Photons are small light particles that make up electromagnetic radiation. As quantum particles, they can exist in multiple states at once, which, among other application, can be used to transport large volumes of data. This is efficient and conserves resources. For example, rather than encoding either 1 or 0 (in the case of traditional binary code), a photon can encode both states at the same time. This is a crucial difference between classical and quantum physics.

Certain light properties enable information to be not only transmitted, but also encoded, in different ways. One example is the colour spectrum (light frequency), which in turn determines the energy. In this case, a blue photon has more energy than a red one.

Whilst the unique properties of photons make them particularly interesting for quantum research, they also pose challenges for researchers. This is due to quantum properties: a light particle is destroyed as soon as it hits a measuring instrument, and it loses its ability to exist in different states. Its energy is then transformed into electricity and can be measured as an electric pulse.