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Experiment shows when quantum ‘cat’ states stop bouncing back

Quantum systems can occupy superpositions, quantum states that combine different possibilities. For instance, a microwave field can be prepared in a superposition of an empty state and a state that contains microwave light.

These two components can interfere, reinforcing or canceling each other’s contributions to the probabilities of measurement outcomes. This interference distinguishes a superposition from a situation in which the microwave field is simply empty or contains light.

A quantum system’s interactions with the surrounding environment can cause interference to fade, a process known as decoherence.

Counting magnetic flux quanta offers new way to measure photon numbers

Researchers at AIST have directly observed magnetic flux quanta generated in a superconductor by photon absorption and demonstrated a new principle of photon detection that identifies the number of photons based on the number of these flux quanta.

Detecting individual photons is a key technology for photonic quantum computers and quantum communication, and several methods have been proposed. While some of these methods are already in practical use for research purposes, their integration into industrial applications has just begun.

In a study appearing in the journal Physical Review Applied, a new approach to photon detection combines two important capabilities: high photon-number resolution, which is difficult to achieve with conventional technologies, and high-speed operation, which is desirable for industrial applications.

Chemically modified sugars enable direct nanostructure formation

Researchers at AIST have demonstrated the synthesis of nanoporous carbonaceous materials and carbonaceous materials with layered nanostructures through a simple process involving the chemical modification of common sugars such as sucrose and fructose.

Nanoporous carbonaceous materials have attracted attention as materials that can help address energy-related challenges, with potential applications as catalyst supports and electrode materials for secondary batteries. In particular, carbonaceous materials with highly uniform pore sizes and shapes, which can be tailored for specific applications, are in increasing demand.

The conventional templating method, however, has several drawbacks, including the need for sacrificial template agents and complex synthesis procedures that consume resources and generate waste. Furthermore, some templating procedures rely on energy-intensive and harsh chemical processes involving high temperatures and strong acids.

Plain silicon grating reveals a hidden ‘twist’ in light from electron beams

In 1953, two physicists showed that an electron beam skimming past a grating emits light whose color depends only on the electron’s speed and the grating’s spacing. Known as Smith-Purcell radiation, this phenomenon has become a useful tool for building compact, tunable light sources and tracking particle beams without touching them.

Now, researchers from Singapore and China have discovered that this well-studied effect has been hiding a property nobody thought to look for: chirality, or “handedness.” In their paper “Observation of inherent chiral Smith-Purcell effect via symmetry breaking,” published in Nature Communications, associate professors Wu Lin and Dong Zhaogang from the Singapore University of Technology and Design (SUTD) showed that the radiation is inherently chiral and demonstrated two simple ways to bring that chirality out with a plain silicon grating.

Artemis I: Crystals of experimental detectors record radiation doses near the moon

Do cosmic radiation doses near the moon differ significantly from those received by astronauts in low Earth orbit? Experimental lithium fluoride detectors, installed aboard the Orion spacecraft during the Artemis I mission, have now made it possible to obtain preliminary estimates.

As the Orion capsule of the uncrewed Artemis I mission orbited the moon in late November and early December 2022, more than 10,000 small crystals, embedded within two human phantoms, were collecting data on cosmic radiation doses. Among them were several dozen experimental fluorescent lithium fluoride detectors, developed at the Institute of Nuclear Physics of the Polish Academy of Sciences (IFJ PAN) in Cracow.

A method for reading the information stored in these detectors, providing insights into radiation doses and the properties of the detectors themselves, has now been presented in the journal Radiation Measurements.

Elusive uranium ‘sandwich’ molecule isolated after more than 50 years

In a study published in Nature Communications, researchers from The University of Manchester and Lancaster University have isolated and characterized uranocenium, the positively charged form of a landmark uranium compound called uranocene. The work shows that this long-sought molecule is stable, and that it behaves in a way that challenges how chemists usually think about bonding in heavy elements.

Uranocene is a ‘sandwich’ molecule: a single uranium atom held between two flat rings, each made of eight carbon atoms. It is the uranium counterpart of ferrocene, an iron sandwich molecule whose discovery contributed to the 1973 Nobel Prize in Chemistry. Ferrocene readily gives up an electron to form the ferrocenium cation, a switch so clean and reliable that it is used as a reference standard in laboratories worldwide. Until now, no one had been able to isolate the equivalent uranium compound.

What makes glass good at conducting heat? Sound holds the key

Glass can keep a drink safely contained, protect a smartphone screen, or serve as a foundation for electronic components. But when it comes to controlling heat, this familiar material still holds some scientific mysteries. Now, researchers have identified a key factor governing how efficiently heat travels through silicate glass, offering a new guideline for designing glass materials for next-generation electronic devices.

A research team led by Tohoku University investigated 13 different silicate glass compositions to understand how their thermal properties influence heat conduction. Their findings, published in Applied Physics Letters, reveal that the speed of sound through glass plays the dominant role in determining its thermal conductivity.

“Thermal conductivity has been studied for a long time, yet it remains one of the least understood properties of non-crystalline materials,” says Sohei Sukenaga, associate professor at Tohoku University.

What if Dark Energy Was Once Negative? Scientists Uncover a Surprising New Possibility

A gravity model that lets dark energy change sign could help resolve a persistent disagreement over how fast the universe is expanding.

In an existing theory of gravity, the same present-day matter density can fit two very different histories of the universe. Researchers had largely pursued the one that kept dark energy’s density positive. Exploring the other has now revealed a possible history in which that density began below zero and turned positive billions of years later.

Dark energy is the mysterious ingredient believed to drive the universe’s accelerating expansion. The simplest explanation treats it as unchanged throughout cosmic history. In the new analysis, however, the effects attributed to dark energy arise from a modified description of gravity. Its density is an effective quantity derived from the gravitational equations, rather than a property of a newly introduced substance.