New material could hold a key to solving the quantum computing problem

UNIVERSITY PARK, Pa. – According to an international team of researchers, a new form of heterostructure of layered two-dimensional (2D) materials could allow quantum computers to overcome important obstacles to their widespread application.

The researchers were led by a team that is part of the Penn State Center for Nanoscale Science (CNS), one of 19 Materials Research Science and Engineering Centers (MRSEC) in the United States funded by the National Science Foundation. Their work was published in Nature Materials on February 13.

A normal computer is made up of billions of transistors called bits controlled by a binary code (“0” = off and “1” = on). A quantum bit, also called a qubit, is based on quantum mechanics and can be “0” and “1” at the same time. This is called superposition and can lead to quantum computers being more powerful than normal, classical computers.

However, there is a problem with building a quantum computer.

“IBM, Google and others are trying to make and scale up quantum computers based on superconducting qubits,” said Jun Zhu, a professor of physics at Pennsylvania State University and corresponding author of the study. “How to minimize the negative effect of a classical environment causing errors in the operation of a quantum computer is a key problem in quantum computing.”

A solution to this problem can be found in an exotic version of a qubit known as a topological qubit.

“Qubits based on topological superconductors are said to be protected by the topological aspect of superconductivity and therefore be more robust against the destructive effects of the environment,” Zhu said.

A topological qubit refers to topology in mathematics, where a structure undergoes physical changes, e.g. B. is bent or stretched, and still retains the properties of their original shape. It’s a theoretical type of qubit and hasn’t been realized yet, but the basic idea is that the topological properties of certain materials can protect the quantum state from perturbations by the classical environment.

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According to Cequn Li, PhD student in physics and first author of the study, a lot of emphasis is currently placed on topological quantum computing.

“Quantum computing is a very hot topic, and people are thinking about how to build a quantum computer with fewer errors in computation,” Li said. “A topological quantum computer is an attractive way to do it. But a key to topological quantum computing is designing the right materials for it.”

The study’s researchers took a step in this direction by developing a type of layered material called a heterostructure. The heterostructure in the study consists of a layer of topological insulator material, bismuth antimony telluride or (Bi,Sb)2Te3, and a layer of superconducting material, gallium.