Conductance and noise signatures of Majorana backscattering

We propose a conductance measurement to detect the backscattering of chiral Majorana edge states. Because normal and Andreev processes have equal probability for backscattering of a single chiral Majorana edge state, there is qualitative difference from backscattering of a chiral Dirac edge state, giving rise to half-integer Hall conductivity and decoupling of fluctuation in incoming and outgoing modes. The latter can be detected through thermal noise measurement. These experimental signatures of Majorana fermions are robust at finite temperature and do not require the size of the backscattering region to be mesoscopic.

Figure 1

Comparison between different SCs. There is no backscattering for $N=2$ TSC, Dirac fermion backscattering for NSC, and Majorana fermion backscattering for $N=1$ TSC. Red (gray) and blue (dark gray) arrows represent $e\pm h$ chiral Majorana edge states, respectively.

Figure 2

Schematic of the backscattering setup. The voltages $V_1$ and $V_2$ are applied to leads 1 and 2, respectively, and set the chemical potential for the incoming modes that are annihilated by ${\mathrm{â}}_{1;e}$ and ${\mathrm{â}}_{2;e}$. In the central region, TSC is induced through proximity to two SC slabs that sandwich the QAH. The TSC is grounded through a contact to its bulk.