Ancilla quantum measurements on interacting chains: Sensitivity of entanglement dynamics to the type and concentration of detectors

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Main Authors: Doggen, Elmer V. H., Gornyi, Igor V., Mirlin, Alexander D.
Format: Preprint
Published: 2023
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author Doggen, Elmer V. H.
Gornyi, Igor V.
Mirlin, Alexander D.
author_facet Doggen, Elmer V. H.
Gornyi, Igor V.
Mirlin, Alexander D.
contents We consider a quantum many-body lattice system that is coupled to ancillary degrees of freedom (``detectors''), which are periodically measured by means of strong projective measurements. The concentration $ρ_a$ of ancillae and their coupling $M$ to the main system are considered as parameters. We explore the dynamics of density and of entanglement entropy in the chain, for various values of $ρ_a$ and $M$ for two models of the detector-chain interaction that couple the local density in the chain to a detector degree of freedom. It is found that, for the density-density ($S_z s_z$-type in spin language) coupling, the critical values $M_c$ for the measurement-induced entanglement transition depends sensitively on $ρ_a$. Moreover, our results indicate that for a sufficiently small $ρ_a$ the transition in this model disappears, i.e., a finite density of detectors is needed to reach a disentangling phase. The behavior is qualitatively different for the second model, with density-hopping ($S_z s_x$-type) coupling. Specifically, the dynamics is much less sensitive to the concentration $ρ_a$ of detectors than in the first model. Furthermore, the dependence of entanglement on the coupling strength $M$ is strongly non-monotonic, indicating re-entrance of the entangling phase at large $M$.
format Preprint
id arxiv_https___arxiv_org_abs_2311_13011
institution arXiv
publishDate 2023
record_format arxiv
spellingShingle Ancilla quantum measurements on interacting chains: Sensitivity of entanglement dynamics to the type and concentration of detectors
Doggen, Elmer V. H.
Gornyi, Igor V.
Mirlin, Alexander D.
Quantum Physics
Disordered Systems and Neural Networks
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
We consider a quantum many-body lattice system that is coupled to ancillary degrees of freedom (``detectors''), which are periodically measured by means of strong projective measurements. The concentration $ρ_a$ of ancillae and their coupling $M$ to the main system are considered as parameters. We explore the dynamics of density and of entanglement entropy in the chain, for various values of $ρ_a$ and $M$ for two models of the detector-chain interaction that couple the local density in the chain to a detector degree of freedom. It is found that, for the density-density ($S_z s_z$-type in spin language) coupling, the critical values $M_c$ for the measurement-induced entanglement transition depends sensitively on $ρ_a$. Moreover, our results indicate that for a sufficiently small $ρ_a$ the transition in this model disappears, i.e., a finite density of detectors is needed to reach a disentangling phase. The behavior is qualitatively different for the second model, with density-hopping ($S_z s_x$-type) coupling. Specifically, the dynamics is much less sensitive to the concentration $ρ_a$ of detectors than in the first model. Furthermore, the dependence of entanglement on the coupling strength $M$ is strongly non-monotonic, indicating re-entrance of the entangling phase at large $M$.
title Ancilla quantum measurements on interacting chains: Sensitivity of entanglement dynamics to the type and concentration of detectors
topic Quantum Physics
Disordered Systems and Neural Networks
Mesoscale and Nanoscale Physics
Strongly Correlated Electrons
url https://arxiv.org/abs/2311.13011