Nonequilibrium Landau-Zener-Stuckelberg spectroscopy in a double quantum dot

TL;DR

This paper develops a theoretical framework for nonequilibrium Landau-Zener-Stückelberg dynamics in driven double quantum dots, revealing environmental fluctuation effects and identifying dominant relaxation mechanisms.

Contribution

It introduces effective nonequilibrium Bloch equations to analyze LZS oscillations and environmental spectra in DQDs, connecting theory with experimental observations.

Findings

LZS oscillations are identified as signatures in experiments.

Super-Ohmic phonon fluctuations dominate relaxation in detuned DQDs.

Ohmic fluctuations are the main relaxation channel at zero detuning.

Abstract

We study theoretically nonequilibrium Landau-Zener-St\"uckelberg (LZS) dynamics in a driven double quantum dot (DQD) including dephasing and, importantly, energy relaxation due to environmental fluctuations. We derive effective nonequilibrium Bloch equations. These allow us to identify clear signatures for LZS oscilations observed but not recognized as such in experiments [Petersson et al., Phys. Rev. Lett. 105, 246804, 2010] and to identify the full environmental fluctuation spectra acting on a DQD given experimental data as in [Petersson et al., Phys. Rev. Lett. 105, 246804, 2010]. Herein we find that super-Ohmic fluctuations, typically due to phonons, are the main relaxation channel for a detuned DQD whereas Ohmic fluctuations dominate at zero detuning.