Eur. Phys. J. Special Topics 224, 969–974 (2015)
https://doi.org/10.1140/epjst/e2015-02441-8

Editorial

¹ KIT, Physikalisches Institut, Wolfgang-Gaede-Str. 1, 76131 Karlsruhe, Germany
² Institut für Theoretische Physik, TU Dresden, 01062 Dresden, Germany

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