Fig. 1: Schematic diagram of the Noise-Induced Barren Plateau (NIBP) phenomenon.
From: Noise-induced barren plateaus in variational quantum algorithms
For various applications such as chemistry and optimization, increasing the problem size often requires one to increase the depth L of the variational ansatz. We show that, in the presence of local noise, the gradient vanishes exponentially in L and hence exponentially in the number of qubits n when L scales linearly in n. This can be seen in the plots on the right, which show the cost function landscapes for a simple variational problem with local noise.
