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The dynamics of a single impurity in an environment is a fundamental problem in many-body physics. In the solid state, a well known case is an impurity coupled to a bosonic bath (such as lattice vibrations); the impurity and its accompanying lattice distortion form a new entity, a polaron. This quasiparticle plays an important role in the spectral function(More)
Pairing of fermions is ubiquitous in nature, underlying many phenomena. Examples include superconductivity, superfluidity of (3)He, the anomalous rotation of neutron stars, and the crossover between Bose-Einstein condensation of dimers and the BCS (Bardeen, Cooper and Schrieffer) regime in strongly interacting Fermi gases. When confined to two dimensions,(More)
Linear polarization of the H α line of hydrogen has been observed in solar flares. The observed polarization degree can be as high as 10 % for a flare located near the limb and a one minute integration time. This polarization is currently explained as anisotropic collisional excitation of the n = 3 level by vertical beams of protons with an energy greater(More)
Biogeosciences Discussions This discussion paper is/has been under review for the journal Biogeosciences (BG). Please refer to the corresponding final paper in BG if available. Abstract A comprehensive assessment of nitrogen (N) flows at the landscape scale is fundamental to understand spatial interactions in the N cascade and to inform the development of(More)
The design, construction and performance of a Raman laser system to be used for spec-troscopy with ultracold 40 K atoms is presented. The laser system uses an optical phase locked loop to stabilize the relative frequencies and phases of two lasers, which produce light at 767nm with a (tunable) frequency difference of 1.8GHz. The RF power spectrum of the(More)
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