Solvable non-Hermitian skin effect in many-body unitary dynamics

We study unitary evolution of bipartite entanglement in a circuit with nearest-neighbor random gates. Deriving a compact nonunitary description of purity dynamics on qudits we find a sudden transition in the purity relaxation rate the origin of which is in the underlying boundary localized eigenmode...

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Main Author: Marko Žnidarič
Format: Article
Language:English
Published: American Physical Society 2022-07-01
Series:Physical Review Research
Online Access:http://doi.org/10.1103/PhysRevResearch.4.033041
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author Marko Žnidarič
author_facet Marko Žnidarič
author_sort Marko Žnidarič
collection DOAJ
description We study unitary evolution of bipartite entanglement in a circuit with nearest-neighbor random gates. Deriving a compact nonunitary description of purity dynamics on qudits we find a sudden transition in the purity relaxation rate the origin of which is in the underlying boundary localized eigenmodes—the skin effect. We provide the full solution of the problem, being one of the simplest iterations of two-site matrices, namely, that each is a sum of only two projectors. This leads to rich dynamics influenced by the Jordan normal form of the kernel and, most importantly, a spectrum that is completely discontinuous in the thermodynamic limit. It provides a simple example of how a seemingly innocuous many-body unitary evolution can harbor interesting mathematical effects: an effective nonsymmetric Toeplitz transfer matrix description causes a phantom relaxation, such that the correct relaxation rate is not given by the matrix spectrum, but rather by its pseudospectrum.
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spelling doaj.art-1c3fa712cffd4a5eb9cae5b6d09804632024-04-12T17:22:48ZengAmerican Physical SocietyPhysical Review Research2643-15642022-07-014303304110.1103/PhysRevResearch.4.033041Solvable non-Hermitian skin effect in many-body unitary dynamicsMarko ŽnidaričWe study unitary evolution of bipartite entanglement in a circuit with nearest-neighbor random gates. Deriving a compact nonunitary description of purity dynamics on qudits we find a sudden transition in the purity relaxation rate the origin of which is in the underlying boundary localized eigenmodes—the skin effect. We provide the full solution of the problem, being one of the simplest iterations of two-site matrices, namely, that each is a sum of only two projectors. This leads to rich dynamics influenced by the Jordan normal form of the kernel and, most importantly, a spectrum that is completely discontinuous in the thermodynamic limit. It provides a simple example of how a seemingly innocuous many-body unitary evolution can harbor interesting mathematical effects: an effective nonsymmetric Toeplitz transfer matrix description causes a phantom relaxation, such that the correct relaxation rate is not given by the matrix spectrum, but rather by its pseudospectrum.http://doi.org/10.1103/PhysRevResearch.4.033041
spellingShingle Marko Žnidarič
Solvable non-Hermitian skin effect in many-body unitary dynamics
Physical Review Research
title Solvable non-Hermitian skin effect in many-body unitary dynamics
title_full Solvable non-Hermitian skin effect in many-body unitary dynamics
title_fullStr Solvable non-Hermitian skin effect in many-body unitary dynamics
title_full_unstemmed Solvable non-Hermitian skin effect in many-body unitary dynamics
title_short Solvable non-Hermitian skin effect in many-body unitary dynamics
title_sort solvable non hermitian skin effect in many body unitary dynamics
url http://doi.org/10.1103/PhysRevResearch.4.033041
work_keys_str_mv AT markoznidaric solvablenonhermitianskineffectinmanybodyunitarydynamics