Kolloquien

Die Gastvorträge im Rahmen des MPQ-Kolloquiums finden von April bis Juli sowie von Oktober bis Januar jeweils dienstags um 14:30 Uhr statt. Verantaltungsort ist der Herbert-Walther-Hörsaal im Foyer des Max-Planck-Instituts für Quantenoptik.

Ansprechpartner für die wissenschaftliche Organisation:

Dr. Stephan Dürr und Dr. Thomas Udem

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χ(2) Nanomaterials for Nonlinear Integrated Photonic Devices (Prof. Rachel Grange)

χ(2) Nanomaterials for Nonlinear Integrated Photonic Devices
Nonlinear optics is present in our daily life with many applications, e.g. light sources for microsurgery or green laser pointer. All of them use bulk materials such as glass fibres or crystals. Generating nonlinear effects from materials at the nanoscale can expand the applications to biology as imaging markers or sensors, and to optoelectronic integrated devices. However, nonlinear signals scale with the volume of a material. Therefore, finding nanostructured materials with high nonlinearities to avoid using high power and large interaction length is challenging. Here I will show several strategies to maximize nonlinear optical signals in nano-oxides with noncentrosymmetric crystalline structure and semiconductors. I will demonstrate how we enhance second-harmonic generation (SHG) by using the scattering properties of individual barium titanate (BaTiO3) nanoparticles1, and AlGaAs standing nanodisks2. Our results suggest that a strong increase of the SHG signal can be obtained without using plasmonics or hybrid nanostructures3 [mehr]

Quantum fluids of light in semiconductor lattices (Prof. Jacqueline Bloch)

Quantum fluids of light in semiconductor lattices
When confining photons in semiconductor lattices, it is possible to deeply modify their physical properties. Photons can behave as finite or even infinite mass particles, photons inherit topological properties and propagate along edge states without back scattering, photons can become superfluid and behave as interacting particles. These are just a few examples of properties that can be imprinted into fluids of light in semiconductor lattices. Such manipulation of light presents not only potential for applications in photonics, but is a great promise for fundamental studies. [mehr]

Connecting the Resource Theories of Purity and Coherence (Prof. Dagmar Bruss)

Connecting the Resource Theories of Purity and Coherence
The resource theory of quantum coherence studies the off-diagonal elements of a density matrix in a distinguished basis, whereas the resource theory of purity studies all deviations from the maximally mixed state. A direct connection between the two resource theories is established by identifying purity as the maximal coherence which is achievable by unitary operations. The states that saturate this maximum form a family of maximally coherent mixed states. Furthermore, purity bounds the maximal amount of entanglement and discord that can be generated by unitary operations, thus demonstrating that purity is the most elementary resource for quantum information processing. [mehr]

High Harmonic Generation Interferometry (Prof. Nirit Dudovich)

High Harmonic Generation Interferometry
Attosecond science is a young field of research that has rapidly evolved over the past decade. The progress in this field opened a door into a new area of research that allows one to observe multi-electron dynamics in in atoms, molecules and solids. One of the most exciting advances in atto-science is high harmonic generation (HHG) spectroscopy. It allows one to combine sub-Angstrom spatial with attosecond temporal resolution, holding the potential of resolving the structure of electronic wavefunctions as they evolve in time. [mehr]

Surface enhanced coherent Raman scattering (Prof. Eric Potma)

Surface enhanced coherent Raman scattering
Surface-enhanced Raman scattering (SERS) is a popular technique that makes it possible to boost the otherwise weak Raman effect to levels that allow single molecule detection. A coherent, nonlinear equivalent of single molecules SERS is highly attractive, because it would allow the use single vibrational quantum oscillators with a narrow line width for a host of interesting applications. The translation of SERS into the domain of coherent Raman spectroscopy (CRS) has, however, not been trivial. This presentation zooms into some of the recent accomplishments in this area, highlights single molecule CRS experiments and discusses the possibilities of performing single vibrational oscillator measurements without the use of nanoscale plasmonic antennae. [mehr]
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