 It is widely believed that quantum computers will be able to perform certain tasks faster than any classical computer. Identifying the resource that enables this speedup is of great interest in quantum information science. This work investigates the circumstances under which generic quantumoptics experiments can be simulated efficiently using only classical resources.
The PRX paper begins by formulating two sufficient conditions for the efficient classical simulation of quantumoptics experiments using quantum light in an optical network. These conditions provide useful practical tools for investigating the effects of imperfectly implementing quantumoptical protocols such as boson sampling. The goal of this work is to determine whether sampling from the output probability distribution can be efficiently simulated using only classical resources. Using the theory of phasespace quasiprobability distributions, it is shown that the negativity of these distributions is a necessary resource for experiments not to be efficiently classically simulatable. Considering several sources of error, the authors show that above some threshold for loss and noise, bosonsampling experiments are classically simulatable. This analysis identifies mode mismatchingimperfect overlap of optical signals on optical elementsas the chief challenge for implementations of bosonsampling experiments of interesting size.
Finding and results of this paper is expected to pave the way for future studies of quantum light in optical networks.  
