  As pointed out by Coleman, physical quantities in the Schwinger model depend
on a parameter $\theta$ that determines the background electric field. There is
a phase transition for $\theta = \pi$ only. We develop a momentum space
formalism on a lattice and use it to perform a quantum computation of the
critical point of this phase transition on the NISQ device IMB Q Lima. After
error mitigation, our results give strong indication of the existence of a
critical point at $m/e\simeq 0.32$, where $m$ is the bare fermion mass and $e$
is the coupling strength, in good agreement with the classical numerical result
$m/e \simeq 0.3335$.
