A somewhat spooky long-distance relationship: how quantum teleportation works—and what role the fiber optic network plays in it.
Anyone who deals with quantum physics must do one thing above all else: forget everything that is familiar from everyday life. An object or thing can only ever be in one place? If I want to transport something from A to B, then I move that object over a distance from A to B, and that takes a certain amount of time.
It's different in the world of the smallest particles; they don't care about our long-proven experiences. They make their own rules. A particle that carries information can equip another, distant particle with it and all its properties 1:1, without it having to travel any distance.
To do this, these two particles, such as light particles/photons, must be entangled. This means that they behave like a single unit or a team, even if thousands of kilometers separate them. No transport. No travel time. A spooky long-distance relationship, so to speak.
This is how teleportation works, for example with the letter “A”
It takes three photons.
- A special light source generates an entangled photon pair:
- Photon 1 remains at the starting point.
- Photon 2 is sent many kilometers away via a fiber optic cable.
- A weak laser in the laboratory generates photon 3, which carries the state to be transmitted—for example, the letter A.
- Photon 3 (the state carrier with the “A”) is then merged with photon 1 (the local entangled photon) and measured together. This special measurement links their properties together.
The following happens:
- The original state of photon 1 disappears at the starting point.
- Due to entanglement, this state, i.e., the letter A, appears on photon 2, which is located far away.
This makes photon 2 a perfect twin of the original photon 1—even though the two have never met. The information “A” is transmitted without transmitting the information carrier itself.
The path to the quantum internet of the future
Quantum teleportation makes it possible to transmit quantum information over long distances with extreme security without moving the particles themselves.
This forms the basis for networking quantum computers worldwide. In the future, when multiple quantum computers are able to teleport states, a distributed, ultra-fast quantum computing center will be created that can do far more than a single quantum computer.
Already possible today using standard fiber optics
The surprising thing is that the conventional fiber optics that carry our Internet today are already capable of transmitting quantum light – Deutsche Telekom has proven this in field trials. So there is no need for a completely new infrastructure. This is a huge advantage for the future development of a quantum internet.
