An adjustable platform made from atomically thin materials may help researchers figure out how to create a robust quantum condensate that can 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.

Designing a Tunable Platform

The underlying theory is simple enough. «If you can get electrons to pair, they can superconduct,» said Dean. According to the Bardeen-Cooper-Schrieffer (BCS) theory, an attractive force between electrons — no matter how weak — will cause those electrons to pair up and form a new kind of particle called a «Cooper pair.» These behave like particles called bosons and, at low enough temperatures, can enter into a collective state and move through a material unimpeded by disorder — a feature any single electron just cannot achieve on its own.

But there’s been a problem. «Electrons do not want to pair,» said Dean. Like repels like, as the saying goes. Rather than trying to force a bond between two negatively charged electrons, the team has been exploring how opposites can attract to yield an equivalent ‘paired’ boson.

Story Source: Materials provided by Columbia University. Original written by Ellen Neff. Note: Content may be edited for style and length.