Unlike traditional secure communication methods, the quantum system uses photons, or bundles of electromagnetic energy, to send the encryption keys needed to decode information. Data contained in the bursts of sub-atomic particles is impossible to intercept as any attempt will cause them to self-destruct, the Xinhua news agency said.
Mr Gregoir Ribordy, co-founder of Geneva-based quantum cryptography firm ID Quantique, likened it to sending a message written on a soap bubble. "If someone tries to intercept it when it's being transmitted, by touching it they make it burst," he told The Wall Street Journal.
Dr Vadim Makarov, a quantum communications expert at the University of Waterloo in Canada, said existing electronic systems like telephones are easy to hack as each piece of data is carried on electrons, which can be intercepted and analysed.
"A wiretap splits off a large number of electrons to read the signal and still leaves enough electrons in the line to carry the same signal to the legitimate recipient," he told The South China Morning Post.
He and other scientists believe the only weakness lies not in the quantum signals, but the hardware.
It is possible for hackers to trick an incautious recipient by shining an intense laser into a quantum receptor, Associate Professor Alexander Ling, principal investigator at the Centre for Quantum Technologies in Singapore, told The Wall Street Journal.
But the level of expertise required for a hack attempt is very high, said the Post. Quantum physicist Li Chuanfeng said: "To be a quantum hacker, you must have a PhD in quantum physics. That's the minimum requirement. Such a high entry barrier will keep most hackers out of this game."