Cavity QED with a Single Quantum Dot in a Photonic Crystal Cavity: Photon Blockade, Dressed States, and Controlled Phase Shift

量子点是一种半导体材料在另一种半导体材料内部的纳米级块，它充当了其中电子的盒子，而光学纳米腔在其纳米级体积内共振地再循环光。最近的研究表明，一个由嵌入在光学纳米腔内的单个量子点组成的系统可以作为一个实用的平台来研究光与物质之间各种新的相互作用机制，甚至在只有一个被称为光子的光粒子的水平上。这个单一研究者的提议侧重于在这个平台上进行一系列实验，包括观察光和物质耦合的真正量子力学状态（称为盛装状态），光子封锁（纳米腔内一个光子的存在阻止另一个光子进入的状态），以及由这种系统介导的仅两个光子之间的受控相互作用（受控相移）。除了探索量子和纳米物理的新体制外，该系统还可用于开发更实用的量子通信和量子计算平台——基于量子力学强大特性的系统，有可能彻底改变信息技术、安全，甚至药物发现。在这个项目的过程中，一些学生将接受最先进的光学技术的培训，并将获得一个连接物理和工程许多学科的领域的专业知识，这将为他们在学术界、工业界或政府工作做好准备。该项目得到了材料研究部和物理部的支持。技术摘要基于光子晶体纳米腔和半导体量子点的固体腔量子电动力学（QED）系统取得了迅速的进展。最近的光致发光实验已经导致观察弱和强耦合机制的光-物质相互作用。此外，共振光散射为直接探测腔-量子点耦合提供了一种手段。这个单一的研究项目专注于探测光的量子态，以及在这样一个固态系统中的腔QED。为了更好地理解光与物质的相互作用，该项目将尝试在单光子水平上观察腔QED系统的修饰态、光子封锁和受控相移（即由这种系统介导的两个单独光子之间的非线性相互作用）。此外，该系统可用于开发更实用的量子通信和量子计算平台，以及超低功耗全光计算平台。在这个项目的过程中，一些学生将接受最先进的光学技术的培训，并将获得一个领域的专业知识，连接许多学科的物理和工程，从量子光学，量子信息科学，介观物理，光子学和光电子学。该项目得到了材料研究部和物理部的支持。

***NON-TECHNICAL ABSTRACT***A quantum dot is a nanoscale chunk of one semiconductor material inside of another, which acts as a box for the electrons within it, while an optical nanocavity resonantly recirculates light inside of its nanoscale volume. It has recently been shown that a system consisting of a single quantum dot embedded inside of an optical nanocavity can be employed as a practical platform to study various new regimes of interaction between light and matter, even at a level of only one particle of light called photon. This single investigator proposal focuses on performing a series of experiments on this platform, including the observation of true quantum mechanical states of coupled light and matter (called the dressed states), photon blockade (the regime in which the presence of one photon inside of a nanocavity prohibits another photon from entering it), and the controlled interaction between only two photons mediated by such a system (controlled phase shift). In addition to probing new regimes of quantum and nanoscale physics, this system can be used to develop a more practical platform for quantum communication and quantum computing - systems based on powerful properties of quantum mechanics which have the potential to revolutionize information technology, security, and even drug discovery. Over the course of this project, a number of students will be trained in state of the art optical techniques, and will gain expertise in an area that bridges many disciplines of physics and engineering, which will prepare them for work in academia, industry or government. The project receives support from the Divisions of Materials Research and Physics.***TECHNICAL ABSTRACT***Solid-state cavity quantum electrodynamics (QED) systems based on photonic crystal nanocavities and semiconductor quantum dots have seen rapid progress. Recent photoluminescence experiments have led to the observation of weak and strong coupling regimes of light-matter interaction. In addition, resonant light scattering has provided a means to directly probe cavity-quantum dot coupling. This single investigator project focuses on probing the quantum states of light, as well as cavity QED, in such a solid state system. In order to obtain an improved understanding of light-matter interactions, the project will attempt to observe dressed states of the cavity QED system, photon blockade, and controlled phase shifts at a single photon level (i.e., a nonlinear interaction between two individual photons mediated by such a system). In addition, the system can be used to develop a more practical platform for quantum communication and quantum computing, as well as for ultra low power all-optical computing. Over the course of this project, a number of students will be trained in state of the art optical techniques, and will gain expertise in an area that bridges many disciplines of physics and engineering, ranging from quantum optics, quantum information science, and mesoscopic physics, to photonics and optoelectronics. The project receives support from the Divisions of Materials Research and Physics.