Measurement-induced phase transitions in disordered fermions

Fuente: arXiv
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Main Authors: Liao, Yunxiang, Matheussen, Max, Zhang, Xinghai
Format: Preprint
Published: 2026
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author Liao, Yunxiang
Matheussen, Max
Zhang, Xinghai
author_facet Liao, Yunxiang
Matheussen, Max
Zhang, Xinghai
contents Measurement-induced phase transitions are nonequilibrium transitions between phases characterized by distinct entanglement scaling behaviors, driven by the competition between unitary dynamics and measurements. Despite recent numerical efforts, how quenched disorder affects these transitions remains unclear. In this work, we study a $d$-dimensional noninteracting fermionic system subject to both quenched disorder and continuous monitoring of the local particle density, and derive an effective field theory describing its long-time universal behaviors. We find that the system is governed by the same nonlinear sigma model as in the case of clean monitored fermions, with disorder entering only through a modification of model parameters. This result suggests that the presence or absence of a measurement-induced phase transition is unaffected by the introduction of disorder: in spatial dimensions d>1, a transition occurs between an area x log law phase and an area law phase, whereas in d=1, the system exhibits only an area law phase and no transition. Numerical results further demonstrate that both clean and disordered one-dimensional free fermions exhibit area-law behavior when the system size is large enough.
format Preprint
id arxiv_https___arxiv_org_abs_2605_05306
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Measurement-induced phase transitions in disordered fermions
Liao, Yunxiang
Matheussen, Max
Zhang, Xinghai
Statistical Mechanics
Disordered Systems and Neural Networks
Quantum Physics
Measurement-induced phase transitions are nonequilibrium transitions between phases characterized by distinct entanglement scaling behaviors, driven by the competition between unitary dynamics and measurements. Despite recent numerical efforts, how quenched disorder affects these transitions remains unclear. In this work, we study a $d$-dimensional noninteracting fermionic system subject to both quenched disorder and continuous monitoring of the local particle density, and derive an effective field theory describing its long-time universal behaviors. We find that the system is governed by the same nonlinear sigma model as in the case of clean monitored fermions, with disorder entering only through a modification of model parameters. This result suggests that the presence or absence of a measurement-induced phase transition is unaffected by the introduction of disorder: in spatial dimensions d>1, a transition occurs between an area x log law phase and an area law phase, whereas in d=1, the system exhibits only an area law phase and no transition. Numerical results further demonstrate that both clean and disordered one-dimensional free fermions exhibit area-law behavior when the system size is large enough.
title Measurement-induced phase transitions in disordered fermions
topic Statistical Mechanics
Disordered Systems and Neural Networks
Quantum Physics
url https://arxiv.org/abs/2605.05306