Silvano de Franceschi, Inac

ERC junior (ERC starting grant)

Engineering electronic quantum coherence and correlations in hybrid nanostructures

Nanoelectronic devices are foreseen to play a significant impact on next-generation technologies. Simultaneously, they can provide versatile and relatively simple systems to study complex quantum phenomena under well-controlled, adjustable conditions. Existing technologies enable the fabrication of nanostructures (so-called artificial atoms) in which it is possible to add or remove individual electrons, turn on and off interactions, tune the electronic state of a confined system, simply by changing a gate voltage or an external magnetic field.

This project aims at developing a novel class of nanodevices based on self-assembled quantum dots grown by molecular beam epitaxy. Following many years of developments, the growth of these nanocrystals can now be controlled to high degree yielding quantum dots of high crystal quality and controllable size. In addition, these quantum dots can be assembled in regular arrays and form good electrical connections with metal electrodes thereby holding promise for the realization of complex planar architectures.

We shall fabricate metal-semiconductor devices by connecting single and multiple quantum dots to different types of electrodes including metals, superconductors and ferromagnets. Lowtemperature magnetotransport experiments will be used to investigate the electronic properties of these hybrid nanosystems with an emphasis on the interplay between spin-related effects (e.g. spinorbit coupling) and strong electronic correlations (Coulomb interactions, superconductivity, ferromagnetism, etc.). We will explore various strategies to realize spin-valve and spin-transistor nanodevices. High-frequency, pump-probe electrical measurements will be used to perform coherent spin manipulation and determine the characteristic time scales for spin dynamics. In the case of SiGe nanocrystals, a direct measurement of these time scales, expected to be particularly long, may open a new promising route towards spin-based quantum computation.