CEA
CNRS
Univ. Paris-Saclay

Service de Physique de l'Etat Condensé


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“Fine structure” of a superconducting circuit: Manipulation of the spin of a single electron

Contact: POTHIER Hugues, , hugues.pothier@cea.fr, +33 1 69 08 55 29
Summary:
We design and fabricate superconducting circuits that are ruled by the laws of quantum mechanics. In this internship, we propose to carry out experiments aiming at the quantum coherent manipulation of the spin of a single quasiparticle excitation.
Possibility of continuation in PhD: Oui
Deadline for application:04/04/2020

Full description:
We design and fabricate superconducting circuits that are ruled by the laws of quantum mechanics. In this internship, we propose to carry out experiments aiming at the quantum coherent manipulation of the spin of a single quasiparticle excitation.

In practice, we use semiconducting nanowires covered with a superconducting shell. The shell is removed in a small section of the nanowire, giving rise to a spectrum of quantized electronic levels in the superconductor-free section. We have recently shown that, due to the spin-orbit interaction in the semiconductor, this spectrum presents a fine structure similar to that of electronic states in atoms [1]. During the internship, the quantum manipulation of the spin of a single electron in the nanowire will be realized using circuit quantum electrodynamics techniques. This will give access to the lifetime and quantum coherence time of the states.

We also plan to test the recent prediction of a magnetic-field-driven phase transition in nanowires fully covered with a superconductor [2]. A topological phase supporting Majorana fermions could be reached, and revealed by the spectroscopy of the circuit.

We look for a strongly motivated student having a good understanding of quantum physics. She/he will be integrated in an active research group on quantum electronics and get acquainted with advanced concepts of quantum mechanics and superconductivity. He/she will also learn several experimental techniques: low temperatures, low-noise and microwave measurements, and nanofabrication.

A thesis is proposed after the internship.

[1] L. Tosi et al., “Spin-Orbit Splitting of Andreev States Revealed by Microwave Spectroscopy”, Phys. Rev. X 9, 011010 (2019).
[2] R. Lutchyn et al., “Topological superconductivity in full shell proximitized nanowires” arXiv :1809.05512 (2018).
Technics/methods used during the internship:
Low temperatures, low-noise and microwave measurements, nanofabrication.

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