Asymmetric Little–Parks oscillations in full shell double nanowires

Abstract

Little–Parks oscillations of a hollow superconducting cylinder are of interest for flux-driven topological superconductivity in single Rashba nanowires. The oscillations are typically symmetric in the orientation of the applied magnetic flux. Using double InAs nanowires coated by an epitaxial superconducting Al shell which, despite the non-centro-symmetric geometry, behaves effectively as one hollow cylinder, we demonstrate that a small misalignment of the applied parallel field with respect to the axis of the nanowires can produce field-asymmetric Little–Parks oscillations. These are revealed by the simultaneous application of a magnetic field perpendicular to the misaligned parallel field direction. The asymmetry occurs in both the destructive regime, in which superconductivity is destroyed for half-integer quanta of flux through the shell, and in the non-destructive regime, where superconductivity is depressed but not fully destroyed at these flux values.

Double nanowires for hybrid quantum devices

“…Furthermore, the full-shell double nanowire devices such as the one represented by Figs. 1c,f show Little-Parks oscillations in low-temperature transport measurements under a parallel magnetic field, 26 underlining that a broad range of quantum transport phenomena can be addressed in these parallel nanowire systems.…”

“…We now turn to electrical transport characterization of the hybrid double nanowire system, focusing here on low temperature transport measurements of two different types of devices in the quantum regime. The objective is to demonstrate that decoupled double nanowires and multi-terminal device functionalities can be achieved (more advanced functionalities are demonstrated in forthcoming dedicated publications [24][25][26] ). Prior transport experiments on parallel nanowires have been based on individual nanowires that were accidentally merged during deposition.…”

Parallel InAs nanowires for Cooper pair splitters with Coulomb repulsion

“…32,33 However, novel hybrid nanostructures became available recently, where double InAs nanowires are grown in close vicinity and are connected by an in-situ evaporated SC Al. [34][35][36][37] The latter property can satisfy a set of strict requirements from the geometry: the direct tunneling between the QDs is prevented, 38,39 and the SC-nanowire interface becomes high-quality, 40,41 rendering them a suitable plat-form for CPS circuits. As a result of the minimal distance of QDs preferred for the CPS in such setups, the inter-dot Coulomb repulsion (U LR ) also becomes considerable (see Fig.…”

Andreev molecule in parallel InAs nanowires

“…This is due to the fact that creation and detection impose a set of challenging constraints on the device: the QDs must be strongly coupled to the SC, their distance should be minimized while preventing direct tunneling between them 32,33 , in addition, individual tunability of the atomic levels is also desired. We construct our artificial atoms in a novel superconducting hybrid nanostructure, where double InAs nanowires are grown in close vicinity and connected by an epitaxial SC Al shell, allowing us to fulfill the requirements outlined above [34][35][36] .…”