Building topological quantum circuits: Majorana nanowire junctions

Abstract

Topological quantum computation using non-Abelian Majorana zero modes localized in proximitized semiconductor nanowires requires careful electrostatic control of wire-junctions so as to manipulate and braid the zero modes enabling anyonic fault-tolerant gate operations. We theoretically investigate the topological superconducting properties of such elementary wire-junctions, the so-called T junctions, finding that the existence of the junction may nonperturbatively affect the Majorana behavior by introducing spurious non-topological subgap states mimicking zero-modes. We propose a possible solution to this potentially serious problem by showing that junctions made lithographically from two-dimensional (2D) electron gas systems may manifest robust subgap topological properties without any spurious zero modes. We propose a 2D structure that enables multiprobe tunneling experiments providing position-dependent spectroscopy, which can decisively settle outstanding open questions related to the origin of the zero-bias conductance peaks observed experimentally. We also find that junctions with trivial superconductors may result in local perturbations that induce extrinsic low-energy states similar to those associated with wire junctions.

Published version, 8 pages, 9 figures

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Cited by in corpus (5)

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• Floquet Majorana zero and $\pi$ modes in planar Josephson junctions
• Electrically tunable chiral Majorana edge modes in quantum anomalous Hall insulator-topological superconductor systems
• Transport Signatures of a Majorana Qubit and Read-out-induced Dephasing
• Confinement versus interface bound states in spin-orbit coupled nanowires