"Type 004 carrier – which is expected to be nuclear-powered and have electromagnetic catapults – have already been constructed." [Type 004]
Nuclear propulsion and electromagnetic catapults are the defining technologies of the most advanced US carriers; their appearance on China's fourth carrier marks a qualitative leap that directly supports the claim of a narrowing capability gap.
Reasoning from this article
The combination of nuclear propulsion and electromagnetic launch systems on a fourth-generation indigenous carrier represents a compressed technology adoption curve — capabilities the US took decades to develop are being fielded by a challenger within a single carrier generation. This generalizes to a broader dynamic in which leading-edge military hardware diffuses faster than historical precedent, compressing the window of unipolar technological advantage.