paper

Universal Entanglement Transitions of Free Fermions with Long-range Non-unitary Dynamics

arXiv:2105.08895 · doi:10.22331/q-2022-05-27-723

Abstract

Non-unitary evolution can give rise to novel steady states classified by their entanglement properties. In this work, we aim to understand its interplay with long-range hopping that decays with in free-fermion systems. We first study two solvable Brownian models with long-range non-unitary dynamics: a large- SYK chain and a single-flavor fermion chain and we show that they share the same phase diagram. When , we observe two critical phases with subvolume entanglement scaling: (i) , a logarithmic phase with dynamical exponent and logarithmic subsystem entanglement, and (ii) , a fractal phase with and subsystem entanglement , where is the length of the subsystem . These two phases cannot be distinguished by the purification dynamics, in which the entropy always decays as . We then confirm that the results are also valid for the static SYK chain, indicating the phase diagram is universal for general free-fermion systems. We also discuss phase diagrams in higher dimensions and the implication in measurement-induced phase transitions.

17 pages, 5 figures

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