Séminaire Nanoélectronique Quantique : Attila Geresdi

14h00 // Salle « Remy Lemaire » (K223)

Institut Néel
25 avenue des martyrs - Grenoble

The Josephson effect in semiconductor channels : From fundamental science to qubit applications
Attila Geresdi (QuTech & Kavli Institute of Nanoscience, Delft University of Technologyt)

Narrow bandgap III-V compounds such as InAs and InSb have become the most studied platform of induced superconductivity in a semiconductor channel due to possibility of creating high quality Ohmic contacts with most metals. While these hybrid systems are interesting from the fundamental physics’ point of view, their main merit is their potential in quantum information processing : several novel qubit designs, such as the gateable transmon (gatemon) [1], Andreev spin qubits [2] or topological qubits [3] use them as building blocks.
In this talk, I will summarize our ongoing efforts to understand and control the Andreev levels in proximitized semiconductor nanowires in various geometries. By adapting the on-chip spectroscopy method pioneered by the Saclay Quantronics group [4], we investigate the Andreev level spectrum in a planar magnetic field up to 0.5 T to extract the Landé g-factor and spin-orbit coupling in the channel [5]. Finally, I will discuss our efforts towards the detection of the 4π-periodic Josephson effect.

References :
[1] Larsen et al, Phys. Rev. Letters, 115, 127001 (2015)
De Lange et al, Phys. Rev. Letters, 115, 127002 (2015)
[2] Park and Yeyati, Phys. Rev. B 96, 125416 (2017)
[3] Aasen et al, Phys. Rev. X 6, 031016 (2016)
[4] Bretheau et al, Nature 499, 3412 (2013)
[5] van Woerkom et al, Nature Physics 11, 547 (2017)

Contact : Attila Geresdi

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