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  • richardmitnick 3:24 pm on April 27, 2020 Permalink | Reply
    Tags: "High pressure experiment sheds light on Earth’s outer core", , RIKEN, SPring-8 synchrotron   

    From physicsworld.com: “High pressure experiment sheds light on Earth’s outer core” 

    From physicsworld.com

    27 Apr 2020
    Sam Jarman

    1
    Under pressure: X-ray scattering at high pressure and temperature provides new insights into the composition of the Earth’s outer core. (Courtesy: Shutterstock/Johan-Swanepoel)

    Extreme conditions close to those found within the Earth’s outer core have been created in the lab by planetary scientists in Japan. Researchers led by Yasuhiro Kuwayama at the University of Tokyo created the temperatures and pressures needed for their experiment using a highly specialized diamond anvil. Their discoveries could lead to a better understanding of the composition and behaviour of the Earth’s outer core, and perhaps even the interiors of other planets.

    The Earth’s core begins about 3000 km below the surface and much of what we know about it comes from looking at seismic waves from earthquakes that have travelled through the centre of the Earth. The core’s properties have also been studied by doing computer simulations and experiments that subject materials to extreme temperatures and pressures. Research has revealed that the centre of our planet is separated into a solid inner core composed mainly of an iron-nickel alloy and an outer core dominated by liquid iron.

    Now, Kuwayama’s team has increased our knowledge of the outer core using a diamond anvil, which exploits diamond’s almost unparalleled hardness to subject samples to extremely high pressures and temperatures. In their study, they compressed a liquid iron sample to pressures of up to 116 GPa and heated it to of 4350 K. While 4350 K is believed to be a typical temperature within the outer core, 116 GPa is slightly lower than the pressure expected at the top of the outer core.

    Sustained pressure

    An important feature of this latest research is that this extreme pressure and temperature can be maintained indefinitely – at least in principle. This is unlike previous studies in which extreme conditions were only sustained for a few microseconds. The team squeezed a tiny liquid droplet of liquid iron to 116 GPa and then heated it to 4350 K using an infrared laser. Then the team probed their sample’s properties in detail, primarily by doing X-ray scattering experiments at RIKEN’S Spring-8 synchrotron in Hyōgo prefecture.


    SPring-8 synchrotron, located in Hyōgo Prefecture, Japan

    After combining their observations with existing data, Kuwayama and colleagues compared the measured thermodynamic properties of their high-pressure, high-temperature liquid iron to what is known about Earth’s outer core. They found that the Earth’s outer core must be around 7.5% less dense than the liquid iron, suggesting that it must contain a high abundance of lighter elements that have yet to be identified. The team also found that material in the outer core must flow around 4% more easily than liquid iron, although both materials display a similar resistance to compression.

    Kuwayama’s team says that its work offers important new insights into the physical properties of Earth’s core. Their work could also inform future studies of other planetary cores – which even within the solar system, encompass a rich variety of compositions, structures, and relative sizes. As Kuwayama concludes, “we were pleasantly surprised by how effective this approach was and hope it can lead to a greater understanding of the world beneath our feet”.

    The research is described in Physical Review Letters.

    See the full article here .


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    We engage with policymakers and the general public to develop awareness and understanding of the value of physics and, through IOP Publishing, we are world leaders in professional scientific communications.
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  • richardmitnick 4:23 pm on February 28, 2020 Permalink | Reply
    Tags: "Massive protostar keeps growing despite ionization heating by ultraviolet light", , , , , Protostar known as G45.47+0.05, RIKEN, This protostar is continuing to grow despite boiling away the gas it feeds on.   

    From RIKEN: “Massive protostar keeps growing despite ionization heating by ultraviolet light” 

    RIKEN bloc

    From RIKEN

    Feb. 28, 2020

    A massive young star has been spotted that is continuing to grow despite boiling away the gas it feeds on.

    1
    Figure 1: An artist’s impression of a protostar—a star in the process of formation. RIKEN astronomers have discovered that a huge protostar is getting bigger despite propelling plumes of hot gas away from itself. © MARK GARLICK/SCIENCE PHOTO LIBRARY

    A gigantic embryonic star is still getting bigger, even though it propels vast plumes of hot gas away from itself, RIKEN astronomers have found [The Astrophysical Journal Letters]. The discovery could help to solve an enduring mystery about how massive stars grow so large.

    Young protostars put on weight by gathering matter from a dense disk of gas and dust that swirls around them (Fig. 1). But once protostars grow beyond a certain size, further accretion is hampered by the light they emit. This may happen when ultraviolet light strips electrons from atoms in the surrounding disk to produce a hot ionized plasma that evaporates from the star, a process called photoevaporative outflow.

    Theoretical calculations have suggested that this and related factors are too weak to stop accretion. But there is insufficient observational evidence to back this up, not least because the most massive protostars are rare and very distant from the Earth.

    Yichen Zhang of the RIKEN Star and Planet Formation Laboratory and colleagues have now studied a protostar known as G45.47+0.05 using the ALMA radio observatory in Chile and the VLA radio observatory in New Mexico. They looked for radio waves and microwaves emitted when an electron falls between two energy levels in a hydrogen atom and when electrons scatter positive ions without being captured—two telltale signs that a gas is being ionized.

    ESO/NRAO/NAOJ ALMA Array in Chile in the Atacama at Chajnantor plateau, at 5,000 metres

    NRAO/Karl V Jansky Expanded Very Large Array, on the Plains of San Agustin fifty miles west of Socorro, NM, USA, at an elevation of 6970 ft (2124 m)

    The researchers identified these signals inside an hourglass-shaped region extending outwards from the protostar. Their observations showed that the gas reaches temperatures of about 10,000 degrees Celsius and moves at about 30 kilometers per second. This suggests that the hourglass-shaped region is filled with ionized gas that has been launched away from the protostar’s disk by light-driven ionization.

    “This is the first robust detection of a resolved photoevaporative outflow driven by a very massive star in formation,” says Zhang. “The outflow structure is clearly resolved, which allows us to scrutinize the material distribution and dynamics in such outflows.”

    The protostar is already 30 to 50 times more massive than our Sun, but the team found a narrower jet structure within the hourglass that indicates it is still growing. “This high-velocity jet is believed to be driven magnetically by the accretion disk, and is thus evidence that accretion is ongoing,” says Zhang.

    The researchers will study G45 in more detail to understand how the ionized outflow interacts with its surroundings. They will also look for other examples of protostars with similar outflows.

    See the full article here .


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    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 11:52 am on December 25, 2019 Permalink | Reply
    Tags: , , BASE Collaboration, , , , , RIKEN   

    From RIKEN: “Could the mysteries of antimatter and dark matter be linked?” 

    RIKEN bloc

    From RIKEN

    Nov. 15, 2019

    Contact

    Chief Scientist
    Stefan Ulmer
    Fundamental Symmetries Laboratory
    Chief Scientist Laboratories

    Jens Wilkinson
    RIKEN International Affairs Division
    Tel: +81-(0)48-462-1225 / Fax: +81-(0)48-463-3687
    Email: pr@riken.jp

    Could the mysteries of antimatter and dark matter be linked?

    Could the profound mysteries of antimatter and dark matter be linked? Thinking that they might be, scientists from the international BASE collaboration, led by Stefan Ulmer of the RIKEN Cluster for Pioneering Research, and collaborators have performed the first laboratory experiments to determine whether a slightly different way in which matter and antimatter interact with dark matter might be a key to solving both mysteries.

    BASE: Baryon Antibaryon Symmetry Experiment

    Dark matter and antimatter are both vexing problems for physicists trying to understand how our world works at a fundamental level.

    The problem with antimatter is that though the Big Bang should have created equal amounts of matter and antimatter, the world we live in is made only of matter. Antimatter is created every day in experiments and even by natural processes such as lightning, but it is quickly annihilated in collisions with regular matter. Predictions show that our understanding of the matter content of the Universe is off by nine orders of magnitude, and no one knows why the asymmetry exists.

    In the case of dark matter, it is known from astronomical observations that some unknown mass is influencing the orbits of stars in galaxies, but no one has been able to determine the exact microscopic properties of these particles. One theory is that they are a type of hypothetical particle known as an axion, which has an important role in explaining the lack of symmetry violation in the strong interaction in the standard model of particle physics.

    The BASE group collaborators wondered whether the lack of antimatter might be because it interacts differently with dark matter, and set out to test this. For the experiment, they used a specially designed device, called a Penning trap, to magnetically trap a single antiproton, preventing it from contacting ordinary matter and being annihilated. They then measured a property of the antiproton called its spin precession frequency. Normally, this should be constant in a given magnetic field, and a modulation of this frequency could be accounted for by an effect mediated by axion-like particles, which are hypothesized dark matter candidates.

    According to the first author of the study, Christian Smorra “For the first time, we have explicitly searched for an interaction between dark matter and antimatter, and though we did not find a difference, we set a new upper limit for the potential interaction between dark matter and antimatter.”

    Looking to the future, Stefan Ulmer of the RIKEN Cluster for Pioneering Research, who is spokesperson for the BASE Collaboration, says, “From now on, we plan to further improve the accuracy of our measurements of the spin precession frequency of the antiproton, allowing us set more and more stringent constraints on the fundamental invariance of charge, parity, and time, and to make the search for dark matter even more sensitive.”

    The work, published in Nature, was carried out by the RIKEN Fundamental Symmetries Laboratory and a working group at the PRISMA+ excellence cluster of the Johannes Gutenberg University Mainz (JGU), which has been active in the search for dark matter. It was conducted at the European Center for Nuclear Research (CERN), using the Antiproton Decelerator (AD). The research also involved scientists from the Max Planck Institute for Nuclear Physics in Heidelberg, CERN, the Johannes Gutenberg University Mainz (JGU), the Helmholtz Institute Mainz (HIM), the University of Tokyo, the GSI Darmstadt, the Leibniz University Hannover and the Physikalisch-Technische Bundesanstalt (PTB) Braunschweig. The research was performed as part of the work of the Max Planck-RIKEN-PTB Center for Time, Constants and Fundamental Symmetries, an international group established to develop high-precisions measurements to better understand the physics of our Universe.

    See the full article here .


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    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 7:47 am on September 2, 2019 Permalink | Reply
    Tags: "Physicists Have Finally Built a Quantum X-Ray Device", , Bar Ilon University, PDC-parametric down-conversion, , Quantum enhancement, , Quantum illumination, Quantum imaging, RIKEN, , X-ray PDC,   

    From Bar Ilon University and Riken via Science Alert: “Physicists Have Finally Built a Quantum X-Ray Device” 

    2

    From Bar Ilon University

    and

    RIKEN bloc

    From RIKEN

    via

    ScienceAlert

    Science Alert

    2 SEP 2019
    MICHELLE STARR

    1
    (APS/Alan Stonebraker)

    A team of researchers has just demonstrated quantum enhancement in an actual X-ray machine, achieving the desirable goal of eliminating background noise for precision detection.

    The relationships between photon pairs on quantum scales can be exploited to create sharper, higher-resolution images than classical optics. This emerging field is called quantum imaging, and it has some really impressive potential – particularly since, using optical light, it can be used to show objects that can’t usually be seen, like bones and organs.

    Quantum correlation describes a number of different relationships between photon pairs. Entanglement is one of these, and is applied in optical quantum imaging.

    But the technical challenges of generating entangled photons in X-ray wavelengths are considerably greater than for optical light, so in the building of their quantum X-ray, the team took a different approach.

    They used a technique called quantum illumination to minimise background noise. Usually, this uses entangled photons, but weaker correlations work, too. Using a process called parametric down-conversion (PDC), the researchers split a high-energy – or “pump” – photon into two lower-energy photons, called a signal photon and an idler photon.

    “X-ray PDC has been demonstrated by several authors, and the application of the effect as a source for ghost imaging has been demonstrated recently,” the researchers write in their paper.

    “However, in all previous publications, the photon statistics have not been measured. Essentially, to date, there is no experimental evidence that photons, which are generated by X-ray PDC, exhibit statistics of quantum states of radiation. Likewise, observations of the quantum enhanced measurement sensitivity have never been reported at X-ray wavelengths.”

    The researchers achieved their X-ray PDC with a diamond crystal. The nonlinear structure of the crystal splits a beam of pump X-ray photons into signal and idler beams, each with half the energy of the pump beam.

    Normally, this process is very inefficient using X-rays, so the team scaled up the power. Using the SPring-8 synchrotron in Japan, they shot a 22 KeV beam of X-rays at their crystal, which split into two beams, each carrying 11 KeV.

    SPring-8 synchrotron


    SPring-8 synchrotron, located in Hyōgo Prefecture, Japan

    The signal beam is sent towards the object to be imaged – in the case of this research, a small piece of metal with three slits – with a detector on the other side. The idler beam is sent straight to a different detector. This is set up so that each beam hits its respective detector at the same place and at the same time.

    “The perfect time-energy relationship we observed could only mean that the two photons were quantum correlated,” said physicist Sason Sofer of Bar-Ilan University in Israel.

    For the next step, the researchers compared their detections. There were only around 100 correlated photons per point in the image, and around 10,000 more background photons. But the researchers could match each idler to a signal, so they could actually tell which photons in the image were from the beam, thus easily separating out the background noise.

    They then compared these images to images taken using regular, non-correlated photons – and the correlated photons clearly produced a much sharper image.

    It’s early days yet, but it’s definitely a step in the right direction for what could be a greatly exciting tool. Quantum X-ray imaging could have a number of uses outside the range of current X-ray technology.

    One promise is that it could lower the amount of radiation required for X-ray imaging. This would mean that samples easily damaged by X-rays could be imaged, or samples that require low temperatures; less radiation would mean less heat. It could also enable physicists to X-ray atomic nuclei to see what’s inside.

    Obviously, since these quantum X-rays require a hardcore particle accelerator, medical applications are currently off the table. The team has demonstrated that it can be done, but scaling down is going to be tricky.

    Currently, determining whether the photons are entangled is the next step. That would require the photons’ arrival at the detectors to be measured within attosecond scales, which is beyond our current technology.

    Still, this is a pretty amazing achievement.

    “We have demonstrated the ability to utilise the strong time-energy correlations of photon pairs for quantum enhanced photodetection. The procedure we have presented possesses great potential for improving the performances of X-ray measurements,” the researchers write.

    “We anticipate that this work will open the way for more quantum enhanced x-ray regime detection schemes, including the area of diffraction and spectroscopy.”

    The research has been published in Physical Review X.

    See the full article here .


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    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 1:31 pm on August 1, 2019 Permalink | Reply
    Tags: , , , , RIKEN,   

    From Lawrence Berkeley National Lab: “Is your Supercomputer Stumped? There May Be a Quantum Solution” 

    Berkeley Logo

    From Lawrence Berkeley National Lab

    August 1, 2019
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    Berkeley Lab-led team solves a tough math problem with quantum computing.

    1
    (Credit: iStock/metamorworks)

    Some math problems are so complicated that they can bog down even the world’s most powerful supercomputers. But a wild new frontier in computing that applies the rules of the quantum realm offers a different approach.

    A new study led by a physicist at Lawrence Berkeley National Laboratory (Berkeley Lab), published in the journal Scientific Reports, details how a quantum computing technique called “quantum annealing” can be used to solve problems relevant to fundamental questions in nuclear physics about the subatomic building blocks of all matter. It could also help answer other vexing questions in science and industry, too.

    Seeking a quantum solution to really big problems

    “No quantum annealing algorithm exists for the problems that we are trying to solve,” said Chia Cheng “Jason” Chang, a RIKEN iTHEMS fellow in Berkeley Lab’s Nuclear Science Division and a research scientist at RIKEN, a scientific institute in Japan.

    “The problems we are looking at are really, really big,” said Chang, who led the international team behind the study, published in the Scientific Reports journal. “The idea here is that the quantum annealer can evaluate a large number of variables at the same time and return the right solution in the end.”

    The same problem-solving algorithm that Chang devised for the latest study, and that is available to the public via open-source code, could potentially be adapted and scaled for use in systems engineering and operations research, for example, or in other industry applications.

    Classical algebra with a quantum computer

    “We are cooking up small ‘toy’ examples just to develop how an algorithm works. The simplicity of current quantum annealers is that the solution is classical – akin to doing algebra with a quantum computer. You can check and understand what you are doing with a quantum annealer in a straightforward manner, without the massive overhead of verifying the solution classically.”

    Chang’s team used a commercial quantum annealer located in Burnaby, Canada, called the D-Wave 2000Q that features superconducting electronic elements chilled to extreme temperatures to carry out its calculations.

    Access to the D-Wave annealer was provided via the Oak Ridge Leadership Computing Facility at Oak Ridge National Laboratory (ORNL).

    “These methods will help us test the promise of quantum computers to solve problems in applied mathematics that are important to the U.S. Department of Energy’s scientific computing mission,” said Travis Humble, director of ORNL’s Quantum Computing Institute.

    Quantum data: A one, a zero, or both at the same time

    There are currently two of these machines in operation that are available to the public. They work by applying a common rule in physics: Systems in physics tend to seek out their lowest-energy state. For example, in a series of steep hills and deep valleys, a person traversing this terrain would tend to end up in the deepest valley, as it takes a lot of energy to climb out of it and the least amount of energy to settle in this valley.

    The annealer applies this rule to calculations. In a typical computer, memory is stored in a series of bits that are occupied by either one or a zero. But quantum computing introduces a new paradigm in calculations: quantum bits, or qubits. With qubits, information can exist as either a one, a zero, or both at the same time. This trait makes quantum computers better suited to solving some problems with a very large number of possible variables that must be considered for a solution.

    Each of the qubits used in the latest study ultimately produces a result of either a one or a zero by applying the lowest-energy-state rule, and researchers tested the algorithm using up to 30 logical qubits.

    The algorithm that Chang developed to run on the quantum annealer can solve polynomial equations, which are equations that can have both numbers and variables and are set to add up to zero. A variable can represent any number in a large range of numbers.

    When there are ‘fewer but very dense calculations’

    Berkeley Lab and neighboring UC Berkeley have become a hotbed for R&D in the emerging field of quantum information science, and last year announced the formation of a partnership called Berkeley Quantum to advance this field.

    3
    Berkeley Quantum

    Chang said that the quantum annealing approach used in the study, also known as adiabatic quantum computing, “works well for fewer but very dense calculations,” and that the technique appealed to him because the rules of quantum mechanics are familiar to him as a physicist.

    The data output from the annealer was a series of solutions for the equations sorted into columns and rows. This data was then mapped into a representation of the annealer’s qubits, Chang explained, and the bulk of the algorithm was designed to properly account for the strength of the interaction between the annealer’s qubits. “We repeated the process thousands of times” to help validate the results, he said.

    “Solving the system classically using this approach would take an exponentially long time to complete, but verifying the solution was very quick” with the annealer, he said, because it was solving a classical problem with a single solution. If the problem was quantum in nature, the solution would be expected to be different every time you measure it.

    Some math problems are so complicated that they can bog down even the world’s most powerful supercomputers. But a wild new frontier in computing that applies the rules of the quantum realm offers a different approach.

    A new study led by a physicist at Lawrence Berkeley National Laboratory (Berkeley Lab), published in the journal Scientific Reports, details how a quantum computing technique called “quantum annealing” can be used to solve problems relevant to fundamental questions in nuclear physics about the subatomic building blocks of all matter. It could also help answer other vexing questions in science and industry, too.

    Real-world applications for a quantum algorithm

    As quantum computers are equipped with more qubits that allow them to solve more complex problems more quickly, they can also potentially lead to energy savings by reducing the use of far larger supercomputers that could take far longer to solve the same problems.

    The quantum approach brings within reach direct and verifiable solutions to problems involving “nonlinear” systems – in which the outcome of an equation does not match up proportionately to the input values. Nonlinear equations are problematic because they may appear more unpredictable or chaotic than other “linear” problems that are far more straightforward and solvable.

    Chang sought the help of quantum-computing experts in quantum computing both in the U.S. and in Japan to develop the successfully tested algorithm. He said he is hopeful the algorithm will ultimately prove useful to calculations that can test how subatomic quarks behave and interact with other subatomic particles in the nuclei of atoms.

    While it will be an exciting next step to work to apply the algorithm to solve nuclear physics problems, “This algorithm is much more general than just for nuclear science,” Chang noted. “It would be exciting to find new ways to use these new computers.”

    The Oak Ridge Leadership Computing Facility is a DOE Office of Science User Facility.

    Researchers from Lawrence Livermore National Laboratory, Oak Ridge National Laboratory, and the RIKEN Computational Materials Science Research Team also participated in the study.

    The study was supported by the U.S. Department of Energy Office of Science; and by Oak Ridge National Laboratory and its Laboratory Directed Research and Development funds. The Oak Ridge Leadership Computing Facility is supported by the DOE Office of Science’s Advanced Scientific Computing Research program.

    See the full article here .

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    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

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  • richardmitnick 6:09 pm on March 4, 2019 Permalink | Reply
    Tags: “What is interesting” says first author Tatsuya Kaneko a postdoctoral researcher at the RIKEN Cluster for Pioneering Research “is that our calculations showed that this takes place based on the , But for the present study the researchers used non-equilibrium dynamics to analyze the effect of pulses of light on a Mott insulator and found that the effect would in fact happen in the real world, , RIKEN, Scientists from the RIKEN Cluster for Pioneering Research have shown that pulses of light could be used to turn these materials beyond simple conductors to superconductors—materials that conduct ele, , Thirty years ago the mathematical physicist Chen-Ning Yang originally proposed the idea of eta-pairing but because it was a purely mathematical concept it was understood as a virtual phenomenon that w, This process would happen through an unconventional type of superconductivity known as “eta pairing”, Under normal electron band theory they ought to conduct electricity but they do not due to interactions among their electrons, What remains is to perform actual experiments with Mott insulators to verify that this process actually takes place   

    From RIKEN: “Light pulses provide a new route to enhance superconductivity” 

    RIKEN bloc

    From RIKEN

    March 4, 2019

    Chief Scientist
    Seiji Yunoki
    Computational Condensed Matter Physics Laboratory
    Chief Scientist Laboratories

    Jens Wilkinson
    RIKEN International Affairs Division
    Tel: +81-(0)48-462-1225 / Fax: +81-(0)48-463-3687
    Email: pr@riken.jp

    1
    Schematic of eta-pairing

    Materials known as Mott insulators are odd things. Under normal electron band theory they ought to conduct electricity, but they do not, due to interactions among their electrons. But now, scientists from the RIKEN Cluster for Pioneering Research have shown that pulses of light could be used to turn these materials beyond simple conductors to superconductors—materials that conduct electricity without energy loss. This process would happen through an unconventional type of superconductivity known as “eta pairing.”

    Using numerical simulations, the researchers found that this unconventional type of conductivity, which is believed to take place under non-equilibrium conditions in strongly correlated materials such as high-Tc cuprates and iron-pnictides, arises due to a phenomenon known as eta pairing. This is different form the superconductivity observed in the same strongly correlated materials under equilibrium conditions, and is thought to involve repulsive interactions between certain electrons within the structure. It is also different from traditional superconductivity, where the phenomenon arises due to interactions between electrons and vibrations of the crystal structure, inducing mutual interactions between electrons through vibrations and thus overcoming the repulsion between the electrons.

    Thirty years ago, the mathematical physicist Chen-Ning Yang originally proposed the idea of eta-pairing, but because it was a purely mathematical concept, it was understood as a virtual phenomenon that would not take place in the real world. But for the present study, the researchers used non-equilibrium dynamics to analyze the effect of pulses of light on a Mott insulator, and found that the effect would in fact happen in the real world. “What is interesting,” says first author Tatsuya Kaneko, a postdoctoral researcher at the RIKEN Cluster for Pioneering Research, “is that our calculations showed that this takes place based on the beautiful mathematical structure that Yang and his followers formulated so many years ago.”

    According to Seiji Yunoki, who led the research team, “This work provides new insights not only into the phenomenon of non-equilibrium dynamics, but also could lead to the development of new high-temperature superconductors, which could be useful in applications. What remains is to perform actual experiments with Mott insulators to verify that this process actually takes place.”

    The research was published in Physical Review Letters.

    See the full article here .


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    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 5:02 pm on February 20, 2019 Permalink | Reply
    Tags: , , Brain clock ticks differently in autism, , RIKEN   

    From RIKEN: “Brain clock ticks differently in autism” 

    RIKEN bloc

    From RIKEN

    February 15, 2019
    Adam Phillips
    RIKEN International Affairs Division
    Tel: +81-(0)48-462-1225
    Fax: +81-(0)48-463-3687
    Email: pr@riken.jp

    The neural ‘time windows’ in certain small brain areas contribute to the complex cognitive symptoms of autism, new research suggests. In a brain imaging study of adults, the severity of autistic symptoms was linked to how long these brain areas stored information. The differences in neural timescales may underlie features of autism like hypersensitivity and could be useful as a future diagnostic tool.

    Sensory areas of the brain that receive input from the eyes, skin and muscles usually have shorter processing periods compared with higher-order areas that integrate information and control memory and decision-making. The new study, published in the journal eLife on February 5, shows that this hierarchy of intrinsic neural timescales is disrupted in autism. Atypical information processing in the brain is thought to underlie the repetitive behaviors and socio-communicational difficulties seen across the spectrum of autistic neurodevelopmental disorders (ASD), but this is one of the first indications that small-scale temporal dynamics could have an outsized effect.

    Magnetic resonance imaging of the brains of high-functioning male adults with autism were compared to those of people without autism. In the resting state, both groups showed the expected pattern of longer timescales in frontal brain areas linked to executive control, and shorter timescales in sensory and motor areas. “Shorter timescales mean higher sensitivity in a particular brain region, and we found the most sensitive neural responses in those individuals with the most severe autistic symptoms,” says lead author Takamitsu Watanabe of the RIKEN Center for Brain Science. One brain area that displayed the opposite pattern was the right caudate, where the neural timescale was longer than normal, particularly in individuals with more severe repetitive, restricted behaviors. These differences in brain activity were also found in separate scans of autistic and neurotypical children.

    The team of Japanese and UK researchers think that structural changes in small parts of the brain link these local dynamics to ASD symptoms. They found changes in grey matter volume in the areas with atypical neural timescales. A greater density of neurons can contribute to recurrent, repetitive neural activity patterns, which underlie the longer and shorter timescales observed in the right caudate and bilateral sensory/visual cortices, respectively. “The neural timescale is a measure of how predictable the activity is in a given brain region. The shorter timescales we observed in the autistic individuals suggest their brains have trouble holding onto and processing sensory input for as long as neurotypical people,” says Watanabe. “This may explain one prominent feature of autism, the great weight given by the brain to local sensory information and the resulting perceptual hypersensitivity.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    stem

    Stem Education Coalition

    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 1:36 pm on December 28, 2018 Permalink | Reply
    Tags: Hybrid qubits solve key hurdle to quantum computing, , RIKEN   

    From RIKEN: “Hybrid qubits solve key hurdle to quantum computing” 

    RIKEN bloc

    From RIKEN

    December 28, 2018

    Spin-based quantum computers have the potential to tackle difficult mathematical problems that cannot be solved using ordinary computers, but many problems remain in making these machines scalable. Now, an international group of researchers led by the RIKEN Center for Emergent Matter Science have crafted a new architecture for quantum computing. By constructing a hybrid device made from two different types of qubit—the fundamental computing element of quantum computers—they have created a device that can be quickly initialized and read out, and that simultaneously maintains high control fidelity.

    Quantum computing – IBM – the current state

    In an era where conventional computers appear to be reaching a limit, quantum computers—which do calculations using quantum phenomena—have been touted as potential replacements, and they can tackle problems in a very different and potentially much more rapid way. However, it has proven difficult to scale them up to the size required for performing real-world calculations.

    In 1998, Daniel Loss, one of the authors of the current study, came up with a proposal, along with David DiVincenzo of IBM, to build a quantum computer by using the spins of electrons embedded in a quantum dot—a small particle that behaves like an atom, but that can be manipulated, so that they are sometimes called “artificial atoms.” In the time since then, Loss and his team have endeavored to build practical devices.

    There are a number of barriers to developing practical devices in terms of speed. First, the device must be able to be initialized quickly. Initialization is the process of putting a qubit into a certain state, and if that cannot be done rapidly it slows down the device. Second, it must maintain coherence for a time long enough to make a measurement. Coherence refers to the entanglement between two quantum states, and ultimately this is used to make the measurement, so if qubits become decoherent due to environmental noise, for example, the device becomes worthless. And finally, the ultimate state of the qubit must be able to be quickly read out.

    While a number of methods have been proposed for building a quantum computer, the one proposed by Loss and DiVincenzo remains one of the most practically feasible, as it is based on semiconductors, for which a large industry already exists.

    For the current study, published in Nature Communications, the team combined two types of quits on a single device. The first, a type of single-spin qubit called a Loss-DiVincenzo qubit, has very high control fidelity—meaning that it is in a clear state, making it ideal for calculations, and has a long decoherence time, so that it will stay in a given state for a relatively long time before losing its signal to the environment.

    Unfortunately, the downside to these qubits is that they cannot be quickly initialized into a state or read out. The second type, called a singlet-triplet qubit, is quickly initialized and read out, but it quickly becomes decoherent. For the study, the scientists combined the two types with a type of quantum gate known as a controlled phase gate, which allowed spin states to be entangled between the qubits in a time fast enough to maintain the coherence, allowing the state of the single-spin qubit to be read out by the fast singlet-triplet qubit measurement.

    According to Akito Noiri of CEMS, the lead author of the study, “With this study we have demonstrated that different types of quantum dots can be combined on a single device to overcome their respective limitations. This offers important insights that can contribute to the scalability of quantum computers.”

    See the full article here .


    five-ways-keep-your-child-safe-school-shootings

    stem

    Stem Education Coalition

    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 4:22 pm on May 29, 2018 Permalink | Reply
    Tags: , HAL QCD Collaboration, Japanese HAL llaboration are calling the particle di-Omega, , , RIKEN, Scientists have predicted a new type of dibaryon particle   

    From Riken and Science Alert: “Hunting the unseen – Scientists Are Hinting at The Existence of a Strange New Type of Particle” 

    RIKEN bloc

    From RIKEN

    July 15, 2011

    Sighting a theoretical exotic particle may become possible thanks to recently developed mathematical simulations.

    A better knowledge about the composition of sub-atomic particles such as protons and neutrons has sparked conjecture about, as yet, unseen particles. A tool based on theoretical calculations that could aid the search for these particles has been developed by a team of researchers in Japan called the HAL QCD Collaboration.

    Science paper from 2011
    Bound H Dibaryon in Flavor SU(3) Limit of Lattice QCD Physical Review Letters 20 April 2011

    At its most fundamental level, matter consists of particles known as quarks. Particle physicists refer to the six different types as ‘flavors’: up, down, charm, strange, top and bottom. The protons and neutrons found in the nucleus of an atom are examples of a class of particle called baryons: particles consisting of three quarks. Two baryons bound together are called dibaryons, but only one dibaryon has been found to date: a bound proton and neutron that has three up quarks and three down quarks in total.

    Models that reveal the potential physical properties of dibaryons, such as their mass and binding energy, are crucial if more of these particles are to be discovered in the future. To this end, the collaboration, including Tetsuo Hatsuda from the RIKEN Nishina Center for Accelerator-Based Science in Wako, developed simulations that shed new light on one promising candidate: the H dibaryon, which comprises two up, two down and two strange quarks (Fig. 1).

    1
    Figure 1: An artistic impression of a bound H dibaryon, a theoretical particle consisting of two up, two down and two strange quarks. © 2011 Keiko Murano

    The dynamics of quarks are described by an intricate theory known as quantum chromodynamics (QCD). The simulations, however, become increasingly difficult when more particles need to be included: dibaryons with six quarks are particularly testing. Hatsuda and his colleagues used an approach known as lattice QCD in which time and space are considered as a grid of discrete points. They simplified the calculation by assuming that all quarks have the same mass, but the strange quark is actually heavier than the up and down quarks. “We know from previous theoretical studies that the binding energy should be at its largest in the equal mass case,” says Hatsuda. “If we had not found a bound state in the equal mass case, there would be no hope that the bound state exists in the realistic unequal mass case.”

    The results from the collaboration’s simulations showed that the total energy of the dibaryon is less than the combined energy of two separate baryons, which verifies that H dibaryons are energetically stable. “We next hope to find the precise binding energy for unequal quark masses, which represents one of the major challenges in numerical QCD simulations,” Hatsuda adds.

    From Science Alerts 29 MAY 2018

    1
    (Keiko Murano/RIKEN) Science Alert 29 MAY 2018

    Using one of the most powerful computers in the world to perform complex simulations, scientists have predicted a new type of dibaryon particle – one that has two baryons instead of the usual one, with quarks all of the same colour.

    The researchers, from the Japanese HAL QCD Collaboration, are calling the particle di-Omega.

    Baryons are particles that contain three quarks, the subatomic particles that are one of the fundamental constituents that make up matter, and they make up most of the normal matter in the Universe. Protons and neutrons – which make up atomic nuclei – are baryons.

    The charge of baryons is dependent on the “colours,” or types, of the quarks inside, of which there are six – up, down, top, bottom, charm, and strange.

    In nature, there is only one known particle that’s made up of two baryons, or a dibaryon particle (also known as a hexaquark). It’s called deuteron, and it consists of a proton and a neutron bound together to form the nucleus of deuterium, or heavy hydrogen.

    Although scientists believe that other dibaryons might exist, so far none have been conclusively found.

    But by running simulations based on quantum chromodynamics (QCD), the theory that describes quark interactions, the HAL-QCD Collaboration is able to model potential stable dibaryons.

    But it’s not easy – the more quarks there are in the mix, the more complex their interactions, which means more computing power is needed.

    That’s why the researchers employed the K Computer at RIKEN’s Advanced Institute for Computational Science, which has a computational power of 10 petaflops, or 10 quadrillion operations per second.

    Riken Fujitsu K Computer at Riken Advanced Institute for Computational Science campus in Kobe, Hyōgo Prefecture, Japan

    Even so, it took almost three years to reach a conclusion on the particle. But reach a conclusion it did.

    Di-Omega consists of two Omega baryons, containing three strange quarks each. It is, the researchers said, the “most strange” of all the potential dibaryons.

    The research builds on the collaboration’s previous work – in 2011, they announced the discovery of a theoretical dibaryon with two up, two down and two strange quarks [above Riken article]. But since then they have refined their methods, devising a new theoretical framework, and a new algorithm, to allow for more efficient calculations.

    And, of course, the access to the K Computer, which became available for use by researchers in 2012, made an enormous difference.

    Going forward, the researchers believe their work can be applied to experimental settings to search for evidence of these particles in the real world.

    “We believe that these special particles could be generated by the experiments using heavy ion collisions that are planned in Europe and in Japan,” said quantum physicist Tetsuo Hatsuda of RIKEN.

    “We look forward to working with colleagues there to experimentally discover the first dibaryon system outside of deuteron.”

    This most recent work is also published in Physical Review Letters, Most Strange Dibaryon from Lattice QCD 23 May 2018

    See the full Riken article here .

    See the full Science Alert article here .


    five-ways-keep-your-child-safe-school-shootings

    stem

    Stem Education Coalition

    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
  • richardmitnick 1:28 pm on January 18, 2018 Permalink | Reply
    Tags: , , Fujitsu SPARC Riken K supercomputer, RIKEN, , Typhoon Soudelor   

    From Riken: “Geostationary satellite enables better precipitation and flood predictions” 

    RIKEN bloc

    RIKEN

    Using the power of Japan’s K computer, scientists from the RIKEN Advanced Institute for Computational Science and collaborators have shown that incorporating satellite data at frequent intervals—ten minutes in the case of this study—into weather prediction models can significantly improve the rainfall predictions of the models and allow more precise predictions of the rapid development of a typhoon.

    2
    No image caption or credit.

    1
    Fujitsu SPARC Riken K supercomputer

    Weather prediction models attempt to predict future weather by running simulations based on current conditions taken from various sources of data. However, the inherently complex nature of the systems, coupled with the lack of precision and timeliness of the data, makes it difficult to conduct accurate predictions, especially with weather systems such as sudden precipitation.

    As a means to improve models, scientists are using powerful supercomputers to run simulations based on more frequently updated and accurate data. The team led by Takemasa Miyoshi of AICS decided to work with data from Himawari-8, a geostationary satellite that began operating in 2015.

    3
    Himawari-8 geostationary satellite

    Its instruments can scan the entire area it covers every ten minutes in both visible and infrared light, at a resolution of up to 500 meters, and the data is provided to meteorological agencies. Infrared measurements are useful for indirectly gauging rainfall, as they make it possible to see where clouds are located and at what altitude.

    For one study, they looked at the behavior of Typhoon Soudelor (known in the Philippines as Hanna), a category 5 storm that wreaked damage in the Pacific region in late July and early August 2015. In a second study, they investigated the use of the improved data on predictions of heavy rainfall that occurred in the Kanto region of Japan in September 2015. These articles were published in Monthly Weather Review [N/A] and Journal of Geophysical Research: Atmospheres.

    3
    Simulation of Typhoon Soudelor at 22:00 on August 2, 2015

    For the study on Typhoon Soudelor, the researchers adopted a recently developed weather model called SCALE-LETKF—running an ensemble of 50 simulations—and incorporated infrared measurements from the satellite every ten minutes, comparing the performance of the model against the actual data from the 2015 tropical storm. They found that compared to models not using the assimilated data, the new simulation more accurately forecast the rapid development of the storm. They tried assimilating data at a slower speed, updating the model every 30 minutes rather than ten minutes, and the model did not perform as well, indicating that the frequency of the assimilation is an important element of the improvement.

    To perform the research on disastrous precipitation, the group examined data from heavy rainfall that occurred in the Kanto region in 2015. Compared to models without data assimilation from the Himawari-8 satellite, the simulations more accurately predicted the heavy, concentrated rain that took place, and came closer to predicting the situation where an overflowing river led to severe flooding.

    According to Miyoshi, “It is gratifying to see that supercomputers along with new satellite data, will allow us to create simulations that will be better at predicting sudden precipitation and other dangerous weather phenomena, which cause enormous damage and may become more frequent due to climate change. We plan to apply this new method to other weather events to make sure that the results are truly robust.”

    See the full article here .

    Please help promote STEM in your local schools.

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    Stem Education Coalition

    RIKEN campus

    RIKEN is Japan’s largest comprehensive research institution renowned for high-quality research in a diverse range of scientific disciplines. Founded in 1917 as a private research foundation in Tokyo, RIKEN has grown rapidly in size and scope, today encompassing a network of world-class research centers and institutes across Japan.

     
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