Hierarchy in temporal quantum correlations
Huan-Yu Ku, Shin-Liang Chen, Neill Lambert, Yueh-Nan Chen, Franco Nori · Physical Review A · 2018
Einstein-Podolsky-Rosen (EPR) steering is an intermediate quantum correlation that lies in between entanglement and Bell nonlocality. Its temporal analog, 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.