Until recently, optical implementations of quantum architectures have been realised using large-scale (bulk) optical elements, bolted onto optical tables. This approach has lead to severe limitations in the miniaturization, scalability and stability of such systems. Our recent demonstration of the first integrated quantum optical circuit has removed this bottleneck and is allowing the realisation of quantum optical schemes with greatly increased capacity for circuit complexity. This key step is crucial for the progress of experimental quantum information science and the development of practical quantum photonic technologies.

This talk presents the latest work in integrated quantum photonics (IQP) within Silica-on-Silicon waveguide chips. Hundreds of devices have been fabricated with the key components found to be robust and highly repeatable. Amongst these demonstrations, we include on-chip quantum interference, quantum phase stability and quantum metrology experiments with two- and four-photon entangled states.