Universal current correlations induced by the Majorana and fermionic Andreev bound states

Majorana bound states have been proposed to induce current-current correlations (CCCs) that are completely different from those induced by low-energy fermionic Andreev bound states. Such characteristics can be used as a signature to detect Majorana bound states and their nonlocality. Herein, we studied the Majorana and fermionic Andreev bound states in a two-dimensional topological insulator system. We found that the coupling of each pair of fermionic Andreev bound states coexists with that of the pair of Majorana bound states, and that the coupling strengths of all pairs of bound states depend on system parameters in the same pattern. Majorana and fermionic Andreev bound states show the same differential CCCs characteristics, thereby indicating a universal behavior for both types of bound states in a two-dimensional topological insulator system. The maximal cross-differential CCCs are robust to the structural asymmetry of the system.