Einstein-Podolsky-Rosen (EPR) steering is an intermediate quantum correlation that lies in between entanglement and Bell non-locality. Its temporal analogue, temporal steering, has recently been shown to have applications in quantum information and open quantum systems. Here, we show that there exists a hierarchy among the three temporal quantum correlations: temporal inseparability, temporal steering, and macrorealism. Given that the temporal inseparability can be used to define a measure of quantum causality, similarly the quantification of temporal steering can be viewed as a weaker measure of direct cause and can be used to distinguish between direct cause and common cause in a quantum network.
@article{arxiv.1710.11387,
title = {Hierarchy in temporal quantum correlations},
author = {Huan-Yu Ku and Shin-Liang Chen and Neill Lambert and Yueh-Nan Chen and Franco Nori},
journal= {arXiv preprint arXiv:1710.11387},
year = {2018}
}