A finite topological superconductor nanowire bears a Majorana fermion at its ends, leading to unique transport properties when connected to normal metal leads. We consider here theoretical proposals based on noise measurements in normal metal–topological superconductor junctions. A first one 1) considers a Hanbury Brown and Twiss setup where a topological superconductor is connected to two normal metal leads. A second proposal 2) deals with the finite frequency noise of a single normal metal–topological superconductor junction. A third one 3) deals with a junction between three topological superconductors. All transport properties are computed using a unified framework of non -equilibrium Keldysh Green's functions using a Hamiltonian approach. Calculations are performed non-perturbatively in the tunnel hopping parameter and address both subgap and above gap regimes. Concerning the Hanbury Brown and Twiss setup, we find in the subgap case that when the two normal metal leads are biased with equal voltage, the noise crossed correlations are negative, as in the case of a three terminal normal metal junction. On the other hand when subgap voltages are opposite, the noise crossed correlations are positive. In the second proposal, the finite frequency emission and absorption noises are computed for a single junction. We observe noticeable structures in these quantities, related to simple transport processes involving the Majorana bound state. In the third proposal, we predict a “giant shot noise” behavior due to the presence of a Majorana zero mode. All results offer an original tool for the further characterization of the presence of Majorana bound states in condensed matter systems.

References:

 1) Hanbury Brown and Twiss noise correlations in a topological superconductor beam splitter, T. Jonckheere, J. Rech, A. Zazunov, R. Egger, and T. Martin, Phys. Rev. B 95, 054514 (2017).

 2) Finite frequency noise in a normal metal–topological superconductor junction, D. Bathellier, L. Raymond,

T. Jonckheere, J. Rech, A. Zazunov, and T. Martin, Phys. Rev. B 99, 104502 (2019).

 3) Giant Shot Noise from Majorana Zero Modes in Topological Trijunctions, T. Jonckheere, J. Rech, A.

Zazunov, R. Egger, A. Levy Yeyati, and T. Martin, Phys. Rev. Lett. 122, 097003 (2019).