Light flips transistor switch

Photons emerge as competitors to electrons in computer circuits.

Transistors, the tiny switches that flip on and off inside computer chips, have long been the domain of electricity. But scientists are beginning to develop chip components that run on light. Last week, in a remarkable achievement, a team led by researchers at the Massachusetts Institute of Technology (MIT) in Cambridge reported building a transistor that is switched by a single photon.

Conventionally, photons are used only to deliver information, racing along fibre-optic cables with unparalleled speed. The first commercial silicon chip to include optical elements, announced last December, did little to challenge the status quo. The on-board beams of light in the device, developed at IBM’s research centre in Yorktown Heights, New York, merely shuttle data between computer chips.

Now, Wenlan Chen of MIT and her colleagues have taught light some new tricks, using a cloud of chilled caesium atoms suspended between two mirrors. [Nature, 06.13.13]