Transient noise spectra in resonant tunneling setups: Exactly solvable models

TL;DR

This paper studies the time-dependent behavior of finite-frequency current noise in exactly solvable mesoscopic models after sudden coupling, revealing unique decay patterns and conditions for negative transient noise.

Contribution

It provides an exact analysis of transient noise spectra in resonant tunneling models, highlighting algebraic decay at zero temperature and temperature-dependent damping effects.

Findings

Transient noise can become negative in certain parameter regimes.

At zero temperature, transient noise decays algebraically over time.

Finite temperature induces an exponential decay with temperature-dependent damping.

Abstract

We investigate the transient evolution of finite-frequency current noise after abrupt switching on of the tunneling coupling in two paradigmatic, exactly solvable models of mesoscopic physics: the resonant level model and the Majorana resonant level model, which emerges as an effective model for a Kondo quantum dot at the Toulouse point. We find a parameter window in which the transient noise can become negative, a property it shares with the transient current. However, in contrast to the transient current, which approaches the steady state exponentially fast, we observe an algebraic decay in time of the transient noise for a system at zero temperature. This behaviour is dominant for characteristic parameter regimes in both models. At finite temperature the decay is altered from an algebraic to an exponential one with a damping constant proportional to temperature.