  Quantum computing may offer the opportunity to simulate strongly-interacting
field theories, such as quantum chromodynamics, with physical time evolution.
This would give access to Minkowski-signature correlators, in contrast to the
Euclidean calculations routinely performed at present. However, as with
present-day calculations, quantum computation strategies still require the
restriction to a finite system size, including a finite, usually periodic,
spatial volume. In this work, we investigate the consequences of this in the
extraction of hadronic and Compton-like scattering amplitudes. Using the
framework presented in Phys. Rev. D101 014509 (2020), we quantify the volume
effects for various $1+1$D Minkowski-signature quantities and show that these
can be a significant source of systematic uncertainty, even for volumes that
are very large by the standards of present-day Euclidean calculations. We then
present an improvement strategy, based in the fact that the finite volume has a
reduced symmetry. This implies that kinematic points, which yield the same
Lorentz invariants, may still be physically distinct in the finite-volume
system. As we demonstrate, both numerically and analytically, averaging over
such sets can significantly suppress the unwanted volume distortions and
improve the extraction of the physical scattering amplitudes.
