Resource efficient linear optics quantum computing using fibre-loop architectures

Linear optics quantum computing is a promising candidate for the implementation of scalable quantum computing. However, it remains extremely technically challenging owing to the large number of optical elements that would be required for a large-scale device, potentially requiring millions of discrete elements. I present a substantially simplified scheme based on time-bin encoding, whereby only three optical elements are required, independent of the size of the computation. The simplicity arises from a fibre-loop architecture that allows the three optical elements to be reused, thereby reducing the number of required optical elements. I first show how this scheme can be used to implement boson-sampling, and then generalise it to implement universal quantum computing. Many of the required technologies for this scheme are available today, thus elementary demonstrations may be viable in the near future.