Contracting Arbitrary Tensor Networks: general approximate algorithm and applications in graphical models and quantum circuit simulations

We present a general method for approximately contracting tensor networks with an arbitrary connectivity. This enables us to release the computational power of tensor networks to wide use in optimization, inference, and learning problems defined on general graphs. We show applications of our algorithm in graphical models, specifically on estimating free energy of spin glasses defined on various of graphs, where our method largely outperforms existing algorithms including the mean-field methods and the recently proposed neural network based methods. We further apply our method to the simulation of random superconducting quantum circuits, and demonstrate that with a trade off of negligible truncation errors, our method is able to simulate large quantum circuits which are out of reach of the state-of-the-art simulation methods.