Coherent oscillations of electrons in tunnel-coupled wells under ultrafast intersubband excitation

TL;DR

This paper investigates ultrafast intersubband electron excitation in tunnel-coupled quantum wells, analyzing coherent oscillations, relaxation effects, and nonlinear responses to understand their dynamics under various excitation conditions.

Contribution

It provides a detailed theoretical analysis of coherent electron oscillations and nonlinear effects in tunnel-coupled wells during ultrafast excitation, including dephasing and population relaxation.

Findings

Identification of oscillation periods and amplitudes dependence on pulse parameters

Analysis of dephasing and relaxation effects on coherence

Description of nonlinear oscillation damping mechanisms

Abstract

Ultrafast intersubband excitation of electrons in tunnell-coupled wells is studied depending on the structure parameters, the duration of the infrared pump and the detuning frequency. The temporal dependencies of the photoinduced concentration and dipole moment are obtained for two cases of transitions: from the single ground state to the tunnel-coupled excited states and from the tunnel-coupled states to the single excited state. The peculiarities of dephasing and population relaxation processes are also taken into account. The nonlinear regime of the response is also considered when the splitting energy between the tunnel-coupled levels is renormalized by the photoexcited electron concentration. The dependencies of the period and the amplitude of oscillations on the excitation pulse are presented with a description of the nonlinear oscillations damping.