Toshiba researchers announce major quantum cryptography breakthrough

Toshiba researchers have developed a major breakthrough in quantum cryptography - the use of quantum mechanics to encrypt data - which could revolutionise the way sensitive material is protected.

Until now, quantum cryptography could only be employed on a small scale and required an elaborate and expensive 'photon detector' for each application; making large scale use prohibitively expensive and so extremely limited.

However, the research team has discovered a technique which enables many users to share a single detector, so greatly reducing the cost and complexity of the network. The breakthrough means that it is now possible for 64 users to connect to a single detector in a quantum access network.

The team believes this will enable the technology to move out of its current niche applications, and towards use in mainstream government, business and smart city networks.

Explaining the power of quantum cryptography, in a statement, Toshiba said: "It can be used to distribute secret digital keys with a security that is not vulnerable to advances in computing, mathematics or engineering, and means any hacker that 'taps' an optical fibre will be detected. At the same time, it could become the first prevailing technology to harness the peculiar laws of quantum physics."

Toshiba's quantum access network uses standard fibre components that allow the signals from multiple users to be combined and transmitted on a single fibre.

The photon detector - the most complex part of the quantum cryptography system - is placed at the shared end of the quantum access network so that only one is required for multiple users. Each user added to the network then only requires a transmitter, an arrangement that greatly reduces the hardware requirement and cost.

The finding by the team, which is composed of researchers from Toshiba Research Europe and Toshiba Corporation working in Cambridge, UK, will be published in the scientific journal 'Nature'.