Manipulation of the quantum state of individual superconducting excitations in nanowires

Contact: Marcelo GOFFMAN,, +33 1 69 08 55 29

We propose to develop experiments aiming at the quantum manipulation of localized states that arise in semiconducting nanowires connecting superconducting electrodes.

Full description:

Electrons in superconductors form Cooper pairs that cannot be probed individually because they are delocalized and overlapping. However, localized states appear at weak links between superconducting electrodes. Using atomic contacts as a weak link, we performed the spectroscopy of these localized states [1] and demonstrated the quantum manipulation of a localized Cooper pair [2].
During the internship, we plan to develop similar experiments with indium arsenide (InAs) semiconducting nanowires. Longer coherence times are expected, and, because of the strong spin-orbit coupling in InAs, one should also be able to manipulate the spin of localized electrons.

The student will be integrated in an active research group on quantum electronics and will acquire several techniques: nanofabrication, low temperatures, low-noise and microwave measurements.

A thesis is proposed after the internship.

[1] L. Bretheau et al., “Exciting Andreev pairs in a superconducting atomic contact”
Nature 499, 312 (2013). arXiv:1305.4091

[2] C. Janvier et al., “Coherent manipulation of Andreev states in superconducting atomic contacts”, Science 349, 1199 (2015), arXiv:1509.03961



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