We consider the Cavalcanti-Foster-Fuwa-Wiseman inequality~\cite{achsh} which is a necessary and sufficient steerability condition for two-qubit states with two measurement settings on each side. We derive the criterion which an arbitrary two-qubit state must satisfy in order to violate this inequality, and obtain its maximum attainable violation in quantum mechanics. The derived condition on the state parameters enables us to establish a tight monogamy relation for two-qubit steering.
@article{arxiv.1711.00872,
title = {Necessary and sufficient state condition for two-qubit steering using two measurement settings per party and monogamy of steering},
author = {Shiladitya Mal and Debarshi Das and Souradeep Sasmal and A. S. Majumdar},
journal= {arXiv preprint arXiv:1711.00872},
year = {2017}
}