Finally some experiments with some interesting results!"What Efimov offered in 1970 was not a general solution for the three-body problem, but it was the next-best thing -- a universal relationship that would hold true for any particle but only under a particular set of circumstances.
Hulet said nuclear physicists tried for decades to find experimental evidence of Efimov trimers using nuclear particles, but they found that there wasn't a strong enough attractive interaction between the particles to satisfy the conditions laid out by Efimov.
In the 1980s, physicists began using a combination of powerful lasers and magnetic fields to trap and cool atoms to ultracold temperatures. As thermodynamic heat is driven from the atoms, they move slower and slower. That let physicists study atoms in a new way, and as the techniques progressed, physicists were eventually able to remove so much thermodynamic energy from these trapped atoms that they began to manifest the effects of quantum physics.
Efimov trimers are one manifestation of quantum physics, and Hulet said a number of research groups worldwide have been racing to study them for several years. The first Efimov trimer was observed in 2006, and the first set of two connected trimers was observed in early 2009.
In their experiments, Hulet, postdoctoral researcher Scott Pollack and graduate student Dan Dries designed a test for Efimov's prediction about universal scaling -- the notion that trimers emerged again and again in a stepwise fashion. The team used a property of ultracold atoms called a "Feshbach resonance" to tune the interactions between lithium atoms. As they dialed up and down the energy scale, they saw Efimov's trimers appear and reappear again and again. The team confirmed another Efimov prediction as well by finding four-body "tetramers" in close proximity to each trimer. In all, Hulet, Pollack and Dries found 11 different signatures for trimers and tetramers, each exactly where Efimov and others had predicted.
Efimov was in the room when Hulet presented the first results of the tests at a scientific meeting in Rome.
"He was so excited that he came up and gave me a high five after the talk," Hulet said. "In his original paper, he had a figure that looked just like what we had found. It was such an amazing prediction, and to see it borne out like this is very special."
Off Topic: Trimers
Off Topic: Trimers
http://www.physorg.com/news179749630.html
This is what we will have to clearly understand now. The beauty of this theory is that it shows that it is merely the addition of the third particle that bounds toghether the other two (which are not bound). This theory and the related experiments might lead finally to a single formula to describe a three body interaction from atom to planetary scale.
This explains it better:
http://physics.aps.org/articles/v2/26
( http://arxiv.org/PS_cache/arxiv/pdf/090 ... 1276v2.pdf )
This explains it better:
http://physics.aps.org/articles/v2/26
Add to this that it has already been proved that a 4-body resonant bound state is directly related to its corrispondent Tetramer via an universal relation, and things start to get interesting.Vitaly Efimov predicted in 1970 [1] that three particles can have an infinity of bound states even when no two of the three are separately bound together. The existence of even a single state so delicate is surprising, but the presence of an infinite sequence of them is doubly so. Even more confounding to our intuition is the fact that making the underlying interactions between the three particles stronger decreases the number of three-body bound states from infinity to a finite value. We normally think, of course, that deepening a potential leads to more bound states, not fewer. Besides a parameter that fixes the short-range behavior of the three bodies, the properties of these Efimov states (as they have come to be called) are universal and characterized by geometric scaling. For instance, given the energy of a bound Efimov three-boson state, you know that the next state is 515 times more weakly bound, and that the state after that is another 515 times more weakly bound, and so on. The spatial size of the states grows by factors of 22.7—the fourth excited state is already at least micron-sized! Geometric scaling is the signature of Efimov states in all low-energy observables.
( http://arxiv.org/PS_cache/arxiv/pdf/090 ... 1276v2.pdf )
...hmm, after a little more trawling around the web, i came up with some interesting related/background info, ...and a smidgen more of an idea what we are looking at. (eg. http://arxiv.org/ftp/arxiv/papers/0810/0810.3876.pdf)
of interest to me in your link was mention of
seems like its a computational solution, yet to be published, based on N-dimensional/nonlinear Schrödinger equation + some 'experimental numbers'/approximative priming. but its not really clear.
reading around (citations), i came across http://arxiv.org/PS_cache/arxiv/pdf/081 ... 3626v3.pdf
btw, i thought a '4 body bound state' was a tetramer. did you mean to say ...'tetramers... universaly related to... trimers.' - which i took to be the implictations of the research.
ps. what do you suppose the possible applications might be? (i have always liked the approach of ultra-cold fusion targets).
of interest to me in your link was mention of
Using a breakthrough in nonperturbative calculations for four-body collisions...
seems like its a computational solution, yet to be published, based on N-dimensional/nonlinear Schrödinger equation + some 'experimental numbers'/approximative priming. but its not really clear.
reading around (citations), i came across http://arxiv.org/PS_cache/arxiv/pdf/081 ... 3626v3.pdf
... never heard of it before. Anyone? (something like the quantum analytical equivalent of van der Waals force, perhaps? - a definition here : http://eom.springer.de/h/h110350.htm)The Hulth´en potential is one of the important short-range potentials which behaves like a Coulomb potential for small values of r and decreases exponentially for large values of r....
btw, i thought a '4 body bound state' was a tetramer. did you mean to say ...'tetramers... universaly related to... trimers.' - which i took to be the implictations of the research.
ps. what do you suppose the possible applications might be? (i have always liked the approach of ultra-cold fusion targets).
I should stop typing posts during meeting breaks, hurry is not good while typing.
Yes, I was meaning that the Tetramer are connected to the Trimers trough an universal relation. See page 2 of the pink I posted:
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 1276v2.pdf
What we have here is a new theory that among other things shows how we might manipulate particles of different nature (and attitude) to aggregate. As example see this:
Yes, I was meaning that the Tetramer are connected to the Trimers trough an universal relation. See page 2 of the pink I posted:
http://arxiv.org/PS_cache/arxiv/pdf/090 ... 1276v2.pdf
What we have here is a new theory that among other things shows how we might manipulate particles of different nature (and attitude) to aggregate. As example see this:
I am not really sure that this might effect or help the polywell or other fusion approaches, but the validity of this new theory really opens for a new research field in particle interaction at short and long distance, that might eventually give us some better knowledge and info also in the fusion applications.AN ULTRA LOW-DENSITY LIQUID, some 10^13 times thinner than water, might form inside Bose-Einstein condensates under the action of the "Efimov effect," a quantum phenomenon in which the atoms in the cloud attract each other when considered two at a time but repel each other when considered three at a time. In such an Efimov cloud the atoms would be some 20 times farther apart that in a BEC, which is itself pretty sparse a million times thinner than air. And yet this new type of condensate would not be a gas but a liquid! According to Aurel Bulgac of the University of Washington the exquisite coordination of atoms in an Efimov condensation would allow it to be self bound (the constraining magnetic fields used to keep a BEC from drifting apart would be unnecessary); moreover, it would be neither compressible nor dilutable. This extraordinary quantum liquid the smallest density condensed matter system yet proposed---could probably only be formed at much colder temperatures than are now available in BEC experiments. Bulgac proposes that Efimov droplets made from boson atoms be called "boselets." The fermion version would be "fermilets." (Bulgac@phys.washington.edu, 206-685-2988, Physical Review Letters, 29 July 2002)
sounds quite useful. i'm sure there are a lot of exotic quantum effects to play with here - might end up making fusion 'old science' - you never know....neither compressible nor dilutable...
by fusion standards, seems like 'ultra cooling' takes a lot less energy than getting things hot/fast (and containing them).