Phase Transitions without gap closing in monitored quantum mean-field systems

Luca Capizzi; Riccardo Travaglino

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arXiv · 2512.04201

Phase Transitions without gap closing in monitored quantum mean-field systems

Luca Capizzi·Riccardo Travaglino

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Abstract

We investigate the monitored dynamics of many-body quantum systems in which projective measurements of extensive operators are alternated with unitary evolution. Focusing on mean-field models characterized by all-to-all interactions, we develop a general framework that captures the thermodynamic limit, where a semiclassical description naturally emerges. Remarkably, we uncover novel stationary states, distinct from the conventional infinite-temperature state, that arise upon taking the infinite-volume limit. Counterintuitively, this phenomenon is not linked to the closing of the Lindbladian gap in that limit. We provide analytical explanation for this unexpected behavior.

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Luca Capizzi, Riccardo Travaglino. 2025-12-03. Phase Transitions without gap closing in monitored quantum mean-field systems. https://arxiv.org/abs/2512.04201

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