Scientists observe electron spin for the first time

The spin of an electron (i.e., the spatial curvature of the electron's existence and motion) has been measured for the first time - the best thing that could happen to quantum technology.

Spin is an intrinsic property of elementary particles that, like electric charge, comes from their rotational angular momentum. The first experimental evidence supporting the existence of spin appeared in 1922, thanks to experiments by German physicists Otto Stern and Walther Gerlach, although scientists did not begin to understand its properties until several years later.

It is not easy to understand what spin is, because it is a quantum phenomenon, so describing it as a conventional rotational motion in space is not entirely correct. Nevertheless, in any case, the quantum nature of this property tells us that it is very difficult to measure.

In fact, this property could not be measured accurately until now. Fortunately, this wall has been broken down: a team of physicists from several universities in Italy, Germany, the United Kingdom and the United States has succeeded in measuring it for the first time. To achieve this, they used a synchrotron type particle accelerator - a machine that accelerates particles on a closed trajectory - and highly advanced techniques for analyzing the behavior of matter.

The research results were published in the journal Nature Physics on May 18 under the title "Flat band separation and robust spin Berry curvature in bilayer kagome metals.

The results achieved may revolutionize the way quantum materials are studied in the future, opening the door to new developments in quantum technology and promising applications in a wide range of technologies: from renewable energy to biomedicine, from electronics to quantum computers.

The international scientists involved in this collaboration include Domenico Di Sante, representative of the University of Bologna, and colleagues from the International Centre for Theoretical Physics in Trieste, the University of the East in Venice, the University of Milan, the University of Würzburg (Germany), the University of St. Andrews (UK), Boston College and the University of California, Santa Barbara (USA).

The team has measured electron spin for the first time through advanced experimental techniques using light generated by synchrotron radiation-based particle gas pedals and modern techniques for modeling the behavior of matter.

Three views of the electron moving surface. On the left is the experimental result, in the middle is the theoretical model, and on the right is the theoretical model. The red and blue colors represent the measurement of the electron velocity. Both theory and experiment reflect the symmetry of the crystal, which is very similar to the texture of a traditional Japanese kagome basket.

"If we compare two objects (such as a soccer ball and a donut), we will notice that their specific shapes determine different topological properties. Because the donut has a hole, while the soccer ball does not." Domenico Di Sante explains, "Similarly, the behavior of electrons in a material is influenced by certain quantum properties that determine their rotation in the matter within it. This is similar to how the trajectory of light in the universe is modified by the presence of stars, black holes, dark matter and dark energy: they bend time and space."

Although this property of electrons has been known for many years, no one has been able to directly measure this "topological spin" until now. To achieve this, the researchers used a special effect known as "circular dichroism": a special experimental technique that can only be used in synchrotron radiation sources and exploits the ability of a material to absorb different amounts of light depending on its polarization.

The physicist's strategy consists in measuring the light absorption capacity of a material according to its polarization: by analyzing the light absorption capacity of the material depending on its polarization and using a synchrotron to produce the light we talked about above.

Spin texture of topological surface states.

The quantum materials used on this occasion are kagome materials, which are revolutionizing quantum physics: the results obtained from the study can help us to learn more about their special magnetic, topological and superconducting properties.

Until now, it was not possible to measure spin directly - and this is exactly what these scientists have achieved. More importantly, though, is what applications this discovery might have: the knowledge this experiment gives could lead to changes in our understanding of the properties of matter, which could then be used in disciplines as diverse as renewable energy, biomedicine or quantum computers.

"These important results are possible thanks to a strong synergy between experimental practice and theoretical analysis." Di Sante said, "The team's theoretical researchers used complex quantum simulations that could only be achieved using powerful supercomputers and in this way guided their experimental colleagues to find specific regions where they could measure circular dichroic effect materials."

Reference links:

[1] https://www.ruetir.com/2023/06/for-the-first-time-the-spin-of-an-electron-has-been-measured-it-is-the-best-thing-that-can- happen-to-quantum-technologies/

[2] https://worldnationnews.com/for-the-first-time-the-spin-of-an-electron-has-been-measured-this-is-the-best-thing-that-could- happen-to-quantum-technologies/

[3]https://phys.org/news/2023-06-quantum-materials-electron.html