September 27, 2009

Integrated circuits Have been made with particles called Excitons

The illustration shows the layerstructure of the coupled quantum well(CQW)device used in the paper.

Physicists at UC San Diego have successfully created speedy integrated circuits with particles called "excitons" that operate at commercially cold temperatures, bringing the possibility of a new type of extremely fast computer based on excitons closer to reality.

Excitonic switches operating at around 100 K

Photonic and optoelectronic devices may offer the opportunity to realize efficient signal processing at speeds higher than in conventional electronic devices. Switches form the building blocks for circuits, and fast photonic switches have been realized. Recently, a proof of principle demonstration of exciton optoelectronic devices was reported. The potential advantages of excitonic devices include high operation and interconnection speed, small dimensions and the opportunity to combine many elements into integrated circuits. Here, we demonstrate experimental proof of principle for the operation of excitonic switching devices at temperatures around 100 K. The devices are based on an AlAs/GaAs coupled quantum well structure and include the exciton optoelectronic transistor (EXOT), the excitonic bridge modulator (EXBM), and the excitonic pinch-off modulator (EXPOM). A two orders of magnitude increase in the operation temperature compared to earlier devices (1.5 K; refs 7,8) is achieved.

2 pages of supplemental information.

Their discovery follows the team's demonstration last summer of an integrated circuit -- an assembly of transistors that is the building block for all electronic devices -- capable of working at 1.5 degrees Kelvin above absolute zero. Now the scientists report that they have succeeded in building an integrated circuit that operates at 125 degrees Kelvin, a temperature that while still a chilly minus 234 degrees Fahrenheit, can be easily attained commercially with liquid nitrogen, a substance that costs about as much per liter as gasoline.

"Our goal is to create efficient devices based on excitons that are operational at room temperature and can replace electronic devices where a high interconnection speed is important," said Leonid Butov, a professor of physics at UCSD, who headed the research team. "We're still in an early stage of development. Our team has only recently demonstrated the proof of principle for a transistor based on excitons and research is in progress."

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