Smell, aka the application of algorithms for molecule classification, uses "quantum" effects ...
BBC News - Quantum physics explanation for smell gains traction
... in 1996, Luca Turin, now of the Massachusetts Institute of Technology in the US, suggested that the "vibrational modes" of an odorant were its signature.
Molecules can be viewed as a collection of atoms on springs, and energy of just the right frequency - a quantum - can cause the spring to vibrate.
Since different assemblages of molecules have different characteristic frequencies, Turin proposed, these vibrations could act as a molecular signature.
The idea has been debated in the scientific literature, but presentations at the American Physical Society meeting put the theory on firmer footing.
Most recently, Dr Turin published a paper showing that flies can distinguish between molecules that are chemically similar but in which a heavier version of hydrogen had been substituted...
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.
Update 3/25/11: I forgot to change my title when doubts crept in. My mistake!