Measurement-induced entanglement transition in chaotic quantum Ising chain

TL;DR

This paper explores the stability of measurement-induced entanglement transitions in a monitored quantum Ising chain under various perturbations, revealing their robustness to certain symmetry and integrability breaking but sensitivity to measurement basis changes.

Contribution

It demonstrates that measurement-induced phase transitions are generally robust to integrability and symmetry breaking, but can be eliminated by changing the measurement basis.

Findings

Phase transition insensitive to integrability breaking.

Phase transition insensitive to symmetry breaking.

Measurement basis change removes the phase transition.

Abstract

We numerically investigate the robustness against various perturbations of measurement-induced phase transition in monitored quantum Ising models in the no-click limit, where the dynamics is described by a non-Hermitian Hamiltonian. We study perturbations that break the integrability and/or the symmetry of the model, as well as modifications in the measurement protocol, characterizing the resulting chaos and lack of integrability through the Dissipative Spectral Form Factor (DSFF). We show that while the measurement-induced phase transition and its properties appear to be broadly insensitive to lack of integrability and breaking of the $\mathbb{Z_2}$ symmetry, a modification of the measurement basis from the transverse to the longitudinal direction makes the phase transition disappear altogether.