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Keeping the photon in the dark: A new method for full control of quantum dots

Excitons—bound pairs of electrons and an electron hole—are quasiparticles that can arise in solids. While so-called “bright” excitons emit light and are therefore accessible, dark excitons are optically inactive. As a result, they have a significantly longer lifetime—which makes them ideal for storing and controlling quantum states and using them for advanced methods to generate entanglement.

Gregor Weihs and his team from the Department of Experimental Physics at the University of Innsbruck, together with researchers in Dortmund, Bayreuth, and Linz, have now demonstrated a versatile method that can be used to control dark excitons in .

The work is published in Science Advances.

Alternating current can reduce friction by redistributing electronic density at material interfaces

A research team led by Prof. Tian-Bao Ma from the Department of Mechanical Engineering at Tsinghua University has proposed a novel strategy to reduce friction and wear by inducing dynamic electronic density redistribution through the application of an alternating electric current.

This method enables flexible and instantaneous modulation of by adjusting the amplitude and frequency of the alternating current. Remarkably, it maintains low friction and wear over long durations under high contact pressure and current density, requiring only a low driving voltage.

The findings are published in the journal Nature Communications.

Visualization of atomic-scale magnetism achieved with new imaging method

An international research team led by Forschungszentrum Jülich has succeeded in visualizing magnetism inside solids with unprecedented precision. Using a newly developed method, the scientists were able to image the finest building blocks of magnetism directly at the atomic level. They have published their findings in the journal Nature Materials.

Magnetism is an integral part of our everyday lives—it is found in , loudspeakers, and the storage media of modern computers. It is generated by the movement and spin of electrons. Previous techniques could only measure these properties to a limited extent and often only on the surface of materials. The team led by Dr. Hasan Ali and Prof. Rafal E. Dunin-Borkowski has now developed a new method using a state-of-the-art electron microscope to measure at a previously unattainable resolution.

“Our technique allows us to visualize the magnetic properties within a material with atomic precision,” explains Dr. Hasan Ali, first author of the study. “This enables us to observe how the movement and spin of electrons behave in the .”

Defects in single-crystal indium gallium zinc oxide could fix persistent display instability

Many displays found in smartphones and televisions rely on thin-film transistors (TFTs) made from indium gallium zinc oxide (IGZO) to control pixels. IGZO offers high transparency due to its large bandgap (the gap existing between the valence and conduction bands), high conductivity, and can operate even in an amorphous (non-crystalline) form, making it ideal for displays, flexible electronics, and solar cells.

However, IGZO-based devices face long-term stability issues, such as negative bias illumination stress, where prolonged exposure to light and electrical stress shifts the voltage required to activate pixels. These instabilities are believed to stem from structural imperfections, which create additional electronic states—known as subgap states—that trap charge carriers and disrupt current flow.

Until recently, most studies on subgap states focused on amorphous IGZO, as sufficiently large single-crystal IGZO (sc-IGZO) samples were not available for analysis. However, the disordered nature of amorphous IGZO has made it difficult to pinpoint the exact causes of electronic instability.

Low-loss spin waveguide network could pave way for energy-efficient AI hardware

The rapid rise in AI applications has placed increasingly heavy demands on our energy infrastructure. All the more reason to find energy-saving solutions for AI hardware. One promising idea is the use of so-called spin waves to process information.

Calculating the electron’s magnetic moment: State-dependent values emerge from Dirac equation

Quantum mechanics has a reputation that precedes it. Virtually everyone who has bumped up against the quantum realm, whether in a physics class, in the lab, or in popular science writing, is left thinking something like, “Now, that is really weird.” For some, this translates to weird and wonderful. For others it is more like weird and disturbing.

Chip Sebens, a professor of philosophy at Caltech who asks foundational questions about physics, is firmly in the latter camp. “Philosophers of physics generally get really frustrated when people just say, ‘OK, here’s quantum mechanics. It’s going to be weird. Don’t worry. You can make the right predictions with it. You don’t need to try to make too much sense out of it, just learn to use it.’ That kind of thing drives me up the wall,” Sebens says.

One particularly weird and disturbing area of physics for people like Sebens is theory. Quantum field theory goes beyond quantum mechanics, incorporating the and allowing the number of particles to change over time (such as when an electron and positron annihilate each other and create two photons).

Studies offer new insights into production and structure of heavy hollow atoms

Hollow atoms are special atoms with multiple missing electrons in their inner shells, while their outer shells are still fully or partially filled with electrons. Studying the production mechanisms, internal structure, and de-excitation properties of these excited-state atoms provides insights into quantum electrodynamics and quantum many-body interactions, with applications in fields such as inner-shell ionization X-ray lasers, high-energy density physics, and molecular imaging.

Researchers at the Institute of Modern Physics (IMP) of the Chinese Academy of Sciences recently confirmed that the fully stripped heavy ion-atom collision is an effective way to produce heavy hollow atoms in high yield. They have also developed a high-resolution planar crystal to measure the fine structure of inner-shell multi-ionization ion X-rays.

The results have been published in Spectrochimica Acta Part B: Atomic Spectroscopy and Physical Review A.

Researchers discover more efficient way to route information in quantum computers

Quantum computers have the potential to revolutionize computing by solving complex problems that stump even today’s fastest machines. Scientists are exploring whether quantum computers could one day help streamline global supply chains, create ultra-secure encryption to protect sensitive data against even the most powerful cyberattacks, or even develop more effective drugs by simulating their behavior at the atomic level.

But building efficient quantum computers isn’t just about developing faster chips or better hardware. It also requires a deep understanding of quantum mechanics—the strange rules that govern the tiniest building blocks of our universe, such as atoms and electrons—and how to effectively move information through .

In a paper published in Physics Review X, a team of physicists—including graduate student Elizabeth Champion and assistant professor Machiel Blok from the University of Rochester’s Department of Physics and Astronomy—outlined a method to address a tricky problem in quantum computing: how to efficiently move information within a multi-level system using quantum units called qudits.

Stoichiometric crystal shows promise in quantum memory

For over two decades, physicists have been working toward implementing quantum light storage—also known as quantum memory—in various matter systems. These techniques allow for the controlled and reversible mapping of light particles called photons onto long-lived states of matter. But storing light for long periods without compromising its retrieval efficiency is a difficult task.

Affordable, room-temperature maser created using LED technology

With the ability to detect and amplify extremely weak electromagnetic signals without adding additional noise, masers have many potential uses, including the production of more sensitive magnetic resonance body scanners, such as those used in airports.

Despite their discovery in the 1950s, there has been little development of the technology since then due to the complex and expensive conditions required to make them—masers are only able to be produced in very cold conditions, while also within a vacuum and a high magnetic field.

Northumbria’s Dr. Juna Sathian is one of the U.K.’s leading experts in maser technology and has previously worked with colleagues at Imperial College London and University College London to develop a room-temperature maser which works using laser light. However, this method is expensive and difficult to replicate in everyday applications.