Quantum reverse engineering and reference-frame alignment without nonlocal correlations

TitleQuantum reverse engineering and reference-frame alignment without nonlocal correlations
Publication TypeJournal Article
Year of Publication2004
AuthorsBagan, E, Baig, M, Muñoz-Tapia, R
JournalPhysical Review A (Atomic, Molecular, and Optical Physics)
Volume70
Issue3
Pagination030301
Date Published09/2004
ISSN1050-2947
Abstract

The estimation of unknown qubit elementary gates and the alignment of reference frames are formally the same problem. Using quantum states made out of N qubits, we show that the theoretical precision limit for both problems, which behaves as 1∕N2, can be asymptotically attained with a covariant protocol that exploits the quantum correlation of internal degrees of freedom instead of the more fragile entanglement between distant parties. This cuts by half the number of qubits needed to achieve the precision of the dense covariant coding protocol.

URLhttp://link.aps.org/doi/10.1103/PhysRevA.70.030301
DOI10.1103/PhysRevA.70.030301
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