Evidence for Majorana phases in the magnetoconductance of topological junctions based on two-dimensional electron gases

Abstract

We calculate the linear conductance of a two-dimensional electron gas (2DEG)-based junction between a normal semiconductor section and a hybrid semiconductor-superconductor section, under perpendicular magnetic field. We consider two important terms often neglected in the literature, the magneto-orbital and transverse Rashba spin-orbit. The strong orbital effect due to the magnetic field yields topological phase transitions to nontrivial phases hosting Majorana modes in the hybrid section. The presence of a potential barrier at the junction interface reveals the Majorana phases as quantized plateaus of high conductance, for low values of the chemical potential. In wide junctions (or large chemical potentials) the phase transitions occur at low magnetic fields but the magnetoconductance becomes anomalous and lacks clearly quantized plateaus. arXiv:1911.11639v2 [cond-mat.mes-hall]

Superconducting Proximity Effect in InAsSb Surface Quantum Wells with In Situ Al Contacts

“…However, their geometry has inherent difficulties to implement braiding and imposes strong constraints on material parameters to achieve topological superconductivity, usually inferred from observation of a quantized zero-bias conductance peak. Instead, to overcome these limitations, there is a growing interest in 2D platforms of proximitized semiconductors, which would also support topological superconductivity . These advantages have recently been demonstrated in planar Josephson junctions − where the phase transition between trivial and topological superconductivity can be tuned using gate voltages and the superconducting phase.…”

“…Instead, to overcome these limitations, there is a growing interest in 2D platforms of proximitized semiconductors, which would also support topological superconductivity. 7 These advantages have recently been demonstrated in planar Josephson junctions 8−10 where the phase transition between trivial and topological superconductivity can be tuned using gate voltages and the superconducting phase. This allows for more complicated networks that could support fusion, braiding, and large-scale Majorana manipulation.…”

Large‐Scale On‐Chip Integration of Gate‐Voltage Addressable Hybrid Superconductor–Semiconductor Quantum Wells Field Effect Nano‐Switch Arrays

“…The designed geometrical parameters of eight hybrid switches in each quantum chip are summarised in Table 1. The junction parameters are chosen to be large enough to investigate topological superconductivity in 2D systems [20][21][22] in the future generation of such devices. The geometrical parameters may vary from device to device after nanofabrication, especially for the length and width of the junctions, as the wet etch technique was used to take the unwanted semiconducting heterostructure areas and form sourcedrain leads and the active 2DEG region in between them.…”