N: Kvantová kryptografie na běžných zařízeních

With an encrypted message, the sender and recipient share a key that unscrambles its contents. Ensuring that the key hasn't been stolen is the problem. With quantum cryptography, the key is created at the sender and receiver by transmitting photons over fiber-optic lines. The polarity of a photon—a quantum property that says whether it is oscillating vertically or at angle—can be determined by the receiver and compared with a second "entangled" photon created at the same time. The polarity of the photons is translated into bits that make up a key to decrypt messages.

With quantum key distribution, the security of the transmission is assured by the Heisenberg uncertainty principle. If an eavesdropper tries to intercept the key, it will change the state of the paired photons—an event that can be detected by the sender of the key.

In research published in Nature last week, the Japanese team describes a method for securing communications that doesn’t rely on the uncertainty principle and needs no regular measurement to see if the key's been tampered with.