  We use coherent pump-probe spectroscopy to measure the photoinduced
reflectivity \DeltaR, and complex dielectric function, {\delta}\in, of the
electron-doped cuprate superconductor Nd_{2-x}Ce_xCuO_{4+\delta} at a value of
x near optimal doping, as a function of time, temperature, and laser fluence.
We observe the onset of a negative \DeltaR at T=85 K, above the superconducting
transition temperature, T_c, of 23 K, that exhibits a form of scaling
consistent with critical fluctuations in the time domain. A positive \Delta R
onsets at T_c that we associate with superconducting order. We find that the
two signals are strongly coupled below T_c, in a manner that suggests a
repulsive interaction between superconductivity and antiferromagnetic
correlations.
