The quantum world is by far larger than the classical one. It is entanglement, closely linked to non-locality, that spans this larger space manifold. Entanglement plays a central role in emerging quantum technology aiming to harvest quantum space. The nanoelectronics group at the University of Basel (www.nanoelectronics.ch) uses a superconductor connected to two quantum-dots in parallel to generate spin entangled electron pairs (ESR pairs). The two electrons of one pair exit through different leads as illustrated in the above figure. In this device, the Cooper-pairs in the superconductor are the resources providing the entanglement. This is why we also term this device “Cooper pair splitter” (CPS).

CPS and related devices will be realized in three low-dimensional material systems, in carbon nanotubes (CNTs), graphene and semiconducting nanowires (NWs). These low dimensional systems have attracted a growing interest in recent years due to the unique properties of charge and spin which stem from strong spin-orbit interaction in NWs and chiral, neutrino-like properties of the quasiparticles in graphene and CNTs. The combination of high-quality low-dimensional materials, such as NWs, CNTs and graphene with nanostructured superconducting and ferromagnetic materials in so-called hybrid devices not only allows the realization and study of CPS, but also provides versatile experimental platforms for the exploration of a wide range of novel physical phenomena, including, for example, unconventional superconductivity, proximity-induced electron correlations and Majorana fermions. Specifically, we will work on improved tunable CPS devices, detect the electrons in the two channels with noise correlation experiments and explore specular Andreev reflection in gateable graphene devices. Ferromagnetic contacts will serve as spin probes and will be applied in combination with superconducting contacts. Finally, we will use CPS and Andreev spectroscopy as a tool to characterize the two ends of a semiconducting NW coupled to an s-wave superconductor which may host Majorana fermions.