Never seen before quantum state discovered in graphene could advance computing
Graphene, also known as the wonder material, continues to surprise scientists. This time, it has revealed new quantum states. A team of researchers has found peculiar topological electronic crystals in twisted graphene layers.
Their study highlights a special way to arrange electrons in graphene, where they freeze into a perfectly ordered pattern. Surprisingly, while staying locked in place, all the electrons spin together like ballet dancers performing synchronized pirouettes without moving.
This unusual quantum behavior allows electric current to flow smoothly along the edges of the material while the interior remains non-conductive because the electrons are stuck in place.
In the future, such quantum states can be utilized for the development of energy-efficient electronic devices and fault-tolerant quantum computing applications.
Topology is the study of shapes and spaces that don't change even if they are stretched, twisted, or deformed—without cutting or gluing.
'An everyday example of topology is the Möbius strip—a simple yet mind-bending object. Amazingly, no matter how you try to manipulate the strip, you cannot untwist it back into a normal loop without tearing it apart,' the study authors note.
A material exhibiting topology is of great importance because it has the uncanny ability to remain unaffected by external factors. Such a material can demonstrate robust quantum behavior, as its quantum states in such material are immune to small disturbances.
For instance, topological electronic crystals like the one mentioned in the current study are quite special. In these unique crystals, electrons move in a very stable way, no matter if there are small defects or impurities in the material.
What makes them special is that their stability comes from the material's internal structure and not from outside influences like temperature or pressure.
However, these crystals are rare because only certain materials have the right atomic arrangement to support topological electron behavior.
The study authors began with two thin layers (flakes) of graphene, a material made of carbon atoms arranged in a honeycomb pattern. Normally, electrons in graphene move freely, similar to how they do in metals like copper.
Next, they stacked the two graphene layers on top of each other but rotated one slightly. This small twist created an interesting pattern called a moiré pattern, where some carbon atoms from both layers were aligned perfectly, but others were misaligned.
When electrons moved through this twisted structure, their behavior completely changed. 'For example, the electrons slow way down, and sometimes they develop a twist in their motion, like the vortex in the water at the drain of a bathtub as it is draining out,' Joshua Folk, one of the study authors and a physics professor at the University of British Columbia (UBC), said.
This behavior resulted in a strange electronic effect. Inside the material, electrons became frozen in place, making it act like an insulator. However, along the edges, electrons moved effortlessly, allowing electricity to flow without resistance.
Generally, when electrons freeze and settle down such a structure is called the Wigner crystal. However, in this case, the rotational motion of electrons along the edges resulted in something different — the topological electronic crystal.
'The rotation of the electrons in the crystal is analogous to the twist in the Möbius strip and leads to the remarkable characteristic of the topological electronic crystal never before seen in the rare cases where electron crystals have been observed in the past,' the study authors said.
This rare discovery could contribute to the development of highly efficient electronic and quantum computing applications.
The study is published in the journal Nature.
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Hamilton Spectator
27-05-2025
- Hamilton Spectator
Canadian researchers develop test they say can help diagnose life-threatening sepsis
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Yahoo
24-05-2025
- Yahoo
Climate change: How a warming planet could affect the taste of B.C. wine
Future sommeliers may have something very different on the nose, as climate change alters the taste of wine in regions around the world. A global study led by UBC researchers, and published this week in the journal PLOS Climate, found that temperatures during the grape-growing season have increased across the world's major wine regions — including B.C. — and that the heat is changing the taste of wine. For the study, researchers analyzed temperatures over the growing seasons in wine regions on five continents and studied 500 varieties of grapes. They studied the temperatures during dormancy, budding, and during harvest. The climate data will eventually allow scientists to recommend which varieties of wine grape are best suited to the changing climate in different regions, including those with unique climate challenges such as intense heat waves, drought and wildfire smoke. 'We want to be able to say to growers, OK, there's 1,000 varieties out there. Here are some recommendations on which ones to consider,' said Elizabeth Wolkovich, senior author of the study and an associate professor at UBC's faculty of forestry. On average, the regions have warmed by the equivalent of almost 100 extra growing degree-days, a measure of the cumulative heat that vines are exposed to, according to the study. Impacts of a hotter climate include lower grape yields, heat damage to berries and vegetation, and an industry that is rapidly working to adapt, the study says. Speaking Friday from Zurich, where she is working with colleagues who contributed to the global study, Wolkovich said this heat can affect harvest times and grape ripening, which changes the taste of the wine. 'Most of the wine you drink from Europe and North America is already a different flavour profile due to climate change than you drank 30 or 40 years ago. The biggest obvious change is that the grapes are more sugar rich, and that means they are also higher in alcohol,' she said. As the weather gets warmer, the grapes develop faster. For instance, she said the grapes are ripening in parts of France in late August instead of September. 'When they ripen in late August, and are exposed to hotter temperatures, the grapes build up sugar faster. The grapes you harvest have higher sugar acid ratios, so the balance in the wine is different.' The acidity, which gives the wine its zest, declines in warmer weather while pigments in wine called anthocyanins, which give the wine its colour, break down. Tannins may not develop if the grapes are plucked too early to compensate for the heat. 'I would say it would taste a little bit more like jam, or what you would call like a fruitier wine, and it would maybe be generally a little darker, less light in the flavour profile, and, on average, a little bit less complex for a red wine,' she said, but emphasized that expert winemakers are skilled at compensating for this change. Around the world, scorching heat, wildfires and other climate-related disasters have already decimated crops, including here in B.C. The province's wine industry is still recovering after two years of climate-related crop losses in the southern Interior. Record-breaking heat, wildfires and smoke tainted grapes, while a destructive cold snap in 2023 and 2024 caused significant crop loss across the province. Varieties of grape most affected in B.C. were Syrah, Merlot and Cabernet Sauvignon, with projected losses of more than 65 per cent, according to a report last year from Wine Growers B.C. Wolkovich said there are hundreds of varieties in Spain, Italy and Greece 'that you've probably never heard of' that could work well at some point for B.C. growers as the heat intensifies. One example is Xinomavro, a wine grape that tolerates the dry heat of Greece. The difference is Mediterranean regions like Greece have longer growing seasons than B.C. so the trick is to find varieties that have a shorter ripening time but are also heat-resistant. On that note, Wolkovich also said there are varieties from the mountainous regions of Spain that B.C. growers haven't tried that could work well as the temperatures increase. 'So regions in Spain that are at higher elevations have shorter growing seasons, but they also are hot — the way the Okanagan is hot. And I know that certain vineyards have looked into them and would love to try them.' She said the problem isn't that the consumer won't want to drink these hardier varieties, but that there are hurdles in Canada to importing the rootstock. Kathy Malone, chair of the B.C. Wine Grape Council research and development committee, said winemakers are wary of testing new varieties when it takes years for the grapes to grow and mature in flavour. Malone, who is also a winemaker at Hillside Winery and Bistro in Naramata, said there are efforts underway to get experimental plots going in B.C. 'You could have very small plots of varieties that no one's ever heard of and make a small amount of wine, but then you could blend that into another wine.' She said it's very difficult for B.C. winemakers to make decisions about new varieties that will be cold-resistant and that the focus should be on the warming climate and what varieties will survive intense heat. After last year's cold snap, Hillside will be planting the Malbec variety, which is less cold-hardy than Merlot but will do much better under the increasingly hotter Okanagan summers. 'I don't think there was much Malbec planted in the 80s and 90s, because it requires longer hang time and more heat. But now we're getting that heat more and more,' she said. 'The seasons are expected to be hotter and longer moving north. In some areas, like in Napa, it's a challenge because it's too hot and they have berries drying up on the vine.' For the study, scientists developed climate metrics for the world's wine regions that spanned the annual plant cycle of a calendar year. They found the biggest impact is in southern and western Europe, where the number of days over 35 C is the highest of all regions, with nearly five times as many extreme heat days compared with 1980. 'The temperature increases here (in B.C.) aren't as dramatic as in Europe, which is something that as a community, we're still trying to understand,' said Wolkovich. Growers are testing methods to adapt. Some are using shade cloth to protect vines from heat while others are planting new rootstocks and varieties. The study also looked at regions affected by wildfire smoke and how widespread fires in Australia led to technologies and approaches that could be used in California or in B.C. For example, some winemakers are now installing sensors in the vineyard to know when smoke is about to affect the grapes. ticrawford@ With files from The Canadian Press 'Clean slate' to reshape B.C. wine industry, after climate-related catastrophes Anthony Gismondi: Wineries step forward to fight climate change Anthony Gismondi: Assessing how deep freeze affected B.C. vineyards remains a work in progress
Scientific American
22-05-2025
- Scientific American
How One Astronomer Helped to Discover Nearly 200 Moons of Saturn
A mere decade ago, astronomers knew of just 62 moons around Saturn. Today the ringed planet boasts a staggering 274 official satellites. That's more than any other world in the solar system—and far too many for most people to keep track of. Astronomer Edward Ashton is no exception, even though he has helped to discover 192 of them—he thinks that's the total, anyway, after pausing to do some mental math. Ashton is now a postdoctoral fellow at the Academia Sinica Institute of Astronomy and Astrophysics in Taiwan. He fell into hunting for Saturn's moons in 2018, when his then academic adviser suggested the project for his Ph.D. at the University of British Columbia. It has been a fruitful search. Most recently, in March, Ashton and his colleagues announced a batch of 128 newfound Saturnian satellites. Scientific American spoke with Ashton about the science of discovering so many relatively tiny moons—most of them just a few kilometers wide—using vast amounts of data gathered by the Canada-France-Hawaii Telescope (CFHT), located in Hawaii. On supporting science journalism If you're enjoying this article, consider supporting our award-winning journalism by subscribing. By purchasing a subscription you are helping to ensure the future of impactful stories about the discoveries and ideas shaping our world today. [ An edited transcript of the interview follows.] How have you found these moons? To detect the moons, we use a technique known as shifting and stacking. We take 44 sequential images of the same patch of sky over a three-hour period because, in that time frame, the moons move relative to the stars at a rate similar to Saturn. If we just stack the images normally, then the moon appears as a streak across the images, and that dilutes the signal of the moon. So what we do is: we shift the images relative to one another at multiple different rates near that of Saturn, and then we basically blink between the different shift rates. If the shift rate is not quite at the rate of the moon, then it's going to be slightly elongated. As you get closer to the rate of the moon, then it slowly combines into a dot. And then, as you get faster than the moon's rate, it expands again. So basically, we look at the images and then quickly blink through the different rates, and you can see the moon coalescing. That's for a single night. But just seeing an object moving at a Saturn-like rate near Saturn doesn't guarantee that it is a moon. It's highly likely that the object is a moon, but that hasn't been confirmed. So what we need to do is track the objects to show that they are in orbit around the planet. To do that, we repeat the [shift and stack] process multiple times over many months and years. Why did this happen now? Did you need new techniques and observatories to do this work? The technique and the technology have been there for a while—the same technique has been used to find moons of Neptune and Uranus. But the sky area around those planets where moons can exist is a lot smaller, so it takes less time to search through the data. One of the reasons why this hadn't been done for Saturn is because it's very time-consuming. Why do those other planets have less space where moons could be than Saturn does? Those planets are less massive, so the stable orbits that moons can have are smaller. I had been wondering if this technique works for other planets, and clearly the answer is yes. But do you think there are other moons that have yet to be found around Saturn or other planets with the method? We did find moon candidates around Saturn that we weren't able to track long enough to be able to confirm them. So if you redo this technique again, you will be able to find more moons around Saturn, but this is a case of diminishing returns. If you use a larger telescope [than the CFHT], then you'd be able to see fainter moons, so you'd be able to find more. At the moment, if you use the same technique for Jupiter, you will be able to find fainter moons. The problem is: the amount of sky that moons of Jupiter can occupy is significantly larger than [the amount of sky that can be occupied by moons of] Saturn, so the method is even more time-consuming for Jupiter. And Jupiter is much brighter than Saturn and the other planets, so there's a lot of scattered light that makes it harder to see the moons. So it's even harder to find satellites around Jupiter, and as you mentioned, other groups have already done this work for Uranus and Neptune. Does that mean we're sort of 'maxed out' on moons until we have better observations? Yeah, you probably have to wait until better technology comes along. Is there something being built or planned right now that could be that 'better technology'? There currently are telescopes that can see deeper [than the CFHT], such as the James Webb Space Telescope (JWST). The problem is: JWST's field of view is very small, so you have to do quite a few observations to be able to cover the required area. But there is a telescope that's set to launch pretty soon, the Nancy Grace Roman Space Telescope, that has quite a large field of view. So that'll be a good telescope to use for hunting more moons. What do we know about these new moons? You basically can only get the moons' orbits and approximate sizes. But if you look at the distribution of the orbits, you can understand a bit more about the history of the system. Moons that are sort of clumped together in orbital space are most likely the result of a collision, so you can see what moons come from the same parent object. Is seeing so many moons around Saturn unusual? What's unusual is how many there are. It appears that the planets have more or less equal numbers of the larger moons. But when you get down to the smaller ones that we're discovering, Saturn seems to shoot up in terms of the numbers. So that's quite interesting. This could just be because there was a recent collision within the Saturnian system that produced a large number of fragments. Do you get to name them all? Do you have to name them all? I guess I don't have to. Some of these new moons, they've been linked back to observations by a different group from more than 10 years ago. That's maybe 20 to 30 of them. For the rest, we get full discovery credit, which, I think, means we get the right to name them. But they can't be named just yet; first, they're just given a number when they have a high-precision orbit, and I'm not sure how long that's going to take. Do you have more moon-hunting observations to analyze? No, I'm taking a little break from moons! I've got other projects to work on, relating to trans-Neptunian objects. They're quite far away. They're hard to see. There are some mysteries about them at the moment. It's interesting to understand their structure and how it relates to planet formation.
