China's quantum jump for mankind

Satellite experiment's recent success brings science fiction concept of teleportation into the realm of reality

The distinguished US physicist Richard Feynman once said that if you think you understand quantum mechanics, you don't.

The science behind the laws that govern the subatomic world has evolved over more than a century, revealing that the smallest particles behave outside the realm of classical physics.

Physicists have had to confront the weird reality that, at the smallest level, objects can behave as both particles and waves and, even more bizarrely, can be described as being in two places at once.

Even though the theories governing the subatomic world are still evolving, giving rise to alternative explanations of the nature of the universe - or, as some would contend, universes - quantum mechanics has already provided the basis for technological advances in the modern world.

Practical applications of quantum theory include superconducting magnets, the laser beam, transistors and the microprocessors that are at the heart of modern computing.

The next stage in this evolution is the field of teletransportation, an even more science fiction sounding concept in which minute objects can be moved instantly across wide distances.

Chinese scientists this month claimed a world distance record with the announcement that they had successfully teleported a subatomic particle from Earth to an orbiting satellite up to 1,400 kilometers away.

In its latest experiment, a Chinese team led by Ji-Gang Ren of Shanghai's University of Science and Technolog y fired a laser from a ground station in Tibet to the orbiting Micius satellite.

In so doing, the scientists effectively teleported a photon across space. Quantum teleportation occurs when the properties of one object are instantly transferred to another at a distance. The remote photon takes on the identity of the one from Earth and, for all intents and purposes, becomes the same object.

Albert Einstein called the phenomenon quantum entanglement, or "spooky action at a distance". The experiment raises familiar science fiction images of larger objects, and even humans, being teleported through space, beamed from one location to another.

That is likely to remain in the realm of science fiction, at least for now. However, scientists have already seized on potential practical uses for teleportation.

The Chinese team not only set a distance record for teleportation. The scientists also proved that it is possible to build a workable system for long-distance quantum communications. That could revolutionize electronic communications by making it impossible for outsiders to listen in without alerting the user, a major advance in the security of online traffic.

Oxford University physicist Ian Walmsley told the BBC that the technology could eventually provide the basis for a cloud-based computing network that allows information to be sent securely. "It's certainly a scientific breakthrough," he said of the Chinese achievement.

China already held the teleportation record, with a 2012 experiment that teleported information across 97 km.

Up until now, it had been impossible to create a longer-distance quantum link because an entangled photon can only travel about 160 km along a fiber-optic cable before being absorbed.

By using a satellite link, the Chinese team took advantage of the fact that photons travel more easily though space. The challenge to overcome was that it had previously proved difficult to transmit the particles through the Earth's atmosphere.

The Chinese city of Jinan has already begun trials of a secure network based on quantum technology. Beijing and Shanghai are also developing a system that uses quantum nodes situated 95 km apart to measure quantum signals and send them on.

Brian Greene, a physics professor at New York's Columbia University, acknowledged that the Chinese breakthrough evoked images of Star Wars and Harry Potter, in which wizards disappear from one location only to re-emerge in another.

"It's somewhere in between," he told the United States' NPR network." But honestly, you should be super excited about that. It's a crazy, wonderful thing that we can do this."

The author is a senior editorial consultant for China Daily. Contact the writer at harveymorris@gmail.com