arXiv subjects

D. Yafaev

Publications and source records attributed to D. Yafaev.

4 recordsLinked to original sources

arXiv2007

On spectral properties of translationally invariant magnetic Schrödinger operators

We consider a class of translationally invariant magnetic fields such that the corresponding potential has a constant direction. Our goal is to study basic spectral properties of the Schrödinger operator ${\bf H}$ with such a potential. In particular, we show that the spectrum of ${\bf H}$ is absolutely continuous and we find its location. Then we study the long-time behaviour of solutions $\exp(-i {\bf H} t)f$ of the time dependent Schrödinger equation. It turnes out that a quantum particle remains localized in the plane orthogonal to the direction of the potential. Its propagation in this direction is determined by group velocities. It is to a some extent similar to a evolution of a one-dimensional free particle but "exits" to $+\infty$ and $-\infty$ might be essentially different.

math.SP↗

arXiv2004

A particle in the Bio-Savart-Laplace magnetic field: explicit solutions

We consider the Schrödinger operator ${\bf H}=(i\nabla+A)^2 $ in the space $L_2({\mathbb R}^3)$ with a magnetic potential $A $ created by an infinite straight current. We perform a spectral analysis of the operator ${\bf H}$ almost explicitly. In particular, we show that the operator ${\bf H}$ is absolutely continuous, its spectrum has infinite multiplicity and coincides with the positive half-axis. Then we find the large-time behavior of solutions $\exp(-i{\bf H}t)f$ of the time dependent Schrödinger equation. Equations of classical mechanics are also integrated. Our main observation is that both quantum and classical particles have always a preferable (depending on its charge) direction of propagation along the current and both of them are confined in the plane orthogonal to the current.

physics.plasm-ph↗

arXiv1998

A class of pseudo-differential operators with oscillating symbols

We study a class of pseudo-differential operators with oscillating symbols or osc illating amplitudes appearing in the long-range scattering theory. We develop the basic calc ulus for operators from such classes and solve some concrete problems posed by applications to scattering theory, especially to the scattering matrix. In particular, we show tha t under natural assumptions the spectrum of a pseudo-differential operator with an oscillating symb ol covers the unit circle.

math.SP↗

arXiv1998

The discrete spectrum in the singular Friedrichs model

A typical result of the paper is the following. Let $H_γ=H_0 +γV$ where $H_0$ is multiplication by $|x|^{2l}$ and $V$ is an integral operator with kernel $\cos< x,y\rang le$ in the space $L_2(R^d)$. If $l=d/2+ 2k$ for some $k= 0,1,...$, then the operator $H_γ$ has infinite number of negative eigenvalues for any coupling constant $γ\neq 0$. For other values of $l$, the negative spectrum of $H_γ$ is infinite for $|γ|> σ_l$ where $σ_l$ is some explicit positive constant. In the case $\pm γ\in (0,σ_l]$, the number $N^{(\pm)}_l$ of negative eigenvalues of $H_γ$ is finite and does not depend on $γ$. We calculate $N^{(\pm)}_l$.

math-ph↗