Aurelia Butler

University of Washington researchers have discovered they can detect atomic “breathing,” or the mechanical vibration between two layers of atoms, by observing the type of light those atoms emitted when stimulated by a laser. The sound of this atomic “breath” could help researchers encode and transmit quantum information.
The researchers also developed a device that could serve as a new type of building block for quantum technologies, which are widely anticipated to have many future applications in fields such as computing, communications and sensor development.
The researchers published these findings June 1 in Nature Nanotechnology.
“This is a new, atomic-scale platform, using what the scientific community calls ‘optomechanics,’ in which light and mechanical motions are intrinsically coupled together,” said senior author Mo Li, a UW professor of both electrical and computer engineering and physics. “It provides a new type of involved quantum effect that can be utilized to control single photons running through integrated optical circuits for many applications.”
Previously, the team had studied a quantum-level quasiparticle called an “exciton.” Information can be encoded into an exciton and then released in the form of a photon — a tiny particle of energy considered to be the quantum unit of light. Quantum properties of each photon emitted — such as the photon’s polarization, wavelength and/or emission timing — can function as a quantum bit of information, or “qubit,” for quantum computing and communication. And because this qubit is carried by a photon, it travels at the speed of light.
“The bird’s-eye view of this research is that to feasibly have a quantum network, we need to have ways of reliably creating, operating on, storing and transmitting qubits,” said lead author Adina Ripin, a UW doctoral student of physics. “Photons are a natural choice for transmitting this quantum information because optical fibers enable us to transport photons long distances at high speeds, with low losses of energy or information.”
The researchers were working with excitons in order to create a single photon emitter, or “quantum emitter,” which is a critical component for quantum technologies based on light and optics. To do this, the team placed two thin layers of tungsten and selenium atoms, known as tungsten diselenide, on top of each other.

When the researchers applied a precise pulse of laser light, they knocked a tungsten diselenide atom’s electron away from the nucleus, which generated an exciton quasiparticle. Each exciton consisted of a negatively charged electron on one layer of the tungsten diselenide and a positively charged hole where the electron used to be on the other layer. And because opposite charges attract each other, the electron and the hole in each exciton were tightly bonded to each other. After a short moment, as the electron dropped back into the hole it previously occupied, the exciton emitted a single photon encoded with quantum information — producing the quantum emitter the team sought to create.
But the team discovered that the tungsten diselenide atoms were emitting another type of quasiparticle, known as a phonon. Phonons are a product of atomic vibration, which is similar to breathing. Here, the two atomic layers of the tungsten diselenide acted like tiny drumheads vibrating relative to each other, which generated phonons. This is the first time phonons have ever been observed in a single photon emitter in this type of two-dimensional atomic system.
When the researchers measured the spectrum of the emitted light, they noticed several equally spaced peaks. Every single photon emitted by an exciton was coupled with one or more phonons. This is somewhat akin to climbing a quantum energy ladder one rung at a time, and on the spectrum, these energy spikes were represented visually by the equally spaced peaks.
“A phonon is the natural quantum vibration of the tungsten diselenide material, and it has the effect of vertically stretching the exciton electron-hole pair sitting in the two layers,” said Li, who is also is a member of the steering committee for the UW’s QuantumX, and is a faculty member of the Institute for Nano-Engineered Systems. “This has a remarkably strong effect on the optical properties of the photon emitted by the exciton that has never been reported before.”
The researchers were curious if they could harness the phonons for quantum technology. They applied electrical voltage and saw that they could vary the interaction energy of the associated phonons and emitted photons. These variations were measurable and controllable in ways relevant to encoding quantum information into a single photon emission. And this was all accomplished in one integrated system — a device that involved only a small number of atoms.
Next the team plans to build a waveguide — fibers on a chip that catch single photon emissions and direct them where they need to go — and then scale up the system. Instead of controlling only one quantum emitter at a time, the team wants to be able to control multiple emitters and their associated phonon states. This will enable the quantum emitters to “talk” to each other, a step toward building a solid base for quantum circuitry.
“Our overarching goal is to create an integrated system with quantum emitters that can use single photons running through optical circuits and the newly discovered phonons to do quantum computing and quantum sensing,” Li said. “This advance certainly will contribute to that effort, and it helps to further develop quantum computing which, in the future, will have many applications.” More

As we move into a world where human-machine interactions are becoming more prominent, pressure sensors that are able to analyze and simulate human touch are likely to grow in demand.
One challenge facing engineers is the difficulty in making the kind of cost-effective, highly sensitive sensor necessary for applications such as detecting subtle pulses, operating robotic limbs, and creating ultrahigh-resolution scales. However, a team of researchers has developed a sensor capable of performing all of those tasks.
The researchers, from Penn State and Hebei University of Technology in China, wanted to create a sensor that was extremely sensitive and reliably linear over a broad range of applications, had high pressure resolution, and was able to work under large pressure preloads.
“The sensor can detect a tiny pressure when large pressure is already applied,” said Huanyu “Larry” Cheng, James L. Henderson Jr. Memorial Associate Professor of Engineering Science and Mechanics at Penn State and co-author of a paper on the work published in Nature Communications. “An analogy I like to use is it’s like detecting a fly on top of an elephant. It can measure the slightest change in pressure, just like our skin does with touch.”
Cheng was inspired to develop these sensors due to a very personal experience: The birth of his second daughter.  
Cheng’s daughter lost 10% of her body weight soon after birth, so the doctor asked him to weigh the baby every two days to monitor any additional loss or weight gain. Cheng tried to do this by weighing himself on a regular home weight scale and then weighing himself holding his daughter to measure the baby’s weight.  
“I noticed that when I put down my daughter in her blanket, when I was no longer holding her, you didn’t see the change in weight,” Cheng said. “So, we learned that trying to use a commercial scale doesn’t work, it didn’t detect the change in pressure.” 

After trying many different approaches, they found that using a pressure sensor consisting of gradient micro-pyramidal structures and an ultrathin ionic layer to give a capacitive response was the most promising.
However, there was a continued issue they faced. The high sensitivity of the microstructures would decrease as the pressure increased, and the random microstructures that were templated from natural objects resulted in uncontrollable deformation and a narrow linear range. In simple terms, when pressure was applied to the sensor, it would change the sensor’s shape and therefore alter the contact area between the microstructures and throw off the readings.
To address these challenges, the scientists designed microstructure patterns that could increase the linear range without decreasing the sensitivity — they essentially made it flexible, so it could still function in the gradience of pressures that exist in the real world. Their study explored the use of a CO2 laser with a Gaussian beam to fabricate programmable structures such as gradient pyramidal microstructures (GPM) for iontronic sensors, which are soft electronics that can mimic the perception functions of human skin. This process reduces the cost and process complexity compared with photolithography, the method commonly used to prepare delicate microstructure patterns for sensors.
“I think in the future it is possible to further improve the model and be able to account for more complex systems and then we can certainly understand how to make even better sensors.”
Huanyu “Larry” Cheng, James L. Henderson Jr. Memorial Associate Professor of Engineering Science and Mechanics, Penn State
Cheng credits Ruoxi Yang, a graduate student in his lab and first author of the study, as the driver of this solution. 

“Yang is a very smart student who introduced the idea to solve this sensor issue, which is really something like a combination of many small pieces, smartly engineered together,” Cheng said. “We know the structure must be microscale and must have a delicate design. But it is challenging to design or optimize the structure, and she worked with the laser system we have in our lab to make this possible. She has been working very hard in the past few years and was able to explore all these different parameters and be able to quickly screen throughout this parameter space to find and improve the performance.” 
This optimized sensor had rapid response and recovery times and excellent repeatability, which the team tested by detecting subtle pulses, operating interactive robotic hands, and creating ultrahigh-resolution, smart weight scales and chairs. The scientists also found that the proposed fabrication approaches and design toolkit from this work could be leveraged to easily tune the pressure sensor performance for varying target applications and open opportunities to create other iontronic sensors, the range of sensors that use ionic liquids such as an ultrathin ionic layer. Along with enabling a future scale where it would be easier for parents to weigh their baby, these sensors would have other uses as well.  
“We were also able to detect not only the pulse from the wrist but also from the other distal vascular structures like the eyebrow and the fingertip,” Cheng said. “In addition, we combine that with the control system to show that this is possible to use for the future of human robotic interactional collaboration. Also, we envision other healthcare uses, such as someone who has lost a limb and this sensor could be part of a system to help them control a robotic limb.” 
Cheng noted other potential uses, such as sensors to measure a person’s pulse during high-stress work situations such as search-and-rescue after an earthquake or carrying out difficult, dangerous tasks in a construction site.  
The research team used computer simulations and computer-aided design to help them explore ideas for these novel sensors, which Cheng notes is challenging work given all the possible sensor solutions. This electronic assistance will continue to push the research forward.  
“I think in the future it is possible to further improve the model and be able to account for more complex systems and then we can certainly understand how to make even better sensors,” Cheng said.  
Aside from Cheng and Yang, other authors on the study from Penn State include Ankan Dutta, Bowen Li, Naveen Tiwari, Wanqing Zhang, Zhenyuan Niu, Yuyan Gao, Daniel Erdely and Xin Xin, and from Hebei University, Tiejun Li.   More

As more and more electric cars are travelling on the roads of Europe, this is leading to an increase in the use of the critical metals required for components such as electric motors and electronics. With the current raw material production levels there will not be enough of these metals in future — not even if recycling increases. This is revealed by the findings of a major survey led by Chalmers University of Technology, Sweden, on behalf of the European Commission.
Electrification and digitalisation are leading to a steady increase in the need for critical metals in the EU’s vehicle fleet. Moreover, only a small proportion of the metals are currently recycled from end-of-life vehicles. The metals that are highly sought after, such as dysprosium, neodymium, manganese and niobium, are of great economic importance to the EU, while their supply is limited and it takes time to scale up raw material production. Our increasing dependence on them is therefore problematic for several reasons.
“The EU is heavily dependent on imports of these metals because extraction is concentrated in a few countries such as China, South Africa and Brazil. The lack of availability is both an economic and an environmental problem for the EU, and risks delaying the transition to electric cars and environmentally sustainable technologies. In addition, since many of these metals are scarce, we also risk making access to them difficult for future generations if we are unable to use what is already in circulation,” says Maria Ljunggren, Associate Professor in Sustainable Materials Management at Chalmers University of Technology.
A serious situation, but Swedish deposit offers hope
Ljunggren points out that the serious situation affecting Europe’s critical and strategic raw materials is underlined in the Critical Raw Materials Act recently put forward by the European Commission. The Act emphasises the need to enhance cooperation with reliable external trading partners and for member states to improve the recycling of both critical and strategic raw materials. It also stresses the importance of European countries exploring their own geological resources.
In Sweden the state-owned mining company LKAB reported on significant deposits of rare earth metals in Kiruna at the start of the year. Successful exploration enabled the company to identify mineral resources of more than a million tonnes of oxides — which they now describe as the largest known deposit of its kind in Europe.

“This is extremely interesting, especially the discovery of neodymium which, among other things, is used in magnets in electric motors. The hope is that it will help make us less dependent on imports in the long run,” she says.
Substantial increase in the use of critical metals
Together with the Swiss Federal Laboratories for Materials Science and Technology, EMPA, Ljunggren has surveyed the metals that are currently in use in Europe’s vehicle fleet. The assignment comes from the European Commission’s Joint Research Centre (JRC), and has resulted in an extensive database that shows the presence over time of metals in new vehicles, vehicles in use and vehicles that are recycled.
The survey, which goes back as far as 2006, shows that the proportion of critical metals has increased significantly in vehicles, a development which the researchers believe will continue. Several of the rare earth elements are among the metals that have increased the most.
“Neodymium and dysprosium usage has increased by around 400 and 1,700 percent respectively in new cars over the period, and this is even before electrification had taken off. Gold and silver, which are not listed as critical metals but have great economic value, have increased by around 80 percent,” says Ljunggren.

The idea behind the survey and the database is to provide decision-makers, companies and organisations with an evidence base to support a more sustainable use of the EU’s critical metals. A major challenge is that these materials, which are found in very small concentrations in each car, are economically difficult to recycle.
Recycling fails to meet requirements
“If recycling is to increase, cars need to be designed to enable these metals to be recovered, while incentives and flexible processes for more recycling need to be put in place. But that’s not the current reality,” says Ljunggren, who stresses that a range of measures are needed to deal with the situation.
“It is important to increase recycling. At the same time, it is clear that an increase in recycling alone cannot meet requirements in the foreseeable future, just because the need for critical metals in new cars is increasing so much. Therefore there needs to be a greater focus on how we can substitute other materials for these metals. But in the short term it will be necessary to increase extraction in mines if electrification is not to be held back,” she says.
More about the survey and the database The survey of metals in the EU’s vehicle fleet has been carried out by Maria Ljunggren at Chalmers in collaboration with the Swiss Federal Laboratories for Materials Science and Technology, EMPA, on behalf of the European Commission’s Joint Research Centre (JRC). The results are set out in the Raw Materials in Vehicles database which covers 60 vehicle types under 3.5 tonnes from all the EU member states. The survey covers eleven different metals in new vehicles, vehicles in use and vehicles that are recycled. It covers the period from 2006 to 2023, with the last three years being a forecast. The research is also described in the report Material composition trends in vehicles: critical raw materials and other relevant metals. Maria Ljunggren is also involved in an ongoing EU project on critical raw materials, FutuRaM, (Future availability of raw materials), which will enhance knowledge about the potential supply of recycled critical raw materials by the year 2050. More

Whether it’s baking a cake, building a house, or developing a quantum device, the quality of the end product significantly depends on its ingredients or base materials. Researchers working to improve the performance of superconducting qubits, the foundation of quantum computers, have been experimenting using different base materials in an effort to increase the coherent lifetimes of qubits. The coherence time is a measure of how long a qubit retains quantum information, and thus a primary measure of performance. Recently, scientists discovered that using tantalum in superconducting qubits makes them perform better, but no one has been able to determine why — until now.
Scientists from the Center for Functional Nanomaterials (CFN), the National Synchrotron Light Source II (NSLS-II), the Co-design Center for Quantum Advantage (C2QA), and Princeton University investigated the fundamental reasons that these qubits perform better by decoding the chemical profile of tantalum. The results of this work, which were recently published in the journal Advanced Science, will provide key knowledge for designing even better qubits in the future. CFN and NSLS-II are U.S. Department of Energy (DOE) Office of Science User Facilities at DOE’s Brookhaven National Laboratory. C2QA is a Brookhaven-led national quantum information science research center, of which Princeton University is a key partner.
Finding the right ingredient
Tantalum is a unique and versatile metal. It’s dense, hard, and easy to work with. Tantalum also has a high melting point and is resistant to corrosion, making it useful in many commercial applications. In addition, tantalum is a superconductor, which means it has no electrical resistance when cooled to sufficiently low temperatures, and consequently can carry current without any energy loss.
Tantalum-based superconducting qubits have demonstrated record-long lifetimes of more than half a millisecond. That is five times longer than the lifetimes of qubits made with niobium and aluminum, which are currently deployed in large-scale quantum processors.
These properties make tantalum an excellent candidate material for building better qubits. Still, the goal of improving superconducting quantum computers has been hindered by a lack of understanding as to what is limiting qubit lifetimes, a process known as decoherence. Noise and microscopic sources of dielectric loss are generally thought to contribute; however, scientists are unsure exactly why and how.

“The work in this paper is one of two parallel studies aiming to address a grand challenge in qubit fabrication,” explained Nathalie de Leon, an associate professor of electrical and computer engineering at Princeton University and the materials thrust leader for C2QA. “Nobody has proposed a microscopic, atomistic model for loss that explains all the observed behavior and then was able to show that their model limits a particular device. This requires measurement techniques that are precise and quantitative, as well as sophisticated data analysis.”
Surprising results
To get a better picture of the source of qubit decoherence, scientists at Princeton and CFN grew and chemically processed tantalum films on sapphire substrates. They then took these samples to the Spectroscopy Soft and Tender Beamlines (SST-1 and SST-2) at NSLS-II to study the tantalum oxide that formed on the surface using x-ray photoelectron spectroscopy (XPS). XPS uses x-rays to kick electrons out of the sample and provides clues about the chemical properties and electronic state of atoms near the sample surface. The scientists hypothesized that the thickness and chemical nature of this tantalum oxide layer played a role in determining the qubit coherence, as tantalum has a thinner oxide layer compared to the niobium more typically used in qubits.
“We measured these materials at the beamlines in order to better understand what was happening,” explained Andrew Walter, a lead beamline scientist in NSLS-II’s soft x-ray scattering & spectroscopy program. “There was an assumption that the tantalum oxide layer was fairly uniform, but our measurements showed that it’s not uniform at all. It’s always more interesting when you uncover an answer you don’t expect, because that’s when you learn something.”
The team found several different kinds of tantalum oxides at the surface of the tantalum, which has prompted a new set of questions on the path to creating better superconducting qubits. Can these interfaces be modified to improve overall device performance, and which modifications would provide the most benefit? What kinds of surface treatments can be used to minimize loss?

Embodying the spirit of codesign
“It was inspiring to see experts of very different backgrounds coming together to solve a common problem,” said Mingzhao Liu, a materials scientist at CFN and the materials subthrust leader in C2QA. “This was a highly collaborative effort, pooling together the facilities, resources, and expertise shared between all of our facilities. From a materials science standpoint, it was exciting to create these samples and be an integral part of this research.”
Walter said, “Work like this speaks to the way C2QA was built. The electrical engineers from Princeton University contributed a lot to device management, design, data analysis, and testing. The materials group at CFN grew and processed samples and materials. My group at NSLS-II characterized these materials and their electronic properties.”
Having these specialized groups come together not only made the study move smoothly and more efficiently, but it gave the scientists an understanding of their work in a larger context. Students and postdocs were able to get invaluable experience in several different areas and contribute to this research in meaningful ways.
“Sometimes, when materials scientists work with physicists, they’ll hand off their materials and wait to hear back regarding results,” said de Leon, “but our team was working hand-in-hand, developing new methods along the way that could be broadly used at the beamline going forward.” More

Rare earth elements, like neodymium and dysprosium, are a critical component to almost all modern technologies, from smartphones to hard drives, but they are notoriously hard to separate from the Earth’s crust and from one another.
Penn State scientists have discovered a new mechanism by which bacteria can select between different rare earth elements, using the ability of a bacterial protein to bind to another unit of itself, or “dimerize,” when it is bound to certain rare earths, but prefer to remain a single unit, or “monomer,” when bound to others.
By figuring out how this molecular handshake works at the atomic level, the researchers have found a way to separate these similar metals from one another quickly, efficiently, and under normal room temperature conditions. This strategy could lead to more efficient, greener mining and recycling practices for the entire tech sector, the researchers state.
“Biology manages to differentiate rare earths from all the other metals out there — and now, we can see how it even differentiates between the rare earths it finds useful and the ones it doesn’t,” said Joseph Cotruvo Jr., associate professor of chemistry at Penn State and lead author on a paper about the discovery published today (May 31) in the journal Nature. “We’re showing how we can adapt these approaches for rare earth recovery and separation.”
Rare earth elements, which include the lanthanide metals, are in fact relatively abundant, Cotruvo explained, but they are what mineralogists call “dispersed,” meaning they’re mostly scattered throughout the planet in low concentrations.
“If you can harvest rare earths from devices that we already have, then we may not be so reliant on mining it in the first place,” Cotruvo said. However, he added that regardless of source, the challenge of separating one rare earth from another to get a pure substance remains.

“Whether you are mining the metals from rock or from devices, you are still going to need to perform the separation. Our method, in theory, is applicable for any way in which rare earths are harvested,” he said.
All the same — and completely different
In simple terms, rare earths are 15 elements on the periodic table — the lanthanides, with atomic numbers 57 to 71 — and two other elements with similar properties that are often grouped with them. The metals behave similarly chemically, have similar sizes, and, for those reasons, they often are found together in the Earth’s crust. However, each one has distinct applications in technologies.
Conventional rare earth separation practices require using large amounts of toxic chemicals like kerosene and phosphonates, similar to chemicals that are commonly used in insecticides, herbicides and flame retardants, Cotruvo explained. The separation process requires dozens or even hundreds of steps, using these highly toxic chemicals, to achieve high-purity individual rare earth oxides.
“There is getting them out of the rock, which is one part of the problem, but one for which many solutions exist,” Cotruvo said. “But you run into a second problem once they are out, because you need to separate multiple rare earths from one another. This is the biggest and most interesting challenge, discriminating between the individual rare earths, because they are so alike. We’ve taken a natural protein, which we call lanmodulin or LanM, and engineered it to do just that.”
Learning from nature

Cotruvo and his lab turned to nature to find an alternative to the conventional solvent-based separation process, because biology has already been harvesting and harnessing the power of rare earths for millennia, especially in a class of bacteria called “methylotrophs” that often are found on plant leaves and in soil and water and play an important role in how carbon moves through the environment.
Six years ago, the lab isolated lanmodulin from one of these bacteria, and showed that it was unmatched — over 100 million times better — in its ability to bind lanthanides over common metals like calcium. Through subsequent work they showed that it was able to purify rare earths as a group from dozens of other metals in mixtures that were too complex for traditional rare earth extraction methods. However, the protein was less good at discriminating between the individual rare earths.
Cotruvo explained that for the new study detailed in Nature, the team identified hundreds of other natural proteins that looked roughly like the first lanmodulin but homed in on one that was different enough — 70% different — that they suspected it would have some distinct properties. This protein is found naturally in a bacterium (Hansschlegelia quercus) isolated from English oak buds.
The researchers found that the lanmodulin from this bacterium exhibited strong capabilities to differentiate between rare earths. Their studies indicated that this differentiation came from an ability of the protein to dimerize and perform a kind of handshake. When the protein binds one of the lighter lanthanides, like neodymium, the handshake (dimer) is strong. By contrast, when the protein binds to a heavier lanthanide, like dysprosium, the handshake is much weaker, such that the protein favors the monomer form.
“This was surprising because these metals are very similar in size,” Cotruvo said. “This protein has the ability to differentiate at a scale that is unimaginable to most of us — a few trillionths of a meter, a difference that is less than a tenth of the diameter of an atom.”
Fine-tuning rare earth separations
To visualize the process at such a small scale, the researchers teamed up with Amie Boal, Penn State professor of chemistry, biochemistry and molecular biology, who is a co-author on the paper. Boal’s lab specializes in a technique called X-ray crystallography, which allows for high-resolution molecular imaging.
The researchers determined that the protein’s ability to dimerize dependent on the lanthanide to which it was bound came down to a single amino acid — 1% of the whole protein — that occupied a different position with lanthanum (which, like neodymium, is a light lanthanide) than with dysprosium.
Because this amino acid is part of a network of interconnected amino acids at the interface with the other monomer, this shift altered how the two protein units interacted. When an amino acid that is a key player in this network was removed, the protein was much less sensitive to rare earth identity and size. The findings revealed a new, natural principle for fine-tuning rare earth separations, based on propagation of miniscule differences at the rare earth binding site to the dimer interface.
Using this knowledge, their collaborators at Lawrence Livermore National Laboratory showed that the protein could be tethered to small beads in a column, and that it could separate the most important components of permanent magnets, neodymium and dysprosium, in a single step, at room temperature and without any organic solvents.
“While we are by no means the first scientists to recognize that metal-sensitive dimerization could be a way of separating very similar metals, mostly with synthetic molecules,” Cotruvo said, “this is the first time that this phenomenon has been observed in nature with the lanthanides. This is basic science with applied outcomes. We’re revealing what nature is doing and it’s teaching us what we can do better as chemists.”
Cotruvo believes that the concept of binding rare earths at a molecular interface, such that dimerization is dependent on the exact size of the metal ion, can be a powerful approach for accomplishing challenging separations.
“This is the tip of the iceberg,” he said. “With further optimization of this phenomenon, the toughest problem of all — efficient separation of rare earths that are right next to each other on the periodic table — may be within reach.”
A patent application was filed by Penn State based on this work and the team is currently scaling up operations, fine-tuning and streamlining the protein with the goal of commercializing the process.
Other Penn State co-authors are Joseph Mattocks, Jonathan Jung, Chi-Yun Lin, Neela Yennawar, Emily Featherston and Timothy Hamilton. Ziye Dong, Christina Kang-Yun and Dan Park of the Lawrence Livermore National Laboratory also co-authored the paper.
The work was funded by the U.S. Department of Energy, the National Science Foundation, the National Institutes of Health, the Jane Coffin Childs Memorial Fund for Medical Research, and the Critical Materials Institute, an Energy Innovation Hub funded by the DOE, Office of Energy Efficiency and Renewable Energy, Advanced Materials and Manufacturing Technologies Office. Part of the work was performed under the auspices of the DOE by Lawrence Livermore National Laboratory. More

Electron microscopes give us insight into the tiniest details of materials and can visualize, for example, the structure of solids, molecules or nanoparticles with atomic resolution. However, most materials in nature are not static. They constantly interact, move and reshape between initial and final configurations. One of the most general phenomena is the interaction between light and matter, which is omnipresent in materials such as solar cells, displays or lasers. These interactions are defined by electrons pushed and pulled around by the oscillations of light, and the dynamics are extremely fast: light waves oscillate at attoseconds, the billionth of a billionth of a second.
Until now, it has been very difficult to directly visualize these extremely fast processes in space and time, but that is exactly what a team of physicists from the University of Konstanz has now succeeded in. They recorded movies with attosecond time resolution in a transmission electron microscope, providing new insights into the functionality of nanomaterials and dielectric meta-atoms. They recently published their results in the scientific journal Nature.
Generation of ultrashort electron pulses
“If you look closely, almost all phenomena in optics, nanophotonics or metamaterials occur on time scales below one oscillation period of a light wave,” explains Peter Baum, physics professor and head of the Light and Matter Group at the University of Konstanz. “To film the ultrafast interactions between light and matter, we therefore need a time resolution of attoseconds.” To achieve such an extreme recording speed, Baum’s research group uses the fast oscillations of a continuous-wave laser to convert the electron beam of an electron microscope into a sequence of ultrashort electron pulses.
In this process, a thin silicon membrane creates a periodic acceleration and deceleration of the electrons. “This modulation causes the electrons to catch up with each other. After some time, they convert into a train of ultrashort pulses,” explains David Nabben, doctoral student and first author of the study. Another laser wave creates the interaction with the sample object. The ultrashort electron pulses are then used to measure the object’s response to the laser light, frozen in time like in a stroboscope. In the end, the researchers obtain a movie of the processes with attosecond time resolution.
Investigation of nanophotonic phenomena
In their study, the scientists present several examples of time-resolved measurements in nanomaterials. The experiments show, for example, the emergence of chiral surface waves that can be controlled by the researchers to travel in a specific spatial direction, or characteristic time delays between different modes of radiation from nanoantennas. What is more, the scientists not only investigate such surface phenomena, but also film the electromagnetic processes inside a waveguide material.
The results are highly interesting for further developments in nanophotonics, but also demonstrate the very broad application range of the new attosecond electron microscopy. “The direct measurement of the electromagnetic functionality of materials as a function of space and time is not only of great value for fundamental science, but also opens up the way for new developments in photonic integrated circuits or metamaterials,” Nabben summarizes the impact of the results. More

While it can take years for the pharmaceutical industry to create medicines capable of treating or curing human disease, a new study suggests that using generative artificial intelligence could vastly accelerate the drug-development process.
Today, most drug discovery is carried out by human chemists who rely on their knowledge and experience to select and synthesize the right molecules needed to become the safe and efficient medicines we depend on. To identify the synthesis paths, scientists often employ a technique called retrosynthesis — a method for creating potential drugs by working backward from the wanted molecules and searching for chemical reactions to make them.
Yet because sifting through millions of potential chemical reactions can be an extremely challenging and time-consuming endeavor, researchers at The Ohio State University have created an AI framework called G2Retro to automatically generate reactions for any given molecule. The new study showed that compared to current manual-planning methods, the framework was able to cover an enormous range of possible chemical reactions as well as accurately and quickly discern which reactions might work best to create a given drug molecule.
“Using AI for things critical to saving human lives, such as medicine, is what we really want to focus on,” said Xia Ning, lead author of the study and an associate professor of computer science and engineering at Ohio State. “Our aim was to use AI to accelerate the drug design process, and we found that it not only saves researchers time and money but provides drug candidates that may have much better properties than any molecules that exist in nature.”
This study builds on previous research of Ning’s where her team developed a method named Modof that was able to generate molecule structures that exhibited desired properties better than any existing molecules. “Now the question becomes how to make such generated molecules, and that is where this new study shines,” said Ning, also an associate professor of biomedical informatics in the College of Medicine.
The study was published today in the journal Communications Chemistry.
Ning’s team trained G2Retro on a dataset that contains 40,000 chemical reactions collected between 1976 and 2016. The framework “learns” from graph-based representations of given molecules, and uses deep neural networks to generate possible reactant structures that could be used to synthesize them. Its generative power is so impressive that, according to Ning, once given a molecule, G2Retro could come up with hundreds of new reaction predictions in only a few minutes.
“Our generative AI method G2Retro is able to supply multiple different synthesis routes and options, as well as a way to rank different options for each molecule,” said Ning. “This is not going to replace current lab-based experiments, but it will offer more and better drug options so experiments can be prioritized and focused much faster.”
To further test the AI’s effectiveness, Ning’s team conducted a case study to see if G2Retro could accurately predict four newly released drugs already in circulation: Mitapivat, a medication used to treat hemolytic anemia; Tapinarof, which is used to treat various skin diseases; Mavacamten, a drug to treat systemic heart failure; and Oteseconazole, used to treat fungal infections in females. G2Retro was able to correctly generate exactly the same patented synthesis routes for these medicines, and provided alternative synthesis routes that are also feasible and synthetically useful, Ning said.
Having such a dynamic and effective device at scientists’ disposal could enable the industry to manufacture stronger drugs at a quicker pace — but despite the edge AI might give scientists inside the lab, Ning emphasizes the medicines G2Retro or any generative AI creates still need to be validated — a process that involves the created molecules being tested in animal models and later in human trials.
“We are very excited about generative AI for medicine, and we are dedicated to using AI responsibly to improve human health,” said Ning.
This research was supported by Ohio State’s President’s Research Excellence Program and the National Science Foundation. Other Ohio State co-authors were Ziqi Chen, Oluwatosin Ayinde, James Fuchs and Huan Sun. More

An optical fibre about the thickness of a human hair can now carry the equivalent of more than 10 million fast home internet connections running at full capacity.
A team of Japanese, Australian, Dutch, and Italian researchers has set a new speed record for an industry standard optical fibre, achieving 1.7 Petabits over a 67km length of fibre. The fibre, which contains 19 cores that can each carry a signal, meets the global standards for fibre size, ensuring that it can be adopted without massive infrastructure change. And it uses less digital processing, greatly reducing the power required per bit transmitted.
Macquarie University researchers supported the invention by developing a 3D laser-printed glass chip that allows low loss access to the 19 streams of light carried by the fibre and ensures compatibility with existing transmission equipment.
The fibre was developed by the Japanese National Institute of Information and Communications Technology (NICT, Japan) and Sumitomo Electric Industries, Ltd. (SEI, Japan) and the work was performed in collaboration with the Eindhoven University of Technology, University of L’Aquila, and Macquarie University.
All the world’s internet traffic is carried through optical fibres which are each 125 microns thick (comparable to the thickness of a human hair). These industry standard fibres link continents, data centres, mobile phone towers, satellite ground stations and our homes and businesses.
Back in 1988, the first subsea fibre-optic cable across the Atlantic had a capacity of 20 Megabits or 40,000 telephone calls, in two pairs of fibres. Known as TAT 8, it came just in time to support the development of the World Wide Web. But it was soon at capacity.

The latest generation of subsea cables such as the Grace Hopper cable, which went into service in 2022, carries 22 Terabits in each of 16 fibre pairs. That’s a million times more capacity than TAT 8, but it’s still not enough to meet the demand for streaming TV, video conferencing and all our other global communication.
“Decades of optics research around the world has allowed the industry to push more and more data through single fibres,” says Dr Simon Gross from Macquarie University’s School of Engineering. “They’ve used different colours, different polarisations, light coherence and many other tricks to manipulate light.”
Most current fibres have a single core that carries multiple light signals. But this current technology is practically limited to only a few Terabits per second due to interference between the signals.
“We could increase capacity by using thicker fibres. But thicker fibres would be less flexible, more fragile, less suitable for long-haul cables, and would require massive reengineering of optical fibre infrastructure,” says Dr Gross.
“We could just add more fibres. But each fibre adds equipment overhead and cost and we’d need a lot more fibres.”
To meet the exponentially growing demand for movement of data, telecommunication companies need technologies that offer greater data flow for reduced cost.

The new fibre contains 19 cores that can each carry a signal.
“Here at Macquarie University, we’ve created a compact glass chip with a wave guide pattern etched into it by a 3D laser printing technology. It allows feeding of signals into the 19 individual cores of the fibre simultaneously with uniform low losses. Other approaches are lossy and limited in the number of cores,” says Dr Gross.
“It’s been exciting to work with the Japanese leaders in optical fibre technology. I hope we’ll see this technology in subsea cables within five to 10 years.”
Another researcher involved in the experiment, Professor Michael Withford from Macquarie University’s School of Mathematical and Physical Sciences, believes this breakthrough in optical fibre technology has far-reaching implications.
“The optical chip builds on decades of research into optics at Macquarie University,” says Professor Withford. “The underlying patented technology has many applications including finding planets orbiting distant stars, disease detection, even identifying damage in sewage pipes.” More