Violation of the Fluctuation-Dissipation Theorem and Heating Effects in the Time-Dependent Kondo Model

Abstract

The fluctuation-dissipation theorem (FDT) plays a fundamental role in understanding quantum many-body problems. However, its applicability is limited to equilibrium systems and it does in general not hold in nonequilibrium situations. This violation of the FDT is an important tool for studying nonequilibrium physics. In this paper we present results for the violation of the FDT in the Kondo model where the impurity spin is frozen for all negative times, and set free to relax at positive times. We derive exact analytical results at the Toulouse point, and results within a controlled approximation in the Kondo limit, which allow us to study the FDT violation on all time scales.A measure of the FDT violation is provided by the effective temperature, which shows initial heating effects after switching on the perturbation, and then exponential cooling to zero temperature as the Kondo system reaches equilibrium.

6 pages, 4 figures; v2: added references and clarified definition of effective temperature

References in corpus (3)

• Evolution of Entanglement Entropy in One-Dimensional Systems
• Ageing Properties of Critical Systems
• On the definition of a unique effective temperature for non-equilibrium critical systems

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• Interaction quench dynamics in the Kondo model in presence of a local magnetic field
• Coupled nonlinear stochastic differential equations generating arbitrary distributed observable with 1/f noise
• Effects from Additional Random Configuration to Linear Response and Modified Fluctuation-Dissipation Relation
• Out-of-equilibrium fluctuation-dissipation relations verified by the electrical and thermoelectrical ac-conductances in a quantum dot