# Which types of particles are affected by the wave-particle duality?

If we take the double slit experiment as a way of demonstrating the wave-particle duality, which types of particles would show an interference pattern?

For example, I know that electrons show such a pattern. But do protons, too? What about atoms? Where is the boundary between "wavey particles" and "classical particles"?

• The largest thing I have heard of is buckyballs: univie.ac.at/qfp/research/matterwave/c60 Mar 11, 2014 at 22:39
• Wow, this is impressive! Mar 12, 2014 at 12:39
• What about collective motions like superconducting qubits? Those are hundreds of microns in size. Feb 21, 2016 at 19:10

All of them. Even molecules show their wave-like nature, as does, in principle, every object. Speaking of these topics an interesting read about diffraction of C60 molecules is: http://www.univie.ac.at/qfp/research/matterwave/c60/

The point is that the wave-like nature of objects can only be observed at lengths comparable the object's De Broglie wavelength, defined by:

$$\lambda = \frac{h}{p}$$

where $h$ is the Planck constant and $p$ is the object momentum. For an object moving at non-relativistic speeds you may remember that the momentum is defined as $\vec{p}=m\vec{v}$; the De Broglie wavelength is then inversely proportional to the object mass. The bigger an object is, the less relevant its wave-like nature is, and that's why in everyday experience we are not used to observing the wave-like nature of massive objects.

• I think the OP was mainly interested in the experimental side of things, so maybe you could expand a little on that?
– Danu
Mar 11, 2014 at 22:57
• The theoretical explanation is already quite sufficent. Thank you! But yes, some experimental examples would also be very interesting. Mar 12, 2014 at 12:38
• I'm not that expert on experiments... However there are "standard" double slit experiments, and in recent times people have tried to see wave-like behaviors for bigger particles... The furthest we got is the Zwillinger's experiments (C60 diffraction, the experiment I was quoting) as far as I know.
– zakk
Mar 12, 2014 at 18:39