Project

Back to overview

Helical states in strained ultrathin Ge nanowires

English title Helical states in strained ultrathin Ge nanowires
Applicant Loss Daniel
Number 145281
Funding scheme Project funding (Div. I-III)
Research institution Departement Physik Universität Basel
Institution of higher education University of Basel - BS
Main discipline Condensed Matter Physics
Start/End 01.10.2013 - 30.09.2016
Approved amount 257'236.00
Show all

Keywords (5)

Ge/Si nanowires; spin qubit; holes; helical states; Majorana fermions

Lay Summary (German)

Lead
Wir untersuchen theoretisch (Basel) und experimentell (Linz) Nanodraehte, die aus dem Halbleitermaterial Germanium umhuellt mit Silizium bestehen. Diese Gemaess unseren theoretischen Modellen und Berechnungen eignen sich diese Systeme hervorragend als Plattform fuer spin-qubits (quantum computing)helikale Zustaende fuer Spintronics, und fuer exotische Quantnmaterie wie zum Beispiel 'fractional fermions' oder Majorana Fermionen.
Lay summary

Ge has emerged as a promising material system for the realization of spin qubits, due to the absence of hyperfine interaction in isotopically purified samples. Very recently a pioneering proposal by our theory group has suggested that core/shell Ge/Si nanowires constitute also an interesting platform for the realization of helical states in a semiconductor due to a new mechanism to generate giant spin orbit interaction by purely electrical means. Such helical states form the basis for spin filter devices and exotic quantum matter such as fractional fermions and Majoranas which can potentially be used for topological quantum computation.

Here in this project we aim at an experimental and theoretical studies of such novel nanowire systems.

Direct link to Lay Summary Last update: 03.03.2013

Responsible applicant and co-applicants

Employees

Awards

Title Year
Blaise Pascal Medal in Physics 2014, European Academy of Sciences. Member of the German National Academy of Sciences Leopoldina (2014). 2014

Abstract

Ge has emerged as a promising material system for the realization of spin qubits, due to the absence of hyperfine interaction in isotopically purified samples. Very recently a theoretical proposal has suggested that core/shell Ge/Si nanowires constitute also an interesting platform for the realization of helical states in a semiconductor. In order to realize helical states in Ge two conditions were predicted to be necessary: a) it needs to be strained and b) the one-dimensional conductor needs to be very thin. Here we aim at investigating unique nanostructures, which have been developed in the last month in the applicant’s group: coherently strained ultra-thin Ge nanowires grown monolithically on flat silicon surfaces, also referred as “hut wires” (HW). In particular we want to assess whether the investigated material has potential in the field of Majorana Physics. By combining experiments and theory we aim at achieving a very good understanding of the system. Specifically we are going to study the influence of strain on the parameters that are relevant for Majorana fermion physics. These parameters are the Landé g-tensor, the spin-orbital splitting of the valence band (due to structural inversion asymmetry), and the proximity-induced superconducting gap in the HW.The final experimental goal of this project is to be able, under the guidance of the theory group, to detect signatures of Majorana bound states in a Ge nanowire coupled to a s-wave superconductor
-