Tungsten Disulfide: Manipulating and Detecting the Electrons in the Valleys To Facilitate Control of Qubits?

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

In brief…

+  In a paper published Sept. 13 in Nature Communications, scientists report that they can manipulate the electronic properties of this super-thin material in ways that could be useful for encoding quantum data.

Image:  A scanning electron microscope image shows tungsten disulfide grown on a sapphire substrate (light area). The medium gray area shows monolayer tungsten disulfide and the dark area shows multilayer tungsten disulfide. After growing the tungsten disulfide on the sapphire, researchers transfer it onto europium sulfide. (Image Credit: Chuan Zhao, University at Buffalo)

+  Two-dimensional tungsten disulfide is a single layer of the material that’s three atoms thick. In this configuration, WS2 has two energy valleys, both with the same energy.

“We show 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,” Zeng says. “When we then apply a magnetic field of 1 Tesla, we are 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.”

“The size of the effect was very large — it was like using a magnetic field amplifier,” Petrou says. “It was so surprising that we had to check it several times to make sure we didn’t make mistakes.”

+  The ability to control where electrons might be found could yield advances in quantum computing, enabling the creation of qubits, the basic unit of quantum information. Qubits have the mysterious quality of being able to exist not just in a state of 1 or 0, but in a “superposition” related to both states.

+  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,” Zeng says.

+  The end result? The ability to manipulate and detect electrons in the valleys is greatly enhanced, qualities that could facilitate the control of qubits for quantum computing.

Source:  University at Buffalo.  Charlotte Hsu,  ‘Valley states’ in this super-thin material could potentially be used for quantum computing…

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