Difficulty of distinguishing product states locally

Croke, S. and Barnett, S. M. (2017) Difficulty of distinguishing product states locally. Physical Review A: Atomic, Molecular and Optical Physics, 95(1), 012337. (doi: 10.1103/PhysRevA.95.012337)

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Nonlocality without entanglement is a rather counterintuitive phenomenon in which information may be encoded entirely in product (unentangled) states of composite quantum systems in such a way that local measurement of the subsystems is not enough for optimal decoding. For simple examples of pure product states, the gap in performance is known to be rather small when arbitrary local strategies are allowed. Here we restrict to local strategies readily achievable with current technology: those requiring neither a quantum memory nor joint operations. We show that even for measurements on pure product states, there can be a large gap between such strategies and theoretically optimal performance. Thus, even in the absence of entanglement, physically realizable local strategies can be far from optimal for extracting quantum information.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Barnett, Professor Stephen and Croke, Dr Sarah
Authors: Croke, S., and Barnett, S. M.
College/School:College of Science and Engineering > School of Physics and Astronomy
Journal Name:Physical Review A: Atomic, Molecular and Optical Physics
Publisher:American Physical Society
ISSN (Online):1094-1622
Published Online:30 January 2017
Copyright Holders:Copyright © 2017 The Authors
First Published:First published in Physical Review A: Atomic, Molecular and Optical Physics 95(1):012337
Publisher Policy:Reproduced under a Creative Commons License

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