Dresden 2017 – wissenschaftliches Programm
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HL: Fachverband Halbleiterphysik
HL 63: Poster: Quantum Dots and Optics
HL 63.9: Poster
Mittwoch, 22. März 2017, 15:00–19:00, P1A
Fermi edge singularity and the functional renormalization group — •Fabian Kugler1,2 and Jan von Delft1 — 1Arnold Sommerfeld Center for Theoretical Physics, Ludwig-Maximilians-Universität München, D-80333 München — 2Max-Planck-Institut für Quantenoptik, D-85748 Garching
We study the Fermi edge singularity, describing the response of a degenerate electron system to optical excitation, in the framework of the functional renormalization group (fRG). Results for the (interband) particle-hole susceptibility from various implementations of fRG are tested against the summation of all leading log. diagrams, achieved by a solution of parquet equations. For the (zero-dimensional) special case of the X-ray edge singularity, we analytically reproduce the (first-order) parquet formula in a consistent way from a truncated fRG flow. Reviewing the underlying diagrammatic structure, we show that this derivation relies on partial cancellations special to the form of and accuracy applied to the X-ray problem and does not generalize. In fact, we show that the truncated fRG flow can only generate a fraction of the parquet graphs.