Generalizing measurement-induced phase transitions to information exchange symmetry breaking

Fuente: arXiv
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Main Authors: Kelly, Shane P., Marino, Jamir
Format: Preprint
Published: 2024
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author Kelly, Shane P.
Marino, Jamir
author_facet Kelly, Shane P.
Marino, Jamir
contents In this work we investigate the conditions for quantum back action to result in a phase transition in the information dynamics of a monitored system. We introduce a framework that captures a wide range of experiments encompassing probes comprised of projective measurements and probes which more generally transfer quantum information from the system to a quantum computer. Our framework explicitly uses a model of unitary evolution which couples system, apparatus and environment. Information dynamics is investigated using the Rényi and von-Neumann entropies of the evolving state, and we construct a replica theory for them. We identify the possible replica symmetries an experiment can possess and discuss their spontaneous symmetry breaking. In particular, we identify a minimum subgroup whose spontaneous symmetry breaking results in an entanglement transition. This symmetry is only possible when the information in the apparatus is as informative about the dynamics of the system as the information transferred to the environment. We call this requirement the information exchange symmetry and quantify it by a relationship between the entropies. We then show how the entanglement transition can be understood as the spontaneously breaking of the information exchange symmetry and without referring to the replica theory. Information exchange symmetry breaking is then shown to generalize the phenomenology of the measurement-induced phase transition (MIPT). We apply this theory to the brickwork quantum-enhanced experiment introduced in an accompanying Letter [Phys. Rev. A 111, L010402 (2025) ] in the case where the unitaries are chosen from the Haar measure, and identify a distinct universality from the MIPT. This notion of information exchange symmetry breaking generalizes the MIPT, and provides a framework for understanding the dynamics of quantum information in quantum-enhanced experiments.
format Preprint
id arxiv_https___arxiv_org_abs_2402_13271
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Generalizing measurement-induced phase transitions to information exchange symmetry breaking
Kelly, Shane P.
Marino, Jamir
Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
High Energy Physics - Theory
In this work we investigate the conditions for quantum back action to result in a phase transition in the information dynamics of a monitored system. We introduce a framework that captures a wide range of experiments encompassing probes comprised of projective measurements and probes which more generally transfer quantum information from the system to a quantum computer. Our framework explicitly uses a model of unitary evolution which couples system, apparatus and environment. Information dynamics is investigated using the Rényi and von-Neumann entropies of the evolving state, and we construct a replica theory for them. We identify the possible replica symmetries an experiment can possess and discuss their spontaneous symmetry breaking. In particular, we identify a minimum subgroup whose spontaneous symmetry breaking results in an entanglement transition. This symmetry is only possible when the information in the apparatus is as informative about the dynamics of the system as the information transferred to the environment. We call this requirement the information exchange symmetry and quantify it by a relationship between the entropies. We then show how the entanglement transition can be understood as the spontaneously breaking of the information exchange symmetry and without referring to the replica theory. Information exchange symmetry breaking is then shown to generalize the phenomenology of the measurement-induced phase transition (MIPT). We apply this theory to the brickwork quantum-enhanced experiment introduced in an accompanying Letter [Phys. Rev. A 111, L010402 (2025) ] in the case where the unitaries are chosen from the Haar measure, and identify a distinct universality from the MIPT. This notion of information exchange symmetry breaking generalizes the MIPT, and provides a framework for understanding the dynamics of quantum information in quantum-enhanced experiments.
title Generalizing measurement-induced phase transitions to information exchange symmetry breaking
topic Quantum Physics
Disordered Systems and Neural Networks
Statistical Mechanics
High Energy Physics - Theory
url https://arxiv.org/abs/2402.13271