The light inside a laser is in sync. Particles like atoms should be thought of as waves according to quantum mechanics. We can buildatom lasers that contain coherent waves of matter. Can we make them last so that they can be used in applications? The answer to this question is affirmative according to research published in Nature.
Getting the bosons to move in a straight line.
The Bose-Einstein Condensate is the basis of the atom laser. fermions and bosons are elementary particles. The building blocks of the matter that we are made of are called perturbons. Unlike fermions, boisons are soft and can move through one another. The smallest amount of light is known as the photon. Particles of light can combine to form a new type of particle called a boson. bosons are so special because they can all be in the exact same state at the exact same time or they can "condense" into a coherent wave. The resulting substance is called a Bose-Einstein Condensate.
We don't know much about these condensates in daily life. It's hard to get atoms to all behave in the same way. It becomes almost impossible to get the particles to behave as one when the temperature goes up. Only at extremely low temperatures, about a millionth of a degree above absolute zero, is there a chance of forming the coherent matter waves of a bec.
There is a burst of fleeting.
The first Bose-Einstein Condensates were made 25 years ago. atom lasers were only able to work for a short time after this. After sending out a pulse of matter waves, a new BEC had to be created before the next pulse was sent out. This was still a step in the right direction. Physicists were able to create continuous lasers before ordinary optical lasers were made. It has been 25 years since the first continuous laser for atom lasers was produced, despite the rapid developments for optical lasers.
The problem was that BECs are very fragile and can be quickly destroyed. The presence of light is needed to cool a substance down to a millionth of a degree. BECs were limited to fleeting bursts because there wasn't a way to sustain them.
There is a Christmas gift.
The problem of creating a continuous Bose-Einstein Condensate was solved by a team of physicists. The leader of the team explained what the trick was. The gradual cooling of atoms was done in one place. We spread the cooling steps not over time, but in space, so that the atoms move while they progress through the cooling steps. Ultracold atoms arrive at the center of the experiment, where they can be used to make waves in a BEC. New atoms are on their way to replenish the bec. We can keep the process going indefinitely.
Carrying the idea out was not easy. The technique that allowed a BEC to be protected from laser cooling light was developed in 2012 by the team in Innsbruck. It was clear that a dedicated machine would be needed to take the challenge to the next level. We moved to Amsterdam with a leap of faith, borrowed funds, an empty room and a team completely funded by personal grants. The experiment was on the verge of working in the early hours of Christmas morning. We added an extra laser beam to solve a technical problem, and every image we took showed the first continuous- wave BEC.
The researchers have solved the open problem of creating a continuous Bose-Einstein Condensate and now want to use the laser to create a stable beam of matter. Nothing stands in the way of technical applications anymore, and matter lasers may start to play an equally important role in technology as ordinary lasers currently do, once their lasers can not only operate forever but can also PRODUCE stable beams.More information: Chun-Chia Chen et al, Continuous Bose–Einstein condensation, Nature (2022). DOI: 10.1038/s41586-022-04731-z Journal information: Nature