Discovery of Matter-Wave Polaritons Sheds New Light on Photonic Quantum Technologies

An artistic rendering of the research findings in the polariton study shows the atoms in an optical lattice forming an insulating phase (left); atoms turning into matter-wave polaritons via vacuum coupling mediated by microwave radiation represented by the green color (center); polaritons becoming mobile and forming a superfluid phase for strong vacuum coupling (right).
Photo Credit: Alfonso Lanuza/Schneble Lab/Stony Brook University.

The development of experimental platforms that advance the field of quantum science and technology (QIST) comes with a unique set of advantages and challenges common to any emergent technology. Researchers at Stony Brook University, led by Dominik Schneble, PhD, report the formation of matter-wave polaritons in an optical lattice, an experimental discovery that enables studies of a central QIST paradigm through direct quantum simulation using ultracold atoms. The researchers project that their novel quasiparticles, which mimic strongly interacting photons in materials and devices but circumvent some of the inherent challenges, will benefit the further development of QIST platforms that are poised to transform computing and communication technology.

The findings are detailed in a paper published in Nature Physics.

The research sheds light on fundamental polariton properties and related many-body phenomena, and it opens up novel possibilities for studies of polaritonic quantum matter.

An important challenge in work with photon-based QIST platforms is that while photons can be ideal carriers of quantum information they do not normally interact with each other. The absence of such interactions also inhibits the controlled exchange of quantum information between them. Scientists have found a way around this by coupling the photons to heavier excitations in materials, thus forming polaritons, chimera-like hybrids between light and matter. Collisions between these heavier quasiparticles then make it possible for the photons to effectively interact. This can enable the implementation of photon-based quantum gate operations and eventually of an entire QIST infrastructure.

Under Ocean Acidification, Embryos of a Key Forage Fish Struggle to Hatch

This photo shows sand lance embryos that have and have not hatched. Sand lance have trouble hatching at future ocean CO2 levels
Credit: Emma Cross.

When carbon is emitted into the atmosphere, about a quarter of it is absorbed by the earth’s oceans. As the oceans serve as a massive ‘sink’ for carbon, there are changes to the water’s pH – a measure of how acidic or basic water is. As oceans absorb carbon, their water becomes more acidic, a process called ocean acidification (OA). For years, researchers have worked to understand what effect this could have on marine life.

While most research so far shows that fish are fairly resilient to OA, new research from UConn, the University of Washington, the National Oceanic and Atmospheric Administration (NOAA), and Southern Connecticut State University, shows that an important forage fish for the Northwest Atlantic called sand lance is very sensitive to OA, and that this could have considerable ecosystem impacts by 2100. The team’s findings have just been published in Marine Ecology Progress Series.

Sand lance spawn in the winter months in offshore environments that tend to have stable, low levels of CO2, explains UConn Department of Marine Sciences researcher and lead author Hannes Baumann.

“Marine organisms are not living in a uniform ocean,” Baumann says. “In near shore environments, large CO2 fluctuations between day and night and between seasons are the norm, and the fish and other organisms are adapted to this variability. When we stumbled upon sand lances, we suspected they're different. We thought that a fish that lives in a more open-ocean offshore environment might be more sensitive than the near-shore fish because there’s just much less variability.”

Scientists Have Spotted the Farthest Galaxy Ever

HD1, object in red, appears at the center of a zoom-in image.
Credit: Harikane et al.
Hi-Res Zoomable Image

An international team of astronomers, including researchers at the Center for Astrophysics | Harvard & Smithsonian, has spotted the most distant astronomical object ever: a galaxy.

Named HD1, the galaxy candidate is some 13.5 billion light-years away and is described today in the Astrophysical Journal. In an accompanying paper published in the Monthly Notices of the Royal Astronomical Society Letters, scientists have begun to speculate exactly what the galaxy is.

The team proposes two ideas: HD1 may be forming stars at an astounding rate and is possibly even home to Population III stars, the universe’s very first stars — which, until now, have never been observed. Alternatively, HD1 may contain a supermassive black hole about 100 million times the mass of our Sun.

“Answering questions about the nature of a source so far away can be challenging,” says Fabio Pacucci, lead author of the MNRAS study, co-author in the discovery paper on ApJ, and an astronomer at the Center for Astrophysics. “It’s like guessing the nationality of a ship from the flag it flies, while being faraway ashore, with the vessel in the middle of a gale and dense fog. One can maybe see some colors and shapes of the flag, but not in their entirety. It’s ultimately a long game of analysis and exclusion of implausible scenarios.”

Insomnia could increase people’s risk of type 2 diabetes, study finds

People who have difficulty getting to sleep or staying asleep have higher blood sugar levels than people who rarely have sleep issues, new research has found. The University of Bristol-led findings suggest insomnia could increase people’s risk of type 2 diabetes, and that lifestyle or pharmacological treatments that improve insomnia could help to prevent or treat the condition.

The study, led by the University of Bristol, supported by the universities of Manchester, Exeter, and Harvard, and funded by Diabetes UK, is published in Diabetes Care.

Insomnia, not getting enough sleep, and having a later bedtime, have been linked in previous studies to a greater risk of type 2 diabetes. In this study, the research team assessed whether these associations are explained by causal effects of sleep traits on blood sugar levels

The researchers used a statistical technique called Mendelian Randomization to see how five sleep measures - insomnia, sleep duration, daytime sleepiness, napping and morning or evening preference (chronotype) - were related to average blood sugar levels assessed by a measure called HbA1c levels. Using Mendelian Randomization, which groups people according to a genetic code randomly assigned at birth, allowed the researchers to remove any bias from the results.

The study of over 336,999 adults living in the UK, showed that people who reported that they often had difficulty getting to sleep or staying asleep had higher blood sugar levels than people who said they never, rarely, or only sometimes had these difficulties. The research team found no clear evidence of an effect of other sleep traits on blood sugar levels.

The findings could improve researchers' understanding of how sleep disturbance influences type 2 diabetes risk. The study also suggests that lifestyle and/or pharmacological interventions that improve insomnia might help to prevent or treat diabetes.

Moving toward cleaner, more efficient hydrogen production

Hydrogen-fueled vehicles could be an important step toward a cleaner planet. They emit no chemicals other than water vapor, and would help reduce harmful carbon dioxide and air pollution levels. But although hydrogen is one of the most abundant elements on the planet, it is currently costly to produce from nonfossil sources.

Hydrogen is conventionally derived from natural gas through a process called methane steam reforming, but splitting water through an electrochemical process is cleaner and more sustainable. That process uses catalysts, which are substances that increase the rate of a chemical reaction without themselves undergoing any permanent chemical change. However, the cost of the greener technique has been a barrier in the marketplace.

Now a team of researchers led by Oregon State University (OSU) has shown that hydrogen can be cleanly produced with much greater efficiency and at a lower cost than is possible with current commercially available catalysts. The new findings, which describe ways to design catalysts that can greatly improve the efficiency of the clean hydrogen production process, were published in Science Advances and JACS Au.

The research team used the resources of the Advanced Photon Source (APS), a U.S. Department of Energy (DOE) Office of Science user facility at DOE’s Argonne National Laboratory, to test and confirm their findings.

Micro­cavities as a sensor plat­form

Nano particles trapped between mirrors might be a promising platform for quantum sensors.
Credit: IQOQI Innsbruck

Sensors are a pillar of the Internet of Things, providing the data to control all sorts of objects. Here, precision is essential, and this is where quantum technologies could make a difference. Researchers in Innsbruck and Zurich are now demonstrating how nanoparticles in tiny optical resonators can be transferred into quantum regime and used as high-precision sensors.

Advances in quantum physics offer new opportunities to significantly improve the precision of sensors and thus enable new technologies. A team led by Oriol Romero-Isart of the Institute of Quantum Optics and Quantum Information at the Austrian Academy of Sciences and the Department of Theoretical Physics at the University of Innsbruck and a team lead by Romain Quidant of ETH Zurich are now proposing a new concept for a high-precision quantum sensor. The researchers suggest that the motional fluctuations of a nanoparticle trapped in a microscopic optical resonator could be reduced significantly below the zero-point motion, by exploiting the fast unstable dynamics of the system.

New Insights into the Neuroscience Behind Conscious Awareness of Choice

Nancy Smith participates in neuroscience experiments to play a digital piano using a brain-computer interface.
Credit: T. Aflalo

When you absentmindedly reach out to pick up your cup of coffee and take a sip, what happens in your brain? Many studies have shown that brain activity begins to ramp up even before you are aware of your choice to move. But this poses a conundrum: Do we have free will to make our own choices, if our brains are already preparing for actions before we are even conscious of them?

Now, a new study from the laboratory of Richard Andersen, James G. Boswell Professor of Neuroscience, and Leadership Chair and Director of the T&C Chen Brain–Machine Interface Center, gives new insights into how the brain encodes for our choices about movement. The research indicates that brain activity of abstract high-level choices (such as the desire to consume more coffee) connects to the actual actions (such as reaching out a hand) even before the awareness of such choices to move.

"The implementation of current brain-machine interfaces that read out the intent of patients assume that they are simultaneously consciously aware of the intent that is being decoded from their brains," says Andersen. "Taking into account this early subconscious activity is critical when designing algorithms for brain-computer interfaces that could one day enable people with spinal or brain damage to regain function."

CUORE team places new limits on the bizarre behavior of neutrinos

CUORE scientists Dr. Paolo Gorla (LNGS, left) and Dr. Lucia Canonica (MIT, right) inspects the CUORE cryogenic systems.
Credit: Yury Suvorov and the CUORE Collaboration

In a Laboratory under a mountain, physicists are using crystals far colder than frozen air to study ghostly particles, hoping to learn secrets from the beginning of the universe. Researchers at the Cryogenic Underground Observatory for Rare Events (CUORE) announced this week that they had placed some of the most stringent limits yet on the strange possibility that the neutrino is its own antiparticle. Neutrinos are deeply unusual particles, so ethereal and so ubiquitous that they regularly pass through our bodies without us noticing. CUORE has spent the last three years patiently waiting to see evidence of a distinctive nuclear decay process, only possible if neutrinos and antineutrinos are the same particle. CUORE’s new data shows that this decay doesn’t happen for trillions of trillions of years, if it happens at all. CUORE’s limits on the behavior of these tiny phantoms are a crucial part of the search for the next breakthrough in particle and nuclear physics – and the search for our own origins.

“Ultimately, we are trying to understand matter creation,” said Carlo Bucci, researcher at the Laboratori Nazionali del Gran Sasso (LNGS) in Italy and the spokesperson for CUORE. “We’re looking for a process that violates a fundamental symmetry of nature,” added Roger Huang, a postdoctoral researcher at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and one of the lead authors of the new study.

CUORE – Italian for “heart” – is among the most sensitive neutrino experiments in the world. The new results from CUORE are based on a data set ten times larger than any other high-resolution search, collected over the last three years. CUORE is operated by an international research collaboration, led by the Istituto Nazionale di Fisica Nucleare (INFN) in Italy and Berkeley Lab in the US. The CUORE detector itself is located under nearly a mile of solid rock at LNGS, a facility of the INFN. U.S. Department of Energy-supported nuclear physicists play a leading scientific and technical role in this experiment. CUORE’s new results were published today in Nature.

Study finds genetic link between childhood and adult anxiety and depression

Hereditary factors are partly responsible for childhood anxiety and depression that persists into adulthood, according to University of Queensland researchers.

In the largest study of its kind in the world, the genetics of 64,641 children, aged between 3 and 18 years, were analyzed using longitudinal data from the Early Genetics and Lifeforce Epidemiology consortium.

Professor Christel Middeldorp, who holds a co-joint appointment with the UQ Child Health Research Centre and Children’s Health Queensland, said the study showed children who had similar levels of anxiety and depression were also alike genetically.

“It also revealed a genetic overlap between childhood and adult mental health disorders when comparing the results in this childhood study with results of previous studies in adults.

“These findings are important because they help identify people most at risk of symptoms continuing across the lifespan, so intense treatment can be provided where needed,” Professor Middeldorp said.

It’s the first-time researchers have conducted such a large-scale study examining the role of genetics in repeated measures of anxiety and depression in children.

Professor Middeldorp said genetic variants needed to be investigated because they increased the risk of recurrence and co-occurrence with other disorders.

“Mental health symptoms often come together, so those who experience anxiety or depression have a greater risk of disorders such as ADHD, aggressive behavior,” she said.

Amazon Rainforest Foliage Gases Affect the Earth’s Atmosphere

PNNL Earth scientist Manish Shrivastava and his team identified an atmospheric process that creates a type of fine particle over the Amazon rainforest. Through the process, semi-volatile gases, which are natural carbon-based chemical compounds that can easily condense to form fine particles in the upper atmosphere, are emitted throughout the Amazon rainforest by previously unrecognized in-plant and surface chemistry processes.
Illustration by Nathan Johnson | Pacific Northwest National Laboratory

Plant-foliage-derived gases drive a previously unknown atmospheric phenomenon over the Amazon rainforest, according to a recent study by researchers at Pacific Northwest National Laboratory (PNNL).

The findings have important applications for atmospheric science and for climate change modeling.

“The tropical Amazon rainforest constitutes the lungs of the Earth, and this study connects natural processes in the forest to aerosols, clouds, and the Earth’s radiative balance in ways that have not been previously recognized,” said Manish Shrivastava, Earth scientist at PNNL and principal investigator of the study.

The findings were recently published in ACS Earth and Space Chemistry.

Filling the missing data gap

Shrivastava and his team were studying fine particles in the upper atmosphere when they discovered a large disparity between their measurements and what would have been expected based on current understanding in atmospheric models. Through further study, the team found that there was key forest–atmosphere interactions missing from current atmospheric models that govern the number of fine particles in the upper atmosphere.

Researchers unravel mummy bird mystery

Carol Anne Barsody scans the mummy bird for a 3D model that will be included in a multisensory exhibition she is planning to hold in October.
Credit: Ryan Young/Cornell University

Over the last several months, a certain bird – believed to be a sacred ibis – has been drawing a lot of attention, and covering a lot of ground, from the College of Arts and Sciences to the College of Veterinary Medicine, College of Engineering and, later, the Lab of Ornithology.

Not bad for an animal that has been dead and mummified for more than 1,500 years.

The so-called “mummy bird” has had help getting around. Carol Anne Barsody, a master’s student in archaeology, has been trying to learn everything she can about the artifact, which is part of the Anthropology Collections in the College of Arts and Sciences, by consulting an array of researchers from across the university.

“One of the things I love about this project is that it incorporates expertise from across Cornell, all working together on a common goal,” Barsody said. “Where else but Cornell can you speak with a curator of vertebrates about a skeleton, and then call the vet school and have it X-rayed? There are so many different resources that students can utilize. And interdisciplinary projects make for stronger research.”

What began as a passion project, and grew into an independent study and then a proposed master’s thesis, has become a cross-campus fascination that encompasses everything from ancient burial rituals to the lost history of donated artifacts, the totemic power of animals, the ways museums can better engage the public, and even Egyptian beer.

Vegetarian birds are more sociable than insect eaters

The lesser masked weaver builds its nests in large colonies and has several partners per breeding season.
Credit: Chao Zhao

Weaver birds that eat seeds flock together and nest in colonies more commonly than those species that eat insects, suggests new research by an international team of scientists led by the Milner Centre for Evolution at the University of Bath. For the first time, the study statistically supports an influential ecological hypothesis on social behavior first proposed 58 years ago.

Weaver birds are a family of 118 songbird species that live mostly in sub-Saharan Africa and are so-called because of the elaborate construction of their nests.

Whilst some species live on the savannah feeding on seeds, other species live in the forest and mostly dine on insects.

The researchers looked at data collected from previously published studies of many weaver species to investigate the relationships between diet, habitat and social behavior.

They observed that birds living in the open savannah tended to flock together, foraging in groups to help find the best sources of seeds. The same birds also nested in large colonies and often had a polygamous breeding behavior, pairing with multiple mates during each season.

In contrast, the species living in the forest tended to be solitary foragers and nesters that did not flock together or live in colonies. These birds tended to be monogamous breeders with a single mate per season.

New Polymer Membrane Tech Improves Efficiency of CO2 Capture

Image credit: Chris Robert.

Researchers have developed a new membrane technology that allows for more efficient removal of carbon dioxide (CO2) from mixed gases, such as emissions from power plants.

“To demonstrate the capability of our new membranes, we looked at mixtures of CO2 and nitrogen, because CO2/nitrogen dioxide mixtures are particularly relevant in the context of reducing greenhouse gas emissions from power plants,” says Rich Spontak, co-corresponding author of a paper on the work. “And we’ve demonstrated that we can vastly improve the selectivity of membranes to remove CO2 while retaining relatively high CO2 permeability.”

“We also looked at mixtures of CO2 and methane, which is important to the natural gas industry,” says Spontak, who is a Distinguished Professor of Chemical and Biomolecular Engineering and Professor of Materials Science & Engineering at North Carolina State University. “In addition, these CO2-filtering membranes can be used in any situation in which one needs to remove CO2 from mixed gases – whether it’s a biomedical application or scrubbing CO2 from the air in a submarine.”

Membranes are an attractive technology for removing CO2 from mixed gases because they do not take up much physical space, they can be made in a wide variety of sizes, and they can be easily replaced. The other technology that is often used for CO2 removal is chemical absorption, which involves bubbling mixed gases through a column that contains a liquid amine – which removes CO2 from the gas. However, absorption technologies have a significantly larger footprint, and liquid amines tend to be toxic and corrosive.

‘Flash Droughts’ Coming on Faster, Global Study Shows

A map of drought conditions across the United States in mid-July 2012, the peak of a flash drought that decimated crops in the Midwest.
Credit: Richard Heim/ NCEI/NOAA

Just like flash floods, flash droughts come on fast — drying out soil in a matter of days to weeks. These events can wipe out crops and cause huge economic losses. And according to scientists, the speed at which they dry out the landscape has increased.

Researchers at The University of Texas at Austin, The Hong Kong Polytechnic University and Texas Tech University found that although the number of flash droughts has remained stable during the past two decades, more of them are coming on faster. Globally, the flash droughts that come on the fastest — sending areas into drought conditions within just five days — have increased by about 3%-19%. And in places that are especially prone to flash droughts — such as South Asia, Southeast Asia and central North America — that increase is about 22%-59%.

Rising global temperatures are probably behind the faster onset, said co-author and UT Jackson School Professor Zong-Liang Yang, who added that the study’s results underscore the importance of understanding flash droughts and preparing for their effects.

“Every year, we are seeing record-breaking warming episodes, and that is a good precursor to these flash droughts,” he said. “The hope and purpose [of this research] is to minimize the detrimental effects.”

Does this artificial intelligence think like a human?

MIT researchers developed a method that helps a user understand a machine-learning model’s reasoning, and how that reasoning compares to that of a human.
Credits: Christine Daniloff, MIT

In machine learning, understanding why a model makes certain decisions is often just as important as whether those decisions are correct. For instance, a machine-learning model might correctly predict that a skin lesion is cancerous, but it could have done so using an unrelated blip on a clinical photo.

While tools exist to help experts make sense of a model’s reasoning, often these methods only provide insights on one decision at a time, and each must be manually evaluated. Models are commonly trained using millions of data inputs, making it almost impossible for a human to evaluate enough decisions to identify patterns.

Now, researchers at MIT and IBM Research have created a method that enables a user to aggregate, sort, and rank these individual explanations to rapidly analyze a machine-learning model’s behavior. Their technique, called Shared Interest, incorporates quantifiable metrics that compare how well a model’s reasoning matches that of a human.

Shared Interest could help a user easily uncover concerning trends in a model’s decision-making — for example, perhaps the model often becomes confused by distracting, irrelevant features, like background objects in photos. Aggregating these insights could help the user quickly and quantitatively determine whether a model is trustworthy and ready to be deployed in a real-world situation.