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What are some examples of quantum mechanical phenomena that have been observed not with electrons but rather with large real-life objects? In particular, what is the largest object for which the double slit experiment has been successfully performed with?

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    $\begingroup$ see vcq.quantum.at/fileadmin/Publications/2003-17.pdf for fullerenes $\endgroup$
    – Sanya
    Sep 15, 2016 at 10:27
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    $\begingroup$ en.wikipedia.org/wiki/Macroscopic_quantum_phenomena $\endgroup$ Sep 15, 2016 at 10:44
  • $\begingroup$ Maybe you should change the title to include just the double slit. Superconductivity and superfluidity are quantum phenomena over large distances. Also one could say that crystals fall in that category. All three are not explainable classically but need quantum mechanics. $\endgroup$
    – anna v
    Sep 15, 2016 at 10:46
  • $\begingroup$ We could then add magnetism as QM-effect, see the bohr van leeuwen theorem en.wikipedia.org/wiki/Bohr%E2%80%93van_Leeuwen_theorem $\endgroup$
    – Sanya
    Sep 15, 2016 at 10:50
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    $\begingroup$ Or I could ask you to mention how this molecule is prepared, how it is done, as you can see below, it's is a bit more sophisticated that an electron gun or a photon source. This may allow us to learn how to eventually perform the DS experiment with a cell, but that is a long way off yet. $\endgroup$
    – user108787
    Sep 15, 2016 at 10:56

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As I say in my comment, there is probably a duplicate of this, that will turn up as soon as I write this, but as technology advances, perhaps it's out of date.

This answer concentrates as much on how you prepare "large" molecules, as I think that aspect is of interest in itself, but we cannot approach the size of a virus or any tiny bacteria as yet, or for the foreseeable futures, as far as I know.

From Largest Molecule Double Slit.

These molecules are around 100 atoms in size, compare to the 180, 000 atoms in the smallest virus.

The relatively large phthalocyanine $C_{32}H_{18}N_8$ and derivative molecules $C_{48}H_{26}F_{24}N_8O_8$ have more mass than anything in which quantum interference has previously been observed. To have wavelengths that are relatively large compared to their sizes, the molecules need to move very slowly. This was achieved this by directing a blue diode laser onto a very thin film of molecules in a vacuum chamber, effectively boiling off individual molecules directly under the beam while leaving the rest unaffected.

After separation from the film, the molecules were sent through a collimator to ensure they formed a beam before reaching the barrier, which had a number of parallel slits to produce the actual interference pattern. To prevent excessive interactions (primarily van der Waals forces) between the molecules and the edges of the slits, the researchers used a specially-prepared grating coated in silicon nitride membranes. Without such preparation, the molecules are likely to be deflected by ordinary interactions with the hardware.

After passing through the slits, the molecules' positions were recorded using fluorescence microscopy, which has both sufficient spatial resolution and fast response to detect when and where the molecules arrive. The positions of individual spots were measured to 10 nanometer accuracy. Additionally, the molecules lodged in the fluorescent screen, meaning their positions could be independently verified in the form of build-up at the experiment's end.

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    $\begingroup$ Great question! CountT10 and the referenced article have given you the answer. But the answer has raised another question with me. What's the smallest object that does not exhibit the wave particle duality? Like with a limit in calculus the wave particle duality "limit" could be found by approaching from both sides. $\endgroup$
    – Lambda
    Sep 15, 2016 at 15:24
  • $\begingroup$ CountT10, the OP's question was what were some large object experiments with the double split?. The article you linked to clearly, in my opinion, gave a example of exactly what was requested by the OP. I should have said that the article answered the question rather than saying CountTo10 and the article answered the question. For that I stand corrected. Thanks for reading my comments. $\endgroup$
    – Lambda
    Sep 15, 2016 at 17:27

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