Frictionless supersolid a step closer

February 14, 2010

Superfluid mixtures of atoms can boil and freeze at ultra-low temperatures. This freezing can result in the formation of supersolids of atoms that can flow alongside each other without friction, but are still set in a fixed structure, says Dutch researcher Koos Gubbels. His research results are contributing to the understanding of superconductors - materials that might help to resolve the energy problem.

Superfluidity and superconductivity cause particles to move without friction. Koos Gubbels investigated under what conditions such particles keep moving endlessly without losing energy, like a swimmer who takes one mighty stroke and then keeps gliding forever along the swimming pool. Superfluidity and superconductivity are of major fundamental and practical significance. The former, for instance, is used for high-precision measurements. Superconductivity allows for the generation of strong magnetic fields for MRI research, the LHC or the Japanese bullet trains. Superconductivity might even be able to help us with our energy problem at some point in the future.

Gubbels investigated atomic gases. These substances are much simpler than the metals that make up , yet still display the basic process of superfluidity. The major advantage of atomic gases is that they are easy to manipulate. Researchers can readily control the temperature and the strength of interaction among the particles. Along with his supervisor, Henk Stoof, Koos Gubbels developed a theory for predicting the behaviour of these superfluid materials, and discovered that the atomic gasses can have very unique properties.

During his research, Gubbels demonstrated that the atomic gases he was investigating start to ‘boil’ just above the temperature of . The mixture then gives rise to phase separation. Everyone comes across phase separation on a day-to-day basis: a pan of boiling water on the stove consists of a liquid, but at the same time also of gas bubbles. It is, therefore, partly liquid and partly gas. Although phase separation is quite rare in superfluid materials, Gubbels discovered that the phenomenon is still possible at ultra-low temperatures and for specific polarisations. In this case, the polarisation determines how many particles interact with each other and become superfluid. Gubbels predicted that specific superfluid mixtures of atoms could also freeze, so that, paradoxically enough, the atoms could flow without and at the same time be trapped in a fixed structure.

The frictionless state of the atomic gases appeared to be surprisingly stable. In a metal, this state would remain superconducting to a temperature of about 1000 degrees Kelvin, which is far hotter than room temperature. The present superconductors have to be kept very cold, though, which is a major problem for large-scale application.

The research done by Koos Gubbels is part of the Vici project led by physicist Henk Stoof, who was awarded a Vici under the NWO Innovational Research Incentives Scheme in 2003.

Explore further: Evidence for high temperature superfluidity in cold 'fermion' gas

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5 / 5 (1) Feb 14, 2010
Fascinating !!

But, "...about a billion times lower than room temperature..." is just plain wrong.

'A billionth of...' would make sense...
2.3 / 5 (3) Feb 14, 2010
Did you notice, how fresh cold snow crackles and crunches under your feet? IMO supersolidity mechanism occurs in thin surface layers of snow or ice, where it is magnified by large number of crystalline particles involved.

It means, thin surface layer of water molecules becomes superfluous to very brief intervals of time and this mechanism corresponds to balistic transport of electrons inside of graphene at room temperature. The reason is high pressure of water molecules or electrons in surface layer of ice or graphite - both these phenomena are quite similar at conceptual level

It would mean, quantum phenomena aren't so distant from our everyday reality, as we often believe.
not rated yet Feb 15, 2010
The frictionless state of the atomic gases appeared to be surprisingly stable. In a metal, this state would remain superconducting to a temperature of about 1000 degrees Kelvin, which is far hotter than room temperature.

Could someone explain this? I was under the impression that the frictionless state is only possible in ultracold solids. So how does an ultracold solid retain its frictionless status at 1000 degrees Kelvin?
not rated yet Feb 15, 2010
Superconductor is frictionless only for electrons, which are more lighter, then the atoms. I presume, the 1000 K is a temperature limit for superconductivity (i wouldn't use "degrees" word there, as Kelvin itself is a name of physical unit).

So far we know about evidence of superconductivity at 254 K in bulk phase: http://www.superc...254K.htm and above 400 K in surface phase: http://www.iop.or...8/3/319/
not rated yet Feb 15, 2010
IMO sufficiently compressed electron or proton gas would have no apparent upper limit in temperature of superconductivity transition - the "only" problem is to construct sufficiently compact "vessel" for keeping of these restless particles together. Some physicists are speculating, the interior of large planets or cold neutron stars should be superconductive too - and the temperature in such cases would certainly exceed 1000 K limit. Personally I cannot understand, why nobody attempted to attract electrons, protons or alpha particles to non-conductive surface by external electrostatic or magnetic field - the behavior of such compressed surface layer could be quite interesting.
not rated yet Feb 22, 2010
But that sounds like a plasma, how can plasma be superconducting? ;o

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