2001 Nobel Prize Winners

The last half of the 20th century, it has been argued with considerable justification, could be called the microelectronics era. During that 50-year period, the world witnessed a revolution based on a digital logic of electrons. From the earliest transistor to the remarkably powerful microprocessor in your desktop computer, most electronic devices have employed circuits that express data as binary digits, or bits - ones and zeros represented by the existence or absence of electric charges. The technologies that emerged from this simple logic have created a multi-trillion-dollar-per-year global industry whose products are ubiquitous. Indeed, the relentless growth of microelectronics is often popularly summarized in Moore's Law, which holds that microprocessors will double in power every 18 months as electronic devices shrink and more logic is packed into every chip.

As seen, from Moore's Law, the chip will run out of momentum one day as the size of features on a chip approaches the dimension of atoms - this has been called the end of the silicon road map.

So if computers are to become smaller in the future, new, quantum technology must replace or supplement what we have now. The point is, however, that quantum technology can offer much more than cramming more and more bits to silicon and multiplying the clock-speed of microprocessors. It can support entirely new kind of computation with qualitatively new algorithms based on quantum principles!

To explain what makes quantum computers so different from their classical counterparts we begin by having a closer look at a basic chunk of information namely one bit. From a physical point of view a bit is a physical system which can be prepared in one of the two different states representing two logical values --- no or yes, false or true, or simply 0 or 1. For example, in digital computers, the voltage between the plates in a capacitor represents a bit of information: a charged capacitor denotes bit value 1 and an uncharged capacitor bit value 0. One bit of information can be also encoded using two different polarisations of light or two different electronic states of an atom. However, if we choose an atom as a physical bit then quantum mechanics tells us that apart from the two distinct electronic states the atom can be also prepared in a coherent superposition of the two states. This means that the atom is both in state 0 and state 1.............

...... Experimental and theoretical research in quantum computation is accelerating world-wide. New technologies for realising quantum computers are being proposed, and new types of quantum computation with various advantages over classical computation are continually being discovered and analysed and we believe some of them will bear technological fruit. From a fundamental standpoint, however, it does not matter how useful quantum computation turns out to be, nor does it matter whether we build the first quantum computer tomorrow, next year or centuries from now. The quantum theory of computation must in any case be an integral part of the world view of anyone who seeks a fundamental understanding of the quantum theory and the processing of information.

Christopher Monroe and David Wineland, Science Spectra, in the press (web-article)

Julian Brown, The Quest for the Quantum Computer. San Francisco: Touchstone 2001

Paul Davis, The Fifth Miracle: The Search for the Origin and Meaning of Life. New York: Simon & Schuster, 1999

Paul Davis and Julian Brown, The Ghost in the Atom: A Discussion of the Mysteries of Quantum Physics. Cambridge: Cambridge University Press, 1993