Controlling and manipulating the quantum state of individual quantum systems is presently an extremely active and fertile field in atomic and condensed matter physics, with a profound impact on our understanding of the laws of quantum physics and with applications in many fields ranging from metrology to quantum information. The MASSS project’s goal was to achieve the coherent manipulation of a single electronic spin within a superconducting device.
I based my strategy on the combination of two basic condensed matter physics phenomena. On the one hand, the trapping of an electron in one of the discrete localized states -called Andreev states- that form at a weak-link between two superconductors. On the other hand, the coupling of the electron spin degree of freedom to its trajectory in space- called spin-orbit coupling-, which is particularly strong in some semiconducting materials. This combination was therefore expected to lead, even in absence of a magnetic field, to spin-split Andreev states for an electron trapped in a semiconducting weak link, the fundamental required ingredient for the spin manipulation.
The project was successful on all its aspects. The original results of the experiments that I carried out were recently published in Phys. Rev. X 9 011010 (2019), and constitute an important step in the field of superconducting spintronics. Moreover, this Marie Skłodowska-Curie fellowship allowed me to build strong collaborations with several groups in Europe and to interact with many of the field leading scientists during international conferences and visits. Finally, it has provided me with the necessary tools to start a career as an independent researcher.
