Searcharxiv⌕ Search

arXiv subjects

Yurii Suhov

Publications and source records attributed to Yurii Suhov.

4 recordsLinked to original sources
arXiv2020

Stationary Distributions and Convergence for M/M/1 Queues in Interactive Random Environment

A Markovian single-server queue is studied in an interactive random environment. The arrival and service rates of the queue depend on the environment, while the transition dynamics of the random environment depends on the queue length. We consider in detail two types of Markov random environments: a pure jump process and a reflected jump-diffusion. In both cases, the joint dynamics is constructed so that the stationary distribution can be explicitly found in a simple form (weighted geometric). We also derive an explicit estimate for exponential rate of convergence to the stationary distribution via coupling.

math.PR↗
arXiv2013

A quantum Mermin--Wagner theorem for quantum rotators on two--dimensional graphs

This is the first of a series of papers considering symmetry properties of quantum systems over 2D graphs or manifolds, with continuous spins, in the spirit of the Mermin--Wagner theorem. In the model considered here (quantum rotators) the phase space of a single spin is a $d-$dimensional torus, and spins (or particles) are attached to sites of a graph satisfying a special bi-dimensionality property. The kinetic energy part of the Hamiltonian is minus a half of the Laplace operator. We assume that the interaction potential is C$^2$-smooth and invariant under the action of a connected Lie group ${\ttG}$. A part of our approach is to give a definition (and a construction) of a class of infinite-volume Gibbs states for the systems under consideration (the class $\fG$). This class contains the so-called limit Gibbs states, with or without boundary conditions. We use ideas and techniques originated from various past papers, in combination with the Feynman--Kac representation, to prove that any state lying in the class $\fG$ (defined in the text) is ${\ttG}$-invariant. An example is given where the interaction potential is singular and there exists a Gibbs state which is not ${\ttG}$-invariant. In the next paper under the same title we establish a similar result for a bosonic model where particles can jump from a vertex of the graph to one of its neighbors (a generalized Hubbard model).

math.PR↗
arXiv2013

A quantum Mermin--Wagner theorem for a generalized Hubbard model on a 2D graph

This paper is the second in a series of papers considering symmetry properties of a bosonic quantum system over an 2D graph, with continuous spins, in the spirit of the Mermin--Wagner theorem. Here we consider bosonic systems on bi-dimensional graphs where particles can jump from a vertex to another (a generalized Hubbard model). The Feynman--Kac representation is used for proving that if the local Hamiltonians are invariant under a continuous group of transformations ${\tt G}$ (a Euclidean space or a torus of dimension $d'$ acting on a torus of dimension $d\geq d'$) then any infinite-volume Gibbs state from a certain class (introduced in the paper) is also ${\tt G}$-invariant.

math-ph↗