  We discuss the potential creation and measurement of coherences in both
dispersive solids and qubit-like single levels using current generation time-
and angle-resolved photoemission technology. We show that in both cases, when
both the pump and the probe overlap energetically with the coherent levels, and
when the probe preferentially measures one level as compared to the other, that
the time-resolved photoemission signal shows a beating pattern at the energy
difference between the levels. In the case of dispersive bands, this leads to
momentum-dependent oscillations, which may be used to map out small energy
scales in the band structure. We further develop the two-sided Feynman diagrams
for time-resolved photoemission, and discuss the measurement of decoherence to
gain insight into the characteristics of qubit and dispersive bands.
