**By João Medeiros**

Just attended one of the best talks so far, here at the “Science beyond Fiction” conference in Prague — a really exciting, wacky and speculative talk by Artur Ekert, on quantum information science.

To Ekert, the questions that are used to “sell” quantum information science to “deciders” and funding bodies are usually of two kinds. A first argument, more scientifically motivated, sells the point that the true power of quantum computation is yet to be achieved, a computational capacity that will likely teach us much more about the fundamentals of nature. The second, more pragmatic approach, appeals to the exploration of the true fundamental limits in exploring quantum systems and what constraints they put on technology.

On the issue of framing the subject of quantum computation, Ekert says that it is really interesting how people from different cultural backgrounds react to the topic.

For instance when discussing the matter with computer scientists, Ekert uses a more philosophically inclined, logic based approach. According to him, computer scientists are naturally not really fond of atoms and messy quantum systems.

The question he asks his computer scientist collaborators is whether it is possible to construct a logic gate operating on a single bit, such that the same two consecutive operations produce a flip of the bit. Classically, of course, you cannot. But this is a possibility when using quantum systems.

Indeed, one of the fundamental differences between quantum and classical computational systems exists in the respective nature of the logical operations allowed by each system.

The bottomline realization is that information and computation are intimately linked to physics. Information is physical. This conclusion was to many computer scientists a shock and it marked the intellectual revolution that kickstarted quantum information science.

Physicists now realize that if you change the physics you change the nature of information. This has been a surprising revelation to many computer scientists, who since the work of Alan Turing have been playing with classical computer logic without a physical foundation, a logical framework which somehow worked.

INTERDISCIPLINARITY

Ekert also pointed out that quantum computation is one of the truly interdisciplinarity subjects.

Not only it has brought together mathematicians, computer scientists and physicists, but it has also brought people together within physics, scientists that beforehand would not talk to each other simply because they were using completely different jargon and codes. A common denominator was found in the language of quantum logic gates.

Ekert, who is based in Singapore, compared this situation with the way that sometimes Koreans and Chinese use to communicate: not by speaking, but via written characters.

QUANTUM SIDE OF LIFE

Ekert also mentioned that recent advances in the study of the quantum aspects of life, such as the study of the role of quantum coherence in photosynthesis, opens the door to discover quantum computation already happening in natural systems. This is a most fascinating topic that will be featured in an upcoming feature by Paul Davies for PW.

BIG QUESTIONS

The final aspect discussed by Ekert was the philosophical aspect of quantum computation, an side of science which has not been avoided by physicists. According to Ekert, quantum Information has elevated the questions about the nature of reality, randomness, complexity to the level of bona-fide scientific conundrums that should be addressed, rather than ignored.

Ekert himself is partial to question about the nature of randomness, the question of whether it is really possible to have events that have no underlying cause? What is so interesting about this question is that it essential goes against one’s understanding of science, which is intrinsically motivated by the notion of causality of phenomena in nature.

CARDANO, THE ORIGINAL WACKY QUANTUM SCIENTIST

In the next issue of PW, Ekert authors a feature about Girolamo Cardano, the “gambling scholar”. Cardano was a Renaissance mathematician which by himself discovered the basic notions of probability and complex numbers, two of the fundamental pillars of quantum theory.

In the future, Ekert will write again for PW about quantum information science.

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