Universal transport properties of a quantum dot system with a laterally-coupled Majorana zero mode

• Majorana zero mode causes zero-bias conductance to be e2/2h when QD-lead couplings are identical.
• The e2/2h conductance is independent of the level number, distribution, and the geometry of QDs.
• This means that QD condition is not a key factor to achieve the detection of Majorana zero mode.
• If decoupling appears, the Majorana zero mode may contribute little to the conductance.

We present a comprehensive analysis about the transport properties of a quantum dot (QD) system with a side-coupled Majorana zero mode. Our calculation result shows that when the coupling manners between the two leads and QDs are identical, the local Andreev reflection and the interlead normal tunneling have the same magnitude at the zero-bias limit. Accordingly, the zero-bias conductance value is always equal to e2/2h, which is exactly one half of the resonant-tunneling conductance. This result is independent of the level number and the level distribution in the single-QD case, and in the coupled-QD case it is irrelevant to the geometry of the QD molecule. The universal transport property is a powerful evidence for the feasibility to detect the MBSs based on a QD circuit. This result also means that the QD condition is not a key factor to achieve the detection. On the other hand, if the decoupling phenomenon appears, the Majorana zero mode may play a trivial role in contributing to the conductance property.