The central aim of this proposal is to design and experimentally demonstrate ultrafast quantum optics in guided-wave circuits integrated on a silicon chip for a new generation of all-optical quantum computing. The use of quantum information can give exponential increases in the power of computing over classical computers, and unique applications such as 100% secure communications guaranteed by the laws of physics. As in the integrated computing revolution that has transformed society over the last 50 years, silicon can provide for the extreme miniaturisation of integrated quantum optics circuits, which will have the potential to transform the field with a step-change in complexity of the circuits realisable over the next 50 years. Future quantum photonics circuits will also have to operate at ultrafast rates, mirroring the demand for bandwidth in today’s classical computers and communications.However, the challenge of transferring the technology to operate at the single photon level useful to quantum optics has only been fully grasped by a few people. This proposal will address this gap by demonstrating the operation of three key components at the single photon level: the frequency converter, optical switch and quantum memory or buffer. My designs will make use of photonic crystal waveguides which give ultra-compact devices and flexible operating options. For example, slow-light modes which can be tailored to optimise the operation of the frequency convertor, optical switch and optical buffer respectively.The combination of expertise in silicon photonics and the position of the host as the World’s leading integrated quantum optics group give a unique opportunity for this fellowship to bridge the gap between the two disciplines.