Macroscopic Quantum Coherence & Macrorealism experiments

[StevieTNZ]

Has anyone performed experiments regarding macroscopic quantum coherence (superposition of and macroscopic object)?

What about testing if macroscopic objects obey macrorealism, or whether QM prevails?

Links to articles or experiments would be apprecited.

 

[tom.stoer]

I have no link at hand but I think macroscopic Bose-Einstein condensates have been prepared.

 

[Demystifier]

Superconductivity is a classic example of macroscopic quantum coherence.

 

[yoda jedi]

Has anyone performed experiments regarding macroscopic quantum coherence (superposition of and macroscopic object)?

What about testing if macroscopic objects obey macrorealism, or whether QM prevails?

Links to articles or experiments would be apprecited.

on: Quantum Superposition & Philosophy
Nov27-10

There was an interesting article published by Nature earlier this year entitled 'No Moon There'. You can read it here: http://www.engr.ucr.edu/~korotkov/news/2010-NatPhys.pdf

i read it, time ago.
i waiting the result on more big object like:

http://www.fqxi.org/community/articles/display/103 -> ONGOING EXPERIMENT
Aspelmeyer, Schwab, and Zeilinger !

it will elucidate too between:
NONLINEAR QUANTUM MECHANICS or STANDARD QUANTUM MECHANICS.
(Self Induced Collapses and Collapse of the Wavefunction on Macroscopic Object).

AND before that:

http://www.nature.com/nature/journal/v464/n7289/full/nature08967.html
Nature 464, 697-703 (1 April 2010)

 

[StevieTNZ]

So, just to clarify, there has be an example of a macroscopic object being placed in a superposition of two distinct states (e.g. dead cat, alive cat)? Would that macroscopic object have just one wavefunction representing it?

 

[DaTario]

In Ecole Normale Superieur there has been several experiments that implemented quantum superposition at a mesoscopic level. The system used was the field inside a superconducting (high Q) cavity. The duration of the photon inside the cavity was of the order of 10^(-2) second.

But there was another work, I tried to recover it from http://arxiv.org but I coudn't, All I remember is that the author succeded in obtaining coherence from two bottles of gas at room temperature. As his paper was not so commented after the publication, it seems that it was not so well accpeted by the community.

Best wishes

DaTario

 

[StevieTNZ]

http://www.nature.com/news/2010/100317/full/news.2010.130.html

Would that be an example of a macroscopic object being in two distinct macroscopic states?

 

[jimgraber]

http://www.nature.com/news/2010/100317/full/news.2010.130.html

Would that be an example of a macroscopic object being in two distinct macroscopic states?

I think it surely qualifies as a macroscopic object. There is also good evidence that it is in a superposition of two distinct states. But the distance between those states is less than the size of a proton in one direction. I would not call that macroscopic.
Just my two cents worth.
Jim Graber

 

[StevieTNZ]

I wonder actually if the experiment mentioned in http://www.engr.ucr.edu/~korotkov/news/2010-NatPhys.pdf takes into account the loophole mentioned in http://mcgill.academia.edu/MarkWild...phole_In_a_Leggett-Garg_Test_of_Macrorealism?

A violation of macrorealism (or even simply the Leggett-Garg inequality) would imply superposition of states wouldn't it? I was reading in 'Sneaking a Look at God's Cards' and the author mentions that although Leggett thought macrorealism implied noninvasive measurement, a contrary answer was given saying the two propositions are logically independent from each other. However, this does not change the final inequality that is a result from combining the two premises.

 

[ZapperZ]

So, just to clarify, there has be an example of a macroscopic object being placed in a superposition of two distinct states (e.g. dead cat, alive cat)? Would that macroscopic object have just one wavefunction representing it?

Check out the Delft[1]/Stony Brook[2] SQUID experiment, where up to 10^11 particles exhibited the superposition principle.

And has been mentioned, superconductivity is the clearest manifestation, at the macroscopic scale, of quantum coherence. That's why experiments exhibiting macroscopic quantum phenomena are typically done using superconductivity, thus, the SQUID experiment mentioned above.

Zz.

[1] C.H. van der Wal et al., Science v.290, p.773 (2000).
[2] J.R. Friedman et al., Nature v.406, p.43 (2000).[ArXiv version http://arxiv.org/abs/cond-mat/0004293" ]

 

[StevieTNZ]

I see in Baggott's book the SQUID size of the SUNY experiment is 140μm by 140μm. Is an object of that size considered macroscopic? I'm just comparing this size to examples:
http://en.wikipedia.org/wiki/1_E-5_m
http://en.wikipedia.org/wiki/1_myriometre

 

[yoda jedi]

https://www.physicsforums.com/showthread.php?p=3006265#post3006265

another...

Large Quantum Superpositions and Interference of Massive Nano-objects.
http://arxiv.org/PS_cache/arxiv/pdf/1103/1103.4081v1.pdf

..."objective collapse models of the wave function"...



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http://arxiv.org/PS_cache/arxiv/pdf/1103/1103.1236v1.pdf


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it will elucidate between:
NONLINEAR QUANTUM MECHANICS or STANDARD QUANTUM MECHANICS.
(Self Induced Collapses and Collapse of the Wavefunction on Macroscopic Object).
CSL models and others.




.

 

[jimgraber]

http://blogs.discovermagazine.com/8...nd-fattest-schrodinger-cats-realized-to-date/

Another recent significant experimental advance. 430 atoms in a cat state.
(I would still call this mesoscopic. ymmv)
Jim Graber

 

[StevieTNZ]

Saw the 430 atom molecule interference article on www.quantum.at

Still wanting results for the superposition of the mirror. ;)

 

[yoda jedi]

Saw the 430 atom molecule interference article on www.quantum.at

Still wanting results for the superposition of the mirror. ;)

much better here:

http://www.univie.ac.at/qfp/publications3/pdffiles/ncomms1263.pdf



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has to be around 10 ¹⁴ atoms.

also waiting...





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