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DY: Fachverband Dynamik und Statistische Physik

DY 36: SYHM Higgs Modes in Condensed Matter and Quantum Gases

DY 36.3: Hauptvortrag

Mittwoch, 18. März 2015, 16:00–16:30, H 0105

Massive Photons and the Anderson-Higgs Mechanism in Superconductors — •Dirk van der Marel — University of Geneva, Geneva, Switzerland

When we tune the temperature or the pressure of a solid transitions can occur between different states of matter. Usually such a phase transition is accompanied by a symmetry breaking and the emergence of one or several collective modes of the material. A superconducting gap has collective oscillations of its amplitude -equivalent to the Higgs particle- and of its phase. As shown by Anderson in 1958, coupling to the electromagnetic field creates an energy gap in the longitudinal oscillations of the charge density, and in the transverse oscillations of mixed photon-matter character. The energy-momentum dispersion of the latter can be measured experimentally, and reveals the mass acquired by the photons due the coupling to the superconducting order parameter. In certain superconductors two or more condensates coexist. Weak coupling between the condensates gives rise to the so-called Leggett-exciton, and the coupling to the electromagnetic field makes that two or more massive photon-branches coexist. Experimental examples of this will be discussed in this talk.