We have considered a numerical scheme for the calculation of the equilibrium properties of spin-12 XY chains. Within its frames it is necessary to solve in the last resort only the 2N × 2N eigenvalue and eigenvector problem but not the 2 × 2 one as for an arbitrary system consisting of N spins 1 2 . To illustrate the approach we have presented some new results. Namely, the xx dynamic structure ...

We consider the one-dimensional Ising-like fully anisotropic S= 1 2 Heisenberg antiferromagnetic Hamiltonian and study the dynamics of domain wall excita-tions in the presence of transverse magnetic field h x. We obtain dynamical spin correlation functions along the magnetic field S xx (q, ω) and perpendicular to it S yy (q, ω). It is shown that the line shapes of S xx (q, ω) and S yy (q, ω) ar...

The approximation of nearest neighbor interaction (NNI) is widely used in short-time spin dynamics with dipole-dipole interactions (DDI) when the intensity spin-spin $\sim 1/r^3$, where $r$ a distance between those spins. However, NNI can not approximate long time evolution such systems. We consider system 1/r^{\alpha}$, $\alpha\ge 3$, and find low boundary $\alpha_c$ applicability to an arbitr...

In this paper we study the localization transition induced by the disorder in random antiferromagnetic spin1 2 chains. The results of numerical large scale computations are presented for the XX model using its free fermions representation. The scaling behavior of the spin stiffness is investigated for various disorder strengths. The disorder dependence of the localization length is studied and ...

A bstract We consider the symmetry resolution of relative entropies in 1+1 dimensional free massless compact boson conformal field theory (CFT) which presents an internal U(1) symmetry. calculate various resolved Rényi between one interval reduced density matrices CFT primary states using replica method. By taking limit, entropy can be obtained. also take XX spin chain model as a concrete latti...

Physical systems have some degree of disorder present in them. We discuss how to treat natural, thermal entanglement in any random macroscopic system from which a thermodynamic witness bounded by a constant can be found. We propose that functional many-body perturbation theory be applied to allow either a quenched or an annealed average over the disorder to be taken. We find, when considering t...

We study zero-temperature quantum spin chains, which are characterized by a nonvanishing current. For the XX model starting from the initial state mid R:cdots, three dots, centered upward arrow upward arrow upward arrow downward arrow downward arrow downward arrowcdots, three dots, centered we derive an exact expression for the variance of the total spin current. We show that asymptotically the...