A team of physicists at the University of California San Diego (UCSD) have created integrated circuits based on excitons that operate at minus 234 degrees Fahrenheit. Excitons are pairs of electrons and positively charged “holes” that require very cold temperatures to function. When the two parts are rejoined, the exciton breaks down and its energy turns into a flash of light. An integrated circuit powered by excitons is faster than a traditional one because it skips a step in the process. Normal devices must use electrons for computation and only then convert them into light for communication, but excitons can transition between the two almost instantly, says UCSD professor Leonid Butov. “Our transistors process signals using excitons, which like electrons can be controlled with electrical voltages, but unlike electrons transform into photons at the output of the circuit,” Butov says. “This direct coupling of excitons to photons allows us to link computation and communication.” Last summer the researchers developed an integrated circuit that could work at minus 457 degrees Fahrenheit, but one that operates at warmer temperatures is more useful. Instead of requiring resources only found in special laboratories, the circuit can be kept cool with liquid nitrogen, which is roughly the same price as gasoline.
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