Shor's Algorithm Does Not Factor Large Integers in the Presence of Noise

We consider Shor’s quantum factoring algorithm in the setting of noisy quantum gates. Under a generic model of random noise for (controlled) rotation gates, we prove that the algorithm does not factor integers of the form $pq$ when the noise exceeds a vanishingly small level in terms of $n$ – the number of bits of the integer to be factored, where $p$ and $q$ are from a well-defined set of primes of positive density. We further prove that with probability $1-o(1)$ over random prime pairs $(p,q)$, Shor’s factoring algorithm does not factor numbers of the form $pq$, with the same level of random noise present.