  We perform digital quantum simulation, using a classical simulator, to study
screening and confinement in a gauge theory with a topological term, focusing
on ($1+1$)-dimensional quantum electrodynamics (Schwinger model) with a theta
term. We compute the ground state energy in the presence of probe charges to
estimate the potential between them, via adiabatic state preparation. We
compare our simulation results and analytical predictions for a finite volume,
finding good agreements. In particular our result in the massive case shows a
linear behavior for non-integer charges and a non-linear behavior for integer
charges, consistently with the expected confinement (screening) behavior for
non-integer (integer) charges.
