The power of simulation for equivalence checking in quantum computing

The rapid rate of progress in the physical realization of quantum computers sparked the development of elaborate design flows for quantum computations on such devices. Each stage of these flows comes with its own representation of the intended functionality. Ensuring that each design step preserves this intended functionality is of utmost importance. However, existing solutions for equivalence checking of quantum computations heavily struggle with the complexity of the underlying problem and, thus, no conclusions on the equivalence may be reached with reasonable efforts in many cases. In this work, we uncover the power of simulation for equivalence checking in quantum computing. We show that, in contrast to classical computing, it is in general not necessary to compare the complete representation of the respective computations. Even small errors frequently affect the entire representation and, thus, can be detected within a couple of simulations. The resulting equivalence checking flow substantially improves upon the state of the art by drastically accelerating the detection of errors or providing a highly probable estimate of the operations' equivalence.