Computers Math

Quantum technologies, i.e. technological devices obtained by building and manipulating quantum mechanical systems, are becoming a reality in recent days. The most prominent example is certainly given by quantum computers, where the unit of information, the bit, is replaced by its quantum mechanical counterpart, informally called the qubit. Contrary to classical computers, quantum computers promise to use the full quantum mechanical features of qubits, in order to address and solve computational problems which would be out of reach by using classical computers. As an example, the Canadian company Xanadu recently claimed that its quantum computer has been able to solve, in just 36 microseconds, a computational task that would have required 9000 years using state-of-the-art supercomputers.
Quantum technologies need energy to operate. This simple consideration has led researchers, in the last ten years, to develop the idea of quantum batteries, which are quantum mechanical systems used as energy storage devices. In the very recent past, researchers at the Center for Theoretical Physics of Complex Systems (PCS) within the Institute for Basic Science (IBS), South Korea have been able to put tight constraints on the possible charging performance of a quantum battery. Specifically, they showed that a collection of quantum batteries can lead to an enormous improvement in charging speed compared to a classical charging protocol. This is thanks to quantum effects, which allow the cells in quantum batteries to be charged simultaneously.
Despite these theoretical achievements, the experimental realizations of quantum batteries are still scarce. The only recent notable counter-example used a collection of two-level systems (very similar to the qubits just introduced) for energy storage purposes, with the energy being provided by an electromagnetic field (a laser).
Given the current situation, it is clearly of uttermost importance to find new and more accessible quantum platforms which can be used as quantum batteries. With this motivation in mind, researchers from the same IBS PCS team, working in collaboration with Giuliano Benenti (University of Insubria, Italy), recently decided to revisit a quantum mechanical system that has been studied heavily in the past: the micromaser. Micromaser is a system where a beam of atoms is used to pump photons into a cavity. Put in simple terms, a micromaser can be thought of as a configuration specular to the experimental model of quantum battery mentioned above: the energy is stored into the electromagnetic field, which is charged by a stream of qubits sequentially interacting with it.
The IBS PCS researchers and their collaborator showed that micromasers have features that allow them to serve as excellent models of quantum batteries. One of the main concerns when trying to use an electromagnetic field to store energy is that in principle, the electromagnetic field could absorb an enormous amount of energy, potentially much more than what is necessary. Making an analogy with a simple case, this would correspond to a phone battery that, when plugged, continues to increase its charge indefinitely. In such a scenario, forgetting that the phone is plugged in could be extremely risky, since there would be no mechanism to stop the charging.
Luckily, the team’s numerical results show that this cannot happen in micromasers. The electromagnetic field reaches quickly a final configuration (technically called a steady state), whose energy can be determined and decided a priori when building the micromaser. This property ensures protection from the risks of overcharging.
In addition, the researchers showed that the final configuration of the electromagnetic field is in a pure state, which means that it brings no memory of the qubits that have been used during the charging. This latter property is particularly crucial when dealing with a quantum battery. It ensures that all the energy stored in the battery can be extracted and used whenever necessary, without the need of keeping track of the qubits used during the charging process.
Finally, it was shown that these appealing features are robust and are not destroyed by changing the specific parameters defined in this study. This property is of clear importance when trying to build an actual quantum battery since imperfections in the building process are simply unavoidable.
Interestingly, in a parallel series of papers, Stefan Nimmrichter and his collaborators have shown that quantum effects can make the charging process of the micromaser faster than classical charging. In other words, they have been able to show the presence of the previously mentioned quantum advantage during the charging of a micromaser battery.
All these results suggest that micromaser could be considered as a promising new platform that can be used to build quantum batteries. The fact that these systems have been already implemented in experimental realizations for many years could give a serious boost in building new accessible prototypes of quantum batteries.
To this end, the IBS PCS researchers and Giuliano Benenti are currently starting a joint collaboration with Stefan Nimmrichter and his collaborators, to further explore these promising models. The hope is that this new research collaboration will finally be able to benchmark and experimentally test the performances of micromaser-based quantum battery devices. More

Researchers at the University of East Anglia have made an important discovery about the way our brains process the sensations of sound and touch.
A new study published today shows how the brain’s different sensory systems are all closely interconnected — with regions that respond to touch also involved when we listen to specific sounds associated with touching objects.
They found that these areas of the brain can tell the difference between listening to sounds such as such as a ball bouncing, or the sound of typing on a keyboard.
It is hoped that understanding this key area of brain function may in future help people who are neurodiverse, or with conditions such as schizophrenia or anxiety. And it could lead to developments in brain-inspired computing and AI.
Lead researcher Dr Fraser Smith, from UEA’s School of Psychology, said: “We know that when we hear a familiar sound such as a bouncing a ball, this leads us to expect to see a particular object. But what we have found is that it also leads the brain to represent what it might feel like to touch and interact with that object.
“These expectations can help the brain process sensory information more efficiently.”
The research team used an MRI scanner to collect brain imaging data while 10 participants listened to sounds generated by interacting with objects — such as bouncing a ball, knocking on a door, crushing paper, or typing on a keyboard. More

Caregivers who consume digital media for relaxation are more likely to engage in negative parenting practices, according to a new multinational study.
The new study led by the University of Waterloo aimed to investigate the relationship between caregivers’ use of digital media, mental health, and parenting practices at the start of the COVID-19 pandemic. On average, caregivers spend three to four hours a day consuming digital media.
“All members of the family matter when we try to understand families in a society saturated with technology,” said Jasmine Zhang, lead author of the study and a master’s candidate in clinical psychology at Waterloo. “It’s not just children who are often on devices. Parents use digital media for many reasons, and these behaviours can impact their children.”
To conduct the study, the researchers surveyed 549 participants who are parents of at least two children between the ages of five and 18. Caregivers provided information about their digital use, their own mental health and their children’s, family functioning, and parenting practices.
The researchers found that caregivers with higher levels of distress engage in more screen-based activities and were more likely to turn to devices for relaxation. This consumption was correlated with negative parenting practices such as nagging and yelling. They also found that negative parenting behaviours were more likely when technology interrupted family interactions. The experiment didn’t focus on specific apps or websites that caregivers use but rather found that caregivers who spend time on screens were retreating from being present with their family, which is correlated with negative parenting practices.
However, not all media consumption was correlated with negative outcomes: maintaining social connections through digital channels was related to lower levels of anxiety and depression and higher levels of positive parenting practices such as listening to their children’s ideas and speaking of the good their children do.
“When we study how parents use digital media, we need to consider caregivers’ motivations for using devices in addition to how much time they spend on them,” Zhang said.
Dillon Browne, Canada Research Chair in Child and Family Clinical Psychology and professor of psychology at Waterloo, expects these patterns to continue after the pandemic.
“The family media landscape continues to grow and become more prominent,” said Browne, a co-author of the study. “Going forward, it’s important to consider the nuances of digital media as some behaviours are related to well-being, and others are related to distress.”
The researchers plan to build on these findings and hope that their work will aid in creating guidelines that will help caregivers manage their screen-based behaviours.
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Children’s outbursts of rage while playing digital games are causing both concern and public debate around the topic. Taking a novel approach to gamer rage, a new study conducted at the University of Eastern Finland examines the topic from a child’s perspective, finding complex reasons for gamer rage in children. As data, the researchers used interviews with, and essays by, children. The study examined children’s views on the reasons for, and background factors of, gamer rage. In addition, the researchers analysed how rage manifested itself.
The results show that a reason for gamer rage in children was often found in their own performance.
“For example, repeated or last-minute in-game failures, or losing to a beginner, caused annoyance and rage. In digital gaming, competitiveness and social factors play a major role in general,” says Project Researcher Juho Kahila from the University of Eastern Finland.
Children often compared their own performance to that of other players. Frustrating actions by other players, such as cheating or losing a game due to incompetent teammates, were perceived as a source of rage. In addition, out-of-game interruptions, such as having to do chores or homework, and technical problems, such as a poor internet connection, were also identified as sources of rage.
Failure, humiliation, noise and hunger predispose to rage
Some games were perceived as rage triggering. For instance, playing against a real human, or getting humiliated by another player were identified as factors predisposing to gamer rage. Besides choice of game, also the gaming environment had an influence on rage.
“Toxicity within the gaming community, such as unpleasant remarks or bullying by other players, as well as a noisy gaming environment, were identified as predisposing to rage. In addition, troubles in daily life, such as having a bad day at school, or feeling hungry, were also recognised as factors contributing to rage,” Kahila says.
In the children’s essays, gamer rage often took the form of verbal expressions, but also physical expressions, as well as quitting gaming. In an outburst of rage, children not only yelled and cursed, but they also kicked, beat and threw items on hand, such as their gaming equipment or pieces of furniture. A gaming session was often quit while feeling outraged. However, the results also showed that quitting a gaming session, or switching to a less infuriating game, were often used as a preventive measure to avoid becoming even more enraged.
The study shows that the reasons behind gamer rage in digital gaming are very complex — and that children are good at naming them. According to Kahila, many of the reasons leading to rage in digital gaming, such as in-game failures, cheating opponents, or a toxic gaming environment, are similar also in other gaming settings.
“For example, feelings of outrage caused by one’s own mistakes, a penalty missed by a referee, or annoying behaviour by an opponent, are all familiar from ice hockey, just to pick an example,” Kahila points out. More

By analyzing DNA with the help of artificial intelligence (AI), an international research team led by Lund University in Sweden has developed a method that can accurately date up to ten-thousand year-old human remains.
Accurately dating ancient humans is key when mapping how people migrated during world history.
The standard dating method since the 1950s has been radiocarbon dating. The method, which is based on the ratio between two different carbon isotopes, has revolutionized archaeology. However, the technology is not always completely reliable in terms of accuracy, making it complicated to map ancient people, how they moved and how they are related.
In a new study published in Cell Reports Methods, a research team has developed a dating method that could be of great interest to archaeologists and paleognomicists.
“Unreliable dating is a major problem, resulting in vague and contradictory results. Our method uses artificial intelligence to date genomes via their DNA with great accuracy, says Eran Elhaik, researcher in molecular cell biology at Lund University.
The method is called Temporal Population Structure (TPS) and can be used to date genomes that are up to 10,000 years old. In the study, the research team analyzed approximately 5,000 human remains — from the Late Mesolithic period (10,000-8,000 BC) to modern times. All of the studied samples could be dated with a rarely seen accuracy.
“We show that information about the period in which people lived is encoded in the genetic material. By figuring out how to interpret it and position it in time, we managed to date it with the help of AI,” says Eran Elhaik.
The researchers do not expect TPS to eliminate radiocarbon dating but rather see the method as a complementary tool in the paleogeographic toolbox. The method can be used when there is uncertainty involving a radiocarbon dating result. One example is the famous human skull from Zlatý kůň in today’s Czech Republic, which could be anywhere between 15,000 and 34,000 years old.
“Radiocarbon dating can be very unstable and is affected by the quality of the material being examined. Our method is based on DNA, which makes it very solid. Now we can seriously begin to trace the origins of ancient people and map their migration routes,” concludes Eran Elhaik.
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Materials provided by Lund University. Note: Content may be edited for style and length. More

Personalized wine lists. Tailored clothing options. Unique experiences just for you.
The world is awash in products and services that promise to provide custom experiences to every consumer. And it turns out our smartphones are pushing us to unconsciously prefer just these kinds of customized options.
A new study from the University of Florida has discovered that consumers gravitate toward customized, rare or special products when they are engrossed in their phones. The highly private and personalized feelings we have toward our phones seem to encourage us to express our unique selves more than if we buy products on a larger computer — or borrow some stranger’s phone.
The findings suggest that companies should — and indeed might already — change what they offer to consumers depending on what device they are using. The smartphone’s activation of a self-expression mindset also likely alters a range of behaviors, such as how people respond to political polls on mobile devices.
“When you use your phone, your authentic self is being expressed to a greater extent. That affects the options you seek and the attitudes you express,” said Aner Sela, a professor in UF’s Warrington College of Business and one of the authors of the study.
Sela and his former doctoral student Camilla Song, now an assistant professor at City University of Hong Kong, published their findings Aug. 3 in the Journal of Marketing Research. More

Lasers are everywhere. Devices that use them transmit information and enable the existence of long-distance communications and the internet; they aid doctors performing surgeries and engineers manufacturing advanced tools and technologies; and day-to-day, we encounter lasers as we scan our groceries and watch DVDs. “In the 60-some years since they were invented, lasers have absolutely transformed our lives,” said Giulio Cerullo, a nonlinear optics researcher at Politecnico di Milano in Italy.
Today, with the help of new research from Cerullo and collaborators at Columbia University published in Nature Photonics, devices that use lasers are poised to become a whole lot smaller.
Working in engineer James Schuck’s lab at Columbia, PhD student Xinyi Xu and postdoc Chiara Trovatello studied a 2D material called molybdenum disulfide (MoS2). They characterized how efficiently devices built from stacks of MoS2 less than one micron thick — that’s 100 times thinner than a human hair — convert light frequencies at telecom wavelengths to produce different colors.
This new research is a first step toward replacing the standard materials used in today’s tunable lasers, which are measured in millimeters and centimeters, said Trovatello, who recently completed her PhD with Cerullo in Milan. “Nonlinear optics is currently a macroscopic world, but we want to make it microscopic,” she said.
Lasers give off a special kind of coherent light, which means all the photons in the beam share the same frequency and thus, color. Lasers operate only at specific frequencies, but devices often need to be able to deploy different colors of laser light. For example, a green laser pointer is actually produced by an infrared laser that’s converted to a visible color by a macroscopic material. Researchers use nonlinear optical techniques to change the color of laser light, but conventionally used materials need to be relatively thick for color conversion to occur efficiently.
MoS2 is one of the most studied examples of an emerging class of materials called transition metal dichalcogenides, which can be peeled into atomically thin layers. Single layers of MoS2 can convert light frequencies efficiently, but are actually too thin to be used to build devices. Larger crystals of MoS2, meanwhile, tend to be more stable in a non-color converting form. To fabricate the necessary crystals, known as 3R-MoS2, the team worked with the commercial 2D-material supplier HQ Graphene.
With 3R-MoS2 in hand, Xu began peeling off samples of varying thickness to test how efficiently they converted the frequency of light. Right away, the results were spectacular. “Rarely in science do you start on a project that ends up working better than you expect — usually it’s the opposite. This was a rare, magical case,” remarked Schuck. Usually, special sensors are needed to register the light produced by a sample, and it takes some time for them to do so, explained Xu. “With 3R-MoS2, we could see the extremely large enhancement almost immediately,” he said. Notably, the team recorded these conversions at telecom wavelengths, a key feature for potential optical communications applications, such as delivering internet and television services.
In a fortunate accident during one scan, Xu focused on a random edge of a crystal and saw fringes that suggested waveguide modes were present inside the material. Waveguide modes keep different color photons, which otherwise move at different speeds across the crystal, in sync, and can possibly be used to generate so-called entangled photons, a key component of quantum optics applications. The team handed their devices off to the lab of physicist Dmitri Basov, where his postdoc Fabian Mooshammer confirmed their hunch.
Currently, the most popular crystal for waveguided conversion and generating entangled photons is lithium niobate, a hard and stiff material that needs to be fairly thick for achieving useful conversion efficiencies. 3R-MoS2 is equally efficient but 100 times smaller and flexible enough that it can be combined with silicon photonic platforms to create optical circuits on chips, following the trajectory of ever-smaller electronics.
With this proof-of-concept result, the bottleneck toward real-life applications is large-scale production of 3R-MoS2 and high-throughput structuring of devices. There, the team says, industry will need to take over. With this work, they hope they’ve demonstrated the promise of 2D materials.
“I’ve been working on nonlinear optics for more than thirty years now. Research is most often incremental, slowly building on what came before. It’s rare that you do something completely new with big potential,” said Cerullo. “I have a feeling that this new material could change the game.” More

Kidney cancer is not always confined to the kidney. In advanced cases, this cancer invades the body’s biggest vein, the inferior vena cava (IVC), which carries blood out of the kidneys back to the heart. Via the IVC, cancer may infiltrate the liver and heart. The Mays Cancer Center at The University of Texas Health Science Center at San Antonio (UT Health San Antonio) is one of the high-volume centers in the U.S. with surgical expertise in treating this serious problem. The Mays Cancer Center is San Antonio’s National Cancer Institute-designated Cancer Center.
In a study featured on the cover of the Journal of Urology (Official Journal of the American Urological Association), researchers from the Mays Cancer Center and Department of Urology at UT Health San Antonio show that robotic IVC thrombectomy (removal of cancer from the inferior vena cava) is not inferior to standard open IVC thrombectomy and is a highly safe and effective alternative approach. The affected kidney is removed along with the tumor during surgery, which is performed at UT Health San Antonio’s clinical partner, University Hospital.
Harshit Garg, MD, urologic oncology fellow in the Department of Urology, is first author of the study, and Dharam Kaushik, MD, urologic oncology fellowship program director, is the senior author. Kaushik is an associate professor and the Stanley and Sandra Rosenberg Endowed Chair in Urologic Research at UT Health San Antonio.
The open surgery requires an incision that begins 2 inches below the ribcage and extends downward on both sides of the ribcage. “It looks like an inverted V,” Kaushik said. Next, organs that surround the IVC, such as the liver, are mobilized, and the IVC is clamped above and below the cancer. In this way, surgeons gain control of the inferior vena cava for cancer resection.
“Open surgery has an excellent success rate, and most cases are performed in this manner,” Kaushik said. “But now, with the robotic approach, we can achieve similar results with smaller incisions. Therefore, we need to study the implications of utilizing this newer approach.”
The study is a systematic review and meta-analysis of data from 28 studies that enrolled 1,375 patients at different medical centers. Of these patients, 439 had robotic IVC thrombectomy and 936 had open surgery. Kaushik and his team collaborated with Memorial Sloan Kettering Cancer Center, New York; Cedars-Sinai Medical Center, Los Angeles; and the University of Washington, Seattle, to perform this study.
“We pulled the data together to make conclusions because, before this, only small studies from single institutions had been conducted to compare the IVC thrombectomy approaches,” Kaushik said.
Findings
The results are encouraging and indicate further study of robotic IVC thrombectomy is warranted. The robotic approach in comparison with open was associated with: Fewer blood transfusions: 18% of robotic patients required transfusions compared to 64% of open patients. Fewer complications: 5% of robotic patients experienced complications such as bleeding compared to 36.7% of open thrombectomy patients.These large, technically challenging surgeries last eight to 10 hours and involve a multidisciplinary team of vascular surgeons, cardiac surgeons, transplant surgeons and urologic oncology surgeons, Kaushik said.
“This study is the largest meta-analysis analyzing the outcomes of robotic versus open IVC thrombectomy,” Kaushik said. “In more than 1,300 patients, we found that overall complications were lower with the robotic approach and the blood transfusion rate was lower with this approach.
“That tells us there is more room for us to grow and refine this robotic procedure and to offer it to patients who are optimal candidates for it,” Kaushik said. “Optimal candidacy for a robotic surgery should be based on a surgeon’s robotic expertise, the extent and burden of the tumor, and the patient’s comorbid conditions. The open surgical approach remains the gold standard for achieving excellent surgical control.” More