Latest news with #ARPES
Yahoo
3 days ago
- Science
- Yahoo
Black phosphorus shines light on hidden quantum distances between electrons
For decades, physicists have talked about quantum distance, a way of measuring how similar or different two quantum states are. In this strange scale, a distance of one means two quantum states are identical, while zero means they are complete opposites. Though it's been a part of theory for a long time, directly measuring quantum distance in real materials has remained out of reach. This is because it requires not just seeing electrons, but understanding their subtle geometry at the quantum level, something extremely hard to capture in solid materials. Now, for the very first time, a team of international researchers has achieved what many thought impossible. These researchers have experimentally measured the quantum distance of electrons in a real crystal. "Measuring the quantum distance is fundamentally important not only to understand anomalous quantum phenomena in solids, including special ones such as superconductors, but also to advance our quantum science and technologies," said Keun Su Kim, one of the study authors, and a physics professor at Yonsei University in Seoul, South Korea. According to Kim, a precise measure of "quantum distances would help develop fault-tolerant quantum computation technologies." A science trick that involves black phosphorus As part of their study, the researchers suggested using black phosphorus, an elemental layered crystal with a simple and well-understood structure. This simplicity made the material an ideal candidate for probing the quantum geometry of electrons. In order to measure the quantum distance in black phosphorus, the scientists used a powerful method called angle-resolved photoemission spectroscopy (ARPES), which can map how electrons behave inside a material. The study then went a step further. By carefully analyzing how the results changed with the polarization of light, the team could reconstruct the pseudospin texture of the electrons in the material's valence band. In simpler terms, the researchers looked at how an intrinsic property of electrons, a kind of quantum orientation, varied across momentum space, or across the map of all possible electron motions. This required extremely precise measurements, so they used synchrotron radiation from the Advanced Light Source in the United States, one of the world's most advanced facilities for producing high-intensity, tunable beams of light. From the data, the team was able to directly calculate the quantum distance and, more importantly, the full quantum metric tensor, a mathematical object that describes the geometry of quantum states. This is the first time the quantum metric tensor of Bloch electrons (electrons in a crystal whose motion is shaped by the crystal's repeating pattern of atoms) in a solid has ever been fully measured. "In this work, we report a direct measurement of the full quantum metric tensors of Bloch electrons in solids using black phosphorus as a representative material," the study authors note. The significance of measuring the full quantum metric tensor Measuring quantum distance is not just about curiosity. It can help explain unusual behaviors in materials, such as why certain solids become superconducting at high temperatures or why some conduct electricity without resistance. It could also guide the design of fault-tolerant quantum computers, where precise control of quantum states is essential. However, this is just the beginning. The method has so far been demonstrated only in black phosphorus under controlled conditions. Applying it to more complex materials, especially those with strong electron interactions, will be more challenging. The researchers hope to expand their work to a wider range of crystalline systems, paving the way for improved semiconductors, better superconductors, and practical quantum technologies. The study is published in the journal Science. Solve the daily Crossword
The Hindu
29-05-2025
- Science
- The Hindu
RRI team find new code for detecting hidden properties of exotic materials
A team from the Raman Research Institute (RRI) found a new code for detecting hidden properties of exotic materials. According to the Department of Science and Technology, scientists have found a new way of spotting a property of topological space called 'topological invariant' in quantum materials, which remains unchanged under continuous deformations or transformations. Topological materials are at the forefront of next-gen technology — quantum computing, fault-tolerant electronics, and energy-efficient systems. 'But detecting their exotic properties has always been tricky. Topological invariance implies that if you can deform one shape into another without cutting or gluing, any topological invariant will be the same for both shapes,' department said. It added that in certain materials like topological insulators and superconductors, strange things happen. 'Electrons behave differently depending on how the material is 'shaped' at the quantum level. These shapes are defined not by their appearance, but by something deeper—topological invariants, such as winding numbers (in 1D systems) and Chern numbers (in 2D systems). These numbers are like hidden codes that determine how particles move through a material,' it added. Spectral function The RRI team found a new way to detect this hidden code using a property called the spectral function. Professor Dibyendu Roy and PhD researcher Kiran Babasaheb Estake have carried this out by analyzing the momentum-space spectral function (SPSF). Traditionally, scientists used techniques like ARPES (Angle-Resolved Photoemission Spectroscopy) to study electron behaviour. The new research published in Physical Review B. showed that the same spectral function holds clues to the material's hidden topology—a revolutionary way to see the structure without directly observing it. 'The spectral function has been used for many years as an experimental tool to probe the physical quantities such as density of states and the dispersion relation of electrons in a system through ARPES. It was not seen as a tool to probe topology or topological aspects of an electronic system.' said Kiran Babasaheb Estake, PhD student in theoretical Physics at RRI and the lead author. Universal tool The study potentially offers a universal tool to explore and classify topological materials, that could pave the way for new discoveries in condensed matter physics that could be useful for quantum computers, next generation electronics, and facilitate energy-efficiency.
Yahoo
20-03-2025
- Science
- Yahoo
Quantum 'Tornadoes' Spotted in Semimetal May Redefine Electronics
Physicists in Germany have led experiments that show the inertia of electrons can form 'tornadoes' inside a quantum semimetal. It's almost impossible for electrons to sit still, and their motions can take on some bizarre forms. Case in point: an analysis of electron behavior in a quantum material called tantalum arsenide reveals vortices. But the story gets weirder. These electrons aren't spiraling in a physical place – they're doing so in a quantum blur of possibility called momentum space. Rather than drawing a map of a particles' potential locations, or position space, momentum space describes their motion through their energy and direction. Similar vortices have previously been observed in position space. Measuring values of the electrons' momenta and plotting them out on a three-dimensional graph, a striking vortex pattern emerges there as well. The discovery could help pave the way for a completely new form of electronics: a field called 'orbitronics' that could tap into the twisting power of electrons instead of their electrical charge to carry information in electronic circuits or quantum computers. The discovery was made in an intriguing semimetal crystal called tantalum arsenide. In a way that's not surprising – it was in this material that the long-predicted Weyl fermion was found for the first time. This massless particle essentially functions like a super-efficient electron, and its discovery required the special quantum properties of tantalum arsenide. Those properties made the material the perfect choice for hunting quantum tornadoes. The problem arose in figuring out how to observe them. Scientists at a research center called Complexity and Topology in Quantum Matter ( in Germany led a study that managed to pull it off using a technique called angle-resolved photoemission spectroscopy (ARPES) on a sample of tantalum arsenide. "ARPES is a fundamental tool in experimental solid-state physics. It involves shining light on a material sample, extracting electrons, and measuring their energy and exit angle," says Maximilian Ünzelmann, experimental physicist at the University of Würzburg. "This gives us a direct look at a material's electronic structure in momentum space. By cleverly adapting this method, we were able to measure orbital angular momentum." Each observation, however, only takes a two-dimensional snapshot of the electrons in the material. To confirm that quantum tornadoes form in this realm, the team had to stack each measurement up into a 3D model, like a CT scan. The end result is a colorful model that shows a very clear vortex structure. "We analyzed the sample layer by layer, similar to how medical tomography works," says Ünzelmann. "By stitching together individual images, we were able to reconstruct the three-dimensional structure of the orbital angular momentum and confirm that electrons form vortices in momentum space." The team says that further work could lead to not only more efficient electronics, but an entirely new class of devices called orbitronics. This could also work alongside another potential successor of electronic technology – spintronics, which encodes information in the spin of electrons. The research was published in the journal Physical Review X. Amazing New Technology Can 'Bend' Sounds Into Your Ears Only New Heavy Metal Molecule Could Reveal What Goes on Inside Nuclear Waste Radical Theory Says Black Holes May Spew Matter And Time as White Holes
