Today's computers obey the laws of
classical physics -- the good ole stuff that we all learned in high school --
Newton's apple bouncing off his head, or something like that. Fundamentally, our computers follow the laws of our everyday reality. Underneath that reality however, is another world -- the world of quantum mechanics -- a world that is not as well understood, still hotly debated, and understood with as many theories as there are laws. In classical computers, bits can only have two states -- 1 or 0. Binary. From a macro level (and this includes the nano scale world) the universe is governed by the nature of this duality. Either or. Never and. Quantum mechanics, and correspondingly, quantum computing have more states. A quantum bit, or qubit, can exist as a 1, 0 or both at the same time, with varying probability of being one or the other. These states can be observed only at the quantum level -- which is very, very small. (Click here for an introduction to
Quantum Computing.) The promises of quantum computing however, are very, very large. A quantum computer, using just 14 calculating atoms, could perform 16,384 simultaneous calculations, more than the fastest supercomputer out there. Research into quantum computing has been going on in labs across world ever since
Richard Feynman speculated in the late 1980s that one way of simulating a
quantum mechanical system would be to use a quantum computer (Feynman had such strange notions
back in 1959 as well). Since then, quantum systems have been assembled, although they hardly constitute a computer. Recently, there appears to be a wake up call in the US.
Darpa has proposed a program, called
Focus Quantum Systems, which aims to build a quantum computer capable of factoring a 128-bit number (the common standard of online encryption) in 30-seconds, with 99.99% accuracy. The US government isn't alone in their quest -- yes, university labs having been working on the problem for a while -- but companies are also increasing their research spending in this direction.
Microsoft has employed mathematician
Michael Freedman to explore the topic.
HP is researching the ways to exploit quantum effects in
molecular electronics.
IBM is looking at ways of generating qubits in the area of
spintronics. Whether quantum computers can be built or not is still a question however -- their promises to revolutionize the computing industry and the world as we know it though is too much of a lure for the possibility to be ignored. For more information, check out these links:
Simulating Physical Systems by Quantum Networks [PPT] - a presentation by J.E. Gubernatis of the Los Alamos National Laboratory. This is a technical presentation, but it is illustrative.
Feynman, Einstein and Quantum Computing [PPT] - this is an introductory presentation on quantum computing.
