Measuring patent quality and national technological capacity in cross-country comparison

China recently surpassed the USA as the greatest global source of patent applications. However, without internationally comparable measures of patent quality it remains questionable whether China's patent expansion constitutes the rise of a new technological superpower. Our novel quality index is based on citations from international search reports and provides internationally comparable, quality-adjusted figures for applications made under the Patent Cooperation Treaty (PCT). We show that China's patent expansion has taken place to the detriment of patent quality. Weighting national PCT counts with our index reveals a widening gap between the technological capacities of China and the leading USA.