PT-symmetric Hamiltonians and their application in quantum information

Croke, S. (2015) PT-symmetric Hamiltonians and their application in quantum information. Physical Review A: Atomic, Molecular and Optical Physics, 91(5), 052113. (doi: 10.1103/PhysRevA.91.052113)

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We discuss the prospect of PT -symmetric Hamiltonians finding applications in quantum information science, and conclude that such evolution is unlikely to provide any benefit over existing techniques. Although it has been known for some time that PT -symmetric quantum theory, when viewed as a unitary theory, is exactly equivalent to standard quantum mechanics, proposals continue to be put forward for schemes in which PT -symmetric quantum theory can outperform standard quantum theory. The most recent of these is the suggestion to use PT -symmetric Hamiltonians to perform exponentially fast database search, a task known to be impossible with a quantum computer. Further, such a scheme has been shown to apparently produce effects in conflict with fundamental information-theoretic principles, such as the impossibility of superluminal information transfer, and the invariance of entanglement under local operations. In this paper we propose three inequivalent experimental implementations of PT -symmetric Hamiltonians, with careful attention to the resources required to realise each such evolution. Such an operational approach allows us to resolve these apparent conflicts, and evaluate fully schemes proposed in the literature for faster time evolution and state discrimination.

Item Type:Articles
Glasgow Author(s) Enlighten ID:Croke, Dr Sarah
Authors: Croke, S.
Subjects:Q Science > QC Physics
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
Copyright Holders:Copyright © 2015 American Physical Society
First Published:First published in Physical Review A: Atomic, Molecular and Optical Physics 91(5):052113
Publisher Policy:Reproduced under a Creative Commons License

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