Particle-Wave Duality Demonstrated With Largest Molecules Yet 107
An anonymous reader tips news that researchers have successfully demonstrated particle-wave duality in molecules that have masses of 514 and 1,298 atomic mass units. The academic paper can be found in Nature Nanotechnology.
"Thomas Juffmann et al. fired molecules composed of over 100 atoms at a barrier with openings designed to minimize molecular interactions, and observed the build-up of an interference pattern. The experiment approaches the regime where macroscopic and quantum physics overlap, offering a possible way to study the transition that has frustrated many scientists for decades. ... The relatively large phthalocyanine (C32H18N8) and derivative molecules (C48H26F24N8O8) 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. Juffmann et al. 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. ... The researchers observed the particle nature of the molecules in the form of individual light spots appearing singly in the fluorescent detector as they arrived. But, over time, these spots formed an interference pattern due to the molecules' wavelike character.'"
Re:Assume a spherical cow... (Score:2, Interesting)
Oh yeah? Well assume a Mobius cow (moobius?):
http://spherecow.files.wordpress.com/2010/10/moobius.jpg [wordpress.com]
Richard Feynman (Score:5, Interesting)
I do not believe in particle-wave duality. I believe in Feynman's path integral formulation.
http://en.wikipedia.org/wiki/Path_integral_formulation [wikipedia.org]
Read QED if you want to know more of this.
http://en.wikipedia.org/wiki/QED:_The_Strange_Theory_of_Light_and_Matter [wikipedia.org]
Using path integral a particle does not need to interference itself in order to produce the interference pattern.
Re:Richard Feynman (Score:5, Interesting)
It's great to study, understand and use Feynman's path integral, especially since it leads to new insights about the nature of Quantum Mechanics (plus, seeing the familiar face of the principle of least action in the quantum world is just awesome). But it seems counter-productive to limit yourself to it. For example, some problems that are relatively simple to solve using the "usual" methods (i.e., thinking about waves and using the Schrodinger equation) can become intractable math nightmares with Feynman's path integral. I'm sure there are problems for which the reverse is true, too.
Most people who work with QM seem to take a very pragmatic approach when dealing with problems outside the foundations of QM: use whatever works for you for the problem at hand. Peter Shor (the guy who invented the quantum algorithm to factor numbers in polynomial time) once wrote:
Interpretations of quantum mechanics, unlike Gods, are not jealous, and thus it is safe to believe in more than one at the same time. So if the many-worlds interpretation makes it easier to think about the research you’re doing in April, and the Copenhagen interpretation makes it easier to think about the research you’re doing in June, the Copenhagen interpretation is not going to smite you for praying to the many-worlds interpretation.
(Source [scottaaronson.com])
And I agree that people should read QED: it's very easy to read, and it's great.
What is a quantum particle wave composed of? (Score:4, Interesting)
We know that water waves are composed of watr molecules, heat waves are composed of air moledcules and electromagnetic waves are composed of electrons or photons.
What is a quantum particle wave composed of?
Re:Macroscopic wave–particle duality (Score:5, Interesting)
umm... the research you're talking about, while interesting, is not an example of quantum phenomena.
the message of the article discussed here is "matter behaves in the weird quantum way even when you're talking about molecules". i.e. "we made an experiment with real molecules, and they act as predicted by quantum mechanics". it is a verification of theoretical predictions, with the purpose of strengthening our belief that quantum physics is "true". it is conceivable, while unlikely, that they would have obtained different results, thus implying that the passage from the quantum world to the macroscopic world is much more complicated then we currently believe.
the message of the thesis you link to is "with a properly set up classical experiment, we can reproduce quantum physics behavior". even if the molecules of liquid are described by classical physics, once you put a drop on a surface that vibrates very rapidly, you will observe that the drop bounces, and it is being carried by a wave on the surface of the liquid. by design the particle is carried by a wave, but only classical physics is relevant. they do talk about quantum physics because (in a somewhat funny situation) the simplification of the classical physics leads to equations that resemble those in quantum physics. it's just like you can write the same equations to describe sound and radio waves, even though the reasons sound waves exist are completely different from the reasons radio waves exist.