Photonic integration of 2D materials for room temperature single photon generation

现代社会是建立在我们安全地交流敏感信息的能力之上的，这是通过密码方法来保护的，这种方法依赖于即使是最强大的超级计算机也无法解决某些数学问题。然而，随着量子计算的到来，这种安全性被打破只是个时间问题。幸运的是，量子技术还可以保证安全通信，其中量子密钥分发(QKD)利用量子态的脆弱性质来检测任何安全漏洞。QKD是一项成熟的技术，其商业系统目前已投放市场，用于最关键的应用，如国家安全和高价值金融交易。随着对移动技术的日益依赖和对传统密码学的日益威胁，开发与手持设备兼容的解决方案至关重要。目前，这受到合适的单光子源的限制，我们在这个项目中的目标是通过开发由二维(2D)材料构建的芯片集成量子光源来解决这一问题。所谓2D材料，即那些只有几个原子单分子层厚度的材料，在这一领域具有巨大的潜力。第一个被发现的是石墨烯，这是一种孤立的单层碳原子，于2004年在实验室首次生产。值得注意的是，第一批石墨烯样品是用胶带从石墨上剥离原子层的，这与普通铅笔中的“铅”没有什么不同。因此，石墨烯样品可以轻松且廉价地生产，使科学家能够在理解物理过程方面取得快速进展，并释放应用潜力。石墨烯的这种成功激发了科学家们寻找其他原子薄材料的灵感，取得了相当大的成功，稳定的2D晶体的名单不断扩大。与石墨烯不同，其中几种化合物发出可见光，使其成为下一代光电子器件的有力竞争者。最近，随着在过渡金属二卤化物和氮化硼的单分子膜中发现了单光子发射器，这种潜力已经扩展到量子光子应用。特别是，氮化硼中的原子级缺陷已被证明在室温下会发出单光子，这使得2D材料成为非常少量的室温量子发射体之一。早期的实验表明，高亮度和稳定的发射可能意味着氮化硼作为室温量子光子学的体系是无与伦比的。在这项工作中，我们试图充分利用这一潜力，并将研究支持量子发射的物理过程和原子结构，制备方法和发射的光子控制。最终，目标将是实现一个由耦合到光子电路的缺陷发射器组成的平台。光子集成电路能够在芯片级别控制和操纵光，并可以从推动微电子工业的相同规模经济中受益；即可以使用光刻技术将大量组件压缩成非常小的体积，以实现复杂和高效的功能。集成光子学的发展正受到数据中心巨大电力需求的推动，这些数据中心越来越多地使用光学互连以及光子学与cmos电子学的直接集成。由于明显的尺寸和重量限制，这种光子集成电路对于将量子光子器件包括在移动设备中是重要的。该项目的目标是将2D材料中的量子发射器与集成光子学结合在一起，为量子保密通信提供室温和便携的解决方案。

Modern society is built upon our ability to communicate sensitive information securely, which is protected through cryptographic methods that rely on the inability of even the most powerful supercomputers to solve certain mathematical problems. However, with the advent of quantum computing it is only a matter of time before this security is breached. It is fortunate that quantum technology can also guarantee secure communication, where Quantum Key Distribution (QKD) employs the fragile nature of quantum states to detect any breach of security. QKD is a mature technology with commercial systems currently reaching the market for the most critical of applications, such as national security and high value financial transactions. With the ever-increasing reliance on mobile technology and the growing threat to conventional cryptography it is vital that solutions compatible with handheld devices are developed. This is currently limited by the availability of suitable single photon sources, which we aim to address in this project through the development of chip integrated quantum light sources built from two-dimensional (2D) materials.So called 2D materials, those with a thickness of just a few atomic monolayers, have great potential in this area. The first to be discovered was graphene, an isolated single layer of carbon atoms, first produced in a laboratory in 2004. Remarkably, the first graphene samples were isolated using sticky tape to peel away atomic layers from graphite, which is not dissimilar to the "lead" found in ordinary pencils. As a result, graphene samples can be produced easily and cheaply, allowing scientists to make rapid progress in the understanding of physical processes and unlock the potential for applications. This success with graphene has inspired scientists to look for other atomically thin materials, with considerable success and an ever-expanding list of stable 2D crystals. Unlike graphene, several of these emit visible light making them great contenders for next-generation optoelectronic devices. Very recently, with the discovery of single photon emitters reported in monolayers of transition metal dichalcogenides and boron nitride, this potential has been expanded to quantum photonic applications. In particular, atomic-scale defects in boron nitride have been shown to emit single photons at room temperature, which puts 2D materials amongst a very small number of room temperature quantum emitters. Early experiments indicate that high brightness and stable emission could mean boron nitride is unmatched as a system for room temperature quantum photonics. In this work we seek to take full advantage of this potential and will investigate the physical processes and atomic structure underpinning the quantum emission, methods of fabrication and photonic control of the emission. Ultimately, the aim will be to realise a platform consisting of defect emitters coupled to photonic circuits. Photonic integrated circuits enable the control and manipulation of light at the chip-scale and can benefit from the same economies of scale that have driven the microelectronics industry; namely that lithographic techniques can be employed to compress a large number of components into a very small volume to realise complex and efficient functionality. Development of integrated photonics is being driven by the huge power demands of data centres, which are increasingly using optical interconnects and the direct integration of photonics with CMOS electronics. Such photonic integrated circuits are important for the inclusion of quantum photonic devices within mobile devices because of the obvious size and weight constraints. The goal of this project will be to bring together quantum emitters in 2D materials with integrated photonics to provide a room temperature and portable solution for quantum secure communication.