Scientists have created the world's smallest engine, the size of a little more than one atom

Experimental physicists from the University of Mainz have created a nano-motor that can convert thermal energy into mechanical energy. At the same time, the size of the engine is slightly larger than an atom, and its efficiency is comparable to the efficiency of an internal combustion engine in a car.

Moreover, an engine paired with a single atom and enclosed in a cone of electromagnetic radiation works according to the principle of classical internal combustion engines - a four-cycle cycle during which expansion and cooling, compression and heating occur, as the experiment leader Johannes Roßnagel explains.
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Rossnagel was the one who first proposed the theoretical basis for a similar engine in 2014. First, an individual atom is trapped in the form of a cone of electromagnetic radiation, from which it cannot escape. And almost any atom will do - calcium-40 was used in a specific experiment.

Then two laser beams are directed to the EM cone. The laser, shining from the sharp end, heats the atom, and the other cools in the process of Doppler cooling . As a result, the atom begins to move inside the cone — in the heated state to the wide end, in the cooled state — to the narrow end. The process becomes more pronounced if the lasers are adjusted so that the periods of cooling and heating coincide with the natural oscillations of the atom.


Part of a laboratory setup laser system

As a result of the oscillations of the atom, they create mechanical energy that can theoretically be collected — for example, an ion placed from the sharp end of the cone will collect this energy like a flywheel in a car engine.

Physicists have noted that the fact that an atom follows essentially the same principles as a four-stroke internal combustion engine is very strange. Having calculated the efficiency of the “engine”, scientists obtained 1.5 kW per kilogram - a figure comparable to the engine's internal combustion engine.

In 2014, Rossnagel also outlined considerations regarding the increase in the energy output of the nano-motor (which has not yet been tested in the experiment). If, during the atomic motions, to force the electromagnetic cone to slightly expand and taper in a certain way, the atom will enter a quantum state known as " squeezed ", which as a result will lead to an increase in the efficiency of the engine.



True, you can’t put such an engine on a nanobot - if it itself has dimensions slightly more than atomic, then the installation that transfers energy to it takes up a whole room. But scientists did not set such a task for themselves - the purpose of the experiment was to study the possibilities of heat engines and to check the theoretical calculations. The possibility of practical application of such an engine is still in question.