Science & Technology

2D Material, Just 3 Atoms Thick, Has Potential for Use in Quantum Computing

UB researchers work with a twin chamber skinny movie deposition system that can be utilized to synthesize skinny movie supplies. Within the new examine, this machine was used to create europium sulfide movies and tungsten trioxide, a precursor for 2D tungsten disulfide. Credit score: Douglas Levere / College at Buffalo

New analysis on two-dimensional tungsten disulfide (WS2) may open the door to advances in quantum computing.

In a paper revealed September 13, 2019, in Nature Communications, scientists report that they’ll manipulate the digital properties of this super-thin materials in ways in which could possibly be helpful for encoding quantum information.

The examine offers with WS2’s vitality valleys, which College at Buffalo physicist Hao Zeng, co-lead creator of the paper, describes as “the native vitality extrema of the digital construction in a crystalline strong.”

Valleys correspond with particular energies that electrons can have in a fabric, and the presence of an electron in one valley versus one other can be utilized to encode info. An electron in one valley can signify a 1 in binary code, whereas an electron in the opposite can signify a 0.

The power to manage the place electrons could be discovered may yield advances in quantum computing, enabling the creation of qubits, the fundamental unit of quantum info. Qubits have the mysterious high quality of having the ability to exist not simply in a state of 1 or 0, however in a “superposition” associated to each states.

The paper in Nature Communications marks a step towards these future applied sciences, demonstrating a novel technique of manipulating valley states in WS2.

College at Buffalo physicists Athos Petrou (far proper) and Hao Zeng (second from proper) had been amongst co-leaders of the brand new examine probing the “valley” physics of 2D tungsten disulfide. Additionally pictured, from left to proper, are UB physics graduate college students Tenzin Norden, Chuan Zhao, and Peiyao Zhang, all co-authors of the brand new examine. Credit score: Douglas Levere / College at Buffalo

Zeng, PhD, professor of physics in the UB Faculty of Arts and Sciences, led the undertaking with Athos Petrou, PhD, UB Distinguished Professor of Physics, and Renat Sabirianov, PhD, chair of physics on the College of Nebraska Omaha. Extra co-authors included UB physics graduate college students Tenzin Norden, Chuan Zhao and Peiyao Zhang. The analysis was funded by the Nationwide Science Basis.

Shifting tungsten disulfide’s vitality valleys

Two-dimensional tungsten disulfide is a single layer of the fabric that’s three atoms thick. On this configuration, WS2 has two vitality valleys, each with the identical vitality.

Previous analysis has proven that making use of a magnetic subject can shift the vitality of the valleys in reverse instructions, reducing the vitality of 1 valley to make it “deeper” and extra engaging to electrons, whereas elevating the vitality of the opposite valley to make it “shallower,” Zeng says.

The brand new examine builds on this prior work by including one other innovation.

A scanning electron microscope picture reveals tungsten disulfide grown on a sapphire substrate (mild space). The medium grey space reveals monolayer tungsten disulfide and the darkish space reveals multilayer tungsten disulfide. After rising the tungsten disulfide on the sapphire, researchers switch it onto europium sulfide. Credit score: Chuan Zhao / College at Buffalo

“We present that the shift in the vitality of the 2 valleys could be enlarged by two orders of magnitude if we place a skinny layer of magnetic europium sulfide below the tungsten disulfide,” Zeng says. “After we then apply a magnetic subject of 1 Tesla, we’re in a position to obtain an infinite shift in the vitality of the valleys — equal to what we’d hope to realize by making use of a magnetic subject of a few hundred Tesla if the europium sulfide weren’t current.”

“The scale of the impact was very massive — it was like utilizing a magnetic subject amplifier,” Petrou says. “It was so shocking that we needed to examine it a number of instances to verify we didn’t make errors.”

The tip outcome? The power to govern and detect electrons in the valleys is significantly enhanced, qualities that might facilitate the management of qubits for quantum computing.

Valley states as qubits for quantum computing

Like different types of quantum computing, valley-based quantum computing would depend on the quirky qualities of subatomic particles — in this case electrons — to carry out highly effective calculations.

Electrons behave in ways in which could seem odd — they are often in a number of locations directly, for occasion. Because of this, 1 and 0 aren’t the one doable states in methods that use electrons in valleys as qubits. A qubit will also be in any superposition of those states, permitting quantum computer systems to discover many prospects concurrently, Zeng says.

“Because of this quantum computing is so highly effective for sure particular duties,” Zeng says. “As a result of probabilistic and random nature of quantum computing, it’s notably appropriate for purposes corresponding to synthetic intelligence, cryptography, monetary modeling and quantum mechanical simulations for designing higher supplies. Nevertheless, numerous obstacles have to be overcome, and we’re possible a few years away if scalable common quantum computing ever turns into a actuality.”

The brand new examine builds on Zeng and Petrou’s prior work, in which they used europium sulfide and magnetic fields to change the vitality of two valleys in one other 2D materials: tungsten diselenide (WSe2).

Although WS2 and WSe2 are comparable, they responded in another way to the “valley splitting” train. In WS2, the valley that received “deeper” was analogous to the valley in WSe2 that turned “shallower,” and vice versa, creating alternatives to discover how this distinction may present flexibility in purposes of the know-how.

One attribute that each supplies share may benefit quantum computing: In each WS2 and WSe2, electrons populating the 2 vitality valleys have reverse spins, a type of angular momentum. Whereas this trait isn’t vital for making a qubit, it “offers sure safety of the quantum states, making them extra sturdy,” Zeng says.

Reference: “Large valley splitting in monolayer WS2 by magnetic proximity impact” by Tenzin Norden, Chuan Zhao, Peiyao Zhang, Renat Sabirianov, Athos Petrou and Hao Zeng, 13 September 2019, Nature Communications.

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