  To get the best possible results from current quantum devices error
mitigation is essential. In this work we present a simple but effective error
mitigation technique based on the assumption that noise in a deep quantum
circuit is well described by global depolarizing error channels. By measuring
the errors directly on the device, we use an error model ansatz to infer
error-free results from noisy data. We highlight the effectiveness of our
mitigation via two examples of recent interest in quantum many-body physics:
entanglement measurements and real time dynamics of confinement in quantum spin
chains. Our technique enables us to get quantitative results from the IBM
quantum computers showing signatures of confinement, i.e. we are able to
extract the meson masses of the confined excitations which were previously out
of reach. Additionally, we show the applicability of this mitigation protocol
in a wider setting with numerical simulations of more general tasks using a
realistic error model. Our protocol is device-independent, simply implementable
and leads to large improvements in results if the global errors are well
described by depolarization.
