Gaussian boson sampling is an alternative model for demonstrating quantum computational
supremacy, where squeezed states are injected into every input mode, instead of applying
single photons as in the case of standard boson sampling. Here by analyzing numerically
the computational costs, we establish a lower bound for achieving quantum computational
supremacy for a class of Gaussian boson-sampling problems. Specifically, we propose a
more efficient method for calculating the transition probabilities, leading to a significant …