
Wave-particle duality in action–big molecules surf on their own waves - rbanffy
https://arstechnica.com/science/2020/07/wave-particle-duality-in-action-big-molecules-surf-on-their-own-waves/
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gus_massa
The description in the press article miss the most important part of the
equipment that is a laser grating.

They don't use a standard glass or mirror grating. (I guess the molecules
would just get stuck against a surface.) They use a powerful ~100W laser and a
retroreflector to create standing electromagnetic waves, that act like a
grating.

Also, the interference is not between the waves of one molecule and the waves
of another molecule. They could repeat the experiment with a very low power to
ensure there is only one molecule flying around, and if they wait enough time
they would get the same result. (This has been done with photons. Yes this is
weird.)

> _What I found most remarkable is that the internal state of the molecule
> didn’t seem to matter at all. [...] They are spinning wildly and vibrating
> like a kid on a sugar high._

The rotations an vibrations of the molecule are also quantized, so they are
not totally arbitrary. For the calculations, they use only the ground state.
I'm still not sure about the technical details, but my guess is that these
produce more broad peaks instead of erasing the interference pattern.

