Word: quantum
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Ordinarily a row of 10 bits (think of them as tiny switches turned on or off) can hold any one of a thousand different numbers (1,024 to be exact). But a row of 10 qubits, because of its quantum nature, can hold all the numbers at once. To find the square root of every number from 1 to 1,000, you would load them all onto a row of 10 atoms, perform a single calculation, and--voila--all the answers would appear...
Mathematicians have proved that a quantum computer with thousands of calculating atoms could rapidly find the factors of numbers hundreds of digits long--a problem that would take the best conventional supercomputers billions of years. Since the codes used to protect corporate and military secrets are based on factoring, this development is of more than academic interest. Program a row of atoms to scan huge databases of information, and the result could be, among other things, the ultimate chess master, a quantum Deep Blue...
Though nothing in the laws of physics rules out quantum computers, qubits are maddeningly delicate. Experiments must be done at temperatures near absolute zero, and the slightest disturbance can cause the teetering quantum states to collapse. Given such obstacles, quantum computing's accomplishments have so far been rather modest: using a short string of atoms to find the factors of the number 15 or to search a "database" of eight items...
What happens from here on out depends on the kind of technological advances that are always hard to predict. About the same time that Schrodinger unleashed his quantum cat, the British mathematician Alan Turing was sketching out the theory of the modern digital computer. A decade later, during World War II, Turing was helping program Colossus, a room-size electronic calculating machine that used 1,800 vacuum tubes to crack German codes. The abstraction had become real...
George Johnson's newest book, A Shortcut Through Time: The Path to the Quantum Computer, was published this month by Alfred A. Knopf