Genuine correlations in finite-size spin systems

TL;DR

This paper investigates how genuine multipartite correlations in finite XY spin chains vary with external magnetic fields, revealing their potential to detect ground state degeneracies and the factorizing point at low temperatures.

Contribution

It demonstrates that multipartite correlations can signal ground state degeneracies and identify the factorizing point in finite-size XY chains, linking correlations to quantum phase transitions.

Findings

Multipartite correlations exhibit minima at ground state degeneracies.

Correlations are sensitive to parity changes in the ground state.

They can be used to detect the factorizing point in finite systems.

Abstract

Genuine multipartite correlations in finite-size XY chains are studied as a function of the applied external magnetic field. We find that, for low temperatures, multipartite correlations are sensitive to the parity change in the Hamiltonian ground state, given that they exhibit a minimum every time that the ground state becomes degenerate. This implies that they can be used to detect the factorizing point, that is, the value of the external field such that, in the termodynamical limit, the ground state becomes the tensor product of single-spin states.