In new research, scientists reveal a special laser made with a Bose-Einstein Condensate that can run forever. The secret is to manipulate the atoms, themselves, into behaving as contained waves, a principle that underpins quantum mechanics. A team of physicists from the University of Amsterdam, most from the Van der Waals-Zeeman Institute, conducted this research on the nature and duration of atom lasers. They published their findings on June 8 in the journal Nature.
A Bose-Einstein condensate (BEC) is a special phase of matter where the atoms combine into a homogeneous cloudy mass that acts as one body. Researchers must specially treat the atoms both to get into BEC state and to stay there, but the matter has special properties while in this phase. Typically, BECs are induced by taking very sparse gases and cooling them so that their interactive properties are further diminished. It’s at this point that the branches between atoms start to express themselves on a macroscopic level. Thus, the BEC is formed.
Technically, classic lasers use light energy, rather than so-called “matter.” A matter laser would unlock applications that a traditional laser is simply not good for, in the same way the traditional laser itself was an improvement over mere light; everything iterates in the sciences. And while before now there has only been a pulsing BEC laser, scientists from this project point out that that, too, was a waypoint on the road to a continuous traditional laser. And now they say they’ve broken the barrier to a continuous matter laser.
But how? It takes a lot of energy and upkeep to hold a BEC in that state. First, the BEC must stay nearly “supercooled,” meaning lowered to its freezing point without becoming a solid; and second, it must be replenished with new atoms in order to replace those that pair off into molecules and fall out of the cloud. It’s common to use lasers to slow the atoms to supercooled range, but light itself is risky for the BEC cloud. This has been one of the obstacles to commercializing BECs or using them on a large scale—they’re costly in energy and resources. Or are they?
“Here we demonstrate the creation of a [continuous wave Bose-Einstein condensate] that can last indefinitely,” the team writes in their paper. “Our experiment comprises both ingredients, gain and continuous supply. The centrepiece of the experiment consists of a large ‘reservoir’ that is continuously loaded with [strontium] atoms and that contains a small and deep ‘dimple’ trap in which the BEC is created. The gas in the reservoir is continuously laser-cooled and exchanges atoms and heat with the dimple gas.”
Their clever design, using a bigger space as well as a second laser, allows the atoms to sift around and cool and replenish themselves in a more natural process. That keeps the supply of atoms near constant and allows the BEC laser to keep running. The pulsing of the past has become continuous at last.
“This proof-of-principle demonstration provides a new, hitherto missing piece of atom optics, enabling the construction of continuous coherent-matter-wave devices,” the team concludes. In other words . . . Let’s do this thing.