The miniaturization of the components of computer chips has proved unstoppable. In each new generation, those components are smaller and more tightly packed than they were in its predecessor. Progress has been so rapid that chip designers are approaching apparently fundamental barriers to further reductions in size and increases in density. One of these is imposed by the need to wire the components in a chip together, so that they can exchange signals. But, in a miniaturized version of the shift to wireless communication in the macroscopic world, a group of researchers led by Alain Nogaret of the University of Bath, in England, think they can make chips whose components talk to each other wirelessly.
At present, the electronics that transmit and receive the radio waves used in wireless devices are too large to be used within individual chips. But Dr Nogaret believes he can overcome this. Last week he and his colleagues at three other British universities, another in Belgium and a research institute in France won the money to try to build such a device.
The researchers intend to use the standard lithographic（平印刷板）techniques employed in chipmaking to coat a semiconductor with microscopic magnets. These magnets will generate local magnetic fields that point in opposite directions at different points on the chip's surface. Electrons have a property called spin that is affected by magnetic fields, and the team hopes to use an effect called inverse electron-spin resonance（谐振）to make electrons passing through the chip emit microwaves. .
The technique they are proposing is the reverse of the process in medical magnetic-resonance imaging. In MRI, the patient is placed in a strong magnetic field that causes some of his body atomic nuclei, which act like tiny magnetized spinning tops, to align themselves with the field. The nuclei are then zapped briefly with a second magnetic field that knocks them out of alignment with the first one. The coils in the scanning apparatus detect these magnetic changes, which are used to build up a map of the part of the body being examined. After a few seconds, the nuclei themselves with the field, radiating small amounts of energy as heat or, more rarely, as radio waves.
In chips, Dr Nogaret proposes to use the spin of the electron rather than the spin of the atomic nucleus. Electrons flowing through the chip would “see” a magnetic field that flips from one direction to the opposite every few hundred nanometres (billionths of a metre). This is the equivalent of zapping to the stationary object with an oscillating magnetic field of the sort used in MRI. The changing magnetic field would force the electrons to oscillate, too, but would not allow them to radiate heat. As a result, they would be forced to emit radio waves— or, rather, microwaves, which are similar but of shorter wavelength.
