Measurement-induced criticality in (2+1)-d hybrid quantum circuits

TL;DR

This paper studies how random quantum gates and measurements induce a phase transition in entanglement scaling in 2D quantum spin systems, revealing a universal critical point distinct from 3D percolation.

Contribution

It introduces a numerical analysis of measurement-induced transitions in 2D hybrid quantum circuits using stabilizer states, identifying a universal critical point with logarithmic entanglement violations.

Findings

Identifies a measurement-induced phase transition between volume-law and area-law entanglement.

Estimates the critical exponent with high precision, indicating universality.

Finds the transition's universality class differs from 3D percolation.

Abstract

We investigate the dynamics of two-dimensional quantum spin systems under the combined effect of random unitary gates and local projective measurements. When considering steady states, a measurement-induced transition occurs between two distinct dynamical phases, one characterized by a volume-law scaling of entanglement entropy, the other by an area-law. Employing stabilizer states and Clifford random unitary gates, we numerically investigate square lattices of linear dimension up to $L=48$ for two distinct measurement protocols. For both protocols, we observe a transition point where the dominant contribution in the entanglement entropy displays multiplicative logarithmic violations to the area-law. We obtain estimates of the correlation length critical exponent at the percent level; these estimates suggest universal behavior, and are incompatible with the universality class of 3D percolation.