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Showing 1–15 of 15 results
Advanced filters: Author: M. Häffner Clear advanced filters

  • An exhausting characterization of the coherence properties of quantum system becomes challenging with increasing system size. Here the authors demonstrate that phonon autocorrelation functions and quantum discord can be measured with local control, and validate it in a string of 42 trapped ions.

    • A. Abdelrahman
    • O. Khosravani
    • H. Häffner
    ResearchOpen Access
    Nature Communications
    Volume: 8, P: 1-5

  • An ultracold gas of atoms can be used as the tip in a new type of scanning probe microscope.

    • M. Gierling
    • P. Schneeweiss
    • J. Fortágh
    Research
    Nature Nanotechnology
    Volume: 6, P: 446-451

  • Exotic theories predict the violation of Lorentz symmetry, which could potentially be spotted in low-energy experiments. Using ytterbium ions could improve the current sensitivity bounds by five orders of magnitude.

    • V. A. Dzuba
    • V. V. Flambaum
    • H. Häffner
    Research
    Nature Physics
    Volume: 12, P: 465-468

  • In open quantum systems the correlations between the system and its environment play an important role. A trapped-ion experiment demonstrates that these correlations can be detected without accessing or knowing anything about the environment or its interactions.

    • M. Gessner
    • M. Ramm
    • H. Häffner
    Research
    Nature Physics
    Volume: 10, P: 105-109

  • In quantum metrology, entangled states can be used to improve the signal-to-noise ratio. The use of a specially designed, entangled state of two Ca+ ions achieves an ultra-precise spectroscopic measurement of the electric quadrupole moment.

    • C. F. Roos
    • M. Chwalla
    • R. Blatt
    Research
    Nature
    Volume: 443, P: 316-319

  • Cooling molecules to ultralow temperatures is difficult owing to the fact they have many degrees of freedom. Now, a dense cloud of molecules in their lowest vibrational and rotational level has been prepared in an optical lattice, paving the way to Bose–Einstein condensation of ground-state molecules.

    • Johann G. Danzl
    • Manfred J. Mark
    • Hanns-Christoph Nägerl
    Research
    Nature Physics
    Volume: 6, P: 265-270

  • An electronic analogue of a Michelson–Morley experiment, in which an electron wave packet bound inside a calcium ion is split into two parts and subsequently recombined, demonstrates that the relative change in orientation of the two parts that results from the Earth’s rotation reveals no anisotropy in the electron dispersion; this verification of Lorentz symmetry improves on the precision of previous tests by a factor of 100.

    • T. Pruttivarasin
    • M. Ramm
    • H. Häffner
    Research
    Nature
    Volume: 517, P: 592-595

  • A quantum mechanical link between two mechanical oscillators has never been directly demonstrated. This study achieves direct coupling between single ions oscillating in traps separated over a distance of 54 micrometres. Additional ions are employed as antennae to amplify the coupling. The system may provide a building block for quantum computers and opportunities for coupling different types of quantum systems, such as trapped Rydberg atoms.

    • M. Harlander
    • R. Lechner
    • W. Hänsel
    Research
    Nature
    Volume: 471, P: 200-203

  • Deep γ-ray observations of the Galactic Centre with arcminute angular resolution show traces of petaelectronvolt protons within the central ten parsecs of our Galaxy; the accelerator of these particles could have provided a substantial contribution to Galactic cosmic rays in the past.

    • A. Abramowski
    • F. Aharonian
    • HESS Collaboration
    Research
    Nature
    Volume: 531, P: 476-479

  • Trapped-ion qubits have great potential for quantum computation, but materials improvements are needed. This Review surveys materials opportunities to improve the performance of trapped-ion qubits, from understanding the surface science that leads to electric-field noise to developing methods for building ion traps with integrated optics and electronics.

    • Kenneth R. Brown
    • John Chiaverini
    • Hartmut Häffner
    Reviews
    Nature Reviews Materials
    Volume: 6, P: 892-905