Measurement-induced phase transitions in monitored infinite-range interacting systems

TL;DR

This paper investigates measurement-induced phase transitions in infinite-range systems, revealing how entanglement saturation and bistability influence the feasibility of observing such transitions experimentally.

Contribution

It demonstrates that entanglement saturation is not inherent to all infinite-range systems and explores how bistability affects measurement-induced phase transitions.

Findings

Entanglement phase transitions occur in monitored infinite-range models.

Bistability regions hinder mitigation of the post-selection barrier.

Proposed experimental realizations for observing these phenomena.

Abstract

A key challenge in observing measurement-induced phase transitions is the mitigation of the post-selection barrier, which causes the reproducibility of specific sequences of measurement readouts--the trajectory--to be exponentially small in system size. Recent studies suggest that some classes of monitored infinite-range systems alleviate this problem by exhibiting a fast saturation of entanglement, resulting in only a polynomial post-selection overhead. This paper answers whether this feature is inherent in infinite-range systems, due to their underlying semiclassical dynamics. We consider three experimentally relevant monitored models: a Tavis-Cummings model, a Superradiance model, and a Bose-Hubbard dimer, each exhibiting non-trivial monitored dynamics. We unveil the occurrence of entanglement phase transitions in these models, showing how the saturation time is strongly affected by bistability regions, which also prevent the mitigation of the post-selection barrier. Finally, we propose experimental realizations of these models, providing a discussion of post selection from an experimental perspective.