Monitored dynamics & emergent phases
Measurements and other non-unitary operations can change which phases emerge from quantum many-body dynamics. I study how they compete with coherent evolution to produce distinct patterns of entanglement, and how stable these patterns are. Both the evolving quantum state and the classical measurement record offer ways to characterize the resulting phases and transitions, including dynamical behavior that has no direct equilibrium counterpart.
Papers
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Measurement-induced phase transition: A case study in the nonintegrable model by density-matrix renormalization group calculations
Physical Review Research 2, 013022 (2020)
Using matrix product state simulations of a nonintegrable Bose–Hubbard chain, we map the entanglement transition driven by local projective measurements. Varying the spatial density and frequency of measurements separates phases with volume-law and area-law entanglement. At criticality, entanglement grows logarithmically with subsystem size and time; scaling of entropy and mutual information provides evidence for a common universality class along the transition line.
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Quantum criticality in the nonunitary dynamics of (2+1)-dimensional free fermions
Physical Review B 103, 174303 (2021)
Non-unitary evolution with randomness in space and time drives two-dimensional free fermions into a critical steady state over a continuous range of non-unitary strengths. We find a logarithmic violation of the entanglement area law, algebraic correlations, and dynamical scaling with z = 1. A quasiparticle-pair picture explains the entanglement scaling, while a classical nonlinear master equation captures the evolution of correlations.
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Probing prethermal nonergodicity through measurement outcomes of monitored quantum dynamics
Physical Review B 112, L180306 (2025)
Rare projective measurements destabilize the prethermal many-body localized regime of a Floquet system and can increase its entanglement. We show that the classical measurement record retains signatures of the underlying nonergodic dynamics. Unsupervised learning and mutual-information analysis reveal this structure, providing a way to probe prethermal behavior through measurement outcomes.