Computers the size of dust particles could be fabricated thanks to newly developed light sources, which achieve high efficiency at low power.

Networks of minuscule computers, although potentially useful, can supply very little power to their components. This makes it difficult to produce the light or radio pulses needed for communication across the network. Light-emitting diodes (LEDs) operated at low power, for example, tend to produce more heat than light.

To address this problem, Ning Li and his colleagues at IBM in Yorktown Heights, New York, built a new type of quantum well, a structure contained in LEDs. It traps electrons and holes, which carry negative and positive charges, respectively; the two can combine to emit either light or heat. The team’s quantum well incorporates layers of various semiconductors that allow it to slow heat generation and speed up light generation, increasing the likelihood of the LED emitting a photon at low power.

The researchers built a miniature LED that can provide communication signals on a power consumption of only 1.1 microwatts — significantly lower than that of conventional LEDs — and are using it to make a computer smaller than one millimetre square.