Toggle light / dark theme

Too much entanglement? Quantum networks can suffer from ‘selfish routing,’ study shows

Quantum technologies, systems that process, transfer or store information leveraging quantum mechanical effects, could tackle some real-world problems faster and more effectively than their classical counterparts. In recent years, some engineers have been focusing their efforts on the development of quantum communication systems, which could eventually enable the creation of a “quantum internet” (i.e., an equivalent of the internet in which information is shared via quantum physical effects).

Networks of quantum devices are typically established leveraging quantum entanglement, a correlation that ensures that the state of one particle or system instantly relates to the state of another distant particle or system. A key assumption in the field of quantum science is that greater entanglement would be linked to more reliable communications.

Researchers at Northwestern University recently published a paper in Physical Review Letters that challenges this assumption, showing that, in some realistic scenarios, more entanglement can adversely impact the quality of communications. Their study could inform efforts aimed at building reliable quantum communication networks, potentially also contributing to the future design of a quantum internet.

New insight into light-matter thermalization could advance neutral-atom quantum computing

Light and matter can remain at separate temperatures even while interacting with each other for long periods, according to new research that could help scale up an emerging quantum computing approach in which photons and atoms play a central role.

In a theoretical study published in Physical Review Letters, a University at Buffalo-led team reports that interacting photons and atoms don’t always rapidly reach thermal equilibrium as expected.

Thermal equilibrium is the process by which interacting particles exchange energy before settling at the same temperature, and it typically happens quickly when trapped light repeatedly interacts with matter. Under the right circumstances, however, physicists found that photons and atoms can instead settle at different—and in some cases opposite—temperatures for extended periods.

Innovative optical atomic clock could combine single-ion accuracy with multi-ion stability

For many years, cesium atomic clocks have been reliably keeping time around the world. But the future belongs to even more accurate clocks: optical atomic clocks. In a few years’ time, they could change the definition of the base unit second in the International System of Units (SI). It is still completely open, which of the various optical clocks will serve as the basis for this.

The large number of optical clocks that the Physikalisch-Technische Bundesanstalt (PTB), as a leading institute in this field, has realized could be joined by another type: an optical multi-ion clock with ytterbium-173 ions. It could combine the high accuracy of individual ions with the improved stability of several ions. This is the result of a cooperation between PTB and the Thai metrology institute NIMT.

The team led by Tanja Mehlstäubler reports on this in the current issue of the journal Physical Review Letters. The results are also interesting for quantum computing and, with a new look inside the atom, for fundamental research.

Optical technique reveals hidden magnetic states in antiferromagnets

Imagine computer hardware that is blazing fast and stores more data in less space. That’s the promise of antiferromagnets, magnetic materials that do not interfere with each other and can switch states at high speed, opening the door to advanced computing and quantum applications.

Magnetism comes from unpaired electrons, tiny particles that orbit an atom’s nucleus. Each electron has a property called spin, which can point up or down. In standard ferromagnets, the atomic spins point in the same direction, creating a strong magnetic field. In antiferromagnets, neighboring spins point in opposite directions, canceling each other out and yielding no net magnetism.

Flipping individual spins in an antiferromagnet requires very little movement of magnetization, which allows ultrafast processing. Antiferromagnets can switch states trillions of times per second, compared with billions for ferromagnets. With net zero magnetism, antiferromagnets can be placed very close together without repelling or attracting each other, allowing more data to be stored in a small space.

Metal clumps in a quantum state: Physicists place thousands of sodium atoms in a ‘Schrödinger’s cat state’

Can a small lump of metal be in a quantum state that extends over distant locations? A research team at the University of Vienna answers this question with a resounding yes. In the journal Nature, physicists from the University of Vienna and the University of Duisburg-Essen show that even massive nanoparticles consisting of thousands of sodium atoms follow the rules of quantum mechanics. The experiment is currently one of the best tests of quantum mechanics on a macroscopic scale.

In quantum mechanics, not only light but also matter can behave both as a particle and as a wave. This has been proven many times for electrons, atoms, and small molecules through double-slit diffraction or interference experiments. However, we do not see this in everyday life: marbles, stones, and dust particles have a well-defined location and a predictable trajectory; they follow the rules of classical physics.

At the University of Vienna, the team led by Markus Arndt and Stefan Gerlich has now demonstrated for the first time that the wave nature of matter is also preserved in massive metallic nanoparticles. The scale of the particles is impressive: the clusters have a diameter of around 8 nanometers, which is comparable to the size of modern transistor structures.

Velocity gradients prove key to explaining large-scale magnetic field structure

All celestial bodies—planets, suns, even entire galaxies—produce magnetic fields, affecting such cosmic processes as the solar wind, high-energy particle transport, and galaxy formation. Small-scale magnetic fields are generally turbulent and chaotic, yet large-scale fields are organized, a phenomenon that plasma astrophysicists have tried explaining for decades, unsuccessfully.

In a paper published January 21 in Nature, a team led by scientists at the University of Wisconsin–Madison have run complex numerical simulations of plasma flows that, while leading to turbulence, also develop structured flows due to the formation of large-scale jets. From their simulations, the team has identified a new mechanism to describe the generation of magnetic fields that can be broadly applied, and has implications ranging from space weather to multimessenger astrophysics.

“Magnetic fields across the cosmos are large-scale and ordered, but our understanding of how these fields are generated is that they come from some kind of turbulent motion,” says the study’s lead author Bindesh Tripathi, a former UW–Madison physics graduate student and current postdoctoral researcher at Columbia University.

Sam Altman Cornered by Discovery: Intent & Emails in Elon’s OpenAI Lawsuit

Elon Musk’s lawsuit against OpenAI and his own ambitious plans for AI and tech innovations, including new devices and massive growth for his companies, are positioning him for a major impact on the tech industry, but also come with significant challenges and risks ## Questions to inspire discussion.

Legal Risk Management.

🔍 Q: How does the discovery process threaten OpenAI regardless of lawsuit outcome?

A: Discovery forces exposure of sensitive internal information including Greg Brockman’s 2017 diary entries revealing intent to become for-profit and violating prior agreements with Elon Musk, creating reputational damage and investor uncertainty even if OpenAI wins the case.

⏱️ Q: Why is lawsuit timing particularly damaging to OpenAI’s competitive position?

A: The lawsuit hits during OpenAI’s massive capital raise preparation, forcing delays in fundraising and implementation that allow competitors like Google and Anthropic to advance while OpenAI falls behind, similar to how Meta became less relevant in the AI race.

Complex building blocks of life form spontaneously in space, research reveals

Challenging long-held assumptions, Aarhus University researchers have demonstrated that the protein building blocks essential for life as we know it can form readily in space. This discovery, appearing in Nature Astronomy, significantly raises the statistical probability of finding extraterrestrial life.

In a modern laboratory at Aarhus University and at an international European facility in Hungary (HUN-REN Atomki), researchers Sergio Ioppolo and Alfred Thomas Hopkinson conduct pioneering experiments. Within a small chamber, the two scientists have mimicked the environment found in giant dust clouds thousands of light-years away. This is no easy feat.

The temperature in these regions is a freezing −260° C. There is almost no pressure, meaning the researchers must constantly pump out gas particles to maintain an ultra-high vacuum. They are simulating these conditions to observe how the remaining particles react to radiation, exactly as they would in a real interstellar environment.

A twitch in time? Quantum collapse models hint at tiny time fluctuations

Quantum mechanics is rich with paradoxes and contradictions. It describes a microscopic world in which particles exist in a superposition of states—being in multiple places and configurations all at once, defined mathematically by what physicists call a “wavefunction.” But this runs counter to our everyday experience of objects that are either here or there, never both at the same time.

Typically, physicists manage this conflict by arguing that, when a quantum system comes into contact with a measuring device or an experimental observer, the system’s wavefunction “collapses” into a single, definite state. Now, with support from the Foundational Questions Institute, FQxI, an international team of physicists has shown that a family of unconventional solutions to this measurement problem—called “quantum collapse models”—has far-reaching implications for the nature of time and for clock precision.

They published their results suggesting a new way to distinguish these rival models from standard quantum theory, in Physical Review Research, in November 2025.

/* */