Tensor Networks or Decision Diagrams? Guidelines for Classical Quantum Circuit Simulation

Abstract

Classically simulating quantum circuits is crucial when developing or testing quantum algorithms. Due to the underlying exponential complexity, efficient data structures are key for performing such simulations. To this end, tensor networks and decision diagrams have independently been developed with differing perspectives, terminologies, and backgrounds in mind. Although this left designers with two complementary data structures for quantum circuit simulation, thus far it remains unclear which one is the better choice for a given use case. In this work, we (1) consider how these techniques approach classical quantum circuit simulation, and (2) examine their (dis)similarities with regard to their most applicable abstraction level, the desired simulation output, the impact of the computation order, and the ease of distributing the workload. As a result, we provide guidelines for when to better use tensor networks and when to better use decision diagrams in classical quantum circuit simulation.