paper

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

arXiv:2311.13011 · doi:10.1103/PhysRevB.109.224203

Abstract

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 of ancillae and their coupling 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 and 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 (-type in spin language) coupling, the critical values for the measurement-induced entanglement transition depends sensitively on . Moreover, our results indicate that for a sufficiently small 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 (-type) coupling. Specifically, the dynamics is much less sensitive to the concentration of detectors than in the first model. Furthermore, the dependence of entanglement on the coupling strength is strongly non-monotonic, indicating re-entrance of the entangling phase at large .

13 pages, 10 figures + 12 pages of Supplemental Material

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