Master's Defense: Deividas Sabonis – University of Copenhagen

Master's Defense: Deividas Sabonis

Superconductor - Semiconductor Quantum Dots in InAs/Al Nanowires for Majorana based Quantum Information

After the first demonstration in 2012 of what is now called the signatures of the Majorana bound states in a condensed matter system, different groups set up experiments to test the effect in the same or very similar solid state systems. After a few more demonstrations of the transport signatures compatible with Majorana bound states the community naturally started aiming for the first steps towards employing the observed states for quantum information purposes.
My contribution in this thesis further investigates these hybrid structures as a potential platform for topological quantum information processing applications. I demonstrate the control, tuning and charge sensing of superconducting islands defined by electrostatic gates in InAs/Al nanowires. Also the technical preparation as well as challenges needed to be overcome to achieve the manipulation of the Majorana qubit are outlined. The methods reported use both slow - DC and fast - RF charge sensing. Charge sensing is done by capacitively coupling the island to a sensor dot - a proximal nanowire. The characterization of devices, building and the integration, both software-wise and hardware-wise, and testing of the fast data acquisition setup forms the cornerstone behind this thesis.