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All two qubit states that are steerable via CHSH-type correlations are Bell-nonlocal

Research paper by Parth Girdhar, Eric G. Cavalcanti

Indexed on: 07 Jan '16Published on: 07 Jan '16Published in: Quantum Physics



Abstract

We derive a new inequality that is necessary and sufficient to show EPR-steering in a scenario employing only correlations between two arbitrary dichotomic measurements on each party. Thus the inequality is a complete steering analogy of the CHSH inequality, a generalisation of the result of Cavalcanti et al, JOSA B, 32(4), A74 (2015). We show that violation of the inequality only requires measuring over equivalence classes of mutually unbiased measurements on the trusted party and in fact assuming a general two qubit system arbitrary pairs of distinct projective measurements at the trusted party are equally useful. Via this it is found that for a given state the maximum violation of our EPR-steering inequality is equal to that for the CHSH inequality, so all states that are EPR-steerable with CHSH-type correlations are also Bell nonlocal.