Information society

Another physics of the universe

A pioneer of the information sciences, Jozef Gruska is above all a theorist who is seeking to break down barriers, both geographical and in the realms of ideas. His work as professor at Masaryk University in Brno (CZ) brings him into contact with researchers from all over the world and is causing him to step outside traditional paradigms to develop an information science that embraces all the major scientific fields. The convergence of quantum physics and the information processing sciences is central to this approach.

Jozef Gruska – “The science of quantum data processing is the marriage of the two most important scientific fields of the 20th century: data processing and quantum physics. It would be very surprising if this marriage did not have major consequences.” Jozef Gruska – “The science of quantum data processing is the marriage of the two most important scientific fields of the 20th century: data processing and quantum physics. It would be very surprising if this marriage did not have major consequences.”

There has been much talk of quantum data processing over recent decades. What exactly is the situation today?

When the first theoretical concepts of quantum computers appeared in 1985, no more than about a dozen experts showed any real interest in them. It was not until between 1993 and 1996 that this discipline received special attention with the discovery, among other things, of quantumteleportation and the concept of error correction codes to fight against its number one enemy: decoherence.

Today, the progress made goes far beyond what the pioneers of the 1990s could have imagined, even if reality does fall far short of the hopes held by some. While there have been many discoveries, the difficulties remain considerable. Today’s experimental processors are limited to a dozen qubits but it is likely that we will soon see significant progress. The technologies able to support them have not yet been identified although attention is now turning towards solid-state supports: semiconductors or supraconductors.

There have been significant results in the field of quantum cryptography. Quantum cryptography systems are already commercially available and offer what is described as unconditional security. This means that the level of security is not dependent on the calculating power of the computer trying to break the code, which is not the case with present conventional systems. However, computing security is a very complex field that is evolving all the time. I am tempted to repeat the opinion expressed by the cryptographer Adi Shamir a few years ago when speaking of security: “We have won many battles, but we are losing the war.” The role that quantum cryptography will play in this war remains a largely open question…

Does introducing the concepts of quantum mechanics to the information sciences amount to a revolution?

These concepts, such as quantum entanglement, already sit uneasily with our vision of the world that originates from conventional physics. Einstein was unable to accept the principles of entanglement or non-local action. The quantum information sciences are trying to exploit these principles and we are only now starting to unravel the mysterious properties of the quantum world.

The use of entanglement marks impressive progress in the field of communications, as shown by the concept of quantum teleportation. More generally, entanglement makes it possible to achieve what is not possible in the conventional world. Combined with the principle of superposition, it also brings surprising ideas. For example, a ‘quantum calculation’ is in fact a series of measurements. One measurement positions the processor to initiate the possible entry values. Another initiates a quantum circuit that ‘makes the calculation’, and a third retrieves the result. Calculating is thus a matter of measuring - an unthinkable idea in the classical world. Quantum data processing overturns the theo - ries on which today’s information sciences are based. Functions, regarded by conventional theories as difficult if not impossible to calculate, could become easy to calculate for quantum data processing. Current research in this field is making many more discoveries possible and nobody really knows where they will lead. This was already the case with the conventional information sciences, the impact of which nobody could estimate, and the progress made 50 years ago. The science of quantum data processing is the marriage of the two most important scientific fields of the 20th century: data processing and quantum physics. It would be very surprising if this marriage did not have major consequences.

Will quantum physics replace its conventional big brother?

Without doubt nobody today regards quantum data processing as an alternative to traditional data processing that will open the door to a radically new generation of computers. It is rather a question of improving current computers by using hybrid machines. An interesting theoretical result mentions that adding a single qubit to a finished automaton model (the theo - retical model of a computer) would produce a hybrid automaton much more powerful than its traditional equivalent. A quantum version of Moore’s Law, which foresees a doubling of computing power every 18 months, could be that the number of qubits would increase by one over the same period. In this case, the power would be effectively doubled.

Is this marriage of quantum mechanics and the information sciences having an impact on the way physicists regard their science and nature?

Physics and the information sciences are two windows to trying to understand our universe. The former is interested in the organisation of matter, the second in processing the information it can convey. The relations between these two worlds are neither simple nor evident. For many years philosophers debated at length the duality of “mind and matter”. Its modern form would be “information and matter”. J.A. Wheeler, one of Einstein’s collaborators, did not hesitate to say that his life as a physicist was divided into three periods. During the first period, it was all particles. During the second, it was all fields. The third period brought a new vision of physics in which everything becomes information. Perhaps the nature of information is the key to a unified vision of the physical world, for the description of which quantum physics would be a pertinent means. Quantum information sciences offer physics new concepts, models, tools, images and paradigms to arrive at a better understanding of the quantum world and its physics.

Another more technical goal involves learning to isolate, handle and transmit particles. Many fields of science could benefit from this in their attempts to understand nature at its very deepest level, at the quantum level.

What is the position of European research in this field?

Globally, the work is good. I would even say very good compared with what is being done in conventional physics. Nevertheless, the emphasis is placed principally on the ‘quantum’ side and less on the ‘information processing’ side. Research in this field is carried out in the same way as European research in general: with a broad prospective and producing abundant knowledge. But it lacks steering structures of the kind the Americans are so good at putting into place…and also the means to attract the world’s best researchers.

François Rebuffat