IAP logo UniBonn logo
  • Increase font size
  • Default font size
  • Decrease font size

Quantum technologies

Dieter Meschede's research group
Home Group members Maximilian Genske
Group members
B. Sc. Maximilian Genske
Last position
in our group:
Master student
Field of research
in our group:
Few-atom quantum systems

Publications(up to 2013)

  • A. Steffen, W. Alt, M. Genske, D. Meschede, C. Robens and A. Alberti
    In-situ measurement of vacuum window birefringence by atomic spectroscopy, Rev. Sci. Instrum. 84, 126103 (2013)arXivBibTeXPDF

    We present an in-situ method to measure the birefringence of a single vacuum window by means of microwave spectroscopy on an ensemble of cold atoms. Stress-induced birefringence can cause an ellipticity in the polarization of an initially linearly-polarized laser beam. The amount of ellipticity can be reconstructed by measuring the differential vector light shift of an atomic hyperfine transition. Measuring the ellipticity as a function of the linear polarization angle allows us to infer the amount of birefringence Δn at the level of 10-8 and identify the orientation of the optical axes. The key benefit of this method is the ability to separately characterize each vacuum window, allowing the birefringence to be precisely compensated in existing vacuum apparatuses.

  • M. Genske, W. Alt, A. Steffen, A. H. Werner, R. F. Werner, D. Meschede and A. Alberti
    Electric quantum walks with individual atoms, Phys. Rev. Lett. 110, 190601 (2013)arXivBibTeXPDF
    We report on the experimental realization of electric quantum walks, which mimic the effect of an electric field on a charged particle in a lattice. Starting from a textbook implementation of discrete-time quantum walks, we introduce an extra operation in each step to implement the effect of the field. The recorded dynamics of such a quantum particle exhibits features closely related to Bloch oscillations and interband tunneling. In particular, we explore the regime of strong fields, demonstrating contrasting quantum behaviors: quantum resonances vs. dynamical localization depending on whether the accumulated Bloch phase is a rational or irrational fraction of 2π.
  • C. Cedzich, T. Rybár, A. H. Werner, A. Alberti, M. Genske and R. F. Werner
    Propagation of Quantum Walks in Electric Fields, Phys. Rev. Lett. 111, 160601 (2013)arXivBibTeXPDF
    We study one-dimensional quantum walks in a homogeneous electric field. The field is given by a phase which depends linearly on position and is applied after each step. The long time propagation properties of this system, such as revivals, ballistic expansion and Anderson localization, depend very sensitively on the value of the electric field Φ, e.g., on whether Φ/(2π) is rational or irrational. We relate these properties to the continued fraction expansion of the field. When the field is given only with finite accuracy, the beginning of the expansion allows analogous conclusions about the behavior on finite time scales.
  • M. Genske
    Electric Quantum Walks with Individual Atoms, (2012), Master thesisBibTeXPDF

    The experimental realisation of electric quantum walks, i.e. quantum walks that are subject to a force, is presented with individual caesium atoms. Hereby, the behaviour of a charged quantum particle in a static electric eld is simulated in a time as well as space discrete system. Building on previous achievements [1], the demonstration of ordinary quantum walks of up to 100 steps is shown. Further thorough theoretical studies expose the underlying simulator properties of such a quantum walk system experiencing a force. Similarities to the continuous time analogue as well as characteristic features that are indebted to the discrete evolution of the system are presented. The implementation of a direct digital synthesizer allows the experimental application of discrete forces in the system by employing frequency ramps, and thus leads to the realisation of electric walks. Results are given for selected force parameters, showing the phenomenon of Bloch oscillations. Additionally, pure ballistic transport of the electric quantum walk due to strong Landau-Zener tunnelling in the strong force regime is demonstrated.