Locally accessible information: How much can the parties gain by cooperating?

Abstract

We investigate measurements of bipartite ensembles restricted to local operations and classical communication and find a universal Holevo-like upper bound on the locally accessible information. We analyze our bound and exhibit a class of states which saturate it. Finally, we link the bound to the problem of quantification of the nonlocality of the operations necessary to extract locally unaccessible information.

4 pages, no figures, RevTeX4; v2: a conjecture partially proven, results unchanged; v3: small changes in presentation, published version