188 research outputs found
Local indistinguishability: more nonlocality with less entanglement
We provide a first operational method for checking indistinguishability of
orthogonal states by local operations and classical communication (LOCC). This
method originates from the one introduced by Ghosh et al. (Phys. Rev. Lett. 87,
5807 (2001) (quant-ph/0106148)), though we deal with pure states. We apply our
method to show that an arbitrary complete multipartite orthogonal basis is
indistinguishable by LOCC, if it contains at least one entangled state. We also
show that probabilistic local distinguishing is possible for full basis if and
only if all vectors are product. We employ our method to prove local
indistinguishability in an example with sets of pure states of 3X3, which shows
that one can have ``more nonlocality with less entanglement'', where ``more
nonlocality'' is in the sense of ``increased local indistinguishability of
orthogonal states''. This example also provides, to our knowledge, the only
known example where d orthogonal states in dXd are locally indistinguishable.Comment: 4 pages, no figures, RevTeX4, partially supersedes quant-ph/0204116,
to appear in Phys. Rev. Let
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