Experiments show theoretical speed limit to computer data storage

If there is an article of faith in computer science, it's that everything can keep getting faster and faster. <br><br>But scientists say they've discovered an apparent speed limit that will restrict

Friday, April 23rd 2004, 12:00 am

By: News On 6

If there is an article of faith in computer science, it's that everything can keep getting faster and faster.

But scientists say they've discovered an apparent speed limit that will restrict how quickly data can be written onto disks and then retrieved.

The good news: This limit is about 1,000 times faster than today's state-of-the-art data storage devices.

When information is stored on disks, minuscule regions that make up each bit of data are magnetized in one direction or its opposite, to represent a 0 or a 1. Rewriting data involves sending an electromagnetic pulse that reverses the spin of selected bits. Accelerate the pulse and you shorten the time needed to store or rewrite information.

But if the pulses come too quickly and intensely, the high energy involved makes some of the magnetic changes happen randomly instead of predictably and reliably, according to a group of researchers writing in Wednesday's edition of the journal Nature.

The scientists confirmed this problem by firing up the particle accelerator at Stanford University and blasting electrons at a piece of the magnetic material used to store computer data.

These pulses of energy traveled at nearly the speed of light, and lasted just 2.3 picoseconds. A picosecond is a millionth of a millionth of a second.

The researchers noticed that the magnetic patterns left behind were somewhat chaotic, an unacceptable outcome when it comes to storing precise bits of data.

The project was led by researchers at Stanford and included a scientist at the Landau Institute for Theoretical Physics in Moscow and engineers at disk-drive maker Seagate Technologies LLC.

The group was the first to examine the physics of magnetic data storage with a particle accelerator, according to two scientists who were not involved in the experiments, C.H. Back of Germany's University of Regensburg and Danilo Pescia of the Swiss Federal Institute of Technology.

In an e-mail interview, Pescia said the experiments were important in that they showed that the speed of magnetic recording _ which already clocks in at several billion bits, or gigabits, per second in the fastest hard drives _ can still get 1,000 times faster.

``In order to go beyond this limit, some completely new technology will be required, of which we do not know anything yet,'' Pescia wrote.

However, Seagate's chief technology officer, Mark Kryder, said the project had few real implications for the data-storage industry.

``Certainly we are not going to start packaging linear accelerators into hard disk drives, so the kinds of speeds achieved in these experiments would never be observed in an actual recording device,'' Kryder said. ``It's not something that's going to impact anything we're contemplating in hard disk drives.''