Electrons flowing through power lines and computers inevitably encounter resistance; when they do, they lose some of their energy, which dissipates as heat. That's why laptops get hot after being used for too long and why the server farms that power the cloud require so much air conditioning to keep the machines from overheating. Likewise, any particles carrying energy tend to lose that energy when they flow in a typical environment. There are a few exceptions, which usually occur at very low temperatures when particles form pairs called quantum condensates. This leads to superconductivity, with vanishing electrical resistance, in some metals such as aluminum, and superfluidity in liquified helium, which can then flow without dissipation.
Many applications, from dissipationless power transmission to quantum computation, have been developed based on superconducting materials showing these quantum condensate states. But, known superconducting materials need to be kept cold—often impractically so. To raise the temperature of energy-loss-free devices, researchers need to better understand what drives the formation of quantum condensates in the first place.
In theory, superconductivity is the result of paired electrons. In most materials however that pairing is weak—two negatively charged particles don't normally want to pair with each other—and the pairing strength is fixed. In a new article in Science, Cory Dean and James Hone at Columbia, Xiaomeng Liu, Philip Kim, and Bert Halperin at Harvard, Jia Li at Brown, and Kenji Watanabe and Takashi Taniguchi at NIMS in Japan describe a tunable, graphene-based platform that uses opposite charges—electrons and holes—to form quantum particle pairs under strong magnetic fields. The strength of that pairing can now be varied along a continuum, which will allow the team to test theoretical predictions about the origins of quantum condensates and how they might increase the temperature limits of superconductivity.
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