"The primary objective of this proposal is to build a large-scale photonic quantum network in order to enter a new and different regime of macroscopic quantum behaviour for light. We intend to implement a network of sufficient scale that the behaviour of the system is uncomputable, and that new physics will emerge from the study of its dynamics that will inform research in a number of fields dealing with complex systems, from fundamental physics to biology. This network will also enable new modes of quantum communications, sensing, simulation and computation that go well beyond anything that is possible using classical physics. Specifically we shall develop a truly scalable approach to building both linear and nonlinear photonic networks, and construct a 20-node, 20-qubit, 20-particle loss-tolerant photonic network that operates palpably beyond classical boundaries. It has not proven possible to break through into a new regime of complexity to date because of the intrinsically probabilistic character of the feasible network operations. In this proposal, we overcome this bottleneck. Our approach will integrate robust, simple, broadband photonic quantum memories together with novel pure-state light sources fabricated in precise 3-D photonic structures, coupled to integrated, highly-efficient photon-number-resolving detectors. Deterministic photon-photon interactions will be engendered either by measurement and storage or by nonlinear interactions in the memory made possible by coherent quantum feedback control. This will deliver a multi-node array of synchronized conditional quantum operations, novel quantum light-matter interactions and distillation of high-quality entangled states. The outcome of this project will be a viable means to explore new regimes of many-body quantum physics, with impact on information processing, including multi-particle quantum simulation, multiparty quantum repeaters, multimode quantum sensors and elementary quantum computing."