What is the scale or density when the double slit experiment stops working?

[jaketodd]

I know even molecules can be used and the result still emerges. What is the density of [pick a type] of atoms or molecules when the experiment stops working? Also, as you increase the density of whatever you're using, does the result get less and less like what you get when you use photons? In other words, is there a gradual loss of the interference pattern as density increases? And like I said, at what density does it actually *stop* working and not resemble an interference pattern at all?

Thanks!

Jake

 

[jaketodd]

Anyone please? I know you experts can answer this ;-)

Thanks,

Jake

 

[physicsjock]

Are you sure anyone has figured out the limit?

Aren't there people preparing to try and send viruses through diffraction gratings to see if an interference pattern is possible?

 

[jaketodd]

I've heard that too. I just thought that some of the experts on here would know already. Maybe I'm making a hasty assumption.

 

[bohm2]

I'm not sure if larger than this has been verified?

We demonstrate quantum interference for tetraphenylporphyrin, the first biomolecule exhibiting wave nature, and for the fluorofullerene C60F48 using a near-field Talbot-Lau interferometer. For the porphyrins, which are distinguished by their low symmetry and their abundant occurrence in organic systems, we find the theoretically expected maximal interference contrast and its expected dependence on the de Broglie wavelength. For C60F48 the observed fringe visibility is below the expected value, but the high contrast still provides good evidence for the quantum character of the observed fringe pattern. The fluorofullerenes therefore set the new mark in complexity and mass (1632 amu) for de Broglie wave experiments, exceeding the previous mass record by a factor of two.

The wave nature of biomolecules and fluorofullerenes
http://arxiv.org/pdf/quant-ph/0309016v1.pdf

 

[jaketodd]

"For C60F48 the observed fringe visibility is below the expected value, but the high contrast still provides good evidence for the quantum character of the observed fringe pattern."

In other words, the de Broglie wavelength is not a comprehensive rule when it comes to superposition, and they are just saying that some level of superposition still exists for C60F48?

Thanks,

Jake

 

[bohm2]

In other words, the de Broglie wavelength is not a comprehensive rule when it comes to superposition, and they are just saying that some level of superposition still exists for C60F48?

Yes. You might also find this recent paper by these authors on the topic interesting:

In as far as the term designates the quantum superposition of two macroscopically distinct states of a highly complex object, the molecules in our new experimental series are among the fattest Schrödinger cats realized to date. Schrödinger reasoned whether it is possible to bring a cat into a superposition state of being ‘dead’ and ‘alive’. In our experiment, the superposition consists of having all 430 atoms simultaneously ‘in the left arm’ and ‘in the right arm’ of our interferometer, that is, two possibilities that are macroscopically distinct. The path separation is about two orders of magnitude larger than the size of the molecules...In conclusion, our experiments reveal the quantum wave nature of tailor-made organic molecules in an unprecedented mass and size domain. They open a new window for quantum experiments with nanoparticles in a complexity class comparable to that of small proteins, and they demonstrate that it is feasible to create and maintain high quantum coherence with initially thermal systems consisting of more than 1,000 internal degrees of freedom.

Quantum interference of large organic molecules
http://www.nature.com/ncomms/journal/v2/n4/pdf/ncomms1263.pdf

 

[jaketodd]

Thanks man

 

[bohm2]

This just came out:

The diffraction of single molecules at a grating is an unambiguous demonstration of the wave–particle duality of quantum physics. It is only explicable in quantum terms, independent of the absolute value of the interference contrast. In contrast to photons and electrons, which are irretrievably lost in the detection process, fluorescent molecules stay in place to provide clear and tangible evidence of the quantum behaviour of large molecules.

Real-time single-molecule imaging of quantum interference
http://www.nature.com/nnano/journal/vaop/ncurrent/pdf/nnano.2012.34.pdf

Wave Character of Individual Molecules Revealed
http://www.sciencedaily.com/releases/2012/03/120328090828.htm

 

[jaketodd]

Thanks again!

 

[bohm2]

The scientists now premiered a movie which shows the build-up of a quantum interference pattern from stochastically arriving single phthalocyanine particles after these highly-fluorescent dye molecules traversed an ultra-thin nanograting. As soon as the molecules arrive on the screen the researchers take live images using a spatially resolving fluorescence microscope whose sensitivity is so high that each molecule can be imaged and located individually with an accuracy of about 10 nanometers. This is less than a thousandth of the diameter of a human hair and still less than 1/60 of the wavelength of the imaging light...In these experiments van der Waals forces between the molecules and the gratings pose a particular challenge. These forces arise due to quantum fluctuations and strongly affect the observed interference pattern. In order to reduce the van der Waals interaction the scientists used gratings as thin as 10 nanometers (only about 50 silicon nitride layers). These ultra-thin gratings were manufactured by the nanotechnology team around Ori Cheshnovski at the Tel Aviv University who used a focused ion beam to cut the required slits into a free-standing membrane...Already in this study the experiments could be extended to phthalocyanine heavier derivatives which were tailor-made by Marcel Mayor and his group at the University of Basel. They represent the most massive molecules in quantum far-field diffraction so far.

Single molecules in a quantum movie
http://atomiumculture.eu/content/single-molecules-quantum-movie

The movie download now available:
http://www.quantumnano.at/

 

[ThomasT]

I know even molecules can be used and the result still emerges. What is the density of [pick a type] of atoms or molecules when the experiment stops working? Also, as you increase the density of whatever you're using, does the result get less and less like what you get when you use photons? In other words, is there a gradual loss of the interference pattern as density increases? And like I said, at what density does it actually *stop* working and not resemble an interference pattern at all?

Thanks!

Jake

I can't answer your question, but you might find this interesting:

http://physicsworld.com/cws/article/news/49145

 

[jaketodd]

Thanks all

 

[mfb]

In theory, there should be no limit to the size of the objects. The only limit is the interaction with the environment. But as the objects get heavier and heavier, you have to make them slower and slower to maintain a reasonable wavelength. This means that the particles have more time to interact, they have more atoms which can interact and smaller interactions can disturb them at the same time.

What would make such a wave when there is just one molecule in the experiment at at time?

Simple answer: the molecule.

 

[akhmeteli]

I know even molecules can be used and the result still emerges. What is the density of [pick a type] of atoms or molecules when the experiment stops working? Also, as you increase the density of whatever you're using, does the result get less and less like what you get when you use photons? In other words, is there a gradual loss of the interference pattern as density increases? And like I said, at what density does it actually *stop* working and not resemble an interference pattern at all?

Thanks!

Jake

As some other posters, I don't think there is any limit on the mass of diffracting objects. Please see the reasoning in https://www.physicsforums.com/showpost.php?p=3724011&postcount=8

 

[lostprophets]

I know even molecules can be used and the result still emerges. What is the density of [pick a type] of atoms or molecules when the experiment stops working?
Thanks!

Jake

there isn't one.
it never stops working
no matter what size you use