Silicon-vacancy color centers in phosphorous-doped diamond for bright single-photon emission under electrical pumping

高效、可扩展的单光子源对于光学量子计算机和无条件安全通信线路等众多量子信息技术的发展至关重要。在过去的二十年中，基于量子点的量子分析取得了很大的进展，但在环境条件下，它们正在被金刚石和相关宽带隙半导体的色心的最新进展所克服。色心是晶格中的点缺陷，其行为几乎像孤立的原子。该特性允许获得具有锐利发射光谱的明亮光和电致发光，这是任何其他量子光电系统在环境条件下无法实现的。然而，基于这些发射器设计可扩展和可重复的技术仍然具有挑战性。特别是，很难精确地将它们与实现高亮度和控制所需的光子和电子纳米结构结合起来。该项目旨在开发和研究一种新型的钻石上的明亮SPSs，它可以在环境条件下工作，并且可以有效地由电力驱动。该项目将产生跨学科合作，并基于最近提出的两个概念。首先，为了增强色心的发射特性，我们将使用平面天线，它可以从具有大折射率的材料中获得高提取效率和强定向发射。这种方法不需要精细的光谱调谐，也不需要在纳米尺度上精确定位发射器，这有利于制造和器件操作。其次，我们将采用一种基于肖特基二极管的新型电泵方案，该方案提供了直接从金属中有效注入少量载流子的可能性，并且不需要复杂和昂贵的p-i-n和p-n金刚石结。我们将在不到100纳米厚的金刚石膜上制造高质量的硅空位（SiV）中心，并在其上构建一个带电极的平面天线。我们将研究光泵浦下的光子发射特性（重点是亮度和方向性），并探索室温和高温下SiV中心电激发的可能性。因此，我们将展示一个高效和芯片级SPS的概念证明，它将作为量子信息和量子通信的新型光子源。我们的活动还将产生纳米光子学和材料科学方面的宝贵知识，并将其转移到其他应用领域。

Efficient and scalable single-photon sources (SPSs) are crucial to the development of numerous quantum information technologies, such as optical quantum computers and unconditionally secure communication lines. SPSs based on quantum dots have shown much progress in the last two decades, but under ambient conditions they are being overcome by the recent advances in color centers in diamond and related wide-bandgap semiconductors. Color centers are point defects in the crystal lattice that behave nearly as isolated atoms. This property allows to obtain bright photo- and electroluminescence with a sharp emission spectrum, which cannot be achieved with any other quantum optoelectronic system under ambient conditions. However, it is still challenging to design scalable and reproducible technologies based on these emitters. In particular, it is difficult to precisely combine them with photonic and electronic nanostructures that are needed for achieving high brightness and control.This project aims at developing and investigating a novel class of bright SPSs on diamond, which operate under ambient conditions and that can be efficiently electrically driven. The project will generate an interdisciplinary collaboration and it is based on two recently proposed concepts. First, to enhance the emission properties of the color center we will use a planar antenna, which enables large extraction efficiencies and strong directional emission from materials with a large refractive index. This approach does not require fine spectral tuning nor precise positioning of the emitter at the nanoscale, which is beneficial for fabrication and device operation. Second, we will employ a novel electrical pumping scheme based on a Schottky diode, which gives the possibility of efficiently injecting minority carriers in diamond directly from the metal and it does not require complex and expensive p-i-n and p-n diamond junctions. We will create high-quality silicon-vacancy (SiV) centers in less than 100-nm-thick diamond membranes and build a planar antenna with electrodes on it. We will investigate the photon emission properties (focusing on brightness, directionality) under optical pumping and explore the possibility of electrical excitation of SiV centers at room an higher temperatures. Thus, we will demonstrate a proof of concepts of a highly efficient and chip-scale SPS that will serve as, and inspire, novel photonic sources for quantum information and quantum communication. Our activities will also generate valuable knowledge in nanophotonics and materials science, which shall be transferred to other application areas.