Glossary

A photon is the smallest elementary particle of light and carries electromagnetic energy, which is why they are also called light quanta. In quantum communication, photons are used to transmit qubits over long distances, often via fiber-optic cables or satellite links. Because they interact very little with their surroundings, photons are particularly well-suited for transmitting information without loss.

Polarization refers to the orientation of the oscillations of light waves. In quantum communication, the polarization of photons is often used to represent qubits. Different polarizations can be used to encode information, which is then transmitted securely.

Post-quantum cryptography refers to cryptographic methods that are secure against attacks by quantum computers. Quantum computers could easily break many of today’s common encryption methods because they can solve certain mathematical problems (such as factoring large numbers) much faster than classical computers. Post-quantum cryptography therefore develops new algorithms that cannot be easily broken, even with the computing power of quantum computers.