Measurement-Induced Phase Transitions in Monitored Lipkin-Meshkov-Glik Model
POSTER
Abstract
Collective spin models provide a paradigmatic setting for exploring many-body quantum dynamics with long-range interactions and experimentally relevant measurement schemes. Among them, the Lipkin–Meshkov–Glick (LMG) model [1] captures essential features of a collection of N self-interacting spin-1/2 particles acted on by an external field.
Measurement-induced phase transitions (MIPTs) were originally discovered in random qubit lattices subjected to local projective measurements [2]. These transitions manifest as sharp changes in the scaling of entanglement entropy along individual quantum trajectories, from volume-law growth to area-law suppression, controlled by the measurement rate [3].
In this work, we investigate the emergence of MIPTs in the LMG model under continuous monitoring. Since measurement-induced transitions are often obscured at the ensemble-averaged level, we analyze entanglement entropy at the level of individual quantum trajectories, where the effects of measurement backaction become manifest. By combining different diagnostic tools such as entanglement entropy and inverse participation ratio, we uncover the nature of these transitions in monitored collective spin systems.
[1] Lipkin, Meshkov, and Glick, Nucl. Phys. 62, 188 (1965).
[2] B. Skinner, J. Ruhman, and A. Nahum, Phys. Rev. X 9, 031009 (2019).
[3] Cao, Tilloy, De Luca, SciPost Phys. 7, 024 (2019).
[4] Passarelli, Turkeshi, Russomanno, Lucignano, Schiro, and Fazio, Phys. Rev. Lett. 132, 163401 (2024).
Measurement-induced phase transitions (MIPTs) were originally discovered in random qubit lattices subjected to local projective measurements [2]. These transitions manifest as sharp changes in the scaling of entanglement entropy along individual quantum trajectories, from volume-law growth to area-law suppression, controlled by the measurement rate [3].
In this work, we investigate the emergence of MIPTs in the LMG model under continuous monitoring. Since measurement-induced transitions are often obscured at the ensemble-averaged level, we analyze entanglement entropy at the level of individual quantum trajectories, where the effects of measurement backaction become manifest. By combining different diagnostic tools such as entanglement entropy and inverse participation ratio, we uncover the nature of these transitions in monitored collective spin systems.
[1] Lipkin, Meshkov, and Glick, Nucl. Phys. 62, 188 (1965).
[2] B. Skinner, J. Ruhman, and A. Nahum, Phys. Rev. X 9, 031009 (2019).
[3] Cao, Tilloy, De Luca, SciPost Phys. 7, 024 (2019).
[4] Passarelli, Turkeshi, Russomanno, Lucignano, Schiro, and Fazio, Phys. Rev. Lett. 132, 163401 (2024).
*PK is supported by FCT grant 2024.01084.BD. The financing support of FCT, Portugal, under contract LA/P/0095/2020, Associated laboratory LaPMET - Laboratory of Physics for Materials and Emerging Technologies - and research unit UID/04540, CeFEMA - Centre of Physics and Engineering of Advanced Materials.
Presenters
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Polina Kofman
- Instituto Superior Tecnico, Universidade de Lisboa, Lisbon, Portugal