Entangled spin pairs in graphene ENTS

• Applicant: Professor Dr. Laurens W. Molenkamp
• Subject Area: Experimental Condensed Matter Physics
• Term: from 2010 to 2021
• Project identifier: Deutsche Forschungsgemeinschaft (DFG) - Project number 162869023

Graphene offers truly unique opportunities for spintronics. The small atomic number of carbon results in an extremely weak strength of spin-orbit interaction, and very long spin relaxation times are expected. The hyperfine interaction between the electron and the nuclear spins, the other main microscopic mechanism responsible for spin relaxation in spintronics devices, is very weak in graphene. Furthermore, single-layer graphite offers the potential to realize spin-filters without the need to use ferromagnetic materials. The possibility to realize these all-graphene spin-active devices would be revolutionary, in that it would solve long standing issues in spintronics based on reduced dimensionality system, such as the conductivity mismatch problem. Graphene is also an ideal host material for spin qubits (quantum dots) because the two major sources of spin decoherence caused by spin-orbit interaction in combination with electron-phonon coupling and hyperfine interaction with the surrounding nuclei are known to be weak. With the generation of separated entangled pairs of spins in hybrid systems between superconductors and graphene, lots of original possibilities can be envisioned. A successful demonstration of this task would be an experimental breakthrough facilitating a multitude of quantum optics type of experiments to be performed in solid state. Our project addresses the above issues by investigating several approaches of Cooper pair splitting and generation of entangled spin pairs in graphene/superconductor/ferromagnet hybrid systems. Graphene provides an exceptionally promising material for this purpose, but, since it is a new material, many questions need to be answered. Our project will work on these open problems in a collaborative manner, either by looking for solutions collectively or by dividing tasks between the nodes as needed. The outcome of the project is expected to be the first demonstration of entangled spin pairs in the solid state.

• DFG Programme: Research Grants
• International Connection: Estonia, Finland, Netherlands, Switzerland
• Participating Persons: Professor Dr. Jaan Aarik; Professor Dr. Carlo W. J. Beenakker; Professor Dr. Pertti Hakonen; Professor Dr. Alberto Morpurgo; Professor Dr. Christian Schönenberger