Hybrid InAs nanowire devices

Around 2010 it became clear that semiconductor nanowire devices cannot be used just for the realization of spin qubits but also for the creation of so called topological qubits [1-3]. Since then several groups started working on semiconductor nanowires with strong spin orbit coupling in order to realize Majorana fermions in solid state devices. Experimental results showing a zero bias peak [4] and an 2e- to e-periodic change in the peak spacing of a Coulomb island [5] have been reported supporting the existence of Majorana fermions. However, in order reach the topological regime high magnetic fields are needed which can lead to a soft superconducting gap.

InAs

Recent theoretical works have suggested experimental setups which would relax the conditions imposed for the magnetic field strength [6,7]. These proposal include on the one hand parallel nanowires in which the electron-electron interactions open up the gap at k equal to zero [6] or nanowires fully covered with an Al shell for which the magnetic flux plays the role of the Zeeman field [7].

In our group we study hybrid superconductor-semiconductor devices based on proximitized InAs nanowires provided by the Microsoft Quantum Materials Lab [8].

[1] Y. Oreg et al., Phys. Rev. Lett. 105 (2010)
[2] R. Lutchyn et al., PRL 105, 077001 (2010)
[3] J. Alicea, Phys. Rev. B 81, 125318 (2010)
[4] V. Mourik et al., Science 336, 1003 (2012)
[5] S. M. Albrecht et al., Nature 531, 206 (2016)
[6] M. Thakurathi et al., Phys. Rev. B 97, 045415 (2018)
[7] R. Lutchyn et al., arXiv:1809.05512 (2018)
[8] P. Krogstrup et al., Nature Materials 14, 400 (2015)