You want to search the eight trillion bytes of data currently held in the world wide web for a name. How do you go about it?
It would take a conventional computer at least a month to scan through this much data, so this is not an option. You could however use a "quantum computer", the next horizon in computing which so far exists largely in theory. A quantum computer should be able to do this search in no more than 27 minutes. Such a machine would also be an impressive number cruncher. Even a very small device would be able to execute a simultaneous computation on 2s0] numbers.
Dr Jason Twamley, of the Department of Mathematical Physics at NUI Maynooth, is studying quantum computing including the theoretical and practical aspects of storing and manipulating quantum information.
These potential new systems take their name from the quantum mechanics on which they are based, Dr Twamley explained. Quantum mechanics describes the behaviour of the world on the smallest possible scale, down at the level of atoms and molecules.
Newton's laws are fine when dealing with cars or planets or solar systems, but these predictable laws don't hold so well at the molecular level. Strange things occur in this realm where motion and processes are discontinuous and highly random, taking place in discrete steps that can happen instantaneously.
One of the key properties the one which makes quantum computing a possibility is known as "quantum superposition". An atom can be zapped with a laser, putting it into a quantum superposition of two or more energy states. In this condition the atom can exist in a multiplicity of possible energy levels all at the same time, something like a flipped coin being heads and tails simultaneously.
This runs against our "real world" intuition which suggests it should have one unique energy level, but things quickly get more confusing in the quantum world. If an observer tries to record the atom's energy two things happen. The measured energy is random and if you repeat the process you may get a different answer. Second, the atom will change its quantum state simply because you read it.
Superposition is a difficult concept and seems to defy logic, Dr Twamley admits. "The good thing about it is that the scientists don't understand it either."
This however has not prevented mathematical physicists from trying to use it to develop computers at a molecular level. It is like the air, Dr Twamley suggests. You can't see it or hold it but you can predict its movements and can employ it to do useful things like drive a windmill.
"Up until now people have been looking at quantum mechanics as something to study rather than something to use," he said. Experimental advances have opened up the possibility of "quantum engineering", the building of tiny quantum devices that can actually do computations. One such quantum device involves trapping a few ions and then cooling them down to near absolute zero. Ions that might move at velocities of many metres per second move at only a metre per hour when chilled to this level, allowing researchers to observe the quantum effects in their slow motion.
A team at the University of Innsbruck has assembled six calcium ions described as quantum bits or qubits in a row and researchers are studying how the chain is affected when a quantum state is induced.
Six such "switches" in a digital computer wouldn't hold much 36 combinations of on or off. Remember however that in a quantum state the on, off and an apparently infinite number of conditions between these two can exist simultaneously in the six qubit chain, giving a vast number of possibilities.
Software for theoretical quantum computers is also being developed. Dr Peter Shor of AT&T Bell Labs developed an algorithm based on quantum computing which theoretically could break most known methods of cryptographically encoding information. If run on a quantum computer Shor's algorithm would render even the most sophisticated banking or security encryption system transparent.
"The quantum computer can work on a whole combination of inputs simultaneously," Dr Twamley explained. "That is a big departure. It can hold a different kind of information than digital information. There is an extra degree of freedom there."
Another more recent algorithm developed by Dr Lov K. Grover of Bell Labs would allow a quantum computer to search a database at lightening speed, making an internet-wide search for a single item or word a possibility.
The problem in all of this is creating the computer. The Shor algorithm would need a quantum computer with about 2,000 qubits. The main problem in building them is their sensitivity to the smallest amount of "noise" in the form of heat or light.
NUI Maynooth, Trinity College and the Dublin Institute for Advanced Studies are planning an international conference on quantum computing. It takes place at Trinity on October 30-31 and will include workshops and tutorials on the potential for quantum computing. The registration website address is: www.thphys.may.ie/qc.html