The researchers had to create a new technique from strontium atoms to achieve their goal and thus meet the challenge of continuously maintaining the emission of coherent matter wave pulses.

Agroup of scientists from the University of Amsterdam (The Netherlands) announced last Wednesday, through a statement, that they had developed an atomic laser that has the particularity of remaining on continuously.

According to those responsible for the scientific project, published in the journal Nature, for the construction of the device they were based on the principle of Bose-Einstein condensation (BEC, for its acronym in English), which is a state of matter created by certain atoms when they are at considerably low temperatures, close to absolute zero (-273.15 degrees Celsius).

This ‘exotic’ state allows atoms to be converted into what scientists call coherent matter waves. However, when there is an increase in temperature, the atoms do not stay together for very long. Due to this situation, atomic lasers work for a short time, since they do not produce pulses of matter waves continuously.

Trying to maintain the continuous generation of matter waves
To solve this problem, a continuous wave (CW) condensate was designed from strontium atoms, which allows the pulses to last indefinitely. According to the researchers, coherent matter waves are maintained by amplification by gaining atoms, which are stimulated by the BEC in a ‘thermal bath’. By subsequently restoring this ‘bath’, the condensation conditions remain as there is no increase in temperature.

“In previous experiments, the gradual cooling of atoms was done in one place,” said researcher Florian Schreck, who assured that using his “configuration” it was possible to “distribute the cooling steps not over time, but in space,” which allowed them “to move the atoms as they go through consecutive cooling steps.”

“In the end, the ultracold atoms get to the heart of the experiment, where they can be used to form coherent matter waves in a BEC,” Schreck said, adding that “while these atoms are being used, new atoms are already on their way” to replenish it, for which “in this way” it will be possible to “keep the process going, essentially forever.”

“Our experiment is the matter-wave analog of a CW optical laser with fully reflecting cavity mirrors,” the scientists explained, explaining that “this test demonstration provides a new, hitherto-lost piece of atomic optics that enables construction of continuous coherent matter wave devices’.

In 1997, physicists at the Massachusetts Institute of Technology (USA) created the first atomic laser, which emitted atoms instead of light. At the time, the researchers stated that, because the atomic laser can only operate in a vacuum, it was likely not to see as widespread use as the optical laser. “It will never be used in supermarket scanners or CD players,” asserted physicist Wolfgang Ketterle.