Slowing Light...

The future: Using simple glass fibres, a world wide web of quantum information can be created. Credit: TU Wien

Topics: Internet, Speed of Light, Quantum Internet, Quantum Mechanics

Light is an extremely useful tool for quantum communication, but it has one major disadvantage: it usually travels at the speed of light and cannot be kept in place. A team of scientists at the Vienna University of Technology has now demonstrated that this problem can be solved - not only in strange, unusual quantum systems, but in the glass fiber networks we are already using today.

By coupling atoms to glass fibers light was slowed down to a speed of 180 km/h. The team even managed to bring the light to a complete stop and to retrieve it again later. This technology is an important prerequisite for a future glassfiber-based quantum-internet, in which quantum information can be teleported over great distances.

In a vacuum, the speed of light is always the same - approximately 300 million meters per second. When light is sent through a medium such as glass or water, it is slowed down a little bit due to its interaction with the material. "In our system, this effect is extreme, because we are creating an exceedingly strong interaction between light and matter", says Professor Arno Rauschenbeutel (TU Wien / Vienna Center for Quantum Science and Technology). "The speed of light in our glass fiber is only 180 kilometers per hour. Any express train can top that."

Phys.org: Glass fiber that brings light to a standstill

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