  We introduce a new open-source software library Jet, which uses task-based
parallelism to obtain speed-ups in classical tensor-network simulations of
quantum circuits. These speed-ups result from i) the increased parallelism
introduced by mapping the tensor-network simulation to a task-based framework,
ii) a novel method of reusing shared work between tensor-network contraction
tasks, and iii) the concurrent contraction of tensor networks on all available
hardware. We demonstrate the advantages of our method by benchmarking our code
on several Sycamore-53 and Gaussian boson sampling (GBS) supremacy circuits
against other simulators. We also provide and compare theoretical performance
estimates for tensor-network simulations of Sycamore-53 and GBS supremacy
circuits for the first time.
