Quantum information research aims to use quantum resources to achieve communication security, computing power and measurement accuracy beyond classical limits. In recent years, a new quantum resource—quantum causal order—has been proposed and proven to be able to provide unique advantages in some kinds of quantum information processes. This article reviews the existing quantum resources and the application of quantum causal order in quantum information and focuses on the super-Heisenberg limit accuracy it can provide in quantum metrology tasks. This new quantum resource may potentially provide essential promotion in various quantum information processing.

quantum resources  /  quantum causal order  /  super-Heisenberg limit