Manipulation and Control of Coherent States in Exciton-Polariton Systems (MacExP)

半导体中激子和光子的强量子耦合导致两个分量的相干叠加，或称为激子-极化子的准粒子。这种混合模式的出现，无论是从基础研究还是从应用研究的角度来看，都是很有意思的。激子组分产生了强烈的粒子间相互作用，而光子组分则产生了极低的有效质量和高的迁移率。激子-极化子凝聚领域在前十年开辟了，不久之后，稀薄原子气体的真实玻色-爱因斯坦凝聚体的演示，揭开了量子光学领域的新篇章。固体中准粒子的这一重大突破导致了与凝聚相关的现象和相变的广泛探索，如自发相干建立、超流和超导。甚至已经提出了使用基于极化拉比振荡的量子比特和在可见或太赫兹(THz)范围内发射的新型光源，如极化激子激光器和THz玻色子激光器。在过去的几年里，一些独立的努力在实验上将THz辐射和极化系统结合起来，目的是研究THz辐射和量子阱微腔系统的相互作用。在这个项目中，我们将更好地了解太赫兹辐射和极化子气体在线性和非线性区域中是如何相互作用的，这将为超快操纵和控制飞行-物质耦合以及未来涉及极化子系统的实用太赫兹产生方案的发展铺平道路。这促使系统地研究了不同配置下的太赫兹诱导效应，包括超快光谱实验和微腔极化电子，这些都在本项目中概述。将使用数字全息技术直接测量拉比振荡，并将研究瞬时太赫兹脉冲对相干态的影响。时间分辨光致发光研究将进一步提供受脉冲太赫兹辐射影响的极化凝聚体的动力学。因此，我们将探索瞬变电场对极化子凝聚体的影响，极化子凝聚体是研究固体凝聚的独特试验台。在这一背景下，光将投射到相干态的操纵和控制上，并将探索在凝聚和未凝聚的极化子气体或极化子和光子之间的超快切换。因此，该项目将加深我们对与太赫兹-激子-极化子耦合相关现象的理解，并通过新颖和复杂的实验促进两个学科交叉点的发展，最终目标是使光-物质相互作用能够进一步用于新的光学量子技术和光源概念。

Strong quantum coupling of excitons and photons in semiconductors results in coherent superpositions of the two components, or quasiparticles called exciton-polaritons. The appearance of such mixed modes is interesting from both the point of view of fundamental and applied research. Strong interparticle interactions result from the exciton component, while extremely low effective mass and high mobility are due to the photonic component. The field of condensation of exciton-polaritons opened up in the previous decade shortly after the demonstration of true Bose-Einstein condensates of dilute atomic gases, which opened a new chapter in the field of quantum optics. This major breakthrough on quasiparticles in solids led to a vast exploration of condensation-related phenomena and phase transitions, such as spontaneous coherence built-up, superfluidity and superconductivity. Even the use of qubits based on polariton Rabi oscillations and novel light sources emitting in the visible or terahertz (THz) range such as polariton lasers and THz bosonic lasers have been proposed. Within the last few years, a few independent efforts have been made to combine THz radiation and polariton systems in experiments, with the aim to study interaction of THz radiation and quantum-well microcavity systems. In this project, a better understanding of how THz radiation and polaritonic gases interact with each other both in the linear and nonlinear regime will be gained, which will pave the way for ultrafast manipulation and control oflight-matter coupling and the development of future practical THz-generation schemes involving polariton systems. This motivates a systematic investigation of THz-induced effects in various configurations involving ultrafast spectroscopy experiments and microcavity polaritons, which are outlined in this project. Rabi oscillations will be directly measured using a digital holography technique and the effects of transient THz pulses on the coherent state will be investigated. Time-resolved photoluminescence studies will further give access to the dynamics of polariton condensates influenced by the presence of pulsed THz radiation. Thereby, the effects of transient electric fields on condensates of polaritons, which are a unique testbed for condensation studies in solids, will be probed. In this context, light will be shed on the manipulation and control of coherent states and the ultrafast switching between a condensed and uncondensed polariton gas or a polaritonic and photonic regime will be explored. Thus, this project will deepen our understanding of phenomena related to THz-exciton-polariton coupling and enhance development at the crossroads of two disciplines with novel and sophisticated experiments, with the ultimate goal of enabling further utilization of light-matter interaction for novel optical quantum technologies and light-source concepts.