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In a recent report published on Science Advances, Andrew Seredinski and co-workers presented a graphene-based Josephson junction with dedicated side gates fabricated from the same sheet of graphene as the junction itself. The interdisciplinary research team in the departments of physics, astronomy and advanced materials in the U.S. and Japan found the side gates to be highly efficient, allowing them to control carrier density along either edge of the junction across a wide range of magnetic fields. For example, they populated the next Landau level (where the number of electrons are directly proportional to the strength of the applied magnetic field) within magnetic fields in the 1 to 2-Tesla (T) range, to result in quantum Hall plateaus. Then when they introduced counter-propagating quantum Hall edge states along either side of the device, they observed a supercurrent localized along the edge of the junction. In the present work, they studied these supercurrents as a function of magnetic field and carrier density.

In quantum mechanics, physicists classify particles either as fermions or bosons. This classification is crucial to understand a variety of physical systems including lasers, metals and superconductors. Interactions between electrons or atoms in some two-dimensional (2-D) systems can lead to the formation of quasi particles that break from the fermion-boson dichotomy; to form 'non-Abelian' states of matter. Many experimental studies attempt to identify non-Abelian states in systems that manifest the quantum Hall (QH) effects (quantization of resistance in two-dimensional electronic systems). The identification of such states will be useful for quantum computation.

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Category: Science