Academic journal article Informing Science: the International Journal of an Emerging Transdiscipline

Quantum Computers: A New Paradigm in Information Technology

Academic journal article Informing Science: the International Journal of an Emerging Transdiscipline

Quantum Computers: A New Paradigm in Information Technology

Article excerpt

"Our greatest glory is not in never failing but in rising up every time we fail"--Ralph Waldo Emerson

"Let chaos reign. Resolution comes through experimentation. Only stepping out of the old ruts will bring new insights."--Andrew Grove, Chairman, Intel


In the last few years, the theoretical study of quantum systems serving as computational devices has achieved tremendous progress. An understanding of quantum mechanics has been absolutely central to today's high-tech, wired world. Without it, computers, television, satellites, telephones and most other modern gadgets would probably not be as sophisticated and plentiful as they are now. The subject of quantum computing brings together ideas from classical information theory, computer science, and quantum physics. Information is something that can be encoded in the state of a physical system, and a computation is a task that can be performed with a physically realizable device. Therefore, since the physical world is fundamentally quantum mechanical, the foundations of information theory and computer science should be sought in quantum physics.

Imagine a computer whose memory is exponentially larger than its apparent physical size or a computer that can manipulate an exponential set of inputs simultaneously. Relatively few and simple concepts from quantum mechanics are needed to make this concept of quantum computers a possibility. A quantum system is in general not in one "classical state", but in a "quantum state" consisting of a superposition of many classical or classical-like states. In fact, quantum information--information stored in the quantum state of a physical system--has weird properties that contrast sharply with the familiar properties of "classical" information. The quantum computer--a new type of machine that exploits the quantum properties of information--could perform certain types of calculations far more efficiently than any foreseeable classical computer.

In describing a computer as a cup of coffee one may be doing so literally since the new computer of tomorrow might be based on molecules in a liquid instead of silicon. This may prove to be a paradigmatic shift in the way we manage information technology today.

Evolution of Computers

As civilization marched forward in search of better ways of doing things, the various physical resources, such as materials, forces and energies, were exploited for their potentials. From the gears of the first Pascal calculating machine in 1642, to the relays and valves of the first decoder in WWII made by Great Britain, to the transistors and integrated circuits of today, the ever-shrinking computer brought forth improvement in speed and functionality. A state-of-the art IBM chip with 0.25 micron features contains 200 million transistors. That single chip is sized about 1/4 of a penny. Present 'state-of-the-art' components possess features only a few hundreds of nanometres across (a nanometre is a thousandth of a micron, or a billionth of a metre).

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Limits In Miniaturization

The continual miniaturization of the transistor over the last few decades has enabled computing power to double every couple of years. As transistors became smaller more could be integrated onto a single chip. However, this miniaturization is now reaching a limit set by nature: a quantum threshold below which principles of transistors will no longer hold true. In other words, there is a limit to the miniaturization of a computer based on silicon. Also one of the difficulties with the program of miniaturizing conventional computers in trying to build a classical computing machine on such a small scale is the difficulty of dissipated heat. If these chips were to be miniaturized further to the scale of tens of nanometres then their operation would be disrupted by the emergence of quantum phenomena, such as electrons tunneling through the barriers between wires. …

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