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Tag: University of Southern California (USC)

  • Quantum computers guess better, study finds

    Quantum computers guess better, study finds

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    Newswise — Daniel Lidar, the Viterbi Professor of Engineering at USC and Director of the USC Center for Quantum Information Science & Technology, and first author Dr. Bibek Pokharel, a Research Scientist at IBM Quantum, achieved this quantum speedup advantage in the context of a “bitstring guessing game.”  They managed strings up to 26 bits long, significantly larger than previously possible, by effectively suppressing errors typically seen at this scale. (A bit is a binary number that is either zero or one).

    Quantum computers promise to solve certain problems with an advantage that increases as the problems increase in complexity. However, they are also highly prone to errors, or noise. The challenge, says Lidar, is “to obtain an advantage in the real world where today’s quantum computers are still ‘noisy.’” This noise-prone condition of current quantum computing is termed the “NISQ” (Noisy Intermediate-Scale Quantum) era, a term adapted from the RISC architecture used to describe classical computing devices. Thus, any present demonstration of quantum speed advantage necessitates noise reduction.

    The more unknown variables a problem has, the harder it usually is for a computer to solve. Scholars can evaluate a computer’s performance by playing a type of game with it to see how quickly an algorithm can guess hidden information. For instance, imagine a version of the TV game Jeopardy, where contestants take turns guessing a secret word of known length, one whole word at a time. The host reveals only one correct letter for each guessed word before changing the secret word randomly.

    In their study, the researchers replaced words with bitstrings. A classical computer would, on average, require approximately 33 million guesses to correctly identify a 26-bit string. In contrast, a perfectly functioning quantum computer, presenting guesses in quantum superposition, could identify the correct answer in just one guess. This efficiency comes from running a quantum algorithm developed more than 25 years ago by computer scientists Ethan Bernstein and Umesh Vazirani. However, noise can significantly hamper this exponential quantum advantage.

    Lidar and Pokharel achieved their quantum speedup by adapting a noise suppression technique called dynamical decoupling. They spent a year experimenting, with Pokharel working as a doctoral candidate under Lidar at USC. Initially, applying dynamical decoupling seemed to degrade performance. However, after numerous refinements, the quantum algorithm functioned as intended. The time to solve problems then grew more slowly than with any classical computer, with the quantum advantage becoming increasingly evident as the problems became more complex.

    Lidar notes that “currently, classical computers can still solve the problem faster in absolute terms.” In other words, the reported advantage is measured in terms of the time-scaling it takes to find the solution, not the absolute time. This means that for sufficiently long bitstrings, the quantum solution will eventually be quicker.

    The study conclusively demonstrates that with proper error control, quantum computers can execute complete algorithms with better scaling of the time it takes to find the solution than conventional computers, even in the NISQ era.

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  • How Will Farming Change in the Future?

    How Will Farming Change in the Future?

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    Newswise — On November 15, 2022, the 8 billionth person on the planet was born. With concerns about food security on the rise, experts are asking: how will we feed everyone? Climate change, natural resource depletion, soil erosion, and fossil fuel use in farming make the task even more challenging. We need to do something differently, but what? 

    Barath Raghavan, an associate professor of computer science at USC Viterbi, is rethinking traditional farming practices by developing computational tools to help farmers design, develop, and manage sustainable farming methods.  Raghavan, a member of the California Rare Fruit Growers organization, currently grows more than 150 different edible plants in his yard. A decade ago, he started to combine his interests by researching how computing could make agriculture more sustainable.

    Raghavan calls this new area of research “computational agroecology,” uniting technology and farming expertise to develop diverse agricultural landscapes based on natural ecosystems. From crop selection to planting to irrigation, the method allows farmers to explore thousands of different potential designs to optimize food production without fossil fuel-derived pesticides.   

    “How can we design an ecosystem that is as productive and sustainable as a natural forest, but instead of producing food for wildlife, it’s producing food for people?” said Raghavan.  

    “It’s an incredibly hard problem because designing an ecosystem is a super complex, dynamic, natural system. We’re trying to build computing tools that can figure out how ecosystems work, so we can grow food plentifully and sustainably.”   

    “A totally new way to think about agriculture”

    In a new paper published in PNAS Nexus on March 16, Raghavan and his colleagues propose “a totally new way to think about agriculture and the benefits it can have for research and farming,” said Raghavan.  

    In this study, the researchers reconceptualize agriculture as a search through a “state space,” which represents all possible configurations of a system—in this context, agricultural land.  

    To better understand the concept of a state space, imagine a box of blocks: each block could be red, blue or yellow. The state space would consist of all the possible ways to arrange these blocks, such as all red, blue or green, or a combination of the three colors. 

    In the same way, a state space for an agricultural system might consist of all the possible variables that the system can take—such as crop or soil type, weather conditions, irrigation, fertilization or pest control.  

    This allows agricultural researchers and farmers to explore the different paths and strategies available—taking different “blocks” or variables and placing them together to see what works.  

    “Once we can conceive of a farm this way, we can then reframe many … farming planning questions.” Barath Raghavan. 

    Essentially, an agricultural “sandbox” to determine optimal configurations to increase crop yield, improve sustainability, and discover entirely new combinations of crops that grow well together. 

    For instance, the framework enables analytics and machine learning that could allow researchers to analyze the patterns between crop yield and soil moisture content or simulate growing different types of crops together for biodiversity.  

    “Once we can conceive of a farm this way, we can then reframe many research questions and farming planning questions as a search through the space of all possible states the farm could possibly end up in, with certain states being more desirable than others,” said Raghavan.  

    “This allows us to compare and contrast different approaches to farming, explore and combine techniques, and then search the state space in simulation for new farming techniques that have never been tried before and where trial and error in the real world would be far too expensive and time-consuming.”  

    “Playing a chess game with nature” 

    For example, in Southern California, farmers have recently discovered that high-quality coffee can grow plentifully between avocado trees. But figuring out the right way to do that, and maybe even add another couple of crops that work well together, is site specific.  

    “Each farmer doesn’t have the time or ability to do trial and error for years to figure out the right way to grow a half dozen crops on their land,” said Raghavan.

    “Instead, with the conceptual framework and eventually software framework of state spaces, a farmer could spell out an objective—such as diversified harvest with high yield and possible high profit for a specific piece of land—and have the system explore the state space and produce possible plant mixtures, placement, and management techniques that meet the farmer’s criteria.”  

    Raghavan compares the process to “playing a chess game with nature, but one that is both competitive and collaborative.”  

    “You’re making moves on the chessboard, which is your land, and nature is making moves too. Pests are going to eat one crop; a flood is going to damage another. What we are building is a computational framework that allows you to explore all the different ways that you might ‘play’ this game of chess with nature so that we can come up with the best one for your land.”  

    The group including Raghavan recently received a grant from the U.S. Department of Agriculture’s National Institute of Food and Agriculture for their research in this area. Now, the team is working through possible use cases with researchers and farmers to incorporate specific use cases and to develop software that can make it easy to simulate and explore state spaces.

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  • Study suggests one solution to America’s opioid epidemic: Tell doctors their patients fatally overdosed

    Study suggests one solution to America’s opioid epidemic: Tell doctors their patients fatally overdosed

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    Newswise — There are no simple solutions to America’s deadly overdose epidemic, which costs 100,000 lives each year and is erasing gains in life expectancy. But a team of USC researchers have found one low-cost intervention can make a difference: a letter notifying providers their patient has died from an overdose.

    A 2018 study by the team found that notifying clinicians through an informational letter from their county’s medical examiner that a patient had suffered a fatal overdose reduced the number of opioid prescriptions they wrote over the next three months. The team’s new study, published today in JAMA Network Open, shows those notifications have a lasting impact up to a year later.

    “Clinicians don’t necessarily know a patient they prescribed opioids to has suffered a fatal overdose,” said lead author Jason Doctor, Chair of the Department of Health Policy and Management at the USC Sol Price School of Public Policy and Co-Director of the Behavioral Sciences Program at the USC Schaeffer Center for Health Policy & Economics. “We knew closing this information loop immediately reduced opioid prescriptions. Our latest study shows that change in prescribing behavior seems to stick.”

    A simple public health intervention with a lasting impact

    Doctor and his team sent letters to 809 clinicians—predominantly medical doctors—who had prescribed opioids to 166 people who had suffered fatal overdoses in San Diego County. The letter was intended to be informative and respectful in tone while providing information about safer prescribing. The researchers compared prescribing patterns among these clinicians to those who had not received the letter.

    While there was a gradual reduction in opioid prescribing across the board, study authors found the rate of the reduction was faster and more robust among those who received the letter. After one year, those who received the letter wrote 7% fewer prescriptions than clinicians who hadn’t received the notification.

    “The new study shows this change is not just a temporary blip and then clinicians went back to their previous prescribing,” said Doctor. “This low-cost intervention has a long-lasting impact.”

    Doctor acknowledged that attention to the number of deaths from drugs prescribed by clinicians has been eclipsed by the focus on rising deaths from illicit opioid use, particularly during the COVID-19 pandemic.

    “The sad truth is, we never addressed the first problem of deaths from prescribed opioids. In fact, it’s all mixed together because nationally, approximately half of people who die of an illicit fentanyl drug overdose have also had an opioid prescription within the past year,” he explained.

    Medical examiners are uniquely positioned to mitigate future opioid overdose deaths

    The big takeaway, said Doctor, is the letters from the medical examiner provide a unique opportunity to get into communication with physicians in the wake of overdose deaths to save lives from both legal and illegal opioids.

    “The letter is a nudge to providers that the opioid epidemic is in their community and affecting their patients. It is easy to read the headlines and assume you are not part of the problem,” said Doctor. “Doctors have an opportunity to talk to their patients and consider alternatives to opioids. I believe we can reach about half of the people in the illicit fentanyl epidemic through a doctor who has seen them.”

    Doctor and other study authors are currently partnering with Los Angeles County on lessons from the research and looking at potential public policy interventions, including mandating such notifications from county medical examiners to clinicians.

    About the study

    Additional study authors include Emily Stewart and Tara Knight of the USC Schaeffer Center; Roneet Lev of the Scripps Mercy Hospital San Diego; Jonathan Lucas of the Department of Medical Examiner-Coroner of the County of Los Angeles; Andy Nguyen of Global Blood Therapeutics, South San Francisco; and Michael Menchine of the Department of Emergency Medicine at UCLA. The work was supported by the California Health Care Foundation (grant 19413) to Doctor, Stewart and Knight; the National Institute on Aging (NIA) at the National Institutes of Health (grants R21-AG057395-01 and R33-AG057395 to Knight); National Institute on Drug Abuse (R01 DA046226) and the NIA Roybal Center for Behavioral Interventions (P30AG024968 to Knight).

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