Toward quantum computational supremacy of boson sampling with random overlap in the photonic spectra. (arXiv:1801.03832v1 [quant-ph])

Multiphoton interference is at the very heart of quantum foundations and
applications in quantum sensing and information processing. In particular,
boson sampling experiments have the potential to demonstrate quantum
computational supremacy while only relying on multiphoton interference in
linear optical interferometers. However, scalable experiments are challenged by
the need to generate the same temporal and frequency spectra for a large number
$N$ of single photons in each experimental sample. Here, we employ sampling
correlation measurements in the photonic inner modes, time and frequency, at
the interferometer input and output to ensure the occurrence of multiphoton
interference even with input photons with random overlap in their input spectra
from one sample to another. This allows us to substantially enhance the
probability to successfully generate a sample and therefore the experimental
scalability of boson sampling schemes. Furthermore, we show that it is
possible, in principle, to approach deterministic boson sampling with a number
of probabilistic sources which is only slightly larger than $N$. This is
achieved by combining sampling in the photonic inner modes with sampling over
the number of input photons per port. Therefore, these results provide an
exciting route toward future demonstrations of quantum computational supremacy
with scalable experimental resources.

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