The prospect of superconducting communications lines with 100 times the capacity of fibre optic telephone cables is opened up by successful experiments at Rochester University, New York, using a thin-film superconductor prepared at Cornell University. The scientists, using a thin film of superconducting ceramic a third of an inch long on a substrate of Zirconium Oxide cooled with liquid nitrogen, demonstrated that pulses with durations measured in nanoseconds – that is to say GigaHertz fre-quencies, passed through the material without any detectable distortion or attenuation. A transmission line made of the material could in the-ory operate at 1GHz or more, carrying 15m telephone conversations – and IBM scientists, commenting on the experiment to the New York Times, say that pulses of considerably shorter duration should be possible. Until the new results were reported, the three most widely-touted applications for high- temperature superconductors were interconnections in integrated circuits for superfast computers, low-loss electric power transmission, and generation of enormous magnetic fields for applications in transport – levitating low-friction trains, and in medicine. The Rochester-Cornell experiment adds super-high capacity terrestrial speech, data and vi-deo communications. The use of a thin film rather than a wire points up research findings published by IBM suggesting that superconducting ceramics laid down as films on a substrate can carry currents 1,000 times greater than can be carried by the same ceramics drawn out into wires.
