Quantum and classical correlations in antiferromagnetic chains and the realization of Werner states with spins

TL;DR

This paper explores how varying exchange couplings in antiferromagnetic spin chains affects pairwise quantum and classical correlations, demonstrating the realization of Werner states and potential for experimental probing of non-classical correlations.

Contribution

It reveals how tuning a single exchange coupling in AFM chains controls correlations and shows that certain two-spin states realize Werner states, offering new experimental possibilities.

Findings

Varying coupling J1 influences pairwise correlations.

Certain two-spin states are exact Werner states.

Tunable exchange coupling enables experimental realization of Werner states.

Abstract

We investigate pairwise correlation properties of the ground state (GS) of finite antiferromagnetic (AFM) spin chains described by the Heisenberg model. The exchange coupling is restricted to nearest neighbor spins, and is constant $J_0$ except for a pair of neighboring sites, where the coupling $J_1$ may vary. We identify a rich variety of possible behaviors for different measures of pairwise (quantum and classical) correlations and entanglement in the GS of such spin chain. Varying a single coupling affects the degree of correlation between all spin pairs, indicating possible control over such correlations by tuning $J_1$. We also show that a class of two spin states constitutes exact spin realizations of Werner states (WS). Apart from the basic and theoretical aspects, this opens concrete alternatives for experimentally probing non-classical correlations in condensed matter systems, as well as for experimental realizations of a WS via a single tunable exchange coupling in a AFM chain.