Title: Supercurrent interference in nanowire-superconductor hybrid systems

Speaker: Prof. Bhaskaran Muralidharan, IIT Bombay, EE Dept

Abstract: Semiconductor nanowire-superconductor hybrid systems provide a promising platform for hosting unpaired Majorana fermions and thus realizing fault-tolerant topological qubits. In this talk, starting from the basic tenets of quantum transport theory, we demonstrate how to adapt the Non-Equilibrium Green’s Function (NEGF) formalism to model quantum transport in normal (N)-superconductor (S) junctions. We analyze Josephson junctions based on semiconductor nanowires and derive the Andreev bound state spectrum and current -phase relations. Recently,[1], and [2] have reported oscillations in the critical supercurrent with an axial magnetic field. Our simulations indicate that this phenomenon arises from the interference of orbital angular momentum modes [3,4] of the cylindrical nanowire. We also add disorder and study its effect on the critical current oscillations, with an aim to gain a thoroughgoing understanding of the experiments.

[1] K. Gharavi et.al., ArXiv:1405.7455v2, (2014).

[2] Zuo, et. al. Phys. Rev. Lett. 119, 187704 (2017)

[3] P. Sriram et. al., ArXiv:1902.10947 (2019).

[4] A. Lahiri et.al., Phys Rev B, 98, 125417, (2018).