Exploring Carrier Spin Injection, Transport, and Trapping in Diamond

控制固态晶体中单个原子之间相互作用的方法对于下一代原子自旋编码信息的技术非常重要。这个项目将开创一种新的方法，可以有条件地根据另一个原子的量子力学自旋来操纵一个原子的自旋。将使用单个原子，如金刚石晶格中的点缺陷，其中氮原子取代了碳原子，称为NV中心。单个NV中心将由光学和电子脉冲控制，这样它们就可以相互发送自旋相关的信号。钻石中的NV中心已经被认为是存储和处理量子信息的宝贵资源。但是，关于如何建立一个能够在几个NV中心之间来回传输量子信息的网络，仍然存在一些基本问题。该项目通过使用激光和电场来创造电荷从一个NV中心到另一个NV中心的自旋相关运动来解决这一挑战。从这项工作中获得的理解将有助于为称为量子计算机的新型更强大的计算机构建组件。此外，这里使用的方法将开创量子计算机组件，使用在室温下工作的固态器件来处理量子信息。除了技术和科学优势外，拟议的研究预计将具有广泛的教育成果，因为它为学生提供了独特的跨学科科学教育，并能够与广泛的合作实验室网络进行互动。这些活动在城市学院具有特殊的意义，这是一所少数民族服务机构，拥有独特的城市学生群体。本研究项目探索利用光产生的载流子作为总线，在金刚石晶体或纳米结构中独立的、不相互作用的nv之间进行通信。金刚石可以说是量子自旋电子学的理想平台，因为它具有反转对称性，含有低浓度的自旋活性原子核，并且具有最弱的自旋轨道耦合之一。然而，几乎没有对金刚石中载流子自旋动力学的研究，因为通过已知的策略（例如光激发或铁磁界面）注入和检测自旋极化载流子已被证明是困难的。该项目通过灵活的方案规避了先前的复杂性，其中NV中心可以作为载流子自旋极化的源或探针。在先前观察的基础上，最初的目标是获得对控制载流子动力学的物理的更全面的理解，包括光电离、扩散和载流子捕获。以NV中心和取代氮中心为重点，研究计划包括一系列旨在探索自旋极化载流子的确定性注入、输运和捕获的实验。将特别关注相干自旋输运的问题，特别是它在不直接相互作用的量子位之间产生纠缠的能力。虽然重点是现象学和物理学，但研究计划也要求各种概念验证设备，以获得对动力学的充分控制。

Methods to control interactions between individual atoms in solid state crystals are important for next generation technologies that will encode information in atomic spins. This project will pioneer a new approach for manipulating one atom's spin conditionally on the quantum mechanical spin of another. Individual atoms such as point defects in a diamond crystal lattice where a nitrogen atom is substituted for a carbon atom, known as NV centers, will be used. Individual NV centers will be controlled with optical and electronic pulses so they can send spin-dependent signals to each other. NV centers in diamond are already known to be valuable resources for storing and processing quantum information locally. But there are still fundamental questions about how to build a network that can shuttle quantum information back and forth between several NV centers. This project addresses that challenge by using laser light and electric fields to create a spin-dependent motion of an electric charge from one NV center to another NV center. The understanding to be gained from this effort will help with the effort to build components for new and more powerful types of computers called quantum computers. Furthermore, the approach used here will pioneer quantum computer components that use solid state devices operating at room temperature to process quantum information. Besides the technological and scientific advantages, the proposed research is expected to have a broad educational outcome because it offers students a unique inter-disciplinary scientific education and the ability to interact with a wide network of collaborating labs. These activities gain special meaning at City College, a minority serving institution with a uniquely diverse population of inner-city students. This research program explores the use of photo-generated charge carriers as a bus to communicate between separate, non-interacting NVs within a diamond crystal or nano-structure. Diamond is arguably an ideal platform for quantum spintronics because it has inversion symmetry, contains a low concentration of spin-active nuclei, and features one of the weakest spin-orbit couplings. However, virtually no investigation of the carrier spin dynamics in diamond has yet been carried out, because injection and detection of spin polarized carriers through known strategies (e.g., optical excitation or ferromagnetic interfaces) has proven difficult. This project circumvents prior complications via a flexible scheme where NV centers alternatively serve as a source or a probe of carrier spin polarization. Building on prior observations the initial goal is to gain a fuller understanding of the physics governing the dynamics of charge carriers, including photo-ionization, diffusion, and carrier trapping. With focus on the NV center and substitutional nitrogen centers, the research plan encompasses a broad set of experiments designed to explore deterministic injection, transport, and capture of spin-polarized carriers. Special attention will be devoted to the problem of coherent spin transport, particularly in its ability to generate entanglement between qubits not interacting directly. While the emphasis is on the phenomenology and physics, the research plan also calls for various proof-of-concept devices conceived to gain adequate control of the dynamics.