Detecting Majorana nonlocality using strongly coupled Majorana bound states

Abstract

Majorana bound states (MBS) differ from the regular zero energy Andreev bound states in their nonlocal properties, since two MBS form a single fermion. We design strategies for detection of this nonlocality by using the phenomenon of Coulomb-mediated Majorana coupling in a setting which still retains falsifiability and does not require locally separated MBS. Focusing on the implementation of MBS based on the quantum spin Hall effect, we also design a way to probe Majoranas without the need to open a magnetic gap in the helical edge states. In the setup that we analyze, long range MBS coupling manifests in the h/e magnetic flux periodicity of tunneling conductance and supercurrent. While h/e is also the periodicity of Aharonov-Bohm effect and persistent current, we show how to ensure its Majorana origin by verifying that switching off the charging energy restores h/2e periodicity conventional for superconducting systems.