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2Physics Quote:
"Can photons in vacuum interact? The answer is not, since the vacuum is a linear medium where electromagnetic excitations and waves simply sum up, crossing themselves with no interaction. There exist a plenty of nonlinear media where the propagation features depend on the concentration of the waves or particles themselves. For example travelling photons in a nonlinear optical medium modify their structures during the propagation, attracting or repelling each other depending on the focusing or defocusing properties of the medium, and giving rise to self-sustained preserving profiles such as space and time solitons or rapidly rising fronts such as shock waves." -- Lorenzo Dominici, Mikhail Petrov, Michal Matuszewski, Dario Ballarini, Milena De Giorgi, David Colas, Emiliano Cancellieri, Blanca Silva Fernández, Alberto Bramati, Giuseppe Gigli, Alexei Kavokin, Fabrice Laussy, Daniele Sanvitto. (Read Full Article: "The Real-Space Collapse of a Two Dimensional Polariton Gas" )

Thursday, March 16, 2006

Efimov State Observed

Rudolf Grimm

A Group of 10 Physicists led by Rudolf Grimm at the University of Innsbruck in Austria reported that they've been successful in converting three normal atoms into a special new state of matter called 'Efimov Quantum state' after the Russian scientist Vitali Efimov who proposed this in 1970. Efimov found a remarkable and counterintuitive solution to the notoriously difficult quantum-mechanical three-body problem, which concluded that 3 interacting particles can form a loosely bound system even if the 2-particle attraction is too weak to allow for the binding of a pair.

In order to prove that such a state can exist, experiments were conducted at Grimm's Laboratory on cesium atoms. There, for the first time, physicists were able to observe the Efimov state in a vacuum chamber at the ultra-cold temperature of a billionth of a degree above absolute zero, or minus 459.6 degrees Fahrenheit. Two of the three atoms repel one another in close proximity, but when you put three of them together, it turns out that they attract and form this new quantum state.

Efimov's result was a landmark in theoretical few-body physics, but until now these exotic states had not been demonstrated experimentally. Now that has been achieved, this may open up a new research specialty devoted to understanding the quantum mechanical behavior of just a few interacting particles.

The development is detailed in the March 16 issue of the journal Nature. If you are a Physicist, you may like to visit the website of Prof. Cheng Chin (University of Chicago) who is a member of the group that conducted this experiment.

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2 Comments:

At 2:13 PM, Blogger Sergei Kopeikin said...

This is a remarkable experimental confirmation of Efimov's outstanding theoretical prediction.

 
At 2:14 PM, Blogger Sergei Kopeikin said...

This is a remarkable experimental work confirming Efimov's outstanding theoretical prediction.

 

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