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China launches world's longest quantum communication line
Dec 03, 2016

Why in News:

China has launched a quantum communication line 712 kilometers in length that is meant to safely transmit sensitive information. It is expected to be extended to 2,000 kilometers soon.

Key Details:

  • The line connecting Hefei, the capital of Anhui Province, and Shanghai.
  • It transmitted a secure video conference between the two cities in one of its first test communications.


Quantum communication uses quantum entanglement of photons to ensure that nobody taps into the line, as doing so would inevitably corrupt the signal. The relay nodes are weak points, because the information is translated back into regular form there before being re-entangled and sent further along the optic fiber link.

What is Quantum communication

  • It is an area of study based on the idea that information science depends on quantum effects in physics.
  • The basic motivation is that quantum states code quantum information - called qubits in the case of 2-dimensional Hilbert spaces and that quantum information allows one to perform tasks that could only be achieved far less efficiently, if at all, using classical information. The best known example is Quantum Key Distribution (QKD).
  • It  is built on a set of disruptive concepts and technologies.
  •  It is driven by fascinating physics and by promising applications. 
  • It requires a new mix of competencies, from telecom engineering to theoretical physics, from theoretical computer science to mechanical and electronic engineering. 
  • First applications have already found their way into niche markets, and many university labs are working on futuristic quantum networks, but most of the surprises are still ahead of us.
  • Quantum communication, and more generally quantum information science and technologies, are here to stay and will have a profound impact on the 21st century

What is Quantum key distribution:

This technology allows one to distribute sequence of random bit whose randomness and secrecy are guaranteed by the laws of quantum physics. These sequences can then be used as secret keys with conventional cryptography techniques to guarantee the confidentiality of data transmissions.


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