Dr. Stephan Dürr
Stephan Dürr
Group Leader
Phone: +49 89 3 29 05 - 291
Room: A 2.22
Prof. Dr. Thomas Udem
Thomas Udem
Phone: +49 89 3 29 05 - 282 // -257
Room: D 0.21 // D 0.39

next colloquium



Our series of Colloquium Talks takes place from October till January and from April till July, on Tuesdays, at 2:30 p.m..

Attention! Due to the recontstruction of the foyer at the MPQ talks will take place at the interims Lecuture Hall in Room B 0.32.

Scientific organization of the talks: Dr. Stephan Dürr and Dr. Thomas Udem

If you wish to view the live stream of the MPQ colloquium, please use the link to subscribe to the corresponding mailing list. Detailed instructions will be sent to all subscribers.


"An elementary quantum network of single atoms in optical cavities."

"Quantum networks form the basis of distributed quantum computing architectures and quantum communication. Single atoms in optical cavities are ideally suited as universal quantum network nodes capable of sending, storing and retrieving quantum information. We demonstrate this by presenting an elementary version of a quantum network based on two identical nodes in remote, independent laboratories. The dynamic control of coherent dark states allows for the reversible exchange of quantum information by exchange of a single photon." [more]

"A quantum information approach to statistical mechanics."

"I will show how one can apply quantum information tools to study various problems in statistical mechanics. We focus on classical spin models, which are toy models used in a variety of fields such as magnetism or quantum gravity, and we tackle them from three different angles. First, we show how the partition function of a class of widely different classical spin models (models in different dimensions, different types of many-body interactions, different symmetries, etc) can be mapped to the partition function a single model. Second, we give efficient quantum algorithms to estimate the partition function of various classical spin models, such as the Ising or Potts model. Finally, we outline the possibility of applying quantum information tools to a model of discrete quantum gravity called causal dynamical triangulation." [more]

"Localization of ultra-cold bosons in a 3D laser speckle disordered potential."

"We have observed 3D localization of ultra-cold atoms of a Bose Einstein Condensate, suspended against gravity, and released in a 3D optical disordered potential with short correlation lengths in all directions. Fluorescence imaging of the expanding cloud yields density profiles composed of a steady localized part and a diffusive part. A phenomenological analysis of the data allows us to determine the localized fraction and the diffusion coefficients of the diffusing part. I will present and discuss these results, in the context of Anderson localization." [more]

"Spinning electrons with intense circularly polarized pulses to generate circular attosecond pulses - a new tool for electron control."

"The main goal of the new attosecond (asec=10**-18s) science is the visualization, control and manipulation of electrons on their natural time scale, the asec (152 asecs being the orbital period of the H atom). High order harmonic generation (HHG) in atoms and Molecular High Order Harmonic Generation (MHOHG) in molecules driven by intense ultrashort low frequency laser pulses are the current main source of asec pulses.The mechanism for generation of harmonics is based on the three-step model of tunnelling ionization, acceleration and collision-recollision of the ionized electron with parent or neighbour ions [1]. So far only linearly polarized isolated asec pulses have been generated for which the recollision model predicts maximum energies [2]. Current research on asec pulse generation is focused on the polarization state in MHOHG [3]. Modelling of laser-molecule interactions in the nonlinear nonperturbative regime requires extensive (expensive) numerical solutions of Time-Dependent Schroedinger Equations (TDSE) from which one can study recollision dynamics with ultrashort intense circularly polarized laser pulses in order to produce circular asec pulses. Semiclassical models of laser induced recollision allow for determining the effect of various laser parameters such as polarization, intensity and duration of circularly polarized asec pulses. Such pulses due to their large band width will allow for the creation of circular coherent electron wave packets (CEWP), ie, « spinning » electrons. Chemistry and biology have lived through 2 centuries of molecular « structure ». Asec pulses will finally allow scientists to study molecular « function » on the electron`s natural time scale, the asec?"[1] PB Corkum, Physics Today, March 2011,p.16[2] AD Bandrauk, S Chelkowski, Intnl Rev Atom Molec Phys, 2, 1-22 (2011).[3] AD Bandrauk, KJ Yuan, J Phys B, S 45, 074001 (2012) [more]

"Recent experiments with ions on microfabricated surface traps."

"In this talk I will report on recent progress made at NIST Boulder in the manipulation of ions using microfabricated surface traps. A first experiment performs a laser-less two qubit logic gate, taking advantage of the high magnetic field gradients that can be generated on ion chips. A second experiment, operated at cryogenic temperature, shows the exchange of a single quantum of vibration between two ions trapped 40 micrometers apart. Lastly, I will describe an experiment where the anomalous heating rate of a trapped ion is reduced by a factor of 100 after in-situ cleaning of the surface of the trap." [more]

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