(Press-News.org) A team of researchers at Lawrence Berkeley National Laboratory (Berkeley Lab) used a quantum computer to successfully simulate an aspect of particle collisions that is typically neglected in high-energy physics experiments, such as those that occur at CERN's Large Hadron Collider.
The quantum algorithm they developed accounts for the complexity of parton showers, which are complicated bursts of particles produced in the collisions that involve particle production and decay processes.
Classical algorithms typically used to model parton showers, such as the popular Markov Chain Monte Carlo algorithms, overlook several quantum-based effects, the researchers note in a study published online Feb. 10 in the journal Physical Review Letters that details their quantum algorithm.
"We've essentially shown that you can put a parton shower on a quantum computer with efficient resources," said Christian Bauer, who is Theory Group leader and serves as principal investigator for quantum computing efforts in Berkeley Lab's Physics Division, "and we've shown there are certain quantum effects that are difficult to describe on a classical computer that you could describe on a quantum computer." Bauer led the recent study.
Their approach meshes quantum and classical computing: It uses the quantum solution only for the part of the particle collisions that cannot be addressed with classical computing, and uses classical computing to address all of the other aspects of the particle collisions.
Researchers constructed a so-called "toy model," a simplified theory that can be run on an actual quantum computer while still containing enough complexity that prevents it from being simulated using classical methods.
"What a quantum algorithm does is compute all possible outcomes at the same time, then picks one," Bauer said. "As the data gets more and more precise, our theoretical predictions need to get more and more precise. And at some point these quantum effects become big enough that they actually matter," and need to be accounted for.
In constructing their quantum algorithm, researchers factored in the different particle processes and outcomes that can occur in a parton shower, accounting for particle state, particle emission history, whether emissions occurred, and the number of particles produced in the shower, including separate counts for bosons and for two types of fermions.
The quantum computer "computed these histories at the same time, and summed up all of the possible histories at each intermediate stage," Bauer noted.
The research team used the IBM Q Johannesburg chip, a quantum computer with 20 qubits. Each qubit, or quantum bit, is capable of representing a zero, one, and a state of so-called superposition in which it represents both a zero and a one simultaneously. This superposition is what makes qubits uniquely powerful compared to standard computing bits, which can represent a zero or one.
Researchers constructed a four-step quantum computer circuit using five qubits, and the algorithm requires 48 operations. Researchers noted that noise in the quantum computer is likely to blame for differences in results with the quantum simulator.
While the team's pioneering efforts to apply quantum computing to a simplified portion of particle collider data are promising, Bauer said that he doesn't expect quantum computers to have a large impact on the high-energy physics field for several years - at least until the hardware improves.
Quantum computers will need more qubits and much lower noise to have a real breakthrough, Bauer said. "A lot depends on how quickly the machines get better." But he noted that there is a huge and growing effort to make that happen, and it's important to start thinking about these quantum algorithms now to be ready for the coming advances in hardware.
Such quantum leaps in technology are a prime focus of an Energy Department-supported collaborative quantum R&D center that Berkeley Lab is a part of, called the Quantum Systems Accelerator.
As hardware improves it will be possible to account for more types of bosons and fermions in the quantum algorithm, which will improve its accuracy.
Such algorithms should eventually have broad impact in the high-energy physics field, he said, and could also find application in heavy-ion-collider experiments.
INFORMATION:
Also participating in the study were Benjamin Nachman and Davide Provasoli of the Berkeley Lab Physics Division, and Wibe de Jong of the Berkeley Lab Computational Research Division.
This work was supported by the U.S. Department of Energy Office of Science. It used resources at the Oak Ridge Leadership Computing Facility, which is a DOE Office of Science user facility.
Founded in 1931 on the belief that the biggest scientific challenges are best addressed by teams, Lawrence Berkeley National Laboratory and its scientists have been recognized with 14 Nobel Prizes. Today, Berkeley Lab researchers develop sustainable energy and environmental solutions, create useful new materials, advance the frontiers of computing, and probe the mysteries of life, matter, and the universe. Scientists from around the world rely on the Lab's facilities for their own discovery science. Berkeley Lab is a multiprogram national laboratory, managed by the University of California for the U.S. Department of Energy's Office of Science.
DOE's Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit energy.gov/science.
An international research team led by Professor Kari Rissanen of the University of Jyvaskyla (Finland) and Professor Antonio Frontera of the University of Balearic Islands (Spain) has demonstrated that positively charged iodine (termed iodonium) is able to favorably interact with a silver cation (Ag+), overcoming the strong electrostatic repulsion. The research was published online in Chem -journal 8th of February 2021.
It is well known and intuitive that iodide (I-) has a strong affinity for Ag+. For instance, AgI is one of the most insoluble inorganic salts ...
When we listen to speech sounds, the information that enters our left and right ear is not exactly the same. This may be because acoustic information reaches one ear before the other, or because the sound is perceived as louder by one of the ears. Information about speech sounds also reaches different parts of our brain, and the two hemispheres are specialised in processing different types of acoustic information. But how does the brain integrate auditory information from different areas?
To investigate this question, lead researcher Basil Preisig from the University of Zurich collaborated with an international team of scientists. In an earlier study, the team discovered that the brain integrates information about speech sounds by 'balancing' the rhythm of gamma waves across ...
Most countries introduced school closures during the spring of 2020 despite substantial uncertainty regarding the effectiveness in containing SARS-CoV-2. In Sweden, upper-secondary schools moved online while lower-secondary schools remained open. A comparison of parents with children in the final year of lower-secondary and first year of upper-secondary school shows that keeping the former open had limited consequences for the overall transmission of the virus. However, the infection rate doubled among lower-secondary teachers relative to upper-secondary ones. The infection rate among partners of lower-secondary teacher was 30 percent higher than among their upper-secondary counterparts.
On March 18, 2020, Swedish ...
T lymphocytes, or T cells, are an important component of our immune system. They can recognize foreign proteins, so-called antigens, as peptide fragments - for instance, those derived from viruses or cancer cells. In principle, they could, but usually do not, attack our own ('self') proteins. "That is why it is important for the organism to tightly control the activities of T cells," says Dr. Reinhard Obst, head of a research group at the Institute for Immunology at LMU's Biomedical Center that studies the activation of T cells. The project contributed to the Collaborative Research Center 1054 that explores the plasticity of cell fate decisions in the immune system.
When ...
Scientists use many different tests to investigate what happens in the brain in people experiencing stress. It is unclear to what extent the various methods with which subjects are placed under stress are comparable to each other. In a meta-analysis, a biopsychology team from Ruhr-Universität Bochum compared 31 previous studies that had investigated stress using functional magnetic resonance imaging (fMRI). The team worked out which regions of the brain are activated as standard during stress and which stress tests trigger similar activation patterns. They describe the results in the journal Neuroscience and Biobehavioral Reviews, published online on 5 February 2021.
To conduct the work, ...
The move from the ancient system of £sd coinage to 100p to £1 was controversial, considered by some to be a sign of the UK's receding importance on the world stage and even as the beginning of the tumultuous relationship with Europe that ultimately led to Brexit.
But as a result of extensive analysis of a quiet backwater of recent history, Andy argues that the move towards decimalisation had little to do with Europe and in fact was a traditional British compromise.
"It was an event that I remember from my youth, but I found that ...
Biomarkers play a central role in the diagnosis of disease and assessment of its course. Among the markers now in use are genes, proteins, hormones, lipids and other classes of molecules. Biomarkers can be found in the blood, in cerebrospinal fluid, urine and various types of tissues, but most of them have one thing in common: They occur in extremely low concentrations, and are therefore technically challenging to detect and quantify.
Many detection procedures use molecular probes, such as antibodies or short nucleic-acid sequences, which are designed to bind to specific biomarkers. When a probe recognizes and binds to its target, chemical or physical reactions give rise to fluorescence signals. Such methods work well, provided they are sensitive enough to recognize ...
Knowledge on how cells communicate is an important key to understanding many biological systems and diseases. A research team led by researchers at the University of Gothenburg has now used a unique combination of methods to map the mechanism behind cellular communication. Their findings can potentially improve understanding of the underlying mechanism behind type 2 diabetes.
We know that human communication is important, but communication between the cells in our bodies is just as vital. The processes where cells synchronize and coordinate their behaviour is required for an organism to function and for human organs to be able to perform their functions.
"How do cells go from monologues ...
Scientists at the Fralin Biomedical Research Institute at VTC have identified a new zebrafish model that could help advance glioblastoma multiforme research. Glioblastoma is an aggressive form of primary brain tumor - fewer than one in 20 patients survive five years after diagnosis.
The research team previously discovered that human-derived brain cancer cells in mice use the brain's blood vessels like highways to spread away from the original mass. In the new study, published in ACS Pharmacology and Translational Science, they show clear cross-over between mammals and fish and describe similar observations in zebrafish.
"Our hope is that this new work in zebrafish will help researchers ...
COLUMBUS, Ohio - On the outskirts of some small Indigenous communities in the Mexican state of Oaxaca, a few volunteer guards keep watch along roads blocked by makeshift barricades of chains, stones and wood.
The invader they are trying to stop is COVID-19.
For many of Mexico's Indigenous people, poor and ignored by state and federal governments, the fight against the COVID-19 pandemic is one that rests primarily with themselves, said Jeffrey Cohen, a professor of anthropology at The Ohio State University.
That means they must take steps like limiting access to their villages.
"Most of these communities only have ...
