Anton Zeilinger is a true renaissance man. Not only is he one of the world’s top experimental physicists, he also has a keen interest in the philosophy of science, and was summoned to India in 1997 to explain quantum physics to the Dalai Lama. He is an accomplished opera singer and expert skier, and collects antique maps in his spare time. With his neat beard and dapper appearance, he looks more like a jazz musician than a physicist.
It is Zeilinger’s work in the field of quantum optics that will ensure he earns a place in the history books. He has performed some of the most delicate and difficult experiments in the history of physics, the most famous being when, in 2004, he teleported a photon (light particle) from one side of the Danube River to the other. Transporting a photon 600 metres across Vienna may seem a far cry from the “Beam me up, Scotty” method of transportation. But the photon didn’t cross the ground, nor did it fly through the air – it moved from one place to another without travelling through any of the in-between places.
“Quantum teleportation”, as it has come to be known, is made possible by a process called “entanglement” that was first noticed by Einstein, who observed that pairs of particles sometimes act as if they are connected. If you poke one, the other jumps instantly. Amazingly, this is true no matter how far apart the particles are (Einstein talked of entanglement as “spooky action at a distance”). Scientists first suggested that entanglement could be used to teleport particles in 1993, but it was Zeilinger who put the theory into practice.
He himself admits that teleporting humans still lies in the distant future. Quantum teleportation works by transferring a complete description of an object from one place to another. While this is relatively easy for a photon, it gets progressively harder for more complex particles such as atoms and molecules. However, the technology does seem likely to lead to revolutionary advances in other fields. In cryptography, teleportation could prevent eavesdropping on the secure electronic codes that are used in a host of applications, from online shopping to military defence. These codes depend on the security of a “key” that must first be transmitted secretly between the sender and receiver. If an eavesdropper intercepts the message with the key, then the code can be broken. But keys transmitted by quantum teleportation would be completely secure. Because it is such a delicate operation, any disturbance – no matter how small – would destroy the key.
Another field that will benefit is information technology. The quantum computers of the future may be linked by teleportation, enabling complex calculations to be performed in seconds that conventional computers would take several years to carry out. Quantum computers will solve currently impossible problems, such as predicting protein structures, thereby revolutionising drug design. And since some claim that the brain works like a quantum computer, it is predicted that they may finally realise the dream of artificial intelligence.
In contrast to many other physicists, Zeilinger has a keen interest in the philosophical implications of his work. As he says: “Scepticism is the only road to new knowledge.” This approach prompts him to question everything, including the nature of matter and energy. He believes that the world we see around us may mask a more fundamental layer of reality: information. Indeed, information – not matter or energy – may be “the ultimate reality of the universe”. If he is right, then it is likely that quantum mechanics, the most successful science of the 20th century, will be superseded in the 21st century by a new science of information. It is too early to say exactly what technologies will emerge, but they are sure to be fascinating.