Chinese and Canadian Physicists Take a ‘Quantum Leap’ in Teleporting Photons –“Pretty Profound”





Teleportation has largely been the realm of science fiction and Star Trek plots. Now, Chinese and Canadian scientists say they have successfully carried out a form of teleportation at the quantum level across an entire city. The two teams working independently have teleported near-identical versions of tiny particles called photons through cables across Calgary in Canada and Hefei in Anhui province.

Quantum teleportation is the ability to transfer information such as the properties or the quantum state of an atom — its energy, spin, motion, magnetic field and other physical properties — to another location without traveling in the space between. While it was first demonstrated in 1997, today’s studies are the first to show the process is technologically possible via a mainstream communications network.

Ben Buchler, Associate Professor with the Centre for Quantum Computation and Communication Technology at the Australian National University, said the technical achievement of completing the experiments in a “non-ideal environment” was “pretty profound”. “People have known how to do this experiment since the early 2000s, but until these papers it hasn’t been performed in fibre communication networks, in situ, in cities,” said Buchler, who was not involved in the research. “It’s seriously difficult to do what they have done.”

A cornerstone of quantum teleportation is quantum entanglement, where two particles are intimately linked to each other in such a way that a change in one will affect the other.

Researchers have long known that a photon particle can be split in two and yet the pair are still “entangled”, which means that any change in the state of one immediately affects the other, although how this happens is still unknown.

The two papers demonstrate that the possibility of quantum [internet] networks that span a city are a realistic proposition, which is an exciting vision for the future

The forms of teleported photons were destroyed in one laboratory and recreated in another more than 8km apart in the two cities through optical fibre. Similar experiments have been carried out before, but only within the same laboratory.

the research was a step forward in the development of a “quantum internet”, a futuristic particle-based information system that could be much more secure than existing forms of digital data. Quantum networks make eavesdropping almost impossible because the particles used cannot be observed without being altered.

But in his commentary on the research in the scientific journal Nature Photonics, French physicist Frederic Grosshans said the two experiments clearly showed that teleportation across metropolitan distances was technologically feasible.

“The two papers demonstrate that the possibility of quantum [internet] networks that span a city are a realistic proposition, which is an exciting vision for the future,” Grosshans said. Professor Zhang Qiang, one of the leaders of the Chinese team, said: “Maybe in the distant future, materials can be teleported through a fibre or even open space, too.”

The research was carried out by scientists at the University of Science and Technology of China and the University of Calgary and their papers were published in the journal on Monday.

This, in theory, means it could be possible to transmit information by manipulating entangled photons, but various factors, including fluctuating temperatures, can interfere with the process over longer distances outside the laboratory. The researchers used sophisticated equipment to counter these and other problems, allowing the Chinese team, led by Professor Pan Jianwei and Professor Zhang, to achieve “full” quantum teleportation of photons over a optical fibre network 12.5km apart.

The Chinese and Canadian teams used different approaches to carry out their experiments. The Chinese team demonstrated a fuller version of the quantum network with higher reliability, but the Canadian approach was more efficient, according to Grosshans.

The Daily Galaxy via and ABC Online

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