Pooling quantum states obtained by indirect measurements

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Title Pooling quantum states obtained by indirect measurements
Author Spekkens, Robert W.; Wiseman, Howard Mark
Journal Name Physical Review A (Atomic, Molecular and Optical Physics)
Editor Gordon W.F. Drake, Margaret Malloy
Year Published 2007
Place of publication Ridge, NY
Publisher American Physical Society
Abstract We consider the pooling of quantum states when Alice and Bob both have one part of a tripartite system and, on the basis of measurements on their respective parts, each infers a quantum state for the third part S. We denote the conditioned states which Alice and Bob assign to S by alpha and beta respectively, while the unconditioned state of S is rho. The state assigned by an overseer, who has all the data available to Alice and Bob, is omega. The pooler is told only alpha, beta, and rho. We show that for certain classes of tripartite states, this information is enough for her to reconstruct omega by the formula omega \propto alpha rho^{-1} beta. Specifically, we identify two classes of states for which this pooling formula works: (i) all pure states for which the rank of rho is equal to the product of the ranks of the states of Alice's and Bob's subsystems; (ii) all mixtures of tripartite product states that are mutually orthogonal on S.
Peer Reviewed Yes
Published Yes
Publisher URI http://pra.aps.org/
Alternative URI http://dx.doi.org/10.1103/PhysRevA.75.042104
Copyright Statement Copyright 2007 American Physical Society. This is the author-manuscript version of this paper. Reproduced in accordance with the copyright policy of the publisher. Please refer to the journal's website for access to the definitive, published version.
Volume 75
Page from 042104-1
Page to 042104-5
ISSN 1050-2947
Date Accessioned 2008-02-25
Language en_AU
Research Centre Centre for Quantum Dynamics
Faculty Faculty of Science, Environment, Engineering and Technology
URI http://hdl.handle.net/10072/18282
Publication Type Journal Articles (Refereed Article)
Publication Type Code c1

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