Elio König

Quantum order in SU(N) impurity models

Quantum order beyond Landau's paradigm is a paradigmatic concept for ultra quantum matter and topological error correction codes, alike. In full analogy to topological order in gapped systems, gapless quantum order is mathematically described by deconfining gauge theories and characterized by anyonic excitations in the system. In this talk, I will report on aspects of quantum order in frustrated SU(N) impurity systems. Specifically, I will exploit an exact mapping to demonstrate that for N≥4, a simple triangular Kondo-Heisenberg cluster impurity displays a topological phase and a trivial phase. Using controlled field theoretical methods in the large N limit, I will demonstrate that these phases are separated by a deconfinement transition which is driven by the proliferation of monopole-like gauge field excitations. Beyond the concrete application to impurity models, these controlled calculations help to conceptually understand analogous deconfinement transitions in 2D U(1) quantum spin liquids and fractionalized Fermi liquids.

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