Random Circuit Sampling (RCS) is the basis of quantum computational advantage experiments.
After sufficient depth, output probabilities p(x) follow the Porter-Thomas distribution: P(p) = (2ⁿ−1)e^{−(2ⁿ−1)p}.
Anticoncentration: most output strings have near-average probability, but rare strings are exponentially enhanced.
The linear cross-entropy benchmark (XEB) score distinguishes quantum from classical spoofing.