I know that quantum phenomena (superposition, uncertainty principle, quantum entanglement, probablistic outcomes, etc.) is readily observed in measurements of the states of fundamental particles. How readily are these phenomena observed at higher scales? Take atoms, for example. Has anyone ever observed atoms in superposition? What about complex molecules? Groups of molecules? How far up the ladder of scale can one go before quantum phenomena become practically unobservable?

You can't observe something in superposition, well, technically maybe you can, but the second you do observe it the atom is no longer in a superposition.

 

The double slit experiment works on molecules up to the size of a buckminsterfullerene (and I actually spelt that correctly!) which is 60 carbon atoms bonded together.

 

You could probably go a bit bigger, maybe it has already been done, but I doubt you'd get much bigger than the C60 molecule.

C60 is the biggest that I've heard of, the issue with bigger particles is that the slits ahve to be on the same order of magnitude of the debrogglie wavelength of the particle.

 

[math]\lambda = \frac {h} {mv}[/math]

One group managed to get quantum interference patterns from fluronated buckyballs C60F48 as well as other large molecules. See http://physicsweb.org/articles/world/18/3/5.

Man thats pretty neat, I didn't know they could get so big and still observe those effects.

'']Man thats pretty neat, I didn't know they could get so big and still observe those effects.

 

Some people think it can actually be done with things as big as bacteria although - sounds pertty strange and no-one has done it yet so it may not be possible.

 

Cheers,

 

Ryan Jones

Is superfluid a kind of macroscopic quantum phenomenum ? there are many pictures of superfluids climbing up the surface of a bottle...

Yes, a superfluidity is a quantum effect which is works when bosons all collapse into the same (and lowest) quantum state. They are also known as Bose-Einstein Condensates (or BEC), see here:

 

http://en.wikipedia.org/wiki/Bose-Einstein_condensate

or here:

http://hyperphysics.phy-astr.gsu.edu/hbase/particles/spinc.html#c4