There is a way to test. Not by clock time though, since at small scales and high noise clock time doesn't come into it. You can use IBM's Qiskit to run an experiment to confirm the query complexity scaling, which is the core of the quantum advantage. Other wors, yes you can test and yes you can know that quadratic scaling powered by quantum mechanics is real. -Run Grover's for a small database of size N1 (e.g., N=4 states). -Count the optimal number of iterations needed to find the answer. -Run Grover for a doubled database of size N2 (e.g., N=8 states).Y -You will find that the optimal number of iterations only increases by a factor of sqrt2, not by 2 (as in no square root). Don't leave it on a loop tho, IMB charges $100 USD per minute of QPU) time :)