Breakthrough by Chinese scientists brings 'unhackable' quantum broadband closer to reality
PUBLISHED : Thursday, 09 April, 2015, 8:00am
UPDATED : Thursday, 09 April, 2015, 8:53am
Stephen Chen
A breakthrough by Chinese scientists has brought high speed, quantum broadband communication closer than ever.
For the first time, scientists at the University of Science and Technology in Hefei, Anhui province, were able to demonstrate that quantum information could be stored and distributed under a broadband communication protocol.
Writing in the British journal Nature Photonics the researchers said the technology "shows great promise for the establishment of quantum networks in high-speed communications".
Unlike traditional communication methods, quantum broadband would be unhackable, the researchers said, thanks to the laws of physics.
Anyone who tried to detect or measure the quantum bits, such as entangled photons that carry information in various quantum states, would unavoidably destroy the qubit, making the data impossible to read and alerting the recipient.
It is primarily these security reasons that the Chinese government has invested a huge amount of resources into quantum communication. The world's longest quantum network and first quantum communication satellite are both currently being constructed in China.
However, existing networks are plagued by narrow bandwidth and slow speeds, mainly due to the difficulty of maintaining fragile quantum states over long distances.
Quantum networks in use today are only able to distribute short key chains used to encrypt data transmitted on conventional networks, an improvement in security but not the dramatic step proposed by the new paper.
Professor Shi Baosen, one of the authors of the paper, said his team's work was partly the result of intense international competition.
Many countries are racing to develop the world’s first quantum communication "expressway", said Shi.
A team in the UK tried to add "fuel" to travelling qubits but increased speed also led to increased instability, leading to more accidents.
Shi’s team took a different approach. In addition to building "pump stations", they also imposed restrictions to regulate the movement of qubits and slow them down when necessary.
To achieve this they used laser to freeze fast moving photons and developed some new methods to control the network flow.
"Our cold approach is more sophisticated and required bulkier equipment setup, but it produced better results, which helped us win the race," Shi said.
The new technology would not only be useful in high speed quantum communication, but shed new light on the construction of quantum computers as well.
The broadband protocol, known as Raman quantum memory, allowed entangled photons to run around and around in a fiber loop with an optical switch that would release them whenever they were needed, thus providing a “memory chip” for quantum computers.
But Shi said that lots of work remained to be done before the first quantum broadband network could be built.
For instance, the laboratory setup was still too large, too sophisticated and too costly for mass application.
Breakthrough by Chinese scientists brings 'unhackable' quantum broadband closer to reality | South China Morning Post
Maybe they mean "as early as possible" in a Chinese way.
