Qubit Twist; April 2005; Scientific American Magazine; by Charles Q. Choi; 1 Page(s)

Before the advent of electricity, the first computers were mechanical, with the Difference Engine invented by Charles Babbage tackling logarithms and trigonometry 150 years ago. Now advanced quantum computers might go back to mechanical roots, using rows of nanometer-scale bars as moving parts.

The bizarre laws of quantum physics suggest that items the size of molecules and smaller can exist in two or more places or states at the same time. An observation or some other action forces them to collapse out of this "superposition," leading to just one outcome. In theory, because quantum bits, or "qubits," can exist in both an on and off state simultaneously, a quantum computer with just 300 qubits can run more calculations in an instant than there are atoms in the universe.