What can we learn from the experiment of electrostatic conveyor belt for excitons?

Abstract

Motivated by the experiment of electrostatic conveyor belt for indirect excitons [A. G. Winbow, \textit{et al.}, Phys. Rev. Lett. \textbf{106}, 196806 (2011)], we study the exciton patterns for understanding the exciton dynamics. By analyzing the exciton diffusion, we find that the patterns mainly come from the photoluminescence of two kinds of excitons. The patterns near the laser spot come from the hot excitons which can be regarded as the classical particles. However, the patterns far from the laser spot come from the cooled excitons or coherent excitons. Taking into account of the finite lifetime of Bosonic excitons and of the interactions between them, we build a time-dependent nonlinear Schrödinger equation including the non-Hermitian dissipation to describe the coherent exciton dynamics. The real-time and imaginary-time evolutions are used alternately to solve the Schrödinger equation in order to simulate the exciton diffusion accompanied with the exciton cooling in the moving lattices. By calculating the escape probability, we obtain the transport distances of the coherent excitons in the conveyor which are consistent with the experimental data. The cooling speed of excitons is found to be important in the coherent exciton transport. Moreover, the plateau in the average transport distance cannot be explained by the dynamical localization-delocalization transition induced by the disorders.