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Phys. Rev. Lett. 98, 160501 (2007) [4 pages]

Discriminating States: The Quantum Chernoff Bound

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K. M. R. Audenaert
Institute for Mathematical Sciences, Imperial College London, 53 Prince’s Gate, London SW7 2PG, United Kingdom

J. Calsamiglia, R. Muñoz-Tapia, and E. Bagan
Grup de Física Teòrica, Universitat Autònoma de Barcelona, 08193 Bellaterra (Barcelona), Spain

Ll. Masanes
DAMTP, University of Cambridge, Wilberforce Road, Cambridge CB3 0WA, United Kingdom

A. Acin
ICFO-Institut de Ciencies Fotoniques, Mediterranean Technology Park, 08860 Castelldefels (Barcelona), Spain

F. Verstraete
Fakultät für Physik, Universität Wien, Boltzmanngasse 5, 1090 Wien, Austria

Received 18 October 2006; published 17 April 2007

We consider the problem of discriminating two different quantum states in the setting of asymptotically many copies, and determine the minimal probability of error. This leads to the identification of the quantum Chernoff bound, thereby solving a long-standing open problem. The bound reduces to the classical Chernoff bound when the quantum states under consideration commute. The quantum Chernoff bound is the natural symmetric distance measure between quantum states because of its clear operational meaning and because it does not seem to share some of the undesirable features of other distance measures.

© 2007 The American Physical Society

URL:
http://link.aps.org/doi/10.1103/PhysRevLett.98.160501
DOI:
10.1103/PhysRevLett.98.160501
PACS:
03.67.−a