Temporal evolution of Seebeck coefficient in an ac driven strongly correlated quantum dot

TL;DR

This paper investigates how the thermopower of a strongly correlated quantum dot in the Kondo regime evolves over time under sinusoidal gate voltage modulation, revealing complex fluctuations and temperature sensitivity.

Contribution

It introduces a time-dependent analysis of thermopower in a quantum dot driven by sinusoidal gate voltage, highlighting new fluctuation behaviors and temperature effects.

Findings

Instantaneous thermopower exhibits complex fluctuations with increased driving amplitude.

Time-averaged thermopower decreases and saturates with inverse driving frequency.

Thermopower is highly sensitive to ambient temperature at large driving amplitudes.

Abstract

We study the response of the thermopower of a quantum dot in the Kondo regime to sinusoidal displacement of the dot energy level via a gate voltage using time dependent non-crossing approximation and linear response Onsager relations. Instantaneous thermopower begins to exhibit complex fluctuations when the driving amplitude is increased at constant driving frequency. We also find that the time averaged thermopower decreases steadily until it saturates at constant driving amplitude as a function of inverse driving frequency. On the other hand, time averaged thermopower is found to be quite sensitive to ambient temperature at all driving frequencies for large driving amplitudes. We discuss the underlying microscopic mechanism for these peculiarities based on the behaviour of the dot density of states.