Friday, March 25, 2011

Quantized scent detection isn't quantum computing

Towards the end of my comments on a  BBC news article titled "quantum physics explanation for smell", I started to have second thoughts about how "quantum" these results were ...

Gordon's Notes: Quantum computing in the nose

... If these results are replicated, then Turin gets a Nobel.

If noses use these 'quantum' effects, then it's pretty much certain that neurons do as well.

Does that mean our brains are 'quantum computers'? I need help from Aaronson. This 'quantization' sites on the micro-macro boundary. Not all quantized vibrations are quantum physics....

I asked Scott Aaronson, MIT prof of computational physics [1] and famed blogger if he'd consider a comment on the original article. Instead he replied by email, and gave me permission to quote ...

These look like *really* interesting experiments!  And it's a priori plausible that smell would involve some quantum effect -- we already know that ... photosynthesis and bird navigation do.
If true, this doesn't IN ANY WAY imply that the brain is a "quantum computer" in the sense of using quantum coherence to speed up computation.  That's a separate question, and any such suggestion would still need to overcome the problem of how entanglement could survive in the brain for any appreciable length of time.
So while we do have evidence that natural selection has made use of some aspects of quantum physics, we have no evidence (yet), that it has made use of entanglement, the spooky action that motivates research into quantum computation. So the nose may be doing quantum physics, but we have no evidence that it's doing quantum computing. [2]

[1] Born in 1981, when I left college. Sob.
[2] Incidentally, if I read Aaronson correctly, he suspects quantum computing is possible, but it won't solve radically new problems (and thus won't destroy the world economy if it works).

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