Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 111: Correlated Electrons: Quantum Impurities, Kondo Physics
TT 111.3: Talk
Friday, March 20, 2015, 10:00–10:15, H 3005
Real-time dynamics induced by quenches across the quantum critical points in gapless Fermi systems with a magnetic impurity — •Christian Kleine1, Julian Musshoff2, and Frithjof B. Anders1 — 1Technische Universität Dortmund, Lehrstuhl für Theoretische Physik II, 44221 Dortmund, Germany — 2Forschungszentrum Jülich GmbH, Institute for Advanced Simulation, 52425 Jülich, Germany
The energy-dependent scattering of fermions from a localized orbital at an energy-dependent rate Γ(є)∝ |є|r gives rise to quantum critical points (QCPs) in the pseudo-gap single impurity Anderson model separating a local moment phase with an unscreened spin moment from a strong-coupling phase which slightly deviates from the screened phase of standard Kondo problem. Using the time-dependent numerical renormalization group (TD-NRG) approach we show that local dynamic properties always equilibrate towards a steady-state value even for quenches across the QCP but with systematic deviations from the thermal equilibrium depending on the distance to the critical coupling. Local non-equilibrium properties are presented for interaction quenches and hybridization quenches. For interaction quenches within the screened phase we find an universal function for the time-dependent local double occupancy. We trace back the discrepancy between our results and the data obtained by a time-dependent Gutzwiller variational approach to restrictions of the wave-function ansatz in the Gutzwiller theory.