An efficient, scalable, high-fidelity classical Gaussian boson sampler

We investigate claims of quantum advantage in Gaussian boson sampling experiments by crafting classical simulations that can efficiently replicate the empirical outcomes of some recent experiments. Our approach builds upon established classical models of multi-photon entangled states and non-Gaussian measurements while introducing two pivotal innovations: the representation of Gaussian multi-photon states as correlated Gaussian random vectors and the integration of non-Gaussian measurements via a deterministic model of amplitude threshold crossing events. These modeling concepts have displayed the capability to replicate various quantum phenomena, providing a potent toolkit to identify quantum advantage and demarcate the quantum/classical boundary in photonic systems. Our classical simulations agree well with experimentally produced outcomes in terms of count distributions and higher-order correlations, and samples can be produced quickly and inexpensively using standard digital hardware.