Quantum coherence in a compass chain under an alternating magnetic field

TL;DR

This paper studies quantum phase transitions and coherence in a quantum compass chain under an alternating magnetic field, revealing how different coherence measures detect critical points and proposing an experimental realization.

Contribution

It analytically solves the model using Jordan-Wigner transformation and compares coherence measures in identifying quantum critical points, providing new insights into quantum phase transitions.

Findings

Relative entropy of coherence accurately detects quantum critical points.

L1 norm of coherence fails to identify phase transitions reliably.

Jensen-Shannon divergence is less effective at exceptional points.

Abstract

We investigate quantum phase transitions and quantum coherence in a quantum compass chain under an alternating transverse magnetic field. The model can be analytically solved by the Jordan-Wigner transformation and this solution shows that it is equivalent to a two-component one-dimensional (1D) Fermi gas on a lattice. We explore mutual effects of the staggered magnetic interaction and multi-site interactions on the energy spectra and analyze the ground state phase diagram. We use quantum coherence measures to identify the quantum phase transitions. Our results show that $l_1$ norm of coherence fails to detect faithfully the quantum critical points separating a gapped phase from a gapless phase, which can be pinpointed exactly by relative entropy of coherence. Jensen-Shannon divergence is somewhat obscure at exception points. We also propose an experimental realization of such a 1D system using superconducting quantum circuits.