A Simulation Framework for Feedforward in Quantum Photonic Systems

It has been known for over two decades that measurement and feedforward—whereby a optical network is dynamically adjusted conditional on single photon measurements—is the only viable path to building scalable quantum technology with photons [1]. Despite this, there has been little work done to simulate these systems physically. Previous models typically are classical, for example stabliser-based approaches in error-correction protocols [2], or operate entirely in the frequency domain. These frequency domain methods provide a simple method to produce an output distribution from a system unitary and its input state [3], but necessarily omit the temporal dynamics of the system, and hence are difficult to apply to systems with measurement and feedforward.