Full paper here.

Boson-sampling has emerged as a promising avenue towards post-classical optical quantum computation, and numerous elementary demonstrations have recently been performed. Spontaneous parametric down-conversion is the mainstay for single-photon state preparation, the technique employed in most optical quantum information processing implementations to-date. Here we present a simple architecture for boson-sampling based on multiplexed parameteric down-conversion and demonstrate that the architecture is limited only by the post-selected detection efficiency. That is, given that detection efficiencies are sufficiently high to enable post-selection, photon-number errors in the down-converters are sufficiently low as to guarantee correct boson-sampling most of the time. Thus, we show that parametric down-conversion sources will not present a bottleneck for future boson-sampling implementations. Rather, photodetection efficiency is the limiting factor and thus future implementations may continue to employ down-conversion sources.