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arXiv · 2505.01508

Driven Non-Unitary Dynamics of Quantum Critical Systems

Bastien Lapierre·Pietro Pelliconi·Shinsei Ryu·Julian Sonner
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Abstract

We investigate the interplay between unitary and non-unitary driven many-body dynamics in (1+1)-dimensional quantum critical systems described by conformal field theory (CFT). By formulating a coherent state approach, we demonstrate that the growth of entanglement entropy and energy can be found analytically for a class of non-unitary driven CFTs, where the evolution alternates between real and imaginary time evolution, the latter corresponding to postselected weak measurements. We find that non-unitary evolution leads to the emergence of steady states at infinite times for the cases of periodic, quasiperiodic, and random drives. In a special class of drives, for mixed initial states, we uncover purification phase transitions that arise as a result of the competition between unitary evolution and weak measurements. We compare the CFT evolution with the corresponding non-unitary dynamics of critical lattice models, finding remarkable agreement.

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Bastien Lapierre, Pietro Pelliconi, Shinsei Ryu, Julian Sonner. 2025-05-02. Driven Non-Unitary Dynamics of Quantum Critical Systems. https://doi.org/10.1103/lwrz-jxrr

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