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Electric Transport Phenomena in Nanoscaled Devices

English title Electric Transport Phenomena in Nanoscaled Devices
Applicant Schönenberger Christian
Number 134619
Funding scheme Project funding (Div. I-III)
Research institution Departement Physik Universität Basel
Institution of higher education University of Basel - BS
Main discipline Condensed Matter Physics
Start/End 01.04.2011 - 31.03.2013
Approved amount 550'000.00
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Keywords (11)

quantum transport; quantum electronics; mesoscopic physics; nanoelectronics; spintronics; Andreev reflection; Cooper-pair splitter; carbon nanotubes; semicondcuting nanowires; graphene; nano devices

Lay Summary (English)

Lead
Electric Transport Phenomena in Nanoscaled Devices
Lay summary

Today, almost everything men made around us use some sort of artificial intelligence to improve and optimize functionality. This intelligence is achieved by embedded electronics and software. The electronics have become powerful and cheap at the same time, that electronics can be added virtually at no price everywhere. To many humans the omnipresence of electronics may not even be obvious anymore.

The tremendous evolution of electronics routes on the gradual downsizing of functional electronic elements. An active electronic switch today is smaller than 1 micrometer, and yet, one can go further, much further indeed! If electronic elements are reduced deep into the sub-micrometer size regime, new physical phenomena show up. This is the world of quantum physics which in recent years researcher have started to uncover also in electronics. Though there is not quantum electronic chip today, we explore some basic elements that may have implications for future electronics.

In the current project, we focus on electronic elements in the quantum regime that are fabricated into novel materials, such as carbon nanotubes, semiconducting nanowires and graphene. The former two systems are quasi one-dimensional and the third is a two-dimensional electron system. The reduced dimensionality offers additional feature, which are not necessarily present in three dimensional materials. Our work focuses in particular on spin-dependent effects which may be exploited for quantum sensing and quantum communication.  

www.nanoelectronics.ch

Direct link to Lay Summary Last update: 04.05.2013

Responsible applicant and co-applicants

Employees

Publications

Publication
Spin Symmetry of the Bilayer Graphene Groundstate
F. Freitag M. Weiss R. Maurand J. Trbovic and C. Schönenberger, Weiss M., Schönenberger C. (2013), Spin Symmetry of the Bilayer Graphene Groundstate, in Phys. Rev. B, 87, 161402.
Near-Unity Cooper-pair Splitting Efficiency
J. Schindele A. Baumgartner and C. Schönenberger (2012), Near-Unity Cooper-pair Splitting Efficiency, in Phys. Rev. Lett., 109, 157002.
Homogeneity of Bilayer Graphene
F. Freitag M. Weiss R. Maurand J. Trbovic and C. Schönenberger (2012), Homogeneity of Bilayer Graphene, in Solid State Communications, 152, 2053.
Graphene: From Diffusive to Ultraclean-Interacting Systems
Freitag Frank, Trbovic J., Schönenberger C., Schönenberger C. (2012), Graphene: From Diffusive to Ultraclean-Interacting Systems.
Spontaneously Gapped Ground State in Suspended Bilayer Graphene
Freitag F., Csonka S., Baumgartner A., Fülöp G., d'Hollosy S., Nygard J., Schönenberger C. (2012), Spontaneously Gapped Ground State in Suspended Bilayer Graphene, in Phys. Rev. Lett., 108, 076602-076602.
Carbon Nanotube Spin-Valve with Optimized Ferromagnetic Contacts
Aurich Hagen (2011), Carbon Nanotube Spin-Valve with Optimized Ferromagnetic Contacts.
Finite bias Cooper pair splitting
Hofstetter L. (2011), Finite bias Cooper pair splitting, in Phys Rev. Lett., 107, 136801-136801.
Conductance fluctuations in graphene devices with superconducting contacts in different charge density regimes
Freitag F. (2011), Conductance fluctuations in graphene devices with superconducting contacts in different charge density regimes, in Phys. Status Solidi B (arXiv:1108.4599), 248, 2649-2649.
Hybrid Quantum Dots in InAs
Hofstetter Lukas, Csonka S., Baumgartner A., Fülöp G. (2011), Hybrid Quantum Dots in InAs.
Gate-tunable split Kondo effect in a carbon nanotube quantum dot
Eichler A., Trbovic J., Schönenberger C. (2011), Gate-tunable split Kondo effect in a carbon nanotube quantum dot, in Nanotechnology, 22, 265201-265201.

Scientific events

Active participation

Title Type of contribution Title of article or contribution Date Place Persons involved
Int. Workshop on Building Blocks for Carbon-Based Electronics 01.04.2013 Regensburg, Germany
Int. Workshop on Spin-Orbit and Interaction Effects 04.02.2013 Aachen, Germany
Workshop on Quantum Noise and Measurements in Engineered Electronic Systems 08.10.2012 Dresden, Germany
Int. Conference on the Physics of Semiconductors 29.07.2012 Zurich, Switzerland
Int. School of Physics Enrico Fermi on Quantum Spintronics and Related Phenomena 19.06.2012 Italy
Int. Conference on Nanoscience and Technology, ICNT 23.05.2012 Paris, France
Quantum Systems and Technology 17.05.2012 Ascona, Switzerland
Graphene 2012 10.04.2012 Brussels
DPG Spring Meeting 26.03.2012 Berlin
NCCR QSIT annual conference 01.02.2012 Arosa
KITP conference on graphene and other carbon allotropes 09.01.2012 Santa Barbara, US
Workshop on Quantum Spintronics 02.10.2011 Porto Ottiolu, Sardinia
Workshop on Entanglement in Solid State Systems 20.09.2011 Lecce, Italy
Swiss FET event 16.09.2011 Neuchatel
Superconducting Hybrids 07.09.2011 Grenoble, France
Swiss-Swedish meeting on Quantum Materials and Devices 25.08.2011 Sweden
Graphene Week 2011 24.04.2011 Obergurgl, Austria
NanoTP Cost workshop at EMPA 01.04.2011 Dübendorf, CH
APS March meeting 21.03.2011 Dallas, US
Recontres de Moriond 13.03.2011 La Thuile, Italy
Int. Winterschool on Electronic Properties in Novel Materials 26.02.2011 Kirchberg i.T. Austria


Knowledge transfer events

Active participation

Title Type of contribution Date Place Persons involved
New fascinating industrial opportunities (organized by Rolic) 01.11.2012 Basel
Nano-tera, annual plenary meeting 26.04.2012 Zurich
Swiss FET event 2011 (EU-FP7) 16.09.2011 Neuchately


Communication with the public

Communication Title Media Place Year
Talks/events/exhibitions Nano, was ist das überhaupt German-speaking Switzerland 19.04.2012
Talks/events/exhibitions Mit dem Lift zum Mond (TecDays) German-speaking Switzerland 16.11.2011
Talks/events/exhibitions Solarzellen, lösen sie das Energieproblem (TecDays) German-speaking Switzerland 23.09.2011

Awards

Title Year
ERC Grant 2012

Associated projects

Number Title Start Funding scheme
124670 Electric Transport Phenomena in Mesoscopic Devices 01.04.2009 Project funding (Div. I-III)
146139 Quantentransport Phänomene in Nanostrukturierten Devices 01.04.2013 Project funding (Div. I-III)
127885 NCCR Nanoscale Science: Impact on Life Sciences, Sustainability, Information and Communication Technologies (phase III) 01.06.2009 National Centres of Competence in Research (NCCRs)
116621 Electric Transport Phenomena in Mesoscopic Devices 01.04.2007 Project funding (Div. I-III)
129378 ENTS: Entangled spin pairs in graphene 01.03.2010 Project funding (special)

Abstract

The ever growing interest in low dimensional systems, such as one-dimensional wires and zero-dimensional quantum dots, is due to the unique properties of charge and spin currents in such systems. Over the last years, we have been very successful in using carbon nanotubes, graphene and in particular semicondcuting nanowires to realize devices with unique contact topologies, enabling to explore new physical phenomena, such as non-local Andreev reflection, the ferromagnetic contact induced exchange coupling to a quantum dot, supercurrent in a quantum dot with Kondo correlations, spin transport through quantum dots and conductance fluctuations in graphene.A very striking result has been the realization of a Cooper pair splitter, see Hofstetter et al. Nature V461, p960 (2009). Making use of confinement and Coulomb blockade in quantum dots, we have shown that the two electrons of individual Cooper-pairs can be split. Though very exciting, this is only the first step. The goal is to demonstrate that this principle provides an efficient source of entangled EPR pairs of electrons. To do so, one has to measure the entanglement, which is a very challenging task, and than see how one can reach the largest possible pair current without loosing the entanglement.We will first explore the physics of the splitting in more depth. We will add ferromagnetic contacts which will allow spin projection measurements. Combing this with noise-correlation experiments provides a means for a Bell-state measurement with which the entanglement can be assessed. To insure that Cooper-pairs are split one by one and that pairs can be launched on ``demand'', one has to either increase the superconducting gap or lower the tunneling coupling from the superconductor to the quantum dots. We will explore both avenues by testing superconductors with a higher transition temperature (e.g. Nb and NbN) and define additional contact barriers withbottom-and/or top gates. As a basis for the quantum dots we will be using InAs nanowires, carbon nanotubes and graphene. At the core of our research are therefore low-dimensional hybrid devices, which are obtained through a combination of contacts employing normal metals, superconductors and ferromagnets.This provides a large space in which novel phenomena in correlated spin and charge transport emerge. We just mention the recent discovery of topological insulators, which appear in so-called inverted small band-gap materials. A similar state can also be generated in one-dimensional conductors with strong spin-orbit interaction (e.g. InAs and InSb) when ferromagnetic and superconducting contacts are added.Information on the group can be found under: www.nanoelectronics.ch
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