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Quantum technologies

Dieter Meschede's research group
Home AMO physics colloquia
  • T. Kampschulte's defense

  • PhD defense: Tobias Kampschulte
    TitleCoherently driven three-level atoms in an optical cavity
    Time and room: 10:00, seminar room 1 in HISKP
  • Prof. Matthias Weidemüller

  • Invited speaker: Prof. Matthias Weidemüller
    Affiliation: Ruprecht-Karls-Universität Heidelberg
    Title: Rydberg Aggregates
    Time and room: 17 h c.t., lecture hall IAP
    Abstract: Due to the long-range character of the interaction between highly excited atoms, the dynamics of an ultracold gas of Rydberg atoms is entirely determined by van-der-Waals and dipole-dipole interactions. One outstanding property is the tunability of the strength and the character of the interactions with static electric fields. This allows one to explore the transition from a weakly coupled two-body system to a strongly coupled many-body system. The long-range interaction leads to many-body entanglement and has possible applications in quantum computing. In my talk I will first give a general introduction into the field of Rydberg gases with special emphasis on our recent experiments.

  • Prof. Hanns-Christoph Nägerl

  • Invited speaker: Prof. Hanns-Christoph Nägerl
    Affiliation: Universität Innsbruck
    Title: Strongly correlated one-dimensional quantum systems
    Time and room: 17 h c.t., lecture hall IAP
    Abstract: I will review our recent experiments with atomic quantum gases in the regime of quantum degeneracy, Bose-Einstein condensation, and strong correlations. Ultracold atomic gases are versatile tunable laboratory systems for the study of complex many-body quantum phenomena as essentially all parameters such as geometry and strength of confinement and the strength of interactions [1] can be controlled with near-perfect isolation from external perturbations. For atoms 1D geometry, I will discuss the strongly-interacting limits of so-called Tonks-Girardeau and super-Tonks-Girardeau phases [2]. We observe the “pinning” quantum phase transition in the presence of an arbitrarily weak lattice potential [3]. Exploiting three-body recombination processes, we determine the value of the three-particle correlation function at the origin from weak to strong interactions [4]. I will finally discuss measurements of impurity transport through a strongly interacting 1D system.

    [1] E. Haller et al., Phys. Rev. Lett. 104, 153203 (2010); [2] E. Haller et al., Science 325, 1224 (2009); [3] E. Haller et al., Nature 466, 597 (2010); [4] E. Haller et al., manuscript in preparation.

  • Prof. Andreas Ruschhaupt

  • Invited speaker: Prof. Andreas Ruschhaupt
    Affiliation: Leibniz Universität Hannover
    Title: Shortcuts to Adiabaticity
    Time and room: 17 h c.t., lecture hall IAP
    Abstract: We present new methods to achieve shortcuts to adiabatic manipulations of atoms in a harmonic trap: a speeded-up adiabatic-like expansion of the trap and a speeded-up adiabatic-like transport of the trap. In both cases, the final atomic state is the same as in the adiabatic process, but the state is achieved with fidelity one in arbitrarily short time, keeping the same populations of vibrational levels in the initial and final trap. These methods can also be generalized to condensates. Moreover, we show how to speed up adiabatic passage from one internal atomic state to another in two-level and three-level atoms.

  • Dr. Ulrich Vogl

  • Invited speaker: Dr. Ulrich Vogl
    Affiliation: NIST Gaithersburg and Joint Quantum Institute
    Title: Quantum Image Processing with Four-Wave Mixing in Hot Atomic Vapor
    Time and room: 17 h c.t., IAP lecture room
    Abstract: Four-wave-mixing in hot atomic vapor is a versatile tool for spatially multimode squeezed light generation. We demonstrate multimode behaviour for different pump-probe configurations producing either single mode squeezing or twin beams. To illustrate the interest of such fields, we perform an imaging experiment with two quantum correlated vacuum beams, where the spatially multimode character of squeezing is used to reconstruct an arbitrarily chosen pattern. We investigate the advantage of squeezing in this configuration and we demonstrate an enhanced sensitivity due to quantum correlations.