Physicists say they’ve built an atomic laser that can last ‘forever’

(ORDO NEWS) — A new breakthrough has allowed physicists to create a beam of atoms that behaves just like a laser, and which theoretically can work “forever”.

This may finally mean that the technology is at its development stage. way to practical application, although there are still significant limitations.

However, this is a huge step forward for the so-called “atomic laser” – a beam of atoms moving as a single wave that can be used to test fundamental physical constants and precision engineering techniques.

Atomic lasers exist for only a minute. The first atomic laser was created by a group of physicists at the Massachusetts Institute of Technology back in 1996.

The concept sounds pretty simple: just as a traditional light-based laser is made up of photons moving in sync with their waves, an atom-based laser would need a wave of its own. -like nature to straighten out before crumbling like a log.

However, like many things in science, it is easier to think about than to implement. At the heart of an atomic laser is a state of matter called a Bose-Einstein condensate, or BEC.

The BEC is created by cooling a cloud of bosons to a fraction above absolute zero. At such low temperatures, atoms plunge into the lowest possible energy state without completely stopping.

When they reach these low energies, the particles’ quantum properties can no longer interfere with each other; they move close enough together that they seem to overlap, resulting in a high-density cloud of atoms that behaves like a single “superatom” or wave of matter.

However, BEC is a kind of paradox. They are very fragile; even light can destroy the BEC. Given that the atoms in the BEC are cooled by optical lasers, this usually means that the existence of the BEC is fleeting.

The atomic lasers that scientists have been able to create to date have been pulsed, not continuous type. ; and include starting just one pulse before a new BEC needs to be generated.

To create a continuous BEC, a group of researchers from the University of Amsterdam in the Netherlands realized that something had to change.

“In previous experiments, the gradual cooling of atoms was all done in one place. In our setup, we decided to separate the cooling stages not in time, but in space: we make the atoms move as they move through successive cooling stages,” explained physicist Florian Schreck.

“Eventually, ultracold atoms get to the center of the experiment, where they can be used to form coherent matter waves in the BEC. atoms are being used, new atoms are already on their way to replenish the BEC. In this way, we can support this process – almost forever.

This “heart of the experiment” is a trap that keeps the BEC protected from light as a reservoir that can be constantly replenished throughout the experiment.

Protect However, getting a BEC from the light produced by a cooling laser, while simple in theory, again proved a little more difficult in practice. There were not only technical difficulties, but also bureaucratic and administrative ones.

“When we moved to Amsterdam in 2013, we started with confidence, leverage, an empty space and a team. funded entirely by personal grants,” said physicist Chun-Chia Chen, who led the study.

“Six years later, in the early hours of Christmas morning 2019, the experiment was finally on the verge of going live. We had the idea to add an extra laser beam to solve the last technical problem, and instantly every image we took showed BEC, the first continuous BEC.”

Now that the first part of the continuous BEC atomic laser has been implemented – part of the “continuous atom” – the next step, according to the team, is to work on maintaining a stable atomic beam. They could achieve this by setting the atoms to an uncaptured state, thereby extracting the propagating wave of matter.

Since they used strontium atoms, a popular choice for BEC, the prospect, they say, opens up exciting possibilities. Atomic interferometry using strontium BEC, for example, can be used to conduct research on relativity and quantum mechanics, or to detect gravitational waves.

“Our experiment is analogous to the matter wave of a cw optical laser from a full mirror with a reflective cavity,” the researchers write in their paper.

“This experimental demonstration provides a new, hitherto missing part of atomic optics, allowing the creation of continuous devices with coherent matter waves.”

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