Optical stuff is great, as everyone knows: optical links mean huge bandwidth right now, and computers running on photons rather than electrons might be truly amazing things - tremendously powerful, very economical of energy, and potentially able to exploit quantum effects to achieve all manner of mindbending feats.

But unfortunately, there is as yet no way to handle photons other than in a fibre. To perform operations with them they generally have to be converted into old school electrical impulses - and that makes Professor Holger Schmidt and his crew mad.

"We can change the speed of light - just by turning the power control knob," boasts the prof, with pardonable smugness.

"Slow light and other quantum coherence effects have been known for quite awhile, but in order to use them in practical applications we have to be able to implement them on a platform that can be mass-produced and will work at room temperature or higher - that's what our chips accomplish... The simplest example of how slow light can be used is to provide a data buffer or tunable signal delay in an optical network, but we are looking beyond that."

The "integrated photonic chip" produced by Schmidt and his collaborators apparently works using "quantum interference effects in a rubidium vapor inside a hollow-core optical waveguide", built into a silicon chip using ordinary manufacturing techniques.

"Normally, the rubidium vapor absorbs the light from the signal laser, so nothing gets through. Then you turn on the control laser and boom, the material becomes transparent and the signal pulse not only makes it through, but it also moves significantly more slowly," says the prof.

"We can potentially use this to create all-optical switches, single-photon detectors, quantum memory devices, and other exciting possibilities."

Schmidt and his colleagues were funded by the US National Science Foundation. They also received money from famous beaten-track-averse battleboffinry bureau DARPA, whose name for the lightspeed-wrangling quantum rubidium optichipware is "iPhoD" (integrated Photonic Delay).

Schmidt and his team's new paper Slow light on a chip via atomic quantum state control can be read in full for free here courtesy of Nature Photonics. ®