Quantum computing technology is at a crossroads. The technological route we choose must scale without limit. For quantum optics to play a part, optical loss, miniaturisation, and manufacturability must be simultaneously addressed. In quantum optics, a loss of a single photon is a loss of irreplaceable quantum information. Macroscale optics offers exceptionally low loss, and high performance, but has no hope to scale to thousands or millions of modes. Microscale optics, and silicon photonics in particular, offer exceptional miniaturisation and large-scale manufacturability, but pay a high price in loss .