Dr. Stephan Dürr
Stephan Dürr
Telefon: +49 89 3 29 05 - 291
Dr. Johannes Kofler
Johannes Kofler
Telefon: +49 89 3 29 05 - 242

kommende Kolloquien

  • The colloquium series will resume at the beginning of the next term in April/October.



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

Ansprechpartner für die wissenschaftliche Organisation:

Dr. Stephan Dürr und Dr. Johannes Kofler

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.


Quantum Magnetism with Ultracold Atoms

Understanding the behaviors of strongly-interacting spin systems is one of the central objectives of modern manybody quantum physics. I will present experiments in which we have realized quantum magnetism with ultracold atoms in an optical lattice. We carry out a quantum simulation of an Ising spin chain and demonstrate a quantum phase-transition from a paramagnetic phase to an anti-ferromagnetic phase.The magnetic phases are detected in situ through our quantum gas microscope. This work opens a wide range of new possibilities for studying quantum magnetism. Exotic states of matter and frustrated spin physics in optical lattices are now within experimental reach. [mehr]

SU(N) magnetism with cold atoms and chiral spin liquid

Certain cold atoms, namely the alkaline earth-like atoms whose electronic degrees of freedom are decoupled from their nuclear spin, can be thought of as quantum particles with an SU(N)-symmetric spin. These have recently been cooled to quantum degeneracy in the laboratories around the world. A new world of SU(N) physics has thus become accessible to experiment, including that described by the SU(N) Hubbard model in various dimensions and by other related models. We show that the Mott insulator of such cold atoms is an SU(N) symmetric antiferromagnet of the type not commonly studied in the literature. We further show that in 2 dimensions, this antiferromagnet is a chiral spin liquid, a long sought-after topological state of magnets, with fractional and non-Abelian excitations. [mehr]

Two-dimensional Fermi gases

Pairing of fermions is ubiquitous in nature and it is responsible for a large variety of fascinating phenomena like superconductivity, superfluidity of 3He, the anomalous rotation of neutron stars, and the BEC-BCS crossover in strongly interacting Fermi gases. When confined to two dimensions, interacting many-body systems bear even more subtle effects, many of which lack understanding at a fundamental level. Most striking is the, yet unexplained, effect of high-temperature superconductivity in cuprates, which is intimately related to the two-dimensional geometry of the crystal structure. In particular, the question how many-body pairing is established at high temperature and whether it precedes superconductivity are crucial questions to be answered. We will report on recent experiments of pairing in a two-dimensional atomic Fermi gas in the regime of strong coupling. We perform angle-resolved photoemission spectroscopy to measure the spectral function of the gas and we observe a many-body pairing gap even above the predicted superfluid transition temperature. [mehr]

Dissipative Preparation of Entanglement

Attempts to perform quantum computation and generate entanglement typically rely on isolating the system from the environment and reach the desired state trough controlled unitary dynamics. In contrast an alternative approach was proposed, which exploits dissipation to generate entanglement and realize quantum computation as the steady state of the dissipative dynamics.Whether this alternative approach is an advantage from an experimental perspective can only be answered by considering concrete physical systems and evaluating what the alternative approach amounts to for those systems. [mehr]

KBBF family crystals and deep UV harmonic generation

KBBF family crystals, ABe2BO3F2 (A=K, Rb, Cs), are the only type of crystals that can generate deep-UV laser light by direct harmonic generations. The talk starts with briefly introduction of the historical background of the discovery of the borate nonlinear optical (NLO) crystals, followed by the description of the growth, structure, basic properties of the KBBF family crystals. Focuses will be given to the recent progresses on the generation of deep-UV lights, e.g. 120mW at 177.3nm and 1.2W at 200nm. Examples of applications of such deep UV light will be discussed at the end of the talk; which includes: super-high resolution of photoemission spectrometers, photon-electronic emission microscope, etc. [mehr]

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