Simply Weird Stuff: Making Supersolids with Ultracold Gas Atoms

January 13, 2009
This is an artistic rendition of a supersolid made from two different types of ultracold atoms. The atoms are arranged in a regularly repeating pattern like a solid, but also can move frictionlessly like a superfluid. Yellow shape represents the electrical forces that the atoms feel, which vary in a regular pattern. Correspondingly. the density of the atoms (represented by the thickness of the spheres) also varies in a periodic fashion. Image: Ludwig Mathey, NIST/JQI

Physicists at the Joint Quantum Institute (JQI) of the National Institute of Standards and Technology and the University of Maryland have proposed a recipe for turning ultracold “boson” atoms—the ingredients of Bose-Einstein condensates—into a “supersolid,” an exotic state of matter that behaves simultaneously as a solid and a friction-free superfluid. 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.

“If you add more clothing to a spinning washing machine, you increase the mass of its rim, and the machine needs to exert a greater force to make the wheel reverse direction,” explains lead author Ludwig Mathey. “But in a supersolid washing machine, some of the clothes would mysteriously hover in space, staying stationary as the washer spins and making it easier for the wheel to reverse direction. Moreover, these hovering, frictionless clothes would form a predictable pattern—such as frictionless socks alternating with frictionless shirts—just as atoms arrange themselves in a repeating pattern in a crystal.”

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. In a paper* to be published in Physical Review A, the JQI team identifies 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, e.g. a chain in which the two different types of atoms alternate regularly, but in which the entire cloud exhibits the frictionless, superfluid properties of a Bose-Einstein condensate (BEC). This remains hard to visualize in familiar terms—the accompanying image shows an artist’s conception of it—but the team identified clear experimental signatures (essentially photographs of the cloud), which could verify the simultaneous existence of these two seemingly incompatible properties.

The underlying technologies of optical lattices and Bose-Einstein condensation were pioneered at NIST and have sparked a renaissance in atomic physics with applications to NIST’s fundamental measurement missions, such as time and frequency standards and improved sensors of magnetic and gravitational forces. The supersolid is an example of a further direction of research in ultracold atomic physics: the design of quantum materials with fundamental properties not previously found in familiar matter.


* L. Mathey, I. Danshita and C. W. Clark, Creating a supersolid in one-dimensional Bose mixtures. Physical Review A. Published as a Rapid Communication on Jan. 12, 2009.

Source: National Institute of Standards and Technology

Explore further: Frictionless supersolid a step closer

Related Stories

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 ...

Simulations lead to design of near-frictionless material

July 22, 2015

Argonne scientists used Mira to identify and improve a new mechanism for eliminating friction, which fed into the development of a hybrid material that exhibited superlubricity at the macroscale for the first time. Argonne ...

A one-way street for spinning atoms

August 30, 2012

Elementary particles have a property called "spin" that can be thought of as rotation around their axes. In work reported this week in the journal Physical Review Letters, MIT physicists have imposed a stringent set of traffic ...

Frozen helium-4 may be an unusual 'superglass'

May 1, 2009

( -- When helium is cooled to around 4 degrees above absolute zero, it turns liquid. Make it a couple of degrees cooler, and it becomes a "superfluid" that flows without resistance from its container, just as ...

Recommended for you

A quantum of light for materials science

December 1, 2015

Computer simulations that predict the light-induced change in the physical and chemical properties of complex systems, molecules, nanostructures and solids usually ignore the quantum nature of light. Scientists of the Max-Planck ...

Quantum dots used to convert infrared light to visible light

December 1, 2015

(—A team of researchers at MIT has succeeded in creating a double film coating that is able to convert infrared light at modest intensities into visible light. In their paper published in the journal Nature Photonics, ...

Test racetrack dipole magnet produces record 16 tesla field

November 30, 2015

A new world record has been broken by the CERN magnet group when their racetrack test magnet produced a 16.2 tesla (16.2T) peak field – nearly twice that produced by the current LHC dipoles and the highest ever for a dipole ...

Turbulence in bacterial cultures

November 30, 2015

Turbulent flows surround us, from complex cloud formations to rapidly flowing rivers. Populations of motile bacteria in liquid media can also exhibit patterns of collective motion that resemble turbulent flows, provided the ...


Adjust slider to filter visible comments by rank

Display comments: newest first

not rated yet Jan 13, 2009
The supersolidity is an superfluid analogy of so called ice regelation. The ice melts at phase interface a well bellow zero temperature. As the result, thin wire can pass through ice block rather freely, glaciers flows under pressure and the iron needle slides without friction along surface of ice. The cracking sound of fresh snow is the manifestation of ballistic mechanism of surface transport of water molecules, analogous to balistic motion of electrons in thin layers of graphene - a manifestation of low space-time distance scale superfluidity.

Supersolid hellium is the phenomena of the same cathegory, with the exception, the melted phase surrounding the crystal boundaries and dislocations is superfluous under elevated pressure. The snow made of frozen hellium flakes would behave like jerky fluid, if we could walk through it along bottom of hellium ocean covering the distant cold planet. Unfortunatelly, Brownian motion of hellium atoms in vacuum would restrict such experience to rather high pressure range only, as the liquid hellium never freeze at room pressure.
not rated yet Jan 13, 2009
Room temperature supersolids would be so AWESOME! No end to the practicle applications of efficiency and such forth. I want skis with supersolid edges. Go from zero to dead in 60 seconds flat.
not rated yet Jan 14, 2009
You can get liquid crystals, which is conceptually the same stuff - just not superfluous...

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.