Researchers across the world have been working on building quantum cryptography systems since the 1980s,but realistic breakthroughs were achieved closer to 2007 and then 2013.
Photons are the tiny building blocks which make up light. Invisible to the naked eye, these unpredictable particles are now successfully being used to encrypt information securely.
In an unpolarised state, these minuscule measures of light can spin vertically, horizontally and diagonally – all at once. It is impossible to know the position and speed of the photon at any given time, making it a game changer for secure communications.
How? The answer is not very simple but breaking it down as much as possible: photons are created one at a time – a string – using LEDs. If the photon is then passed through a polarising filter, depending on the type of the filter, the light particle will either spin vertically or horizontally or diagonally.
When this photon is transmitted, the receiver needs to know the type of filter used to determine whether the photon is in a horizontal, vertical or diagonal spin so the same filter can be used to receive the photon. The photons are used to transmit a key, not actual messages. Anyone who tries to use an incorrect filter to intercept the photon would fundamentally change its orientation, rendering it useless.
So how does the encryption work? Turkish scientists explain quantum encryption to TRT World's Sourav Roy.