Lithium niobate integrated quantum photonics

量子信息科学通过安全通信、精确测量以及超强的模拟和最终计算，有可能在21世纪给信息和通信技术(ICT)带来革命性的变化。光子学注定要发挥核心作用--光子是一种理想的量子比特，即用于编码、处理和传输量子信息的“量子比特”。然而，现实世界的应用需要集成的光子器件，包括光子源、探测器和电路。正如硅集成电路的发明将晶体管的巨大潜力变成了现实一样，该项目旨在开发所有必要的组件，以实现量子光子技术所需的高水平的性能和集成。该项目将是第一个同时处理所有组件及其集成的项目。因此，它将克服实现未来量子技术的巨大潜力的重大挑战。在我们的方法的开发和应用中的一个关键挑战是将波导电路与有源组件集成在一起：单光子源、相位和幅度调制器以及高效的单光子探测器。我们的初步基准和表征结果已确定Nb酸锂(LN)是实现所有这些组件并从而创建集成量子光子学的新范式的完美材料体系。该方案的目标是制造LN材料系统中的所有关键器件，并将它们集成在一起，实现第一个原型系统。电信波长业务将能够与现有的电信系统(例如现有的光纤网络)对接，并采用强大的电信技术(调制器、波分复用、阵列波导光栅等)。该计划中开发的设备和系统将彻底改变光子量子技术的方法，为实际应用铺平道路。该项目汇集了在量子光子技术和液氮器件制造(布里斯托尔)、超导单光子探测器(Heriot-Watt)以及超导薄膜生长和纳米制造(剑桥)等领域的世界领先团队实现这些雄心勃勃目标所需的所有必要专业知识。这项建议建立在这些组织内部和之间成功工作的基础上，并得到了我们现有的工业合作伙伴(英国国家物理实验室、诺基亚和量子技术研究有限公司)的大力支持。在过去的几年里，申请者已经在集成量子光子技术方面取得了长足的进步，开发了片上波导量子光子电路，结合实用的超导单光子探测器和非线性光子源。这项研究建议非常及时地解决了光学量子信息技术发展中的一个关键瓶颈：能够支持所有必需组件及其集成的单一材料系统。我们的研究计划将为运行在电信波长的新一代紧凑型、高性能量子光子器件提供一个发射台。我们采用了一种非常新颖和雄心勃勃的方法，将硅基硅波导电路移植到LN波导电路。这将使我们能够首次将周期性极化的铌酸锂(PPLN)光子源、快速可重构的波导电路和高性能超导单光子探测器集成在一起，并实现在电信波长的高性能运行。这种方法承诺为实现安全通信网络、精密测量系统、模拟重要的物理、化学和生物系统(包括新材料和药品)以及最终实现超强计算机提供一个新的技术平台。

Quantum information science has the potential to revolutionise information and communications technologies (ICT) in the 21st century via secure communication, precision measurement, and ultra-powerful simulation and ultimately computation. Photonics is destined for a central role - the photon is an ideal quantum bit, or 'qubit', for encoding, processing, and transmitting quantum information. However, real-world applications require integrated photonic devices, incorporating photon sources, detectors and circuits. Just as the invention of the silicon integrated circuit turned the tremendous potential of the transistor into reality, this project aims to develop all necessary components to the high levels of performance and integration required to realise quantum photonic technologies. This project will be the first to simultaneously address all components and their integration simultaneously. It will thereby overcome the major challenges to realising the tremendous potential of future quantum technologies. A key challenge in the development and application of our approach is to integrate waveguide circuits with active components: single-photon sources, phase- and amplitude-modulators and high-efficiency single-photon detectors. Our initial benchmarking and characterisation results have identified lithium niobate (LN) as the perfect material system in which to realise all of these components and thereby to create a new paradigm for integrated quantum photonics. The goals of this proposal are to fabricate all of the key devices in the LN material system and to integrate them to realise the first prototype systems. Telecom wavelength operation will enable interfacing with existing telecom systems (existing fibre optic networks for example) and the adoption of powerful telecom technologies (modulators, wavelength division multiplexing, arrayed waveguide gratings, etc.). The devices and systems developed in this programme will revolutionise approaches to photonic quantum technologies, paving the way to practical applications. This project brings together all of the essential expertise required to achieve these ambitious goals in world-leading groups in quantum photonic technologies and LN device fabrication (Bristol), superconducting single-photon detectors (Heriot-Watt), and superconducting thin film growth and nanofabrication (Cambridge). This proposal builds on successful work within and between these groups and has substantial support from our exisiting industrial partners (The UK National Physical Laboratory, Nokia and Quantum Technology Research Ltd.). Over the last several years the applicants have already made great strides towards integrated quantum photonic technologies, developing waveguide-on-chip quantum photonic circuits, combined with practical superconducting single photon detectors, and non-linear photon sources. This research proposal is extremely timely in addressing a critical bottleneck in the development of optical quantum information technologies: a single material system that can support all of the required components and their integration. Our research programme will provide a launching pad to a new generation of compact, high performance quantum photonic devices operating at telecom wavelengths. We adopt a highly novel and ambitious approach in migrating from silica-on-silicon waveguide circuits to LN waveguide circuits. This will enable us to integrate periodically poled lithium niobate (PPLN) photon sources, rapidly reconfigurable waveguide circuits and high performance superconducting single-photon detectors together for the first time, and to achieve high performance operation at telecom wavelengths. This approach promises a new technology platform for realising secure communication networks, precision measurement systems, simulation of important physical, chemical and biological systems, including new materials and pharmaceuticals, and ultimately ultra-powerful computers.