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Category: computing

Record-breaking photons at telecom wavelengths—on demand

A team of researchers from the University of Stuttgart and the Julius-Maximilians-Universität Würzburg led by Prof. Stefanie Barz (University of Stuttgart) has demonstrated a source of single photons that combines on-demand operation with record-high photon quality in the telecommunications C-band—a key step toward scalable photonic quantum computation and quantum communication. “The lack of a high-quality on-demand C-band photon source has been a major problem in quantum optics laboratories for over a decade—our new technology now removes this obstacle,” says Prof. Stefanie Barz.

In everyday life, distinguishing features may often be desirable. Few want to be exactly like everyone else. When it comes to quantum technologies, however, complete indistinguishability is the name of the game. Quantum particles such as photons that are identical in all their properties can interfere with each other—much as in noise-canceling headphones, where sound waves that are precisely inverted copies of the incoming noise cancel out the background.

When identical photons are made to act in synchrony, then the probability that certain measurement outcomes occur can be either boosted or decreased. Such quantum effects give rise to powerful new phenomena that lie at the heart of emerging technologies such as quantum computing and quantum networking. For these technologies to become feasible, high-quality interference between photons is essential.

Beyond the eye of the beholder: Mathematically defining attributes essential to color perception

Research on the perception of color differences is helping resolve a century-old understanding of color developed by Erwin Schrödinger. Los Alamos scientist Roxana Bujack led a team that used geometry to mathematically define the perception of color as it relates to hue, saturation and lightness.

Presented at the 2025 Eurographics Conference on Visualization, their work formalizes Schrödinger’s model of color, decisively establishing the perception of color attributes as an intrinsic property. The paper, “The Geometry of Color in the Light of a Non-Riemannian Space,” was published in the Computer Graphics Forum.

“What we conclude is that these color qualities don’t emerge from additional external constructs such as cultural or learned experiences but reflect the intrinsic properties of the color metric itself,” Bujack said. “This metric geometrically encodes the perceived color distance—that is, how different two colors appear to an observer.”

2D discrete time crystals realized on a quantum computer for the first time

Physical systems become inherently more complicated and difficult to produce in a lab as the number of dimensions they exist in increases—even more so in quantum systems. While discrete time crystals (DTCs) had been previously demonstrated in one dimension, two-dimensional DTCs were known to exist only theoretically. But now, a new study, published in Nature Communications, has demonstrated the existence of a DTC in a two-dimensional system using a 144-qubit quantum processor.

Like regular crystalline materials, DTCs exhibit a kind of periodicity. However, the crystalline materials most people are familiar with have a periodically repeating structure in space, while the particles in DTCs exhibit periodic motion over time. They represent a phase of matter that breaks time-translation symmetry under a periodic driving force and cannot experience an equilibrium state.

“Consequently, local observables exhibit oscillations with a period that is a multiple of the driving frequency, persisting indefinitely in perfectly isolated systems. This subharmonic response represents a spontaneous breaking of discrete time-translation symmetry, analogous to the breaking of continuous spatial symmetry in conventional solid-state crystals,” the authors of the new study explain.

Mapping ‘figure 8’ Fermi surfaces to pinpoint future chiral conductors

One of the biggest problems facing modern microelectronics is that computer chips can no longer be made arbitrarily smaller and more efficient. Materials used to date, such as copper, are reaching their limits because their resistivity increases dramatically when they become too small. Chiral materials could provide a solution here. These materials behave like left and right hands: they look almost identical and are mirror images of each other, but cannot be made to match.

“It is assumed that the resistivity in some chiral materials remains constant or even decreases as the chiral material becomes smaller. That is why we are working on using electronic chirality to develop materials for a new generation of microchips that are faster, more energy-efficient and more robust than today’s technologies,” says Professor Niels Schröter from the Institute of Physics at MLU. Until now, however, it has been difficult to produce thin layers of these materials without the left-and right-handed areas canceling each other out in their effects.

This is precisely where the new study, in which the Max Planck Institute for Microstructure Physics in Halle was also involved, comes in. “For the first time, we have found materials that are not yet chiral themselves. However, they have the potential to be converted into electronically chiral materials with only a single-handedness through targeted distortion. These achiral materials can serve as so-called parent materials for engineering chiral conductors with reduced resistivity,” explains Schröter.

Physicists Discover a New Way To Connect Qubits Using Crystal Imperfections

A new study suggests that crystal defects in diamond may hold the key to scalable quantum interconnects. Connecting large numbers of quantum bits (qubits) into a working technology remains one of the biggest obstacles facing quantum computing. Qubits are extraordinarily sensitive, and even small di

The Linux community now has a succession plan for when Linus Torvalds checks out, after an apparently uplifting discussion about ‘our eventual march toward death’

The room discussed various options but, per LWN.net, “it is sufficient to say that there was not a lot of disagreement” before two things were agreed upon. The first was acknowledging that there are already some provisions in place, with multiple people being able to commit to Torvalds’ repository, and redundancy measures in place for the stable repository.

The hoped-for scenario is that Torvalds will decide to step back, arrange a smooth transition to any replacement himself, and go off to enjoy a long retirement. Torvalds made it known he has no plans in this direction anytime soon, but why would he.

Then the big question: what if something goes wrong that does prevent this smooth transition, whether it’s a freak skydiving incident or Bill Gates in the library with a candlestick. “As I put it in the discussion,” writes LWN.net co-founder Jonathan Corbet, “in the absence of an agreed-upon process, the community would find itself playing Calvinball at an awkward time.”

Neuralink’s Brain Chip: How It Works and What It Means

Elon Musk recently announced that Neuralink, his company aiming to revolutionize brain-computer interfaces (BCIs), has successfully implanted a brain chip in a human for the first time. The implantation of the device, called “the Link,” represents a leap forward in the realm of BCIs, which record and decode brain activity, that may allow for new innovations in health care, communication, and cognitive abilities.

Though limited information on the technology is available and Neuralink’s claims have not been independently verified, here’s a look at the Link, its functionality, and the potential implications of this groundbreaking innovation.

A New Ingredient for Quantum Error Correction

Entanglement and so-called magic states have long been viewed as the key resources for quantum error correction. Now contextuality, a hallmark of quantum theory, joins them as a complementary resource.

Machines make mistakes, and as they scale up, so too do the opportunities for error. Quantum computers are no exception; in fact, their errors are especially frequent and difficult to control. This fragility has long been a central obstacle to building large-scale devices capable of practical, universal quantum computation. Quantum error correction attempts to circumvent this obstacle, not by eliminating sources of error but by encoding quantum information in such a way that errors can be detected and corrected as they occur [1]. In doing so, the approach enables fault-tolerant quantum computation. Over the past few decades, researchers have learned that this robustness relies on intrinsically quantum resources, most notably, entanglement [2] and, more recently, so-called magic states [3].

Quantum batteries could quadruple qubit capacity while reducing energy infrastructure requirements

Scientists have unveiled a new approach to powering quantum computers using quantum batteries—a breakthrough that could make future computers faster, more reliable, and more energy efficient.

Quantum computers rely on the rules of quantum physics to solve problems that could transform computing, medicine, energy, finance, communications, and many other fields in the years ahead.

But sustaining their delicate quantum states typically requires room-sized, energy-intensive cryogenic cooling systems, as well as a system of room-temperature electronics.

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