Largest Mass Diffraction I have read "Matter-wave interference with particles selected from a molecular library with masses exceeding 10000 amu" which claims to observe diffraction patterns in objects of around 10'000 amu. What is the largest mass objects shown to have diffraction patterns and show wave-particle duality? I have heard a claims of this type have been shown for small amino acids, and possibly protein strands or even small viruses, but have struggled to find any references.
 A: According to this website, photons, electrons, atoms, and some molecules, including buckyballs, have displayed wave-particle duality. Here is a paper that talks about some of the experimentation for larger molecules. This paper talks about molecules with over 6,000 amu showing a wave-particle duality, and this article talks about the discoveries behind your paper. The article was written at the end of 2013, and it calls it a broken record. Everything I've looked at says this is the record. Interestingly, I did find a few sources (like this one) that said scientists have tested molecules with a mass over 10,000 amu; obviously, it could be that better experimental equipment will allow this to happen.
In reference to amino acids/DNA/viruses: The mass of the DNA strand Enterobacteria Phage T4 is roughly 40,000 amu. The mass of a DNA strand only makes up a small component of the mass of a virus, so I highly doubt that either DNA or viruses show their wave-particle duality (see this website). However, it should be mentioned that viruses are within an order of magnitude of 10,000 amu (100,000 amu).
I'll keep looking for information. Hope this helps!
A: Yes, up to now, that is the paper showing the largest-mass particle interference experiment. The possibility of using larger particles, like small viruses and other kinds of biomaterials are discussed in this paper:
http://iopscience.iop.org/article/10.1088/0031-8949/91/6/063007/meta
This is the most up to date reference I can find on the topic.
There is also a recent blog post here that is relevant and might be of interest to you:
https://thiscondensedlife.wordpress.com/2016/06/24/schrodingers-cat-and-macroscopic-quantum-mechanics/
A: According to http://hyperphysics.phy-astr.gsu.edu/hbase/nuclear/mossfe.html it takes 200,000 iron nuclei to preserve the natural line width of the 57Fe transition used in Moessbauer spectroscopy, so that gets you to approx. 11 million AU of coherently moving mass. I don't know if one can do better than this with phonon spectroscopy, but it might be possible.
