How Nonlinearity Distorts the Evidence for Photoinduced Superconductivity

We show evidence that a systematic error is present in nearly all the reported evidence for photoinduced superconductivity and describe how it may create the appearance of photoinduced superconductivity where none exists. The error results from a saturation nonlinearity that distorts the photoconductivity depth profile at high pump intensities, and by extension distorts the photoconductivity spectrum. Similar errors may emerge in other pump-probe spectroscopy measurements, and we discuss how to correct for them.