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Quantum mereology: Factorizing Hilbert space into subsystems with quasiclassical dynamics

Carroll, Sean M. and Singh, Ashmeet (2021) Quantum mereology: Factorizing Hilbert space into subsystems with quasiclassical dynamics. Physical Review A, 103 (2). Art. No. 022213. ISSN 2469-9926. doi:10.1103/PhysRevA.103.022213.

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We study the question of how to decompose Hilbert space into a preferred tensor-product factorization without any preexisting structure other than a Hamiltonian operator, in particular the case of a bipartite decomposition into “system” and “environment.” Such a decomposition can be defined by looking for subsystems that exhibit quasiclassical behavior. The correct decomposition is one in which pointer states of the system are relatively robust against environmental monitoring (their entanglement with the environment does not continually and dramatically increase) and remain localized around approximately classical trajectories. We present an in-principle algorithm for finding such a decomposition by minimizing a combination of entanglement growth and internal spreading of the system. Both of these properties are related to locality in different ways. This formalism is relevant to questions in the foundations of quantum mechanics and the emergence of spacetime from quantum entanglement.

Item Type:Article
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URLURL TypeDescription Paper
Carroll, Sean M.0000-0002-4226-5758
Singh, Ashmeet0000-0002-4404-1416
Alternate Title:Quantum Mereology: Factorizing Hilbert Space into Subsystems with Quasi-Classical Dynamics
Additional Information:© 2021 American Physical Society. Received 29 May 2020; revised 21 January 2021; accepted 2 February 2021; published 16 February 2021. We would like to thank Anthony Bartolotta, Ning Bao, ChunJun (Charles) Cao, Aidan Chatwin-Davies, Jason Pollack, and Jess Riedel for helpful discussions during the course of this project. We are also thankful to two anonymous referees for their comments to help us improve the manuscript. This research is funded in part by the Walter Burke Institute for Theoretical Physics at Caltech, by the Foundational Questions Institute, and by the U.S. Department of Energy, Office of Science, Office of High Energy Physics, under Award No. DE-SC0011632.
Group:Walter Burke Institute for Theoretical Physics
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Walter Burke Institute for Theoretical Physics, CaltechUNSPECIFIED
Foundational Questions Institute (FQXI)UNSPECIFIED
Department of Energy (DOE)DE-SC0011632
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Issue or Number:2
Record Number:CaltechAUTHORS:20200528-092234945
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Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:103515
Deposited By: Joy Painter
Deposited On:28 May 2020 16:28
Last Modified:16 Nov 2021 18:22

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