Showing papers by "Hartmut Häffner published in 2011"
TL;DR: In this paper, the authors studied a driven-dissipative system of atoms in the presence of laser excitation to a Rydberg state and spontaneous emission, where the atoms interact via the blockade effect, whereby an atom in the rydberg level shifts the level of neighboring atoms.
Abstract: We study a driven-dissipative system of atoms in the presence of laser excitation to a Rydberg state and spontaneous emission. The atoms interact via the blockade effect, whereby an atom in the Rydberg state shifts the Rydberg level of neighboring atoms. We use mean-field theory to study how the Rydberg population varies in space. As the laser frequency changes, there is a continuous transition between the uniform and antiferromagnetic phases. The nonequilibrium nature also leads to a novel oscillatory phase and bistability between the uniform and antiferromagnetic phases.
157 citations
TL;DR: In this paper, a chain of trapped ions embedded in microtraps generated by an optical lattice can be used to study oscillator models related to dry friction and energy transport.
Abstract: We show that a chain of trapped ions embedded in microtraps generated by an optical lattice can be used to study oscillator models related to dry friction and energy transport. Numerical calculations with realistic experimental parameters demonstrate that both static and dynamic properties of the ion chain change significantly as the optical lattice power is varied. Finally, we lay out an experimental scheme to use the spin degree of freedom to probe the phase space structure and quantum critical behavior of the ion chain.
105 citations
TL;DR: In this article, the authors used a single ion as a movable electric field sensor with accuracies on the order of a few V/m and observed a strong buildup of stray charges around the loading region on the trap resulting in an electric field of up to 1.3 kV/m at the ion position.
Abstract: We use a single ion as a movable electric field sensor with accuracies on the order of a few V/m. For this, we compensate undesired static electric fields in a planar radio frequency trap and characterize the static field and its curvature over an extended region along the trap axis. We observe a strong buildup of stray charges around the loading region on the trap resulting in an electric field of up to 1.3 kV/m at the ion position. We also find that the profile of the stray field remains constant over a time span of a few months.
67 citations
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TL;DR: In this paper, the authors used a single ion as an movable electric field sensor with accuracies on the order of a few V/m. They observed a strong buildup of stray charges around the loading region on the trap resulting in an electric field of up to 1.3 kV/m at the ion position.
Abstract: We use a single ion as an movable electric field sensor with accuracies on the order of a few V/m. For this, we compensate undesired static electric fields in a planar RF trap and characterize the static fields over an extended region along the trap axis. We observe a strong buildup of stray charges around the loading region on the trap resulting in an electric field of up to 1.3 kV/m at the ion position. We also find that the profile of the stray field remains constant over a time span of a few months.