Robustness of coherence between two quantum dots mediated by Majorana fermions

We study three important measurements used to identify the quantum correlations between two quantum dots (QDs) mediated by a pair of Majorana fermions (MFs) in a superconducting quantum wire. We find that, in addition to the quantum discord, the robustness of coherence (ROC) can also be considered as a quantity to measure the quantum correlation for the special case where the quantum entanglement is vanishing. For comparison, we study the quantum correlation between two QDs mediated by other fermions, i.e., regular fermions and superconducting fermions. We find that, when the quantum entanglement is not vanishing, i.e., the concurrence is finite, the detailed difference between the concurrence and ROC can be considered as an important implication for the existence of MFs.