The potential and global outlook of integrated photonics for quantum technologies

Integrated quantum photonics uses classical integrated photonic technologies and devices for quantum applications. As in classical photonics, chip-scale integration has become critical for scaling up and translating laboratory demonstrators to real-life technologies. Integrated quantum photonics efforts are centred around the development of quantum photonic integrated circuits, which can be monolithically, hybrid or heterogeneously integrated. In this Roadmap, we argue, through specific examples, for the value that integrated photonics brings to quantum technologies and discuss what applications may become possible in the future by overcoming the current roadblocks. We provide an overview of the research landscape and discuss the innovation and market potential. Our aim is to stimulate further research by outlining not only the scientific challenges of materials, devices and components associated with integrated photonics for quantum technologies but also those related to the development of the necessary manufacturing infrastructure and supply chains for delivering these technologies to the market. Photonics is one of the key platforms for emerging quantum technologies, but its full potential can only be harnessed by exploiting miniaturization via on-chip integration. This Roadmap charts new directions and discusses the challenges associated with the hybrid integration of a variety of materials, devices and components.