arXiv subjects

Rudolf A. R"omer

Publications and source records attributed to Rudolf A. R"omer.

3 recordsLinked to original sources

arXiv1996

No enhancement of the localization length for two interacting particles in a random potential

We study two interacting particles in a random potential chain by means of the transfer matrix method. The dependence of the two-particle localization length $λ_2$ on disorder and interaction strength is investigated. Our results demonstrate that the recently proposed enhancement of $λ_2$ as compared to the results for single particles is entirely due to the finite size of the systems considered. This is shown for a Hubbard-like onsite interaction and also a long-range interaction.

cond-mat.dis-nn↗

arXiv1993

Exiton, Spinon and Spin Wave Modes in an Exactly Soluble One-Dimensional Quantum Many-Body System

In this paper, we present the exact solution to a one-dimensional, two-component, quantum many-body system in which like particles interact with a pair potential $s(s+1)/{\rm sinh}^{2}(r)$, while unlike particles interact with a pair potential $-s(s+1)/{\rm cosh}^{2}(r)$. We first give a proof of integrability, then derive the coupled equations determining the complete spectrum. All singularities occur in the ground state when there are equal numbers of the two components; we give explicit results for the ground state and low-lying states in this case. For $s>0$, the system is an antiferromagnet/insulator, with excitations consisting of a pair-hole--pair continuum, a two-particle continuum with gap, and excitons with gaps. For $-1<s<0$, the system has excitations consisting of a hole-particle continuum, and a two-spin wave continuum, both gap-less.

cond-mat↗

arXiv1993

Conformal Invariance in Periodic Quantum Chains

We show how conformal invariance predicts the functional form of two-point correlators in one-dimensional periodic quantum systems. Numerical evidence for this functional form in a wide class of models --- including long-ranged ones --- is given and it is shown how this may be used to significantly speed up calculations of critical exponents.

cond-mat↗