Turning off a light just became a much smaller task. A team of researchers has developed the world's smallest optical switch, which uses just a single atom to control the flow of light. Developed by a team from ETH Zurich, the device is surprisingly simple. A platinum pad sits just below a shaped silver pad. Apply a voltage, and a single silver atom moves from the top plate into the gap between the two plates. That creates a short circuit between the two metals, allowing electricity to flow between them -- which in turn stops light being able to pass. Lose the voltage, and light can pass once more.
By adding fibre optic guides at each side, the team can create a device capable of modulating light that's 1000 times smaller than similar devices in the past. In fact, the piece of hardware itself is smaller than the wavelength of the laser light that it switches. The research is published in Nano Letters.
The team expects the device could be used in microscopic optical computing situations -- though also cautions that the device is "not ready for series production". A little more research is required to make them at that kind of scale.