New quantum state observed at room temperature could revolutionize electronics

The search for new topological properties of matter is the new gold rush in modern physics. For the first time, physicists have observed new quantum effects in a topological insulator based on the element bismuth, at room temperature. This discovery opens up a new set of possibilities for developing efficient and energy-saving quantum technologies.

In recent years, studying Topological states The material is of great interest among physicists and engineers and is currently the subject of significant international interest and research. This study area combines Quantum physics with topology, a branch of theoretical mathematics that explores geometric properties that can deform, but do not change in nature.

In other words, the file Structure It is the branch of mathematics that studies the properties of geometric objects held by continuous deformation without tearing or sticking to each other, like a rubber band that can be stretched without breaking.

Zahid Hassan, Professor of Physics at Princeton University, lead author of the current study, points out in communication : ” The new topological properties of matter have become one of the most sought-after treasures of modern physics, both from a fundamental physics perspective and for finding potential applications in quantum engineering and next-generation nanotechnology. “.

In this context, the Spentronics appeared. It is based on using a fundamental property of particles, known as spin, to process information. Spin is a quantum property of particles closely related to the properties of their spin. It plays a fundamental role in the properties of matter.

X-electronics is similar to electronics, in that the latter uses the electric charge of a rather than spin Electron. Carrying information about both the charge and spin of the electron is likely to provide devices with a greater diversity of functions.

Princeton researchers discovered that a substance of this type Topological insulator, made of the elements bismuth and bromine, exhibit quantum behaviors, only observed under extreme experimental conditions of high pressure and temperatures close to absolute zero. This discovery opens up a new field of possibilities for developing efficient quantum techniques based on x-electronics. Their work has been published in the magazine nature materials.

The world’s first at room temperature

It is worth noting that scientists have been using topological insulators to demonstrate quantum effects for more than a decade. It is a unique device that acts as a buffer in size – Electrons Inside the insulation they are not free to move and therefore do not conduct electricity – but its surface can nonetheless become conductive.

The experiment described in this study is the first to be observed at room temperature. Extrapolation and observation of quantum states in topological insulators usually require temperatures close to absolute zero (about −273 °C).

In fact, ambient or elevated temperatures create what physicists call “thermal noise,” which is defined as a rise in temperature such that atoms begin to vibrate violently. This action can disrupt micro-quantum systems, and thus collapse the quantum state.

In topological insulators, in particular, these high temperatures create a state in which electrons on the surface of the insulator invade the volume of the insulator, and also cause the electrons to start conducting, which dampens or breaks the special quantum effect.

Therefore, the solution is to subject these experiments to extremely cold temperatures, usually at or near absolute zero. At these temperatures, the atomic and subatomic particles cease to vibrate and are therefore easier to handle. However, creating and maintaining an extremely cold environment is impractical for many reasons: cost, quantity, and high energy expenditures.

Unique topological insulator

Hassan and his team have developed an innovative way to solve this problem. Based on their experience with topological materials, they fabricated a new type of topological insulator based on bismuth bromide, an inorganic crystalline compound sometimes used for water treatment and chemical analysis.

Concretely, you should know that insulators, like semiconductors, have what are called dielectric (or tape) gaps. The authors explained that they are essentially “barriers” between orbiting electrons, a kind of “no man’s land” where electrons cannot go to. These band gaps are very important, as they provide the cornerstone to overcome the limitations of quantum state acquisition imposed by thermal noise.

However, they do so if the bandgap width exceeds the width of the thermal noise. But a very large bandgap can disrupt electron orbital coupling – this is the interaction between an electron’s spin and its orbital motion around the nucleus. When this perturbation occurs, the topological quantum state collapses. Therefore, the trick to creating and maintaining a quantum effect is to strike a balance between the wide bandgap and spin-orbit coupling effects.

The insulator studied by Hassan and his team has an insulating gap of more than 200 meV, which is large enough to overcome thermal noise, but small enough not to disturb the spin-orbit coupling effect and the reflection topology of the bandages.

A revolutionary discovery of electronics

Hassan says: In our experiments, we found a balance between the effects of spin-orbit coupling and a large bandgap. We discovered that there is a ‘beautiful spot’ where there can be relatively large spin-orbit coupling to create a topological wrap and increase the bandgap without destroying it. It’s kind of like the equilibrium point for bismuth-based materials, which we’ve been studying for a long time. “.

To highlight this property, the researchers used a subatomic resolution tunneling microscope, a unique device that uses a property known as “quantum tunneling.” Concretely, when the tip of the monoatomic microscope approaches within 1 nm of the surface, the tip electrons are reluctant to stay on the tip and can be transferred to the surface, illustrating the tunneling effect. The microscope determines the electrical conductivity between the tip and the surface, that is, the amount of current that passes through it. Scanning line by line, we get an electronic map of the surface and of each atom or molecule placed on it.

This is how the researchers observed the apparent quantum spin Hall edge state, an important property that only exists in topological systems. This requires additional new devices to uniquely isolate the topological effect.

Nana Shumiya, a postdoctoral researcher in electrical and computer engineering, and one of the study’s three co-authors explains: It’s great that we found them without giant pressure or ultra-high magnetic fields, making the materials more accessible for developing next-generation quantum technologies. She adds: I think our discovery will greatly advance the limits of quantum “.

The researchers now want to identify other topological materials that might operate at room temperature and, most importantly, provide other scientists with tools and new hardware methods to identify materials that are viable at room temperature and elevated temperatures.

source : nature materials