Quench dynamics in the Multi-Channel Kondo system

Iksu Jang^1*, Po Yao Chang¹

¹Physics, National Tsing Hua University, Hsin Chu, Taiwan

* Presenter:Iksu Jang, email:jisjhm@gmail.com

Although quantum quench is the most simple setting for non-equilibrium physics, it can show various exotic phenomena. However, even for the simple quench setting, it is extremely difficult to figure out the physical properties of the non-equilibrium phenomena if the system is strongly interacting. Usually, high-level numerics are the only ways to study non-equilibrium phenomena in strongly correlated systems. However, there are few theoretical models which provide a simple platform for non-equilibrium physics even with strong interaction. One famous example is the Sachdev-Ye-Kitaev (SYK) model which has been intensively studied regarding the AdS/CFT duality and the quantum chaos due to its solvability in large-N limit. Resorting to its solvability and interesting properties such as the quantum chaos and non-Fermi liquid behavior, there have been many theoretical studies of SYK-based models and their quantum dynamics. However, it is not easy to realize the SYK-based models in the real world. As a result, it is necessary to have a more physical model showing similar properties to the SYK model. With this motivation, we have been investigating quench dynamics in the Multi-Channel Kondo model showing similar behavior to the SYK model but physically realizable in the quantum dot setting. Additionally, since the Multi-Channel Kondo system has a finite temperature transition at the Kondo temperature, it can show more exotic phenomena compared to the SYK model in a quench setting. Using the Keldysh formalism, we solved the self-consistent Kadanoff-Baym equations numerically and obtained the non-equilibrium solutions of the impurity spin under the sudden quench of the Kondo coupling constant. From the non-equilibrium solutions, we have observed that impurity spin shows quite different dynamics depending on whether the Kondo coupling constant increases or decreases. For more quantitative analysis, we also calculated the effective temperatures and the thermalization time under several different conditions.

Keywords: Quench dynamics, Multi Channel Kondo, Non-Fermi liquid, Thermalization