  We investigate quantum radiation reaction in laser-electron interactions
across different energy and intensity regimes. Using a fully quantum approach
which also accounts exactly for the effect of the strong laser pulse on the
electron motion, we identify in particular a regime in which radiation reaction
is dominated by quantum interference. We find signatures of quantum radiation
reaction in the electron spectra which have no classical analogue and which
cannot be captured by the incoherent approximations typically used in the
high-intensity regime. These signatures are measurable with presently available
laser and accelerator technology.
