ansprechpartner

Dr. Stephan Dürr
Stephan Dürr
Gruppenleiter
Telefon: +49 89 3 29 05 - 291
Prof. Dr. Thomas Udem
Thomas Udem
Wissenschaftler
Telefon: +49 89 3 29 05 - 282 // -257




kommende Kolloquien

Kolloquien

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.

Achtung! Ab Oktober 2017 finden die Vorträge, aufgrund der Bauarbeiten, vorübergehend im Interims-Hörsaal, Raum B 0.32 am Max-Planck-Instituts für Quantenoptik statt.

Ansprechpartner für die wissenschaftliche Organisation:

Dr. Stephan Dürr und Dr. Thomas Udem

Wenn Sie einen Vortrag im Livestream verfolgen möchten, ist es nötig, dass Sie sich in eine entsprechende Mailing Liste eintragen. Daraufhin erhalten Sie Instruktionen zum Empfang des Livestreams.

Monat:

"Observation of Correlated Particle-Hole Pairs and String Order in Low-Dimensional Mott Insulators."

Quantum phases of matter are characterized by the underlying correlations of the many-body system. Although this is typically captured by a local order parameter, it has been shown that a broad class of many-body systems possesses a hidden nonlocal order. In the case of bosonic Mott insulators, the ground state properties are governed by quantum fluctuations in the form of correlated particle-hole pairs that lead to the emergence of a nonlocal string order in one dimension. By using high-resolution imaging of low-dimensional quantum gases in an optical lattice, we directly detect these pairs with single-site and single-particle sensitivity and observe string order in the one-dimensional case. [mehr]

"Observation of Correlated Particle-Hole Pairs and String Order in Low-Dimensional Mott Insulators."

Quantum phases of matter are characterized by the underlying correlations of the many-body system. Although this is typically captured by a local order parameter, it has been shown that a broad class of many-body systems possesses a hidden nonlocal order. In the case of bosonic Mott insulators, the ground state properties are governed by quantum fluctuations in the form of correlated particle-hole pairs that lead to the emergence of a nonlocal string order in one dimension. By using high-resolution imaging of low-dimensional quantum gases in an optical lattice, we directly detect these pairs with single-site and single-particle sensitivity and observe string order in the one-dimensional case. [mehr]

"Extreme Localization of Electrons in Space and Time."

Waveform control of few-cycle laser pulses allows steering of electrons in atoms, molecules, and clusters in the gas phase, which has led to, for example, attosecond pulse generation and time-resolved imaging of molecular orbitals. We have observed strong-field effects from nanoscale metal tips [1], including re-scattering and strong carrier-envelope phase effects, which reveal themselves via matter wave interference in the time-energy domain [2]. This paves the way towards light-based steering of electrons in a solid-state system. In a separate experiment we have demonstrated guiding of electrons in a linear Paul trap [3], which might lead to a new quantum system. We will report on both experiments. [1] M. Schenk, M. Krüger, P. Hommelhoff, PRL 105, 257601 (2010) [2] M. Krüger, M. Schenk, P. Hommelhoff, Nature 475, 78 (2011) [3] J. Hoffrogge, R. Fröhlich, M. Kasevich, P. Hommelhoff, PRL 106, 193001 (2011) [mehr]

"Chasing the Neutrino Mass."

In the thirties of the last century Pauli and Fermi had solved the apparent violation of conservation laws in nuclear beta-decay by introducing a so far undetected, weakly interacting, neutral, and practically mass less particle – the neutrino. Twenty years later Reines finally could detect this missing particle in beta-decay by experiment. The further exploration of neutrino properties and interactions revealed great discoveries and surprises: parity violation, the existence of three neutrino flavours, and finally, at the turn of the century, the oscillation between neutrino flavours by superposition of three mass eigenstates with tiny mass differences. But the question about the absolute neutrino mass is still open. The experimental part of the talk will focus on the neutrino mass searches based on terrestrial experiments within the KATRIN collaboration at Forschungszentrum Karlsruhe. [mehr]

"Optics beyond the Abbe limit: molecular resolution imaging by farfield light microscopy."

New developments in far-field light microscopy made possible to radically overcome the diffraction limit (ca. 200 nm laterally, 600 nm along the optical axis) of conventional far field microscopy. Presently, three principal “nanoscopy” families have been formed: “Nanoscopy” based on highly focused laser beams; nanoscopy based on Structured Illumination Excitation (SIE); and nanoscopy allowing superresolution even in the case of homogeneous excitation. With such techniques, it has become possible to analyze the spatial distribution of fluorescent molecules on surfaces and in biostructures with a greatly increased light optical resolution down to a few nanometers, corresponding to 1/100 of the exciting wavelength, and with single target/molecule localization accuracies down to a few Angstrom. [mehr]

 
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