Making supersolids with ultracold gas atoms

January 14th, 2009 - 3:44 pm ICT by ANI  

Washington, Jan 14 (ANI): A team of physicists has proposed a recipe for turning ultracold boson atoms into a supersolid, an exotic state of matter that behaves simultaneously as a solid and a friction-free superfluid.

The physicists were from the Joint Quantum Institute (JQI) of the National Institute of Standards and Technology (NIST) and the University of Maryland in the US.

While scientists have found evidence for supersolids in complex liquid helium mixtures, a supersolid formed from such weakly interacting gas atoms would be simpler to understand, potentially providing clues for making a host of new quantum materials whose bizarre properties could expand physicists notions of what is possible with matter.

First theorized in 1970, a supersolid displays the essential characteristics of a solid, with atoms arranged in regularly repeating patterns like that of a crystal lattice, and of a superfluid, with the particles flowing frictionlessly and without losing any energy.

Able to exist only at low temperatures, a supersolid behaves very differently from objects in the everyday world.

In 2004, Moses Chan and Eun-Seong Kim of Pennsylvania State University published a groundbreaking experiment on helium at low temperatures and gathered evidence for a supersolid phase.

However, the interpretation of their observations has considerable uncertainties due to the complex nature of the particular system used in their experiments.

Now, physicists Ludwig Mathey, Ippei Danshita and Charles Clark have identified a technique for making a simpler-to-understand supersolid, using two species of ultracold atoms confined in an optical lattice, a web of light that traps atoms in regular positions.

The JQI team has identified conditions under which a cloud of ultracold atoms of two species (such as rubidium and sodium, or two slightly different forms of rubidium) can spontaneously condense into a state in which there is crystalline structure in the relative positions of atoms.

The team identified clear experimental signatures (essentially photographs of the cloud), which could verify the simultaneous existence of these two seemingly incompatible properties. (ANI)

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