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Quantum technologies

Dieter Meschede's research group
Home AMO physics colloquia
Colloquia
  • Henk Stoof

    (22/10/13)
  • Invited speaker: Prof. Henk Stoof
    Affiliation: Universiteit Utrecht
    Title: Bosonic Spintronics
    Time and room: 17:15 lecture hall IAP
    Abstract: Presently new solid-state systems are becoming available that can show dissipationless transport, possible even at room temperature, due to the Bose-Einstein condensation of bosonic particles. Examples of such particles are magnons, exciton-polaritons, and even photons. In all these cases the bosons have also spin degrees of freedom that allow for interesting spin-dependent mass and heat transport. Where possible we will emphasize the differences between these new systems and a spin mixture of ultracold atoms.

  • Gershon Kurizki

    (08/10/13)
  • Invited speaker: Prof. Gershon Kurizki
    Affiliation: Weizmann Institute of Science, Rehovot, Israel
    Title: Control of Quantum Thermodynamics
    Time and room: special colloquium, 10:00 h,  lecture hall IAP
    Abstract: A combination of dynamical control and quantum-state preparation may allow heat engines and refrigerators to outperform their classical counterparts, while adhering to the basic laws of thermodynamics.

  • Goran Pichler

    (09/07/13)
  • Invited speaker: Prof. Goran Pichler
    Affiliation: Kuwait University and Institute of Physics, Zagreb
    Title: Laser Spectroscopy Of Dense Metal Vapor
    Time and room: 17:15 lecture hall IAP
    Abstract: We shall discuss our results on several topics on metal vapors that have been studied by laser spectroscopy  in two different laboratories.  The lasers used are predominantly femtosecond (fs) pulsed lasers, and sometimes nanosecond pulsed lasers. The metal vapors are heavy alkalis, Cs, Rb and K, and we shall describe conical emission using fs lasers. We shall also report the results of the search for new satellite bands in mixed Rb-Cs and K-Rb vapors. Alkaline earth metal vapors will be discussed in connection with dense barium vapor in the atmosphere of noble gases. Thermionic detection of the autoionizing (AI) levels of barium will reveal number of interesting phenomena connected with Fano profiles which will be modified due to collisions with He, Ar, Kr and Xe.  Two-photon excitation of Ba AI levels brings about new spectral features at elevated noble gas pressures. The possible cause will be discussed. 

  • Claus Ropers

    (25/06/13)
  • Invited speaker: Prof. Claus Ropers
    Affiliation: Universität Göttingen
    Title: Ultrafast Low-Energy Electron Diffraction Using Nanotip Emitters
    Time and room: 17:15 lecture hall IAP
    Abstract: Ultrafast structural dynamics in solids and nanostructures can be investigated by an increasing number of sophisticated electron and x-ray diffraction techniques. Despite successful implementations of ultrafast reflection high-energy electron diffraction, the time-resolved diffractive probing of  structural processes at surfaces remains an experimental challenge.
    We have recently implemented ultrafast low-energy electron diffraction (ULEED) to study structural changes with high temporal resolution and ultimate surface sensitivity, at electron energies from 100 eV to 500 eV. We utilize nanoscopic needle emitters in an electrostatic lens geometry as high-brightness sources of pulsed electrons. The spatial confinement of the source is realized by the local enhancement of nonlinear photoemission at the tip apex.
    In this talk, the benefits of nanoscopic cathodes for ultrafast diffraction studies will be introduced, and first time-resolved data will be presented. Specifically, the ultrafast melting dynamics of ordered adsorbate structures on freestanding graphene is investigated in transmission with a temporal resolution below 5 ps. Finally, future improvements of the approach will be discussed.

  • Oliver Schmidt

    (18/06/13)
  • Invited speaker: Prof. Oliver Schmidt
    Affiliation: Leibniz-Institut für Festkörper- und Werkstoffforschung, Dresden
    Title: Stretching And Shaping Inorganic Nanomembranes: From Tunable Single Photon Sources To Nanorobotics
    Time and room: 17:15 lecture hall IAP
    Abstract: Nanomembranes are thin, flexible, and transferrable and can be shaped into many different 3D geometries. These properties make nanomembranes an exciting class of materials which have stimulated great interest in the interdisciplinary field of nanosciences.  For instance, we are able to transfer single crystalline GaAs nanomembrane devices incorporating epitaxial quantum dots onto piezoelectric substrates. In this way, the electronic structure of a single quantum dot can be tuned with unprecedented control. It is possible to tune biexciton and exciton recombination lines into perfect resonance or to reduce the fine structure splitting to zero for practically any quantum dot. Differentially strained nanomembranes can roll-up into tubular structures once they are released from their mother substrate. Among others, such tubes can serve as vertical optical ring resonators which can be employed as optofluidic components to sense single cells and submonolayer condensates. Rolled-up nanomembranes can be exploited to rigorously compact electronic circuitry and energy storage devices. Novel phenomena and unconventional on- and off-chip applications such as self-propelled nanorobotic machines  will be discussed.


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