Cambridge scientists in quantum cryptography breakthrough

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 extremely limited. Now, however, the research team has discovered a technique which lets multiple users share a single detector, thereby greatly reducing the complexity of the network. The breakthrough means that with current technology, it would be possible for 64 users to connect to a single detector in a quantum access network. Toshiba believes this will enable the technology to move out of its current niche applications, towards use in mainstream government, business and smart city networks. The team's detector can count up to 1billion individual photons per second. Its high detection rate also means it can be shared between multiple transmitters in a point-to-multipoint link. Tests on an eight channel quantum access network showed that a user can transmit secret keys with a bit rate in excess of 250kbit/s or 80GByte per month, enough for each user to encrypt 1million emails.