Quantum Beat of Excitons in the Prolate Ellipsoidal Quantum Dots

Abstract

In this paper, renormalized wavefunction method was applied to study quantum beats of excitons in the InGaAs/InAlAs prolate ellipsoidal quantum dots (QDs). The obtained results show that, without the pump laser, the exciton absorption intensity is just a smooth curve. In contrast, when the system is illuminated by a strong pump laser resonating with two exciton levels, the oscillation behavior of exciton absorption intensity, which is known as quantum beats of excitons, is observed. That result can be interpreted as an indirect consequence of the Pauli exclusion principle leading to a splitting of the electron levels, which forms two close exciton levels, and if two excitons are excited coherently, the interference of these two excitons will finally form a quantum beat. The study also shows that the geometry shape of the QDs has strong influence on the properties of quantum beats. Changing the period of quantum beats in particular or optical properties in general in QDs thus becomes more flexible through changing their geometry shapes. This is one interested advantage of the ellipsoidal QDs and is expected to increase their applicability more than the spherical QDs.