June 2011
Abstracts of the QSIT Lunch Seminar, June 9, 2011
Cotunneling and one-dimensional localization in graphene nanoribbons
Susanne Dröscher, Nanophysics Group, ETH Zurich
Since its recent discovery, graphene has been subject of a large number of studies probing the special electronic properties of this truly two-dimensional material. Due to the absence of a band gap in single layer graphene, electrostatic confinement (as implemented in e.g. GaAs devices) is not possible. It has however been shown that a transport gap can be induced by etching graphene into nanoribbons. This feature has been utilized as tunneling barrier in graphene nanostructures such as single- and double-quantum dots. A detailed understanding of the transport mechanisms in such narrow constrictions is therefore of great interest. In recent experiments we have investigated the microscopic picture of transport mechanisms through these narrow constrictions in temperature dependent measurements.
Optomechancially Induced Transparency
Stefan Weis*, Laboratory of Photonics and Quantum Measurements, EPF Lausanne
Electromagnetically induced transparency is a quantum interference effect observed in atoms and molecules, in which the optical response of an atomic medium is controlled by an electromagnetic field. We demonstrate a form of induced transparency enabled by radiation pressure coupling of an optical and a mechanical mode. A control optical beam tuned to a sideband transition of a micro-optomechanical system leads to destructive interference for the excitation of an intracavity probe field, inducing a tunable transparency window for the probe beam. Optomechanically induced transparency may be used for slowing and on-chip storage of light pulses via microfabricated optomechanical arrays.
*Co-auhors: Rémi Rivière2, Samuel Deléglise1,2, Emanuel Gavartin1, Olivier Arcizet3, Albert Schliesser1,2, and Tobias Kippenberg1,2
1Ecole Polytechnique Fédérale de Lausanne (EPFL), Switzerland
2Max-Planck-Institut für Quantenoptik, 85748 Garching, Germany
3Institut Néel, 38042 Grenoble, France