Towards faster-than-light transmission by slowing down light

Quantum teleportation is one of the weirdest concepts in the very weird field of quantum mechanics. It refers to the instantaneous transmission of information over long distances, which should be impossible under classical physics, where no information can be transmitted instantaneously because of the insurmountable limit of the speed of light. But physicists at the Technical University of Vienna believe they may have taken an important step towards it — not by speeding up the transmission of information but by slowing a light pulse to a dead stop, then speeding it up again.

The team, led by Professor Arno Rauschenbeutel, who is also attached to the Vienna Centre for Quantum Science and Technology, was looking at the transmission of data by light pulses along optical fibre: a standard method of moving information. When light enters transparent glass, it slows down a little because even though glass is transparent, its atoms interact with photons. The Vienna team slowed the pulse down to a much greater degree than usual by coupling the glass atoms in a tapered scetion of the fibre to caesium atoms.