Synopsis: Steps toward a new quantum fluid

Experimenters have created overlapping quantum fluids of lithium and ytterbium, en route to creating quantum fluids of molecules that have unpaired electronic spins.
Synopsis figure
Credit: H. Hara et al., Phys. Rev. Lett. (2011)

Physicists regularly trap and cool atoms with lasers to form quantum fluids such as the Bose-Einstein condensate, but some researchers have recently shifted their attention from atoms to molecules, whose internal complexity could give rise to new phenomena.

One way to do this is to cool pre-existing molecules, and so far, it has been possible to cool a diverse set of molecules, though not yet to both high densities and ultracold temperatures. An alternative method is to first cool overlapping clouds of individual atoms and only then coax them into forming molecules. Using this technique, researchers have created ultracold molecules from weakly bound pairs of different alkali metals, notably potassium and rubidium. But such molecules always contain an even number of spins, so that electrons with opposite spins tend to pair up. Hideaki Hara of Kyoto University and colleagues are instead working to make molecules that combine atoms from different columns of the periodic table, which will contain unpaired spins and should reveal new types of behavior.

As a step towards that goal, the researchers report in Physical Review Letters simultaneously trapping lithium and ytterbium. By weakening the trap to let the most energetic ytterbium atoms evaporate, they cooled the remaining ones to below a microkelvin. Collisions cooled the lithium-6 to the same low temperature, which was one tenth of its Fermi temperature. This degenerate state coexisted, in separate experiments, with either fermionic ytterbium-173 or bosonic ytterbium-174, each of which was also in the quantum regime. – Don Monroe


Announcements

More Announcements »

Subject Areas

Atomic and Molecular Physics

Previous Synopsis

Fluid Dynamics

Reluctant swimmers

Read More »

Next Synopsis

Materials Science

X rays scratch the surface

Read More »

Related Articles

Synopsis: Losing Light in a BEC
Atomic and Molecular Physics

Synopsis: Losing Light in a BEC

The index of refraction in a gas of bosons is enhanced relative to its value in a classical gas, a predicted quantum effect that has now been observed in ultracold sodium atoms. Read More »

Focus: Atoms As Thermometers
Atomic and Molecular Physics

Focus: Atoms As Thermometers

A small number of atoms in repeated trials can accurately measure the temperature of an ultracold gas cloud—a step toward measuring temperature on the micrometer scale. Read More »

Synopsis: Bad Cavities for Precise Lasers
Optics

Synopsis: Bad Cavities for Precise Lasers

The frequency of a laser based on trapped ultracold atoms can be made insensitive to fluctuations in the laser cavity’s length. Read More »

More Articles