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MIT, Vienna university develop 'optical transistors'

Mark Hachman | July 10, 2013
The future of optical computing has gotten brighter, as separate announcements by MIT and an Austrian university each claim breakthroughs in "optical transistors".

The researchers also noted that changing the polarization of light without a large part of it being lost is difficult, but failed to say how much (if any) is being lost by their method.

MIT uses light to control light
MIT researchers took a different approach, developing an experimental optical switch that could be controlled via a single photon--using light to control light, versus using electricity to control light, as the Viennese researchers did.

What MIT did was to design a pair of mirrors that were transparent to a given wavelength of light when "on," allowing light to pass through. When "off," the mirrors should have blocked the photons, but they didn't. About 20 percent of the light passed through. By filling the space between the mirrors with supercooled cesium atoms, the light was blocked entirely.

MIT also believes that a more fruitful avenue of research would be to use quantum computing, where particles in a "superposition" state could be both on or off at the same time, allowing operations to be run in parallel.

"It's exactly the same story, except that instead of using these ultracold atoms in the cavity, you use a microscopic cavity on a semiconductor chip on a semiconductor and you use a quantum dot grown inside of the semiconductor as an artificial atom," said Jelena Vuckovic, a professor of electrical engineering at Stanford University cited by MIT. "There would be extra steps that people would have to take in order to implement the right energy-level structure. But in principle, the physics could be translated to a platform that could be cascaded and more easily integrated."

Quantum computing, however, is an entirely different field, one that is still not wholly understood. D-Wave Systems has built what it calls the first quantum computer, one of which  has been bought by Google and installed in a Quantum Artificial Intelligence Lab it built with the cooperation with NASA's Ames Research Center. But the D-Wave Two, the company's latest "qubit processor," is housed inside a cryogenics system within a 10 square meter shielded room.


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