Detecting and stabilizing measurement-induced symmetry-protected topological phases in generalized cluster models

TL;DR

This paper investigates measurement-induced symmetry-protected topological phases in quantum circuits, demonstrating their stability and coexistence with symmetry breaking using string order parameters and tensor network simulations.

Contribution

It introduces a framework combining stabilizer formalism and tensor networks to identify and analyze SPT phases in generalized cluster models within quantum circuits.

Findings

SPT phases are stable under circuit extensions to Haar unitaries.

String order parameters effectively distinguish different SPT phases.

Coexistence of SPT order and spontaneous symmetry breaking is demonstrated.

Abstract

We study measurement-induced symmetry-protected topological (SPT) order in a wide class of quantum random circuit models by combining calculations within the stabilizer formalism with tensor network simulations. We construct a family of quantum random circuits, generating the out-of-equilibrium version of all generalized cluster models, and derive a set of non-local string order parameters to distinguish different SPT phases. We apply this framework to investigate a random circuit realization of the XZX cluster model, and use the string order parameter to demonstrate that the phase diagram is stable against extending the class of unitary gates in the circuit, from Clifford gates to Haar unitaries. We then turn to the XZZX generalized cluster model, and demonstrate the coexistence of SPT order and spontaneous symmetry breaking, by relying on string order parameters and a connected correlation function.