The day is fast approaching when miniaturization of silicon computer chips will be so extreme that classical physics will no longer be able to describe how electrical charges flow through them. Design principles that have worked for decades will be out the window.

And that may not be such a bad thing, according to Hrvoje Petek, a professor of physics and chemistry at the University of Pittsburgh.

Petek, working with collaborators at Japan's National Institute for Materials Science, has used ultrashort laser pulses to explore silicon's quantum mechanical properties, which will come into play as silicon transistors eventually shrink to dimensions similar to the thickness of a bacterial cell wall.

As reported in today's issue of the journal Nature, the Pitt experiment triggered the birth of a "quasiparticle," an entity in the strange world of quantum mechanics, the physical principles that hold sway at atomic scale. Petek believes this quasiparticle has properties that could be exploited to improve electronic devices.

Lasers might someday be used to control silicon devices, he said.

"And if we learn how to do that, we could have transistors that work on the order of 1,000 times faster than they do at present," he added.

That's speculation, of course. But the measurements that the researchers made using a one-of-a-kind laser that Petek built "are truly a tour de force," said Alfred Leitenstorfer, a physicist at the University of Konstanz in Germany, who wrote a commentary that accompanied Petek's article.

It's not yet clear whether the phenomena observed in this experiment directly match what typically occurs in silicon semiconductors, Leitenstorfer said. But the article poses a number of fascinating questions that scientists ultimately will have to answer.

"The day will come when quantum physics directly influences the functionality of computers and other electronic equipment that we use in everyday life," he wrote. "The question is: when?"

Since computer chips were first invented four decades ago, engineers have progressively packed more and more transistors onto each chip, making the chips cheaper and more powerful. But packing more transistors into the same space means making each transistor smaller.

Within the decade, Petek said, transistors may be smaller than 50 billionths of a meter, or 50 nanometers. And Leitenstorfer suggests they might well drop below 10 nanometers.

Today, the flow of electrical current can be explained as the movement of electron particles through a silicon crystal. But as dimensions shrink to tens of nanometers, electron behavior will bear greater resemblance to a wave than to a particle, Petek said, and chip design will need to change accordingly.

In his latest experiments, Petek used very short bursts of ultraviolet laser light -- 10 femtoseconds, or 10 quadrillionths of a second in duration -- to excite a piece of silicon, transforming it from an electrical insulator into a conductor.

What he found is that at these very short time scales and small dimensions, the movement of the electrons and the normal vibrations of the atoms in the silicon crystal do not behave as separate entities. Rather, they become entangled, as quantum physicists put it, forming a quasiparticle that somehow has some characteristics of the vibrating atoms and some characteristics of the electrons.