 But quantum computers are much faster for certain problems;
Quantum supremacy Shor's algorithm for factoring integers is exponentially faster than best classical algorithms
 So if the brain exploits a quantum algorithm with no efficient classical alternative, standard computers will be unable to run AGI efficiently
The brain is almost certainly not a quantum computer.^{1}
 Quantum computers require environments isolated from vibration and other external influences to prevent
decoherence from erasing the state information. Although the brain has some cushioning, it’s not nearly enough
 Quantum phenomena operate on timescales of \( 10^{13} \) seconds, but neuron spiking frequencies are on the order of \( 10^{3} \) seconds.
 i.e. brain is quantum computer implies that neuron spikes cannot be involved in processing
 The temperature in the brain is probably too high for stable quantum computation
So the brain’s algorithms will run on classical computers without exponential slowdown.*Be skeptical!

Litt, A., Eliasmith, C., Kroon, F.W., Weinstein, S. and Thagard, P. (2006), Is the Brain a Quantum Computer?. Cognitive Science, 30: 593603 ↩︎