Image of a cloud of cesium molecules in Bose-Einstein condensate.
For the first time, scientists have achieved a state in which many molecules are aggregated together into a single state at a low temperature close to absolute zero and behave like a single quantum body, also known as a Bose-Einstein condensate (BEC) molecular cloud. This technology provides a good experimental platform for developing these new materials, such as superconductors at room temperature.
Previously, scientists have realized frozen atomic clouds, where a large number of atoms come together at low temperatures in a completely stationary state to form a high-density cloud of atoms that behaves as a whole like a single “superatom”.
The Bose-Einstein condensed state is also often referred to as the fifth state in addition to the solid, liquid, gas and plasma states. Each microscopic particle of matter in this state has the same quantum properties.
Since the 1990s, scientists have been studying Bose-Einstein condensed states composed of various atoms. But for molecules, it’s much harder to cool them to that low temperature.
“There’s no way to cool them down to a point where there’s no way to keep them cool,” says Cheng Chin of the University of Chicago, the principal investigator of the new study.
The group found a new way to cool the molecules to near absolute zero with the energy of a laser removing them, successfully allowing several thousand cesium molecules to form a single Bose-Einstein condensed state.
The researchers first created a single, atomic Bose-Einstein condensate, then applied a magnetic field to them to induce the atoms to bond in pairs to form molecules. A very wide, but very thin, laser beam is then used to hold these molecules in place, maintaining the morphology of a flat sheet of atoms.
This allows them to maintain a stable molecular structure and remain in a Bose-Einstein condensed state at temperatures as low as 10 nanometers Kelvin, which is very close to absolute zero.
This state is the ideal initial state for conducting R&D experiments, Qiancheng said, because a lot of instability is reduced in this state. “They act together and form a whole. They are like one giant molecule.”
Peter Krüger of the University of Sussex says, “They are taking a technology that has been implemented at the atomic level for almost 25 years to a new level. This level is much more complex.” Krüger believes the breakthrough will pave the way for the development of room-temperature superconducting materials.
The study was published April 28 in the journal Nature.