UNIVERSITY PARK, Pennsylvania — A brand new technique to mix two supplies with particular electrical properties — a single-layer superconductor and a topological insulator — offers the very best platform but for exploring an uncommon type of superconductivity referred to as topological superconductivity. The mix may present the premise for topological quantum computer systems which are extra secure than their conventional counterparts.

Superconductors – utilized in highly effective magnets, digital circuits and imaging units – permit electrical present to circulation with out resistance, whereas topological insulators are skinny movies just a few atoms thick that prohibit the motion of electrons at their edges, which can lead to distinctive properties. A workforce led by Penn State researchers describes how they put the 2 supplies collectively in an article that appeared Oct. 27 within the journal Nature Supplies.

“The way forward for quantum computing is dependent upon a sort of fabric we name a topological superconductor, which may be shaped by combining a topological insulator with a superconductor, however the precise course of of mixing these two supplies is tough,” stated Cui-Zu Chang. , Henry W. Knerr Early Profession Professor and Affiliate Professor of Physics at Penn State and chief of the analysis workforce. “On this examine, we used a way referred to as molecular beam epitaxy to synthesize each topological and superconducting insulating movies and create a two-dimensional heterostructure that gives a wonderful platform for exploring the phenomenon of topological superconductivity.”

In earlier experiments geared toward combining the 2 supplies, superconductivity in skinny movies normally disappears as soon as a layer of topological insulator is grown on high. Physicists had been ready so as to add a topological insulating movie to a three-dimensional “bulk” superconductor and retain the properties of each supplies. Nevertheless, purposes of topological superconductors, resembling low-power chips inside quantum computer systems or smartphones, are anticipated to be two-dimensional.

On this paper, the analysis workforce stacked a topological insulating movie fabricated from bismuth selenide (Bi2Se3) with completely different thicknesses on a superconducting movie fabricated from monolayer niobium diselenide (NbSe2), leading to a two-dimensional finish product. By synthesizing the heterostructures at very low temperatures, the workforce was capable of retain each topological and superconducting properties.

“In superconductors, electrons type ‘Cooper pairs’ and might circulation with zero resistance, however a robust magnetic subject can break these pairs,” stated Hemian Yi, postdoctoral researcher at Penn State’s Chang Analysis Group and first creator. of the merchandise. . “The one-layer superconducting movie we used is thought for its ‘Ising-type superconductivity’, which implies that Cooper pairs are extremely proof against in-plane magnetic fields. We might additionally anticipate the topological superconducting part shaped in our heterostructures to be strong on this manner.

By subtly adjusting the thickness of the topological insulator, the researchers found that the heterostructure shifted from Ising-type superconductivity – the place the electron spin is perpendicular to the movie – to a different sort of superconductivity referred to as “Ising superconductivity”. Rashba sort” – the place the spin of the electron is parallel to the movie. This phenomenon can be noticed within the theoretical calculations and simulations of the researchers.

This heterostructure is also a very good platform for exploring Majorana fermions, an elusive particle that will go a good distance towards making a topological quantum laptop extra secure than its predecessors.

“This is a wonderful platform for exploring topological superconductors, and we hope to search out proof for topological superconductivity in our continued work,” Chang stated. “As soon as we have now robust proof for topological superconductivity and reveal Majorana physics, then this kind of system may very well be appropriate for quantum computing and different purposes.”

Along with Chang and Yi, the Penn State analysis workforce consists of Lun-Hui Hu, Yuanxi Wang, Run Xiao, Danielle Reifsnyder Hickey, Chengye Dong, Yi-Fan Zhao, Ling-Jie Zhou, Ruoxi Zhang, Antony Richardella, Nasim Alem, Joshua Robinson, Moses Chan, Nitin Samarth and Chao-Xing Liu The workforce additionally consists of Jiaqi Cai and Xiaodong Xu from the College of Washington.

This work was primarily supported by the Penn State MRSEC for Nanoscale Science and in addition partially supported by the Nationwide Science Basis, Division of Vitality, College of North Texas, and the Gordon and Betty Moore Basis.

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