete Hamiltonian when the field is considered in three dimensions may be not purely absolutely continuous and may have an eigenvalue. The appearance of eigenvalue has a threshold character. If the field is considered in two dimensions the spectrum always has an eigenvalue and the decay is absent.
Źródło:
Opuscula Mathematica; 2021, 41, 6; 849-859
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
Tytuł:
A first-order spectral phase transition in a class of periodically modulated Hermitian Jacobi matrices
Autorzy:
Pchelintseva, I.
Powiązania:
https://bibliotekanauki.pl/articles/255740.pdf
Data publikacji:
2008
Wydawca:
Akademia Górniczo-Hutnicza im. Stanisława Staszica w Krakowie. Wydawnictwo AGH
Tematy:
Jacobi matrices
spectral phase transition
absolutely continuous spectrum
pure point spectrum
discrete spectrum
subordinacy theory
asymptotics of generalized eigenvectors
Opis:
We consider self-adjoint unbounded Jacobi matrices with diagonal q(n) = b(n)n and off-diagonal entries λ(n) = n, where b(n) is a 2-periodical sequence of real numbers. The parameter space is decomposed into several separate regions, where the spectrum of the operator is either purely absolutely continuous or discrete. We study the situation where the spectral phase transition occurs, namely the case of b(1)b(2) = 4. The main motive of the paper is the investigation of asymptotics of generalized eigenvectors of the Jacobi matrix. The pure point part of the spectrum is analyzed in detail.
Źródło:
Opuscula Mathematica; 2008, 28, 2; 137-150
1232-9274
2300-6919
Pojawia się w:
Opuscula Mathematica
Dostawca treści:
Biblioteka Nauki
Artykuł
    Wyświetlanie 1-6 z 6

    Ta witryna wykorzystuje pliki cookies do przechowywania informacji na Twoim komputerze. Pliki cookies stosujemy w celu świadczenia usług na najwyższym poziomie, w tym w sposób dostosowany do indywidualnych potrzeb. Korzystanie z witryny bez zmiany ustawień dotyczących cookies oznacza, że będą one zamieszczane w Twoim komputerze. W każdym momencie możesz dokonać zmiany ustawień dotyczących cookies