Berlin 2015 – scientific programme
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TT: Fachverband Tiefe Temperaturen
TT 56: Correlated Electrons: Quantum-Critical Phenomena – Theory
TT 56.13: Talk
Wednesday, March 18, 2015, 12:45–13:00, A 053
Steady state dynamics and effective temperatures of quantum criticality in open systems — •Farzaneh Zamani1, Pedro Ribeiro2, and Stefan Kirchner3 — 1Max Planck Institute for Physics of Complex Systems, 01187 Dresden, Germany — 2Russian Quantum Center, Business-center "Ural", Novaya street 100A, Skolkovo village, Odintsovo district, Moscow area, 143025 Russia — 3Center for Correlated Matter, Zhejiang University, China
We present our results for the steady-state --both thermal and non-thermal-- scaling functions and steady-state dynamics in a quantum impurity model of local quantum criticality. Our model, the pseudogap Kondo model, allows us to obtain full scaling functions in and out of equilibrium. We discuss the (equilibrium) zero-temperature residual entropy at various fixed points. We also consider the non-equilibrium steady-state, obtained by applying a finite bias voltage and study the concept of effective temperatures near fully interacting as well as weak-coupling fixed points. In the vicinity of each fixed point we establish the existence of an effective temperature --different at each fixed point-- such that the equilibrium fluctuation-dissipation theorem is recovered. Interestingly, steady-state scaling functions in terms of the effective temperatures coincide with the equilibrium scaling functions in terms of the temperature. This result extends to higher correlation functions as is explicitly demonstrated for the Kondo singlet strength. We also study the non-linear charge transport in terms of the effective temperatures.