Transient quantum evolution of 2D electrons under photoexcitation of a deep center

TL;DR

This paper investigates the quantum dynamics of 2D electrons after ultrashort photoexcitation, revealing oscillatory transient behavior due to quantum interference effects in the Wigner distribution.

Contribution

It introduces a quantum model for transient electron evolution in 2D heterostructures, highlighting the role of negative Wigner function contributions.

Findings

Wigner distribution exhibits alternating signs indicating quantum interference.

Transient oscillations in electron concentration and energy are observed.

Quantum effects cause deviations from classical diffusive behavior.

Abstract

We have considered the ballistic propagation of the 2D electron Wigner distribution, which is excited by an ultrashort optical pulse from a short-range impurity into the first quantized subband of a selectively-doped heterostructure with high mobility. Transient ionization of a deep local state into a continuum conduction c-band state is described. Since the quantum nature of the photoexcitation, the Wigner distribution over 2D plane appears to be an alternating-sign function. Due to a negative contribution to the Wigner function, the mean values (concentration, energy, and flow) demonstrate an oscillating transient evolution in contrast to the diffusive classical regime of propagation.