Researchers observe exotic quantum particle in bilayer graphene

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"Observing the 5/2 state in any system is a remarkable

scientific opportunity, since it encompasses some of the most perplexing concepts in modern condensed matter physics, such as emergence, quasi-particle formation, quantization, and even superconductivity," Dean says. "Our observation that, in bilayer graphene, the 5/2 state survives to much higher temperatures than previously thought possible not only allows us to study this phenomenon in new ways, but also shifts our view of the FQH state from being largely a scientific curiosity to now having great potential for real-world applications, particularly in quantum computing."
First discovered in the 1980s in gallium arsenide (GaAs) heterostructures, the 5/2 fractional  remains the singular exception to the otherwise strict rule that says fractional quantum hall  can only exist with odd denominators. Soon after the discovery, theoretical work suggested that this state could represent an exotic type of superconductor, notable in part for the possibility that such a phase could enable a fundamentally new approach to quantum computation. However, confirmation of these theories has remained elusive, largely due to the fragile nature of the state; in GaAs it is observable only in the highest quality samples and even then appearing only at milikelvin temperaures (as much as 10,000 times colder than the freezing point of water).
The Columbia team has now observed this same state in bilayer graphene and appearing at much higher temperatures??reaching several Kelvin. "While it's still 100 times colder than the freezing point of water, seeing the even-denominator state at these temperatures opens the door to a whole new suite of experimental tools that previously were unthinkable," says Dean. "After several decades of effort by researchers all over the world, we may finally be close to solving the mystery of the 5/2."


Read more at: https://phys.org/news/2017-10-exotic-quantum-particle-bilayer-graphene.html#jCp