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arXiv · 2602.05914

Local measurements and the entanglement transition in quantum spin chains

Sven Bachmann·Mahsa Rahnama·Gabrielle Tournaire
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Abstract

We consider the transition between short-range entangled (SRE) and long-range entangled states of infinite quantum spin chains which is induced by local measurements. Specifically, we assume that the initial state is in a non-trivial symmetry-protected topological phase of a compact local symmetry group $\mathcal{G}$. We show that the on-site measurements of an appropriate local charge on intervals of increasing lengths transform the initial SRE state into a family of states with increasingly long-range correlations. In particular, the post-measurement states cannot be uniformly short-range entangled. In the case where the initial state is obtained from a product state using a quantum cellular automaton, we construct the infinite-volume post-measurement state and exhibit almost local observables that are maximally correlated.

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Sven Bachmann, Mahsa Rahnama, Gabrielle Tournaire. 2026-02-05. Local measurements and the entanglement transition in quantum spin chains. https://arxiv.org/abs/2602.05914

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