  As quantum error corrections still cannot be realized physically, quantum
noise is the most profound obstacle to the implementations of large-scale
quantum algorithms or quantum schemes. It has been well-known that if a quantum
computer suffers from too strong quantum noise, its running can be easily
simulated by a classical computer, making the quantum advantage impossible.
Generally speaking, however, the dynamical process that how quantum noise of
varying strengths from 0 to a fatal level impacts and destroys quantum
advantage has not been understood well. Undoubtedly, achieving this will be
extremely valuable for us to understand the power of noisy intermediate-scale
quantum computers. Meanwhile, correlation generation is a precious theoretical
model of information processing tasks in which the quantum advantage can be
precisely quantified. Here we show that this model also provides us a valuable
insight into understanding the impact of noise on quantum advantage.
Particularly, we will rigorously prove that when the strength of quantum noise
continuously goes up from 0, the quantum advantage gradually declines, and
eventually fades away completely. Surprisingly, in some cases we observe an
unexpected phenomenon we call the sudden death of the quantum advantage, i.e.,
when the strength of quantum noise exceeds a certain point, the quantum
advantage disappears suddenly from a non-negligible level. This interesting
phenomenon reveals the tremendous harm of noise to quantum information
processing tasks from a new viewpoint.
