Majorana Fermions
Lead Research Organisation:
Cardiff University
Department Name: School of Physics and Astronomy
Abstract
There is currently great excitement surrounding the investigation of Majorana zero modes (MZMs) in topological superconducting networks: A possible technology route to an all solid state quantum processor. Recently, significant work on semiconductor nanowires has offered tentative evidence for the existence of MZMs, which are predicted by theory to be robust quantum states that can be exploited for quantum processing, and yet unlike other demonstrator quantum technologies are potentially realisable in familiar solid state technology. However there is now considerable debate in the literature about the certainty of these observations, and the necessary extension to more exploitable planar (2DEG) technology is elusive. States occur at the interface between a one-dimensional (1D) semiconductor that has strong spin-orbit coupling (SOC), and a proximity superconductor. Through electrical study this project will explore state-of-the-art Indium Antimonide (InSb) based quantum well heterostructures that have the largest SOC of all the compound semiconductors, and investigate MZM formation at the interface with superconducting material.
We will exploit material grown at our long standing collaborators at the University of Sheffield (EPSRC UK National epitaxy facility), together with Warwick University, and a new collaboration with the group of Chris Palmstrom at the University of California Santa Barbara (UCSB). Material will be both grown with superconducting Al on the surface, or have superconducting material deposited whilst investigating different sulfonation surface preparations to achieve different band alignments of the superconductor to semiconductor interface.
The project will involve device fabrication within the Institute for Compound Semiconductors (ICS) cleanroom facility, using both photo and electron beam lithography, working alongside process engineers to build on existing process technology to investigate proximity induced superconduction in the semiconductor material, low leakage surface gating to enable the creation of tunnel barriers, and ultimately the unambiguous observation of Majorana Fermions. These devices will be measured at low temperature (potentially down to 15mK) with high sensitivity electrical conductivity measurement, and where appropriate high magnetic field.
We will exploit material grown at our long standing collaborators at the University of Sheffield (EPSRC UK National epitaxy facility), together with Warwick University, and a new collaboration with the group of Chris Palmstrom at the University of California Santa Barbara (UCSB). Material will be both grown with superconducting Al on the surface, or have superconducting material deposited whilst investigating different sulfonation surface preparations to achieve different band alignments of the superconductor to semiconductor interface.
The project will involve device fabrication within the Institute for Compound Semiconductors (ICS) cleanroom facility, using both photo and electron beam lithography, working alongside process engineers to build on existing process technology to investigate proximity induced superconduction in the semiconductor material, low leakage surface gating to enable the creation of tunnel barriers, and ultimately the unambiguous observation of Majorana Fermions. These devices will be measured at low temperature (potentially down to 15mK) with high sensitivity electrical conductivity measurement, and where appropriate high magnetic field.