No nonlocal advantage of quantum coherence beyond quantum instrumentality

Abstract

Recently, it has been shown that quantum steerability is stronger than the bound set by the instrumental causal network and quantum instrumentality cannot simulate EPR-nonlocal correlations. In this work, we show that although quantum steering may be stronger than what is allowed by the instrumental causal network, the non-local advantage of quantum local coherence (NAQC) can only be achieved under ordered causal network but not under one-sided quantum instrumentality (1SQI) and outcome communications. As a consequence of our work, it is observed that there is a qualitative difference between the idea of NAQC and EPR non-locality. Furthermore, the principle of no NAQC beyond quantum instrumentality can also be used to single out EPR-nonlocality.