Robust new device could intensify quantum technology, say researchers

Researchers have been trying for many years to build a quantum computer that the industry could develop, but the building blocks of quantum computing, the qubits, are still not robust enough to support the noisy environment of what would be a computer quantum.

A theory developed just two years ago proposed a way to make qubits stronger by combining a semiconductor, indium arsenide, with a superconductor, aluminum, in a planar device. . Now, this theory has received experimental support in a device that could also help scale qubits.

This semiconductor / superconducting combination creates a state of "topological superconductivity", which would protect against even small changes, from the environment of a qubit that interfere with its quantum nature, a so-called problem called "decoherence" ".

The device is potentially scalable due to its flat "flat" surface – a platform that the industry already uses in the form of silicon wafers for building conventional microprocessors.

The work, published in Nature, led by the Microsoft Quantum laboratory of the Niels Bohr Institute at the University of Copenhagen, which manufactured and measured the device. Purdue University's Microsoft Quantum lab developed the semiconductor-superconducting heterostructure using a technique called molecular beam epitaxy and performed the initial characterization measurements.

The theorists at Station Q, a Microsoft research laboratory in Santa Barbara California, as well as the University of Chicago and the Weizmann Scientific Institute in Israel, also participated in the study.

"The technology of planar semiconductor devices having been so successful in the field of conventional hardware, several approaches to developing a quantum computer have been developed," said Michael Manfra, Bill & Dee O & Chair. Brien from Purdue University, and professor of Electrical and Computer Engineering and Materials Engineering, who runs Purdue's Microsoft Station Q site.

These experiments provide evidence that aluminum and indium arsenide, when they come together to form a device called Josephson junction, can support Majorana zero modes, which, according to scientists, possess topological protection against decoherence.

It is also known that aluminum and indium arsenide work well because a supercurrent flows well between them.

Indeed, unlike most semiconductors, indium arsenide has no barrier that prevents electrons from one material from entering another. In this way, the superconductivity of aluminum can also transform the upper layers into indium arsenide, a superconducting semiconductor.

"The device still does not work as a qubit, but this article shows that it has the necessary ingredients to become a scalable technology," said Manfra, whose lab is specialized in creating platforms and understanding of the physics of quantum technologies to come.

The combination of the best properties of superconductors and semiconductors in planar structures, which the industry could easily adapt, could help make quantum technology evolutionary. Billions of switches, called transistors, installed on a single slice currently allow conventional computers to process information.

"This work is an encouraging first step in the construction of evolving quantum technologies," Manfra said.