Driven Non-Unitary Dynamics of Quantum Critical Systems
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.
Cite
@article{arxiv.2505.01508,
title = {Driven Non-Unitary Dynamics of Quantum Critical Systems},
author = {Bastien Lapierre and Pietro Pelliconi and Shinsei Ryu and Julian Sonner},
journal= {arXiv preprint arXiv:2505.01508},
year = {2025}
}