contact

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




next colloquium

Colloquia

Colloquia

Our series of Colloquium Talks takes place from October till January and from April till July, on Tuesdays, at 2.30pm.

Venue is the Herbert Walter Auditorium in the foyer of the Max Planck Institute of Quantum Optics.

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.

Month:

"Few-cycle intense mid-IR waveforms and novel electron dynamics: Strong field physics and extreme nonlinear optics in the mid-IR."

"Liberation of an electron is the first step of the recollision model describing high order harmonic generation and attosecond pulse generation. Orbital tomography and electron self-diffraction imaging furthermore intimately rely on a firm grasp of electron dynamics in the Coulomb field of their parent molecular ion. These strong field effects all rely on tunneling dynamics which we study with true mid-IR waveforms. I will show unexpected electron dynamics, and first 3D momentum measurements, when probed, without the ubiquitous ambiguities at the Ti:Sa range, in the non-perturbative tunneling regime. The availability of intense ultrashort pulses at 3100 nm permits exploitation of nonlinear pulse propagation in the anomalous dispersion regime leading to interesting X-wave dynamics, unprecedentedly large supercontinua and stable pulse self-compression in bulk media." [more]

"Variational methods in quantum many-body physics."

"We will review successes and limitations of the variational method in quantum many-body physics; both the time-independent and the time dependent variational method will be illustrated. Special attention will be paid to the role of entanglement in strongly correlated systems and quantum field theory, to classes of wavefunctions that naturally encompass the required entanglement, and to Ansätze for describing elementary excitations and particles on top of the strongly correlated vacuum." [more]

"A Centrifuge Decelerator: Slowing down Molecular Beams with an Inertial Force."

"Achieving better control and ability to manipulate molecules by decelerating and cooling them is important for various fields of research, such as, many-body physics, quantum information science, cold chemistry, investigation of the fundamental properties of matter, etc. Towards this end, here we present the concept of and demonstrate the first experimental results from a novel and versatile decelerator for continuous beams of neutral polar molecules, which employs the centrifugal potential in a rotating frame. With this technique, deceleration of continuous supersonic beams from a cryogenic source is conceivable. This is expected to provide large samples of slow and internally cold molecules amenable to further cooling down to quantum degenerate regimes." [more]

"Strong-field-induced electron dynamics and attosecond phenomena in solids."

"In this talk, I will give an overview of our recent work on studying electron dynamics in dielectrics exposed to few-cycle laser pulses with a peak intensity just below the damage threshold. Until recently, detailed time-resolved measurements of electron dynamics in this extreme regime of light-matter interaction used to be out of reach. The situation has recently changed due to the progress in the generation of few-cycle laser pulses and the related progress in attosecond physics. After a brief presentation of recent experiments performed in the Laboratory for Attosecond Physics (MPQ, Garching), I will report on our related theoretical work, where we studied the dynamics of interband excitations and the light-driven motion of charge carriers under conditions where the conventional nonlinear optics breaks down, and the Bragg-like scattering of electrons at edges of the Brillouin zone (Bloch oscillations) starts to play an important role." [more]

"A Little Big Bang: Strong Interactions in Ultracold Fermi Gases."

"Fermions, particles with half-integer spin such as electrons, protons and neutrons, are the building blocks of matter. When fermions strongly interact, complex collective behavior emerges, as found for electrons in high-temperature superconductors, for neutrons in neutron stars or for quarks in the primordial matter of the early universe. Ultracold Fermi gases of atoms are a new type of strongly interacting fermionic matter that can be created and studied in the laboratory with exquisite control. Non-equilibrium processes are observable in real time. We can study the collision of "spin up" and "spin down" Fermi gases with resonant, quantum limited interactions. In equilibrium, direct absorption images of the trapped atomic gas reveal the entire thermodynamics of the system, including the transition into the superfluid state. The specific heat of the gas displays a characteristic lambda-like feature at the superfluid critical temperature of 17% of the Fermi temperature. Scaled to the density of electrons, superfluidity would occur far above room temperature. We were recently able to follow the evolution of fermion pairing from three to two dimensions and to engineer spin-orbit coupling in these systems, connecting quite directly to models of layered superconductors and topological states of matter. Our measurements in and out of equilibrium provide benchmarks for current many-body theories and will help to understand other strongly interacting Fermi systems, such as high-temperature superconductors and neutron stars." [more]

 
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