Engineering and Manipulating Exciton Wave Packets

TL;DR

This paper demonstrates how tailored laser pulses can create, control, and manipulate exciton wave packets in semiconductors, enabling advanced quantum information and energy transport applications.

Contribution

It introduces a method to engineer and manipulate excitonic superpositions with prescribed properties using laser pulses and superlattices, advancing quantum control techniques.

Findings

Laser pulses can generate exciton wave packets with controlled speed and direction.

Structured excitons can be selectively passed, rejected, or dissociated.

The approach is validated with Tight-Binding and TDDFT simulations.

Abstract

When a semiconductor absorbs light, the resulting electron-hole superposition amounts to a uncontrolled quantum ripple that eventually degenerates into diffusion. If the conformation of these excitonic superpositions could be engineered, though, they would constitute a new means of transporting information and energy. We show that properly designed laser pulses can be used to create such excitonic wave packets. They can be formed with a prescribed speed, direction and spectral make-up that allows them to be selectively passed, rejected or even dissociated using superlattices. Their coherence also provides a handle for manipulation using active, external controls. Energy and information can be conveniently processed and subsequently removed at a distant site by reversing the original procedure to produce a stimulated emission. The ability to create, manage and remove structured excitons comprises the foundation for opto-excitonic circuits with application to a wide range of quantum information, energy and light-flow technologies. The paradigm is demonstrated using both Tight-Binding and Time-Domain Density Functional Theory simulations.