Swiss scientists have managed to assemble one of the tiniest engines in the world: the system consists of exactly 16 atoms and works, according to the authors, on the border of classical and quantum physics. The nanodevice obtained by specialists from the Swiss National Laboratories for Materials Science (Empa) and the Federal Polytechnic School of Lausanne (EPFL) is presented in an article published in the journal PNAS… The size of the entire system does not even reach a nanometer.

Like conventional macroscopic motors, the system includes both a moving part (rotor) and a stationary part (stator). Only in this case, the stator is formed of six palladium and six gallium atoms, forming two equilateral triangles superimposed on each other. The rotor consists of a tetraatomic acetylene molecule.

It rotates in a random direction on the stator surface under the action of ordinary thermal energy, making several million revolutions per second at room temperature. However, if electricity is supplied to the device – the scientists did this using a scanning electron microscope needle – a steady flow of electricity causes the acetylene to rotate in the same direction 99 times out of 100. According to the authors, one turn requires six electrons.

This is achieved due to the nanoscale analogue of the ratchet mechanism. In a conventional ratchet, turning in the opposite direction is blocked by a pawl, which rests on teeth of a special asymmetrical shape. So in the “atomic engine”: the stator structure has no mirror symmetry, making the rotation of the acetylene molecule in one direction more preferable than in the opposite direction.

Under some conditions, the 16-atom nanodevice manifested its quantum nature as well. For example, the engine continued to run even when it received less thermal and electrical energy than the limit required for rotation, at temperatures below 17 Kelvin (minus 256 ° C) and an applied voltage of less than 30 mW. The authors explain this by the tunneling effect – the ability of microparticles to spontaneously overcome energy barriers, which has no analogues in our macroscopic world.

Scientists hope that someday such devices will be able to drive nanomachines – such as the “nanocrane” or “nanofactory”, which we wrote about earlier.