Simulating phi-4 scalar field on quantum computers

Digital quantum simulation of lattice quantum field theory models could significantly enhance our ability to investigate those models, in particular, with strong interaction or under non-equilibrium conditions. We present a quantum algorithm to prepare the ground state of a lattice scalar-field model with a quartic interaction. This gives an insight into the anharmonic effect on a relativistic field and serves as a stepping stone toward simulating more complex models. Our algorithm combines a local variational approach with an adiabatic state transfer to allows efficient state preparation with high fidelity. We show that this algorithm can be flexibly employed under various conditions and is scalable to large lattices.