IBM Develops Advanced Quantum Computer

N E W   Y O R K, Aug. 15, 2000 -- IBM said today it had developed the world’s most advanced quantum computer, a device based on the mysterious quantum physics properties of atoms that allow them to worktogether as a computer’s processor and memory.

International Business Machines Corp. said the computer, which uses five atoms to work as itsprocessor and memory, demonstrates for the first time thepotential of such devices to solve certain problems at a rateremarkably faster than conventional computers. The experimentalmachine is considered the next step toward a new class ofdevices capable of superfast calculations.

“A quantum computer could eventually be used for practicalpurposes such as database searches — for example searching theWeb could be sped up a great deal — but probably not for moremundane tasks such as word processing,” said Isaac Chuang, theIBM researcher who led the team of scientists from IBM,Stanford University and the University of Calgary.

Code-Breaking Machine

A quantum computer could also be used for cryptography, orthe making and breaking of codes. This has drawn the interest ofthe U.S. National Security Administration and the Department ofDefense, which are funding Stanford’s efforts to build thequantum computer.

The current method of creating processors, which are becomingincreasingly smaller and more powerful as described by an axiomknown as Moore’s Law, is expected to reach a barrier sometime inthe next decade or so. This process, lithography, will not allowfor the creation of microchips the size of molecules, promptingresearchers to try to build computers by using genetic strands ordeveloping other tiny technologies.

“Quantum computing begins where Moore’s Law ends — aboutthe year 2020, when circuit features are predicted to be the sizeof atoms and molecules,” said Chuang. “Indeed, the basicelements of quantum computers are atoms and molecules.”

Chuang said in an interview that his team used the testquantum computer to solve a typical mathematical problem usedin cryptography — finding the period of a function. The computerwas able to solve any example of the problem in one step, while aconventional computer would require repeated cycles to solve theproblem.

Chuang said the experiment showed the viability of thequantum computer.

“I think this experiment shows we are on a pathway which ispredictable and understandable, that quantum computers will beuseful someday,” he said.

Physics Behind It

The quantum computer is based on the spin of an electron oratomic nucleus, and the strange properties of quantum particlesin which they can spin simultaneously in different directionsif they are not observed.

When the spin of a particle is up, the atom can be read as aone, and the spin down can be read as a zero, corresponding tothe digital ones and zeros that form the binary language oftraditional computers. Such devices use transistors, which areturned on and off to represent the ones and zeros.

What makes quantum computers unique, however, is that quantumparticles can also be in a state of “superposition” — spinningsimultaneously up and down.

“Due to their small size and if they are very wellisolated, they can be spinning up and down at the same time,”said Chuang.

This state would represent both zero and one and everythingin between. Instead of solving the problem by adding all thenumbers in order, a quantum computer would add all the numbers atthe same time.

This phenomenon permits a quantum computer to have enormouspower, Chuang said. For certain types of calculations, likecomplex algorithms for cryptography or searches — a quantumcomputer using several hundred more atoms in tandem would be ableto perform billions of calculations at the same time.

However, it is unclear when such a computer would becommercially available. Chuang said it is expected that betweenseven and 10 atoms will be used in tandem in more advancedquantum computers within the next two years.