Dipolar exciton hydrodynamics, controlled interactions and multi-functional integration: towards an exciton-based opto-electronic multiplexer

半导体纳米结构中的偶极(或间接)激子(IX)是由一个电子和一个空穴组成的激子，它被限制在两个紧密间隔的量子阱(QW)中。电荷分离通常是通过在双量子阱结构上施加电场来形成的，在保持电子-空穴库仑相互作用的同时，提高了IX：辐射寿命(最高可达ms-范围)。长的寿命允许存储大密度的冷激子，以及它们在ns时间尺度上的输运和操纵。此外，它们的偶极性质导致了很强的激子-激子相互作用。最后，IXS是复合玻色子，因此容易受到超流和玻色-爱因斯坦凝聚等集体玻色子效应的影响。这一提议旨在研究介观(~1微米)横向受限势中IXS的相互作用和集体行为之间的相互作用。限制将被用来控制IX密度：它将由横向结构的闸门以及通过移动声波产生的声场来提供。后者还将用于运输IXS以及研究它们在运动中的流体动力学性质。激子-激子相互作用将被用来实现激子控制门。研究结果将被应用于展示一种基于激子的光电多路复用器，该多路复用器能够耦合相隔数百微米的激子流体。

A dipolar (or indirect) exciton (Ix) in semiconductor nanostructures is an exciton consisting of an electron and a holes confined in two closely spaced quantum wells (QWs). The charge separation, which is normally formed by applying an electric field across the double QW structure, enhances the Ix: radiative lifetime (up to the ms-range) while still maintaining the electron-hole Coulomb interaction. The long lifetimes allow for the storage of a large density of cold excitons, as well as for their transport and manipulation in the ns time scale. In addition, their dipolar nature induces a strong exciton-exciton interactions. Finally, Ixs are composite bosons and, therefore, susceptible to collective bosonic effects like superfluidity and Bose-Einstein condensation.This proposal aims at the investigation of the interplay between interactions and collective behavior of Ixs in laterally confined potentials with mesoscopic ( ~1 µm) dimensions. Confinement will be used to control the Ix density: it will be provided by laterally structured gates as well as by moving acoustic fields created by acoustic waves. The latter will also be used to transport IxS as well as to investigate their hydrodynamic properties under motion. Exciton-exciton interaction will be exploit for the realization of exciton control gates. The results of the studies will be applied to demonstrate an exciton-based opto-electronic multiplexer capable of coupling exciton fluids separated by several hundreds of µm.