Multimode integrated time-frequency quantum photonics

量子物理学是技术革命的核心，这场革命有望改变信息和通信技术（ICT），使其从安全通信、更高的测量精度、高容量模拟和计算，超越仅使用传统资源的能力。这些量子增强技术将大大提高安全传输和处理全球经济所依赖的不断增长的数据量的能力。模拟量子和经典复杂系统的能力，可以创造新的功能材料，从设计药物到太阳能电池，提高效率。此外，测量灵敏度的提高为探索以前无法获得的基础物理学以及更实际的应用（如微光光谱学）开辟了道路。光将在许多量子技术中发挥核心作用，如光谱学，成像，通信和计算。当寻址单个光子时，信息通常被编码为每个传输光子的一个量子比特（或量子比特）信息。然而，这严重地限制了当前方法的信息处理能力到小尺寸。最近一种增加量子光学系统复杂性的方法是利用集成量子光子学，其中光子在硅芯片上产生、引导和操纵。然而，这些技术仍然依赖于将信息编码为量子比特，并且没有利用单个光子的丰富结构。该项目将采用一种新的方法对每个光子的信息量进行编码，从而显著提高系统的复杂性。为了提高集成光子学中单个光子的信息容量，该项目将专注于在单个光子的时频状态下对信息进行编码，其中光子的时间形状和颜色携带信息。这种方法类似于经典的信息和通信技术中使用的方法，例如波分复用和时分复用，其中信息以光脉冲的波长（颜色）或到达时间编码。牛津大学最近在基于光纤的光子源和集成量子光子学方面的发展使这种新方法成为可能，这些光子源和集成量子光子学允许对单个光子进行确定性频率控制。通过在集成平台上实现每光子信息容量的增加，该项目旨在实现量子增强技术的重大进步。在更远的地方，在该项目期间开发的微光时频传感技术可以用于从光谱学到光学网络诊断的各种应用中

Quantum physics is at the centre of a technological revolution that promises to transform information and communications technologies (ICT) from secure communications, enhanced precision in measurement, high-capacity simulation and computation beyond that capable using only classical resources. These quantum-enhanced technologies will significantly increase the capacity to securely transmit and process the ever-rising volumes of data on which the global economy is based. The ability to simulate complex systems, both quantum and classical, could allow creation of new functional materials ranging from designer drugs to solar cells with improved efficiency. Furthermore, improved sensitivity in measurements opens paths to probe fundamental physics previously not accessible, as well as more practical applications such as low-light-level spectroscopy. Light will play a central role in many of these quantum technologies such as spectroscopy, imaging, communications, and computation. When addressing individual photons, information is most often encoded as one quantum bit (or qubit) of information per transmitted photon. However, this severely limits the information processing capacity of current approaches to small sizes. One recent approach to increase the complexity of quantum optical systems that can be achieved utilizes integrated quantum photonics, in which photons are generated, guided and manipulated on silicon chips. However, these techniques still rely on encoding information as qubits and do not take advantage of the rich structure of individual photons. This project will take a new approach to encoding an increased amount of information per photon, and thus allow significantly increased system complexity to be achieved.To increase the information capacity of single photons for integrated photonics this project will focus on encoding information in the time-frequency state of individual photons, in which the temporal shape and colour of the photon carry the information. This approach parallels methods used in classical ICT such as wavelength- and time-division multiplexing where information is encoded in the wavelength (colour) or arrival time of light pulses. This new approach is made possible by recent developments at Oxford in fibre-based photon sources and integrated quantum photonics, which allow deterministic frequency control of single photons. By moving to this regime of increased information capacity per photon on an integrated platform, the project aims to enable significant advances in quantum-enhanced technologies. Further afield the techniques for low-light-level time-frequency sensing developed during the project could be utilized in a diverse range of applications from spectroscopy to optical network diagnostics