 Today's powerful computers that run on microscopic transistor chips won't begin to match the speed of a totally different kind of computer which may be available 50 years from now, thanks to researchers at The University of Arizona in Tucson.
We all know that information technology has been driving our economic engine over the past decade or two. But for that to continue, a new paradigm for information processing will be needed by the middle of the next century. It looks like quantum information may be a candidate, there are no fundamental barriers in the way. There is no basic fundamental law that says this cannot be done. Still, it's going to be very hard.
Quantum computing has potential to shatter the entire concept of binary computing, the use of zero's and one's, "on" and "off," to represent information digitally.
Researchers at the University of New Mexico propose a new concept for how individual atoms might be controlled at the very quantum level for computers for the future.
The researchers at the Optical Sciences Center are now about to begin experiments to test their theory that neutral or chargeless atoms, trapped like individual eggs in an egg carton by a lattice created by interfering laser beams and super cooled to the point of zero motion, will work for quantum computing.
Researchers have succeeded in cooling light trapped atoms to the zero point of motion, a pure vibrational state that is the crucial initialisation step to using atoms as quantum information bits. The pure quantum state would be the logical zero for a quantum mechanical computer. The scientists' success at cooling atoms was no small achievement. Atoms in this super cooled state are colder than liquid helium by roughly the same factor that liquid helium is colder than the center of the sun.
The researchers have reported that their scheme for stacking atom filled optical lattices so the neutral atoms will sufficiently interact to make quantum logic operations possible. If the scheme works, the big advantage is that atoms can be easily accessible for laser manipulation but remain isolated from the surrounding environment. Random forces from the outside world that act on the tiny quantum bits is perhaps the greatest problem confronting researchers trying to build a real quantum computer.
In today's computers, transistors store and process information that is coded as a combination of the numbers "1" and "0." The transistors in these classical computers have decreased in size and increased in speed exponentially during the past decades. But in a couple of decades from now, conventional technology will no longer be able to increase computer performance, scientists predict.
So mathematicians, physicists and computer scientists visualise replacing transistors with single atoms, creating a new kind of computer where information is manipulated according to the laws of quantum physics. A quantum mechanical computer would manipulate information as bits that exist in two states at once.
A classical computer takes one input at a time, does its computation and gives you one answer. A quantum computer, very loosely speaking, allows you to enter all possible inputs at one time and perform all the corresponding computations in parallel. However, this is a very simplistic way of putting it. The laws of quantum physics only allow you to observe one of the many possible outputs each time you run the computer, so you have to be very clever about how you look at the results. Surprisingly, researchers have discovered that several classes of computational problems can be solved in ways that take advantage of quantum parallelism.
 Exactly how powerful is this quantum parallelism? A quantum computer would simultaneously carry out a number of computations equal to two to the power of the number of input bits. That is, if you were to feed a modest 100 bits of information into such a computer, the machine would process in parallel two to the power of 100 different inputs, or simultaneously perform a thousand billion billion billion different computations. The higher the number of bits fed into such a computer, the exponentially greater advantage a quantum mechanical computer has over a classical computer.
Computational scientists have proved in theory that a quantum mechanical computer can solve a number of problems conventional computers cannot. At the moment, one of the driving motivations for developing a quantum mechanical computer is that it can be used to crack secret codes and on the flip side, to communicate information more securely. A quantum mechanical computer could crack a code encrypted for security with a 200 bit number, a problem that would take current classical computers the age of the universe to solve. A quantum mechanical computer could also send information that is fundamentally impossible to decode by anyone other than the intended recipient.
It is important to be honest and say that physicists and computational scientists are far from done with the study of quantum information, and it's not really yet known what kinds of problems such computers might do better than a classical computer, and which you won't do any better than can already be done by classical computers.
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