# Long range quantum coherence, quantum & classical correlations in Heisenberg XX chain

## TL;DR

This paper investigates long-range quantum coherence, quantum, and classical correlations in the 1D Heisenberg XX spin chain, highlighting their roles in quantum phase transitions and robustness against temperature for potential quantum information applications.

## Contribution

It introduces a comprehensive analysis of quantum coherence alongside correlations in the Heisenberg XX chain, emphasizing its effectiveness in detecting phase transitions and robustness compared to traditional measures.

## Key findings

- Quantum correlations reveal phase transitions.
- Quantum discord remains robust at higher temperatures.
- Quantum coherence outperforms traditional correlations in temperature resilience.

## Abstract

A comparative study of pairwise quantum coherence, quantum and classical correlations is addressed for non-nearest spin pairs of the 1D Heisenberg spin-$\frac{1}{2}$ XX chain. Following the Jordan-Wigner mapping, we diagonalise the hamiltonian of the chain and we check this procedure numerically as well. Using the "Pauli basis expansion" formalism we get the pairwise quantities studied in this work at any distance. We then, show the role of quantum correlations in revealing quantum phase transitions, the robustness of quantum discord to the temperature and the dominance of quantum correlations over their classical counterpart in the magnetic and thermal interval in quantum spin chains. We conclude the paper by shedding light from a resource-driven point of view on the new born quantity "quantum coherence" where we discuss its role in detecting quantum phase transitions being a long-range quantity, and how it outclasses the usual quantum correlations measures in the robustness against the temperature, which indicates potential uses in the framework of quantum information processing.