‘Valley states’ in this super-thin material could potentially be used for quantum computing

Phys.org September 23, 2019
Past research has shown that applying a magnetic field can shift the energy of the valleys in opposite directions, lowering the energy of one valley to make it “deeper” and more attractive to electrons, while raising the energy of the other valley to make it “shallower,” A team of researchers in the US (SUNY Buffalo, University of Nebraska) showed that the shift in the energy of the two valleys can be enlarged by two orders of magnitude if we place a thin layer of magnetic europium sulfide under the tungsten disulfide. After that when they applied a magnetic field of 1 Tesla, they were able to achieve an enormous shift in the energy of the valleys—equivalent to what we might hope to achieve by applying a magnetic field of about a hundred Tesla if the europium sulfide were not present. Though WS2 and WSe2 are similar, they responded differently to the “valley splitting” exercise. In both materials electrons populating the two energy valleys have opposite spins, a form of angular momentum which provides certain protection of the quantum states, making them more robust for quantum computing…read more. Open Access TECHNICAL ARTICLE

A scanning electron microscope image shows tungsten disulfide grown on a sapphire substrate (light area). Credit: Chuan Zhao / University at Buffalo

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