1B: Quantum Spintronics

PL: T. Ihn

Involved PIs: M. Büttiker, K. Ensslin, J. Faist, A. Fontcuberta i Morral, A. Fuhrer, A. Imamoglu, D. Loss, A. Morpurgo, G. Salis, C. Schönenberger, R. Warburton, W. Wegscheider, D. Zumbühl

The goal of the quantum spintronics project is the investigation of spin-related quantum states in solid-state devices, and the achievement of well-controlled coherent  spin manipulation. It is at the level of explorative fundamental research with the prospect of implementing novel information processing schemes at the advanced level. The project rests on a range of highest-quality materials such as layered semiconductors (e.g., Ga[Al]As, Si, Ge), semiconductor nanowires, few-layer graphene, and carbon nanotubes. The participating researchers contribute a wealth of state-of-the-art experimental techniques and theoretical tools ranging from electronic transport and tunneling spectroscopy at ultra-low temperatures and high magnetic fields to optical spectroscopy techniques with temporal and spatial resolution. These techniques are the tools that are to be used for controlling the spin degree of freedom in tailored nanostructures coherently.

The aim of coherent control of spin-related quantum states has two complementary aspects: on one hand, control can only be exerted, if the spin interacts with the controlling parameter with reasonable strength. On the other hand, excessive interaction with environmental degrees of freedom leads to relaxation and decoherence. One way of overcoming the problem of short coherence times is to build quantum dots (QDs) from materials with lower abundance of nuclear spin-carrying isotopes, such as carbon-based systems (graphene, carbon nanotubes), or silicon. The activities in this project will address questions of spin-orbit interaction and hyperfine interaction, the generation, manipulation, and detection of spins with optical means, and the injection of spins in hybrid structures employing ferromagnetic and superconducting materials. The manipulation of individual spins, and the creation of entangled spin-states will be a major concern.