Tuesday, July 08, 2025

Stoichiometric crystal shows promise in quantum memory

University of Illinois Grainger College of Engineering

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.

In recent years, rare earth atoms in solid materials at cryogenic temperatures have shown to be promising for quantum memory. As part of this inquiry, researchers from The Grainger College of Engineering at the University of Illinois Urbana-Champaign have identified favorable properties in a stoichiometric europium material with a layered structure. Their observations, published in Physical Review Letters, report the growth and characterization of NaEu(IO₃)₄, a rare earth material that may have future implications in quantum memory.

Although classical memory—like the type used to store text messages between users—is relatively simple to facilitate, quantum information cannot be stored, copied, or retained in this way.

“If I want to send someone quantum information or a quantum bit, I can't make a copy of it or hold onto it locally,” said Elizabeth Goldschmidt, a professor of physics and a supporting author of the paper. “Once I send it, it’s gone. If it gets lost on the way, it’s lost forever.”

One way around this challenge is using rare earth elements such as europium, which can be used to store quantum information long-term. Photons tend to degrade when stored for long periods, but europium can both absorb and preserve photons. Scientists can dope these rare earth species into crystals to facilitate quantum light storage. However, stoichiometric — or undoped — crystals tend to have fewer defects due to the lack of intentional doping.

Leaning into this property, Illinois Grainger engineers sought to pack a crystal with as much europium as possible by pivoting to stoichiometric crystals where the europium is part of the structure, rather than a randomly distributed dopant.

By combing the literature for crystals with attractive properties and evaluating their efficacy in photonic integration, the research team zeroed in on NaEu(IO₃)₄, a layered stoichiometric europium-containing crystal that is environmentally stable with strong bonds that produce 2D layers. If a single layer of NaEu(IO₃)₄ were to be isolated, it could be integrated with a photonic chip—an important step towards building a good quantum memory. However, the behavior of europium atoms can change when they are positioned too closely together, which required careful characterization of those properties in this new and novel material. An additional benefit of the material was enhanced storage time.

“Millisecond or longer quantum memory allows us to store a quantum state for the time it takes to communicate to anyone anywhere else on earth,” Goldschmidt said. “The maximum time it takes to communicate elsewhere is some tens of microseconds or milliseconds: up to a satellite and back down, or via an optical fiber circling the earth. That’s the time scale that we’re talking about.”

So far, Illinois researchers have demonstrated storage times of up to 800 nanoseconds. Going forward, they aim to demonstrate longer storage times and isolate a single layer of their stoichiometric material in hopes of one day building a quantum memory.

“Today’s computing hardware got its start the same way: as shards and plates of crystals from the past century,” said Daniel Shoemaker, a professor of materials science and engineering whose lab grew the crystals for this research. “We don’t know what the next century will hold for quantum memory, but we know they will rely on the actions of electrons on individual atoms and ions, like the europium in our materials here. Right now, we are exploring the first few materials, so it’s an exciting time.”

Journal

Physical Review Letters

DOI

10.1103/p39m-pnvt

Article Title

Narrow optical linewidths in stoichiometric layered rare-earth crystals

Scientists develop method to build tiny custom microrobots

University of Colorado at Boulder

image:
Kendra Kreienbrink, a materials science and engineering
PhD student in the Shields Lab, is the paper's first author.
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Credit: Courtesy of University of Colorado Boulder

Researchers at the University of Colorado Boulder have created a new way to build and control tiny particles that can move and work like microscopic robots, offering a powerful tool with applications in biomedical and environmental research.

The study, published in Nature Communications, describes a new method of fabrication that combines high-precision 3D printing, called two-photon lithography, with a microstenciling technique. The team prints both the particle and its stencil together, then deposits a thin layer of metal, such as gold, platinum or cobalt through the stencil’s openings. When the stencil is removed, a metal patch remains on the particle.

The particles, invisible to the naked eye, can be made in almost any shape and patterned with surface patches as small as 0.2 microns — more than 500 times thinner than a human hair. The metal patches guide how the particles move when exposed to electric or magnetic fields, or chemical gradients.

“The shape of surface patches gives particles information about where to go,” said Assistant Professor Wyatt Shields, one of the paper’s authors. “We've not had good methods to control the shape of those patches until now.”

With this control, these particles could potentially help improve how drugs spread through human organs, improving the drug’s overall effectiveness, or aid in the removal of pollutants from contaminated environments.

The research team includes first author Kendra Kreienbrink, a materials science and engineering PhD student in the Shields Lab, along with two undergraduate students: Zoe Cruse, majoring in chemical and biological engineering and computer science, and Alisha Kumari, in biomedical engineering.

“This paper not only represents the exciting things that can be accomplished in active particles and microrobots using non-conventional microfabrication,” Shields said, “but that the inclusion and mentorship of undergrads early in research can lead to innovative outcomes.”

Journal

Nature

DOI

10.1038/s41467-025-61218-x

Article Title

Precise surface patches on active particles of arbitrary shape through microstenciling

Article Publication Date

7-Jul-2025

USC study: mindfulness meditation can sharpen attention in adults of all ages

30 days of app-guided meditation linked to improvements in how quickly and accurately participants directed their focus, as measured by eye movement tracking

University of Southern California

A new study from the USC Leonard Davis School of Gerontology reveals that just 30 days of guided mindfulness meditation can significantly enhance key aspects of attentional control — especially how quickly and accurately people direct their focus — regardless of age.

The study is among the first to use eye tracking, a powerful and objective measure of attention, to test the effects of mindfulness training on young, middle-aged, and older adults. The findings demonstrate that even short-term meditation can lead to measurable cognitive improvements, said USC Leonard Davis School postdoctoral researcher Andy Jeesu Kim, the study’s first author.

“This study shows that mindfulness isn’t just about feeling more relaxed—it can literally change the way your brain handles attention,” Kim said. “And that’s incredibly important for maintaining cognitive health as we age.”

Why Attention Matters in Aging

As people age, they often experience slower reaction times and increased difficulty tuning out distractions. These changes are tied to a brain system called the locus coeruleus–noradrenaline (LC-NA) system, which plays a critical role in attention, arousal, and memory. Prior research, including work led by USC Leonard Davis Professor and study senior author Mara Mather, links age-related decline in this system to early Alzheimer’s disease changes.

Previous investigation has also shown that mindfulness meditation can enhance brain areas involved in attention and may increase activity in the LC-NA system. However, this is the first study to examine how mindfulness training affects attention using precise eye-tracking methods and whether the benefits differ across age groups, Kim explained.

The Study: Mindfulness vs. Audiobook

The USC study enrolled 69 adults split into three age groups: young (18–30), middle-aged (50–65), and older adults (65–80). Participants were randomly assigned to practice one of two options:

Mindfulness meditation using the Headspace app, 10–15 minutes per day for 30 days
An audiobook control, listening to chapters from a novel for the same duration

All participants completed three in-person lab visits and performed two eye-tracking visual search tasks that measured their speed and accuracy in focusing attention and ignoring distractions.

Key Findings: Faster Focus, Stronger Control

After the mindfulness training, participants showed improvements in several core aspects of attention:

Faster reaction times: Participants were quicker to move their eyes toward target shapes, showing more efficient visual processing.
Improved goal-directed focus: They made more direct saccades (eye movements) toward relevant targets and were better able to resist being pulled off course by distracting objects.
Reduced distractibility: In some tasks, participants were less likely to fixate on irrelevant but visually “loud” items.

Interestingly, the benefits were not limited to one age group.

“We expected older adults to benefit the most, but we found that mindfulness improved attention similarly across young, middle-aged, and older adults,” Kim said. “This suggests mindfulness can be a useful tool at any stage of life.”

However, these improvements were not reflected in self-reported mindfulness scores from questionnaires, underscoring the value of objective eye-tracking measures.

A Powerful Tool for Everyday Attention

Although mindfulness has been widely embraced for stress relief and emotional wellness, this study provides compelling evidence for its cognitive benefits, too. The improvement was particularly apparent in attention control, a mental ability that is crucial for everything from driving to reading to social interactions.

Importantly, the study also compared the effects of the mindfulness intervention to an audiobook control. While both groups showed some improvement in attention, mindfulness participants improved more quickly and more significantly in certain areas, particularly reaction speed.

What’s Next

The researchers note that while the study demonstrates promising short-term benefits, future studies should explore whether longer or more intensive mindfulness training could produce even greater effects, especially for older adults facing age-related cognitive decline.

“We’re excited about the potential of digital mindfulness interventions to help people support their brain health,” Kim said. “It’s simple, low-cost, and widely accessible. The key is consistency.”

—

“The effects of mindfulness meditation on mechanisms of attentional control in young and older adults: A preregistered eye tracking study,” appeared in eNeuro on July 7, 2025. The study was funded by the National Institute on Aging (F32-AG076288) and the USC Center for Mindfulness Science. Along with Kim and Mather, coauthors included Keran Chen and Ying Tian of the USC Leonard Davis School.

Journal

eNeuro

DOI

10.1523/ENEURO.0356-23.2025

Method of Research

Randomized controlled/clinical trial

Subject of Research

People

Article Title

The effects of mindfulness meditation on mechanisms of attentional control in young and older adults: a preregistered eye tracking study

Article Publication Date

7-Jul-2025

Eliminating invasive rats may restore the flow of nutrients across food chain networks in Seychelles

Study suggests seabird populations play mediating role in coral reef ecosystem function

PLOS

Eliminating invasive rats may restore the flow of nutrients across food chain networks in Seychelles — image:
Scientists conducting a survey on a coral reef.
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Credit: Casey Benkwitt (CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)

Ecosystems are characterized by interconnected structure and functions. A study published July 8th in the open-access journal PLOS Biology by Casey Benkwitt at Lancaster University, United Kingdom and colleagues suggests that restoring seabird populations via eradication of rats may help coral reefs by restoring nutrient connectivity in disrupted food chains.

Invasive rats in the Seychelles have decreased native seabird populations. However, the mechanism by which seabirds may impact coral reef ecosystem structure and function across multiple food chain links is unknown. In order to quantify the ecosystem-wide food chain disruptions from species decline, researchers analyzed the movement of nutrients from seabirds through a marine ecosystem in five marine study sites across four islands in the inner Seychelles. One of the islands had invasive rats that predate seabirds, one island had rats eradicated, and two of the islands were historically rat-free. They accessed breeding bird survey data to estimate seabird biomass and measured seabird-derived nutrients in turf algae, as well as turf algae growth and cover, and herbivorous fish biomass and productivity across all five study sites. The researchers then used a causal modelling framework to test the effect of seabird nutrient inputs on structure and function across two different food chain levels.

The researchers found that seabird guano increased turf algae growth on coral reefs, but not algal cover. Through seabird-derived nutrient (guano) uptake, algal turf grew more quickly, which led to an increase in both the mass and productivity of herbivorous fishes beneficial to reefs. This feedback loop between producers and consumers limited the amount of turf algal cover on reefs.

The study was limited by its small sample size of four islands, and future studies are needed to replicate the results in different sites.

According to the authors, “These findings could be used to predict the benefits of removing introduced rats from islands, which can increase seabird populations and restore nutrient connectivity, thus potentially enhancing ecosystem function across multiple trophic levels on coral reefs. In terms of conservation, these findings add to the body of evidence that herbivores are key to preventing coral to algae regime shifts on coral reefs, and additionally suggest that restoring ecosystem connectivity, combined with effective fisheries management, is another route to help achieve this goal”.

Casey Benkwitt says, “We show that natural nutrient inputs, provided by seabirds, cause turf algae on coral reefs to grow faster. This boost in primary productivity, in turn, enhances herbivorous fish biomass and productivity, and stimulates top-down controls that limit turf algal cover.”

Benkwitt notes, “It was amazing to see how much faster turf algae grew where seabirds are nearby, because this is something that you normally can't see with your naked eye. That seabird nutrients increased algal growth, but not how much of a reef it covers, shows the hidden pathways by which seabirds can influence coral reefs.”

Co-author Anna Zora (Conservation and Sustainability Manager on Fregate Island, Seychelles), adds, “Living and working on a small island—observing its wildlife on land and beneath the sea—you witness firsthand the profound connection between a healthy terrestrial ecosystem and the vibrant reef that surrounds it. You can’t help but think: the land and sea are deeply intertwined. This study confirms that protecting the ocean begins on land. A thriving island fosters a thriving reef.”

In your coverage, please use this URL to provide access to the freely available paper in PLOS Biology: https://plos.io/4mB50th

Citation: Benkwitt CE, Zora A, Ebrahim A, Govinden R, Lange ID, Evans S, et al. (2025) Nutrient connectivity via seabirds enhances dynamic measures of coral reef ecosystem function. PLoS Biol 23(7): e3003222. https://doi.org/10.1371/journal.pbio.3003222

Author countries: United Kingdom, Seychelles

Funding: This work was funded by the Bertarelli Foundation as part of the Bertarelli Programme in Marine Science (CEB, IDL, NAJG). The funder did not play a role in the study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Example herbivore exclusion cages used to measure algal turf productivity, shown one day after installation (left), and upon removal after 4-7 days (right). Turf algae grows quickly in the absence of herbivores.

Colony of frigatebirds, which provide nutrient inputs to nearby coral reefs.

Large school of herbivorous fish, which eat turf algae enriched by nutrients from seabirds.

White-tailed tropicbird, which provides nutrient inputs to nearby coral reefs.

Credit

Casey Benkwitt (CC-BY 4.0, https://creativecommons.org/licenses/by/4.0/)

Journal

PLOS Biology

DOI

10.1371/journal.pbio.3003222

Method of Research

Observational study

Subject of Research

Animals

COI Statement

Competing interests: The authors have declared that no competing interests exist.

World’s first: Lithuanian scientists’ discovery may transform OLED technology and explosives detection

An international team of scientists from Kaunas University of Technology, KTU, Lithuania, has, for the first time, observed the luminescence of an excited complex formed by two donor molecules.

Kaunas University of Technology

image:
explains Dr Juozas Gražulevičius, Professor at KTU Faculty of Chemical Technology
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Credit: KTU

In modern devices, such as phone screens or advanced sensors, light is often generated by pairs of organic molecules, where one molecule, known as the donor, transmits electrons, and the other, referred to as the acceptor, receives them. An international team of scientists from Kaunas University of Technology, KTU, Lithuania, has, for the first time, observed the luminescence of an excited complex formed by two donor molecules. This discovery opens new possibilities for developing simpler, more efficient, and more sustainable optoelectronic devices.

“Until now, such interactions were considered practically impossible. This discovery challenges the fundamental principles we have used to understand how light-emitting materials work and pushes us to rethink the potential of donor interactions,” explains Dr Juozas Gražulevičius, Professor at KTU Faculty of Chemical Technology.

Used in sensors for detecting explosives

One of the most important applications of this discovery is in organic light-emitting diodes (OLEDs). OLED technology is widely used in everyday devices such as phones, TVs, smartwatches, and car dashboards. Compared to traditional LEDs, OLEDs offer flexibility, brighter colours, higher contrast, and higher energy efficiency.

However, OLEDs are often made from complex or costly components, for example, metal-organic complexes containing iridium or platinum. To make OLEDs more accessible, researchers are exploring organic compounds as alternatives. The KTU team, in collaboration with Ukrainian scientists, has not only designed new organic compounds suitable for OLED technology but also successfully synthesised them. Their discovery allows for simplified OLED architectures where all active materials are organic, with efficient molecular interactions.

“Our discovery can facilitate OLED production, which is crucial both for technological advancement and sustainability,” notes a co-inventor, Ehsan Ullah Rashid, a PhD student at KTU.

Besides their technical advantages, these materials are easy to synthesise, stable in the solid state, and do not require complicated manufacturing processes. This flexibility enables not only the improvement of the technology but also its faster implementation in real products.

The applications of KTU-synthesised materials extend beyond displays and lighting. One compound shows high sensitivity to nitroaromatic substances, such as picric acid, used in explosives manufacturing. Improperly stored, picric acid can become highly sensitive to friction or heat, posing serious safety risks. When exposed to this compound, the luminescence of the newly developed molecules is quenched, allowing it to act as an optical sensor capable of detecting even very low concentrations of dangerous explosive substances.

“Materials that intensively emit light and whose light emission is drastically suppressed in the presence of nitroaromatic compounds enable the creation of sensitive, reliable, and convenient sensors. Such solutions are important not only for military and security applications but also for environmental protection,” says Dr Monika Čekavičiūtė, the scientist who developed and synthesised the new compounds.

Challenging established scientific beliefs

The luminescence of a complex formed by two donor molecules is a novel phenomenon in science. “One of the most exciting aspects of our invention is discovering new ways molecules can behave and emit light, not only individually but also in unexpected combinations with similar molecules. This challenges traditional scientific views,” Prof. Gražulevičius says.

The research of KTU scientists encompasses the design and synthesis of a series of new multifunctional organic semiconductors tailored for modern organic optoelectronic systems.

“Our materials stand out for their multifunctionality, simple structures, and exceptional photophysical properties. They can form two types of complexes, which is unusual for organic semiconductors,” adds Čekavičiūtė.

In one case, interaction with picric acid creates a non-luminescent complex, while in the other, two donor molecules form an emissive exciplex. This complex exhibits thermally activated delayed fluorescence (TADF), which significantly boosts OLED efficiency without relying on heavy-metal derivatives. This improves the conversion of electricity into light, enabling OLED displays and lighting devices to shine brighter using less energy.

“Unlike many organic emitters whose luminescence decreases when molecules are closely packed, our developed molecules show the opposite effect – their luminescence increases. This phenomenon is known as aggregation-enhanced emission,” explains Rashid.

This feature not only enhances performance and lowers energy consumption but also improves device stability and lifespan. Moreover, the layers of the material are less prone to crystallisation, extending device durability without performance loss.

“In our study, molecular aggregation, previously seen as a problem, becomes a functional advantage. This fundamentally changes how we approach the use of organic materials in optoelectronics,” says Prof. Gražulevičius.

The article From Donor-Donor Exciplex-Forming Interfaces to Detection of an Explosive Compound with Phenylethenyl Derivatives Redefining OLED Efficiency and Extremely High Sensitivity to Picric Acid is available here.

Dr Monika Čekavičiūtė, the scientist who developed and synthesised the new compounds

Ehsan Ullah Rashid, a PhD student at KTU

Journal

ACS Applied Electronic Materials

DOI

10.1021/acsaelm.5c00123

Article Title

From Donor–Donor Exciplex-Forming Interfaces to Detection of an Explosive Compound with Phenylethenyl Derivatives Redefining OLED Efficiency and Extremely High Sensitivity to Picric Acid