Scientists have created the smallest engine ever, in which the piston and connecting rod are replaced by a single atom of calcium.
By alternately heating and cooling the electrically-charged atom, an ion of calcium-40, they were able to turn heat energy into useful work.
In principle, this is exactly the same process as occurs in the petrol-powered internal combustion engine in a car, but this unimaginably small motor could prove to be many times more efficient.
Johannes Rossnagel, a physicist at the University of Mainz in Germany, describes the breakthrough in the journal Science.
In his experiment, the calcium ion – a million times smaller than a human hair – is confined in a linear Paul trap.
This is a device that can trap and hold atoms in a force-field of electrical energy.
Its invention won the Nobel Prize for physics in 1989 for Wolfgang Paul, after whom it is named.
The Paul trap used in this experiment has tapering geometry, being wider at one end than the other.
To drive the engine, heat and cooling is applied to the calcium ion.
Heat is provided by stimulating electrical ‘noise’ in the trap, which can be turned on and off.
Cooling is provided by a laser, and is continuously on.
The geometry of the trap means that the ion oscillates back and forth within the electrical field as it is heated and then allowed to cool.
The force created is proportional to the temperature, and the researchers report the work produced can be stored and used to drive a harmonic oscillator against friction.
A conventional internal combustion engine can never have a thermodynamic efficiency greater than about 25 per cent.
This is called the Carnot limit, after the Frenchman who first described the mathematics, Nicolas Carnot, almost 200 years ago.
This new engine has already exceeded that limit, achieving an efficiency of 28 per cent, and the researchers hope to enhance it further to produce even more efficiency.
Mr Rossnagel said: ‘Our results demonstrate that machines can be reduced to single atoms. This offers a platform for future experiments into single-ion refrigerators and pumps, and the exploration of genuine quantum effects in thermodynamics.’
Read more: http://www.dailymail.co.uk/sciencetech/article-3540285/World-s-tiniest-engine-size-ATOM-Breakthrough-paves-way-powerful-quantum-machines.html#ixzz45tW6qMDm
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Powerful quantum machines? That’s great. I’ll take 30 billion of them, and maybe they’ll push my truck down the road.