20,435 research outputs found
Local distinguishability of orthogonal 2\otimes3 pure states
We present a complete characterization for the local distinguishability of
orthogonal pure states except for some special cases of three
states. Interestingly, we find there is a large class of four or three states
that are indistinguishable by local projective measurements and classical
communication (LPCC) can be perfectly distinguishable by LOCC. That indicates
the ability of LOCC for discriminating states is strictly more
powerful than that of LPCC, which is strikingly different from the case of
multi-qubit states. We also show that classical communication plays a crucial
role for local distinguishability by constructing a class of
states which require at least rounds of classical
communication in order to achieve a perfect local discrimination.Comment: 10 pages (revtex4), no figures. This is only a draft. It will be
replaced with a revised version soon. Comments are welcom
Conditions for entanglement transformation between a class of multipartite pure states with generalized Schmidt decompositions
In this note we generalize Nielsen's marjoization criterion for the
convertibility of bipartite pure states [Phys. Rev. Lett \textbf{83},
436(1999)] to a special class of multipartite pure states which have
generalized Schmidt decompositions.Comment: 3 pages (Revetex 4), no figures. A brief note on entanglement
transformation. Comments are welcom
Any subspace is locally distinguishable
A subspace of a multipartite Hilbert space is called \textit{locally
indistinguishable} if any orthogonal basis of this subspace cannot be perfectly
distinguished by local operations and classical communication. Previously it
was shown that any bipartite system such that and has
a locally indistinguishable subspace. However, it has been an open problem
since 2005 whether there is a locally indistinguishable bipartite subspace with
a qubit subsystem. We settle this problem by showing that any
bipartite subspace is locally distinguishable in the sense it contains a basis
perfectly distinguishable by LOCC. As an interesting application, we show that
any quantum channel with two Kraus operations has optimal environment-assisted
classical capacity.Comment: 3 pages (Revtex 4).Comments are welcome
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