Physicists design an atomic laser that can last “forever” | Science and Ecology | Dr..

Conventional lasers produce a coherent light wave, which means that all the light vibrates synchronously. For its part, according to quantum mechanics, particles such as atoms must also be considered waves, and thus, technically speaking, an “atom laser” that contains coherent waves of matter can be built. However, the problem is to make these matter waves so durable that they can be used in practical applications.

Now a team of physicists from Amsterdam has shown that this is possible with some fiddling with the concept behind the atomic laser, the so-called intense Bose Einstein, or BEC for short. According to a press release. the study Posted in temperamental nature.

Bose-Einstein condensation

Elementary particles in nature come in two types: fermions and bosons. Fermions are particles like electrons and quarks, the basic building blocks of matter that we are made of. Bosons are of a completely different nature: they are not hard like fermions, but soft: for example, they can pass without a problem.

The best known example of a boson is the photon, the smallest possible amount of light. But the particles of matter can also combine to form bosons; In fact, whole atoms can behave like particles of light. What makes bosons so special is that they can all be in exactly the same state at the same time, or in a more technical sense, they can “condense” into a coherent wave. When this type of condensation of matter particles occurs, physicists call the resulting matter Bose-Einstein condensation.

difficult synchronization

In everyday life, we are not familiar with such capacitors at all. The reason: It is very difficult to make all atoms behave as one. The reason for the destruction of synchrony is temperature: when a substance is heated, its constituent particles begin to move and it becomes virtually impossible to make them behave as one. Only at extremely low temperatures, about a millionth of a degree above absolute zero (about minus 273 degrees on the Celsius scale), is there a chance for coherent matter waves to form from BEC.

A quarter of a century ago, the first Bose-Einstein condensers were created in physics laboratories. This opened up the possibility of building atomic lasers, devices that literally shoot beams of matter, but these devices can only work for a very short time.

The laser can produce pulses of matter waves, but after that pulse is sent, a new BEC must be generated before the next pulse is sent. As a first step towards atomic lasers, it wasn’t bad at all. In fact, ordinary optical lasers were also manufactured in a pulsed variant before physicists could produce a continuous laser.

A long way to atomic laser

But while developments for optical lasers have proceeded very quickly, with the first continuous lasers produced within six months of their pulsed counterpart, for atomic lasers, a continuous version has remained elusive for more than 25 years.

It was clear what the problem was: BECs are very fragile and are quickly destroyed when light falls on them. However, the presence of light is crucial to the formation of capacitors: to cool a substance to a millionth of a degree, its atoms must be cooled by laser light. As a result, BECs have become limited to transient bursts, with no way to maintain them consistently.

A team of physicists from the University of Amsterdam has now managed to solve the difficult problem of creating a continuous Bose-Einstein capacitor.

What the trick is, Florian Schick, the team leader, explains in a statement. “In previous experiments, the gradual cooling of the atoms was done in one place. In our setup, we decided to distribute the cooling steps not over time, but over space: we make the atoms move as they move through successive cooling steps. Ultimately, the extremely cold atoms reach the heart of the experiment, where They can be used to create coherent material waves in the BEC, but while using these atoms, the new atoms are already on their way to regenerating the BEC and we can keep the process going forever.”

FEW (Europe Press, University of Amsterdam, temper nature)

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