Quantum dynamics of monitored free fermions: Evolution of quantum correlations and scaling at measurement-induced phase transition

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Autori principali: Poboiko, Igor, Mirlin, Alexander D.
Natura: Preprint
Pubblicazione: 2025
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author Poboiko, Igor
Mirlin, Alexander D.
author_facet Poboiko, Igor
Mirlin, Alexander D.
contents We explore, both analytically and numerically, the quantum dynamics of a many-body free-fermion system subjected to local density measurements. We begin by extending the mapping to the nonlinear sigma-model (NLSM) field theory for the case of finite evolution time $T$ and different classes of initial states, which lead to different NLSM boundary conditions. The analytical formalism is then used to study how quantum correlations gradually develop, with increasing $T$, from those determined by the initial state towards their steady-state form. The analytical results are confirmed by numerical simulations for several types of initial states. We further consider the long-time limit, when the system in $d+1$ space-time dimensions becomes quasi-one-dimensional, and analyze the scaling of the ``localization'' time (which is simultaneously the purification time and the charge-sharpening time for this class of problems). The analytical predictions for scaling properties are fully confirmed by numerical simulations in a $d=2$ model around the measurement-induced phase transition. We use this dynamical approach to determine numerically the measurement-induced transition point and the associated correlation-length critical exponent.
format Preprint
id arxiv_https___arxiv_org_abs_2512_01772
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Quantum dynamics of monitored free fermions: Evolution of quantum correlations and scaling at measurement-induced phase transition
Poboiko, Igor
Mirlin, Alexander D.
Disordered Systems and Neural Networks
Mesoscale and Nanoscale Physics
We explore, both analytically and numerically, the quantum dynamics of a many-body free-fermion system subjected to local density measurements. We begin by extending the mapping to the nonlinear sigma-model (NLSM) field theory for the case of finite evolution time $T$ and different classes of initial states, which lead to different NLSM boundary conditions. The analytical formalism is then used to study how quantum correlations gradually develop, with increasing $T$, from those determined by the initial state towards their steady-state form. The analytical results are confirmed by numerical simulations for several types of initial states. We further consider the long-time limit, when the system in $d+1$ space-time dimensions becomes quasi-one-dimensional, and analyze the scaling of the ``localization'' time (which is simultaneously the purification time and the charge-sharpening time for this class of problems). The analytical predictions for scaling properties are fully confirmed by numerical simulations in a $d=2$ model around the measurement-induced phase transition. We use this dynamical approach to determine numerically the measurement-induced transition point and the associated correlation-length critical exponent.
title Quantum dynamics of monitored free fermions: Evolution of quantum correlations and scaling at measurement-induced phase transition
topic Disordered Systems and Neural Networks
Mesoscale and Nanoscale Physics
url https://arxiv.org/abs/2512.01772