title: High Efficiency CVD Graphene-lead (Pb) Cooper Pair Splitter.
abstract: Generation and manipulation of quantum entangled electrons is an important concept in quantum mechanics, and necessary for advances in quantum information processing; but not yet established in solid state systems. A promising device is a superconductor-two quantum dots Cooper pair splitter. Early nanowire based devices, while efficient, are limited in scalability and further electron manipulation. We demonstrate an optimized, high efficiency, CVD grown graphene-based Cooper pair splitter. Our device is designed to induce superconductivity in graphene via the proximity effect, resulting in both a large superconducting gap Δ = 0.5 meV, and coherence length ξ = 200 nm. The flat nature of the device lowers parasitic capacitance, increasing charging energy EC. Our design also eases geometric restrictions and minimizes output channel separation. As a result we measure a visibility of up to 86% and a splitting efficiency of up to 62%. This will pave the way towards near unity efficiencies, long distance splitting, and post-splitting electron manipulation.
authors.affiliation: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: I V
authors.initials: IV
authors.lastname: Borzenets
authors.affiliation: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.
authors.forename: Y
authors.initials: Y
authors.lastname: Shimazaki
authors.affiliation: Centre for Graphene Science, University of Exeter, Exeter EX4 4QL, UK.
authors.forename: G F
authors.initials: GF
authors.lastname: Jones
authors.affiliation: Centre for Graphene Science, University of Exeter, Exeter EX4 4QL, UK.
authors.forename: M F
authors.initials: MF
authors.lastname: Craciun
authors.affiliation: Centre for Graphene Science, University of Exeter, Exeter EX4 4QL, UK.
authors.forename: S
authors.initials: S
authors.lastname: Russo
authors.affiliation: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.|PRESTO, JST, Kawaguchi-shi, Saitama 332-0012, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Department of Applied Physics, University of Tokyo, Bunkyo-ku, Tokyo 113-8656, Japan.|Center for Emergent Matter Science (CEMS), RIKEN, Wako-shi, Saitama 351-0198, Japan.
authors.forename: S
authors.initials: S
authors.lastname: Tarucha