Quantum Leaps


Technodoomster Bill Joy, the Sun Microsystems "chief scientist" who recently fretted in Wired that "it is far easier to create destructive uses for nanotechnology than constructive ones," must be despondent at the recent rapid progress of research in that field. Nanotech is the still speculative but increasingly plausible notion of computing and manufacturing at the molecular level.

Earlier this year IBM scientists announced that they had created an atomic-scale circuit based on "quantum mirages." The mirage appears in a quantum corral measuring 20 nanometers across. (A nanometer is around 40 billionths of an inch—about five atoms placed side by side.) The elliptical corral was created using cobalt atoms precisely placed by a scanning tunneling microscope on a copper surface. When an additional cobalt atom was put inside the corral at one of the foci of the ellipse, the quantum waves transmitted a weak duplicate image or "mirage" of the atom to the other focus in the corral. This technique makes it possible to transmit information without using wires and allows for far greater densities of circuits, which would need far less power to operate.

Still, Joy can relax for a few more years. "We must make significant improvements before this method becomes useful in actual circuits. Making each ellipse…is currently impractically slow," researcher Hari Manoharan noted in IBM's press release. "They would have to be easily and rapidly produced, connections to other components would also have to be devised and a rapid and power-efficient way to modulate the available quantum states would need to be developed."

But there's been progress on that front, too. Using tunneling magnetic junction random access memory (TMJ-RAM for short), IBM's Stuart Parkin is devising new memory chips that will be ultra-fast, will consume less power, and will retain stored data when a computer shuts down. Unlike conventional semiconductor chips, which operate using the charge of electrons, Parkin's chips exploit a weird quantum mechanical property called "spin."

Every electron exists in one of two states, spin-up or spin-down. Spintronic researchers sandwich gold atoms between two thin films of magnetic material that act as filters or valves, permitting electrons in one of the two spin states to pass. A tiny burst of current can change the state of the filter and thus the spin of the electrons. Once they pass through the filters, the atoms keep their spin state indefinitely, so the memory doesn't need any power to maintain it. Furthermore, spintronic devices can be made vastly smaller than electronic devices.

Asked how such technology will evolve in the future, Parkin made a prediction that would no doubt send an eschatological chill down Bill Joy's spine. "It will be completely integrated and pervasive, like a sufficiently intelligent black box that will take care of everything for you—even work for you," he said. "This invisible interface and seamless technology environment will be all around us."

If history is any guide, failing to let people take advantage of such technologies will be far more risky for humanity than the timid stagnation Joy evidently prefers.