Digital Quantum Simulation of the Schwinger model with Topological term

Recently computational resource of quantum computers sounds growing well. In this article, we discuss how we can apply this development to numerically simulate quantum field theories. In contrast to the conventional approach by (Marlov chain) Monte Carlo method suffering from the infamous sign problem, we work in Hamilton formalism and adopt quantum algorithms which do not rely on Monte Carlo sampling. After brief discussion on how to put quantum field theories on quantum computers, we present our recent numerical results on the charge-q Schwinger model, where q is an electric charge of a Dirac fermion. We observe an exotic phenomena such as negative string tension behavior in potential between heavy charged particles which essentially come from presense of non-small theta-angle.