Quantum Plasmonics for Low-Photon-Number Nonlinear Optics and Quantum Circuits

题目：用于低光子数非线性光学和量子电路的量子等离子体元金属纳米结构可以将光以表面等离子体激元的形式限制在纳米长度尺度，表面等离子体激元是在金属和介电表面之间的界面传播的电磁波。表面等离子体可以将光学器件缩小到纳米级，也可以产生极高的电磁强度，从而产生强烈的光-物质相互作用。这些特性为超紧凑的有源光学器件（如光开关、调制器和波长转换器）开辟了可能性，这些器件可以在非常高的速度和低能量下工作。然而，要实现这些功能，需要具有强非线性光学响应的等离子体纳米结构。最近的理论工作表明，当表面等离子体与单个量子发射器相互作用时，两个系统可以杂交形成新的光与物质耦合模式。在这种混合状态下，单个等离子体可以产生非线性光学响应，为在基本量子能量极限下运行的非线性等离子体电路铺平了道路。然而，到目前为止，这种杂化状态仍然难以捉摸，因为量子发射体通常由于声子和光谱漫游而遭受大的失相。在本项目中，我们将研究金属纳米结构与砷化铟量子点之间的相互作用，以研究杂化机制并开发超快速非线性和量子器件。砷化铟量子点表现出光谱纯发射，使其成为实现杂化的理想选择。我们将使用这些高质量的量子发射体来演示杂化，并探索其非线性和量子光学性质。该项目最终将为超低能耗的纳米级光子器件以及提供指数级计算加速和无条件安全通信的紧凑量子电路铺平道路。该项目还将支持一项拓展工作，为本科生和高中生提供研究机会。技术描述等离子体纳米结构可以通过将光以表面等离子体激元（或简称等离子体激元）的形式限制在纳米尺度上，从而强烈增强光与物质的相互作用。最近，从理论上预测了当一个量子发射器被放置在等离子体纳米结构的高场区域时，两个系统可以杂化。在这种杂化状态下，发射器和等离子体形成了具有原子和光子特性的新耦合模式。这些杂化模式在单光子水平附近表现出强烈的光学非线性，使它们成为开发具有超低功耗的光电和量子器件的高度引人注目的系统。单量子发射体和等离子体之间的杂化尚未得到证实，因为量子发射体通常由于声子散射和光谱漫游而表现出快速的偶极子脱相。这种消相破坏了产生杂化模式的量子干涉。我们建议使用砷化铟（InAs）量子点来克服这个问题，该量子点具有狭窄且几乎变换有限的光发射，使其成为实现杂化状态的有希望的系统。将这些InAs量子点与金属纳米结构耦合的一个关键挑战是，它们嵌入在砷化镓基体中，不容易沉积到等离子体器件上。我们将通过结合器件设计和最先进的纳米制造技术来解决这一挑战。我们将描述制造器件的线性和非线性特性。然后，我们将利用杂交制度来演示一个纳米光子光学晶体管，其中单个吸收的控制光子可以切换许多信号光子。我们还将利用杂化机制在量子点中的单个被捕获自旋和表面等离子体激元之间创建一个界面，这可以作为纳米级量子电路的基本构建块。该项目最终将为超低能耗的纳米级非线性光子器件和紧凑的量子电路铺平道路，从而提供指数级的计算加速和无条件的安全通信。

Title: Quantum Plasmonics for Low-Photon-Number Nonlinear Optics and Quantum CircuitsMetallic nanostructures can confine light to nanometer length scales in the form of surface-plasmon polaritons, which are electromagnetic waves that propagate at the interface between metallic and dielectric surfaces. Surface plasmons can miniaturize optical devices to the nanoscale, and also generate extremely high electromagnetic intensities that create strong light-matter interactions. These properties open up the possibility for ultra-compact active optical devices such as optical switches, modulators, and wavelength converters, that operate at very high speeds and low energies. To achieve these capabilities, however, requires plasmonic nanostructures with a strong nonlinear optical response.Recent theoretical work has shown that when surface plasmons interact with single quantum emitters the two systems can hybridize to form new coupled modes of light and matter. In this hybridized regime, a single plasmon can produce a nonlinear optical response, paving the way for nonlinear plasmonic circuits operating at the fundamental quantum energy limit. To date, however, this hybridized regime remains elusive because quantum emitters typically suffer from large dephasing due to phonons and spectral wandering. In this program, we will investigate the interaction between metallic nanostructures and indium arsenide quantum dots to study the hybridized regime and develop ultra-fast nonlinear and quantum devices. Indium arsenide quantum dots exhibit a spectrally pure emission making them ideal for achieving hybridization. We will use these high quality quantum emitters to demonstrate hybridization, and explore its nonlinear and quantum optical properties. This program could ultimately pave the way towards nanoscale photonic devices with ultra-low energy dissipation, as well as compact quantum circuits that provide exponential computational speedup and unconditionally secure communication. The program will also support an outreach effort that provides research opportunities for undergraduate and high school students.Technical DescriptionPlasmonic nanostructures can strongly enhance light-matter interactions by confining light to the nanoscale in the form of surface plasmon polaritons (or simply plasmons). Recently, it has been theoretically predicted that when a quantum emitter is placed in the high field region of a plasmonic nanostructure the two systems can hybridize. In this hybridized regime, the emitter and plasmon form new coupled modes that take on both atomic and photonic properties. These hybridized modes exhibit strong optical nonlinearities near the single photon level, making them a highly compelling system for developing opto-electronic and quantum devices with ultra-low power dissipation. Hybridization between single quantum emitters and plasmons has yet to be demonstrated because quantum emitters usually exhibit rapid dipole dephasing due to phonon scattering and spectral wandering. This dephasing destroys the quantum interference that creates the hybridized mode. We propose to overcome this problem using indium arsenide (InAs) quantum dots that exhibit a narrow and nearly transform limited optical emission, making them promising systems for attaining the hybridized regime. A key challenge to coupling these InAs quantum dots to metal nanostructures is that they are embedded in a gallium arsenide matrix and cannot be easily deposited onto plasmonic devices. We will address this challenge through a combination of device design and state-of-the-art nanofabrication techniques. We will characterize the linear and nonlinear properties of fabricated devices. We will then utilize the hybridized regime to demonstrate a nanophotonic optical transistor where a single absorbed control photon can switch many signal photons. We will also utilize the hybridized regime to create an interface between a single trapped spin in a quantum dot and a surface plasmon, which could serve as a fundamental building block for nanoscale quantum circuits. This program could ultimately pave the way towards nanoscale nonlinear photonic devices with ultra-low energy dissipation, and compact quantum circuits that provide exponential computational speedup and unconditionally secure communication.