Tuneable Excitonic Integrated Circuits

Lead Research Organisation: University of Exeter
Department Name: Physics and Astronomy

Abstract

This project is a fundamental science exploration of novel ways to manipulate and confine quasiparticles known as excitons emerging in atomically thin (2D) semiconductors and their heterostructures, with the aim to demonstrate the control over fluxes of these hydrogen-like bosonic particles and therefore open a pathway to the study of excitons in controllable potential profiles. This studies are cornerstone to pioneer the on-chip bosonic counterpart of quantum electronics and novel macroscopic quantum states. At the same time the on-chip control of excitons dynamics and flow may offer radically new approaches to interface efficient photon-based signal communication to electron-based signal processing technologies. In this proposal we will undertake the timely and ambitious search for radically novel physical concepts needed to enable the development of tuneable excitonic integrated circuits working in ambient conditions.

2D semiconductors transition metal dichalcogenides (TMDC) typically have an exciton binding energy exceeding the room temperature thermal energy. In addition, their photo-physical properties can be tuned by controlling the electrostatic doping, the dielectric environment and stacking sequences of materials assembled in so-called van der Waals heterostructures leading to the observation of long lived interlayer excitons consisting of spatially separated electron-hole pairs in 2D heterostructures, Moiré excitons, a high-temperature macroscopic state corresponding to the condensation of interlayer excitons akin to a condensate of atoms and the electric field control of interlayer excitons in heterostructures. Whilst 2D systems are an ideally suited platform for exploring the novel fundamental science of excitons, the ambitious and timely quest at the core of this project will have to overcome four main challenges. Can an exciton effective pressure be engineered in 2D materials to displace these charge neutral quasiparticles which do not respond to an electric field? Is there any new type of exciton with a non-zero electric dipole and a sufficiently large oscillator strength to enable room temperature electrical tuneability in 2D heterostructures? Which 2D materials are better suited for tuneable excitonic integrated circuits working in ambient conditions? Are there ways to control the exciton lifetimes?

This proposal will pioneer answers and solutions to the aforementioned challenges to accomplish a step change in the control of excitons in integrated circuits operating in ambient conditions. This timely and ambitious goal will be accomplished by exploring novel fundamental science of the physics of excitons in some of the most promising material systems for the on-chip control of exciton fluxes such as atomically thin semiconductors.

Publications

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