New quantum state in a solid element that no one predicted

April 10 () –

Physicists at Princeton University have observed a new quantum effect called “hybrid topology“in a crystalline material.

This finding opens a new range of possibilities for materials development and efficient technologies for next-generation quantum science and engineering, according to researchers.

The discovery, published in Nature, came about when scientists discovered that an elemental solid crystal made of arsenic (As) atoms harbors a never-before-observed form of topological quantum behavior. They were able to explore and image this new quantum state using a scanning scanning microscope (STM) and photoemission spectroscopy, the latter a technique used to determine the relative energy of electrons in molecules and atoms.

This state combines, or “hybridizes”, two forms of topological quantum behavior: edge states and surface states, which are two types of two-dimensional electron quantum systems. These have been observed in previous experiments, but never simultaneously in the same material where they mix to form a new state of matter.

NOBODY PREDICTED IT THEORETICALLY

“This finding was completely unexpected,” he said. it's a statement M. Zahid Hasan, professor of physics at Princeton University, who led the research. “No one predicted it in theory before it was observed.”

In recent years, the study of topological states of matter has attracted considerable attention among physicists and engineers and is currently the focus of great international interest and research. This area of ​​study combines quantum physics with topology, a branch of theoretical mathematics that explores geometric properties. that can be deformed but not intrinsically changed.

For more than a decade, scientists have used bismuth (Bi)-based topological insulators to demonstrate and explore exotic quantum effects in bulk solids, primarily by fabricating composite materials, such as mixing Bi with selenium (Se), for example. However, this experiment is the first time that topological effects have been discovered in crystals made of the element As.

“The search and discovery of new topological properties of matter have become one of the most sought-after treasures of modern physics, both from the point of view of fundamental physics and to find potential applications in next generation quantum science and engineering“Hasán said. “The discovery of this new topological state created in an elemental solid was made possible by multiple innovative experimental advances and instrumentation in our Princeton laboratory.”

An elementary solid serves as a valuable experimental platform for testing various topology concepts. Until now, bismuth has been the only element that harbors a rich network of topology, giving rise to two decades of intense research activities. This is attributed in part to the cleanliness of the material and ease of synthesis. However, the current discovery of topological phenomena Even more rich in arsenic will potentially pave the way for new and sustained research directions.

“For the first time, we show that, like different correlated phenomena, different topological orders can also interact and give rise to new and intriguing quantum phenomena,” Hasan said.

A topological material is the main component used to investigate the mysteries of quantum topology. This device acts as an insulator inside, which causes the electrons inside No They have freedom of movement and, therefore, do not conduct electricity.

However, the electrons at the edges of the device can move freely, meaning they are conductors. Furthermore, due to the special properties of the topology, the electrons flowing along the edges are not hindered by any defects or deformation. This type of device has the potential not only to improve technology but also to generate a greater understanding of matter itself by probing quantum electronic properties.

Hasan noted that there is a lot of interest in using topological materials for practical applications. But two important developments need to happen before this can be done. First, quantum topological effects should manifest themselves at higher temperatures. Secondly, it is necessary to find simple and elementary material systems (such as silicon for conventional electronics) that can host topological phenomena.

“In our laboratories, we make efforts in both directions: we are looking for simpler material systems with ease of fabrication where essential topological effects can be found,” Hasan said. “We are also looking at how to make these effects survive at room temperature.”

The roots of the discovery lie in the operation of the quantum Hall effect, a form of topological effect that was the subject of the Nobel Prize in Physics in 1985. Since then, topological phases have been studied and many new classes of quantum materials with properties have been developed. topological. Electronic structures have been found. In particular, Daniel Tsui, professor emeritus of electrical engineering at Princeton, he won the Nobel Prize in Physics in 1998 for discovering the fractional quantum Hall effect.