Heat engine built using a single atom

Science :Internal combustion engines, steam turbines, and other heat engines all generate power by converting thermal energy into mechanical energy. Now a team of researchers in Germany has constructed what is possibly the world’s smallest heat engine, which generates power from just a single atom of ionized calcium. The ion is confined in an 8-mm-long funnel-shaped electrical trap created by four electrodes. Another set of electrodes creates a randomly fluctuating electric field that transfers energy to the ion in a way akin to heat. The extra energy drives the ion to the wider part of the funnel, where it is hit by photons from a laser, which cools the ion down. The ion then returns to the narrower part of the funnel. By cycling the electric field on and off, the researchers can make the ion match the trap’s natural oscillation frequency, so that over time it travels farther and farther down the trap. When it builds up enough extra energy, a second laser is used to absorb the energy, about 10^–24 J. That might be enough to power a tiny electrical generator, but the device is more a proof of concept than an attempt to create a usable engine.