Speedup in Classical Simulation of Gaussian Boson Sampling

TL;DR

This paper introduces a method to significantly reduce the classical simulation costs of Gaussian boson sampling, demonstrating that larger photon numbers can be simulated more feasibly, thus impacting the pursuit of quantum supremacy.

Contribution

It proposes a new approach to simplify calculations in Gaussian boson sampling, establishing lower bounds for classical simulation and demonstrating practical simulation capabilities.

Findings

Simulate 18 photons on a laptop

Simulate 20 photons on a 256-core workstation

Estimate about 30 photons feasible on supercomputers

Abstract

Gaussian boson sampling is a promising model for demonstrating quantum computational supremacy, which eases the experimental challenge of the standard boson-sampling proposal. Here by analyzing the computational costs of classical simulation of Gaussian boson sampling,we establish a lower bound for achieving quantum computational supremacy for a class of Gaussian boson-sampling problems, where squeezed states are injected into every input mode. Specifically, we propose a method for simplifying the brute-force calculations for the transition probabilities in Gaussian boson sampling, leading to a significant reduction of the simulation costs. Particularly, our numerical results indicate that we can simulate 18 photons Gaussian boson sampling at the output subspace on a normal laptop, 20 photons on a commercial workstation with 256 cores, and suggest about 30 photons for supercomputers. These numbers are significantly smaller than those in standard boson sampling, suggesting Gaussian boson sampling may be more feasible for demonstrating quantum computational supremacy.