Calculating the phase shift of a scattering process on a trapped-ion quantum computer

Simulating real-time evolution for lattice quantum chromodynamics (QCD) on a large Hilbert space is unfeasible with current classical methods. Quantum computers offer an alternative approach to solve this problem. Estimating the phase shift of a scattering process in the quantum Ising model on quantum computers forms a tentative first step towards this goal. However, gate errors and decoherence limit the evolution depth that can be realized on near-term quantum devices. We demonstrate a method to extract the phase shift using information obtained in the early stages of the scattering event. We implement real-time evolution of a one-dimensional scattering process for the quantum mechanics limit with two qubits and the field theory formulation with four qubits on a trapped-ion quantum computer.