title: Magnetic Field Tuning and Quantum Interference in a Cooper Pair Splitter.
abstract: Cooper pair splitting (CPS) is a process in which the electrons of the naturally occurring spin-singlet pairs in a superconductor are spatially separated using two quantum dots. Here, we investigate the evolution of the conductance correlations in an InAs CPS device in the presence of an external magnetic field. In our experiments the gate dependence of the signal that depends on both quantum dots continuously evolves from a slightly asymmetric Lorentzian to a strongly asymmetric Fano-type resonance with increasing field. These experiments can be understood in a simple three-site model, which shows that the nonlocal CPS leads to symmetric line shapes, while the local transport processes can exhibit an asymmetric shape due to quantum interference. These findings demonstrate that the electrons from a Cooper pair splitter can propagate coherently after their emission from the superconductor and how a magnetic field can be used to optimize the performance of a CPS device. In addition, the model calculations suggest that the estimate of the CPS efficiency in the experiments is a lower bound for the actual efficiency.
authors.affiliation: Department of Physics, Budapest University of Technology and Economics, and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki út 8, 1111 Budapest, Hungary.
authors.forename: G
authors.initials: G
authors.lastname: Fülöp
authors.affiliation: Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
authors.forename: F
authors.initials: F
authors.lastname: Domínguez
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: S
authors.initials: S
authors.lastname: d'Hollosy
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: A
authors.initials: A
authors.lastname: Baumgartner
authors.affiliation: Department of Physics, Budapest University of Technology and Economics, and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki út 8, 1111 Budapest, Hungary.|Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: P
authors.initials: P
authors.lastname: Makk
authors.affiliation: Center for Quantum Devices & Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
authors.forename: M H
authors.initials: MH
authors.lastname: Madsen
authors.affiliation: Laboratory for Micro- and Nanotechnology, Paul Scherrer Institute, CH-5232 Villigen PSI, Switzerland.
authors.forename: V A
authors.initials: VA
authors.lastname: Guzenko
authors.affiliation: Center for Quantum Devices & Nano-Science Center, Niels Bohr Institute, University of Copenhagen, Universitetsparken 5, DK-2100 Copenhagen, Denmark.
authors.forename: J
authors.initials: J
authors.lastname: Nygård
authors.affiliation: Department of Physics, University of Basel, Klingelbergstrasse 82, CH-4056 Basel, Switzerland.
authors.forename: C
authors.initials: C
authors.lastname: Schönenberger
authors.affiliation: Departamento de Física Teórica de la Materia Condensada, Condensed Matter Physics Center (IFIMAC), and Instituto Nicolás Cabrera, Universidad Autónoma de Madrid, E-28049 Madrid, Spain.
authors.forename: A
authors.initials: A
authors.lastname: Levy Yeyati
authors.affiliation: Department of Physics, Budapest University of Technology and Economics, and Condensed Matter Research Group of the Hungarian Academy of Sciences, Budafoki út 8, 1111 Budapest, Hungary.
authors.forename: S
authors.initials: S
authors.lastname: Csonka