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  • richardmitnick 9:14 am on April 11, 2019 Permalink | Reply
    Tags: "New Quantum Computer Can Hold a Superposition of Many Possible Futures Simultaneously", , Griffith University, Nanyang Technological University,   

    From Griffith University via Science Alert: “New Quantum Computer Can Hold a Superposition of Many Possible Futures Simultaneously” 

    Griffith U bloc

    From Griffith University

    via

    ScienceAlert

    Science Alert

    10 APR 2019
    DAN ROBITZSKI

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    (StationaryTraveller/iStock)

    2
    Unlike classical particles, quantum particles can travel in a quantum superposition of different directions. Mile Gu, together with researchers from Griffith harnessed this phenomena to design quantum devices that can generate a quantum superposition of all possible futures. Credit: NTU, Singapore.

    A team of scientists says they’ve built a quantum computer that generates a superposition of several possible futures the computer could experience.

    The research, published Tuesday in Nature Communications, describes how this quantum system could help futuristic artificial intelligence learn much faster than it can today – and it could mean quantum computers are finally becoming practical tools.

    For now, the quantum computer built by Griffith University and Nanyang Technological University scientists can hold two superpositions of 16 different possibilities, according to the research.

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    A picture of the Experimental Device used for the experiment. Credit: Griffith’s University

    It also uses less memory than a classical computer would, suggesting it could outperform classical systems at certain tasks.

    “This is what makes the field so exciting. It is very much reminiscent of classical computers in the 1960s,” Griffith University scientist Geoff Pryde said in a press release.

    “Just as few could imagine the many uses of classical computers in the 1960s, we are still very much in the dark about what quantum computers can do.”

    Right now, artificial intelligence learns by analyzing example after example and looking for patterns. The scientists behind this research argue that their quantum superpositions could vastly improve the process.

    “By interfering these superpositions with each other, we can completely avoid looking at each possible future individually,” Griffith researcher Farzad Ghafari said in the press release.

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    “In fact, many current artificial intelligence algorithms learn by seeing how small changes in their behaviour can lead to different future outcomes, so our techniques may enable quantum enhanced AIs to learn the effect of their actions much more efficiently.”

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Griffith U Campus

    In 1971, Griffith was created to be a new kind of university—one that offered new degrees in progressive fields such as Asian studies and environmental science. At the time, these study areas were revolutionary—today, they’re more important than ever.

    Since then, we’ve grown into a comprehensive, research-intensive university, ranking in the top 5% of universities worldwide. Our teaching and research spans five campuses in South East Queensland and all disciplines, while our network of more than 120,000 graduates extends around the world.

    Griffith continues the progressive traditions of its namesake, Sir Samuel Walker Griffith, who was twice the Premier of Queensland, the first Chief Justice of the High Court of Australia, and the principal author of the Australian Constitution.

     
  • richardmitnick 11:03 am on March 19, 2019 Permalink | Reply
    Tags: "Quantum tunnelling is instantaneous researchers find", , Griffith University, Griffiths’ Australian Attosecond Science Facility,   

    From Griffith University via COSMOS Magazine: “Quantum tunnelling is instantaneous, researchers find” 

    Griffith U bloc

    From Griffith University

    via

    Cosmos Magazine bloc

    COSMOS Magazine

    19 March 2019
    Alan Duffy

    Physicists establish that electrons waste no time bashing through a barrier.

    1
    A diagrammatic representation of quantum tunnelling. Normaals/Getty Images

    Researchers have found that electrons passing through solid matter in a quantum process known as “tunnelling” do so instantaneously.

    The finding, led by scientists from Australia’s Griffith University, contradicts previous experiments [Nature] that suggested a degree of time elapses between the start and finish of a tunnelling event.

    The work is detailed in a paper in the journal Nature.

    Quantum tunnelling is one of the more bizarre differences between our everyday, classical world and the surprising realm of quantum mechanics.

    “If you lean on a wall, that wall pushes back in force so that you don’t go through it,” co-author Robert Sang says.

    “But when you go down to the microscopic level, things behave quite differently. This is where the laws of physics change from classical to quantum.”

    A particle in the quantum world actually can pass through that wall. The experimental question was, how long does it take to transition through a given obstacle – in this case, the electric barrier potential of a hydrogen atom.

    “We use the simplest atom, atomic hydrogen, and we’ve found that there’s no delay in what we can measure,” says Sang.

    The Nature paper is the culmination of a three-year international project, in which the team shot a hydrogen atom and its lone electron with an enormously powerful, ultra-fast laser contained in Griffiths’ Australian Attosecond Science Facility. The laser was circularly polarised, meaning that it imparted a rotation to an emitted electron.

    That resulting rotation in the electron’s “phase” could then be measured as if it were a clock hand ticking around – or in this case, more precisely, an atto-clock.

    “There’s a well-defined point where we can start that interaction, and there’s a point where we know where that electron should come out if it’s instantaneous,” explains Sang.

    “So anything that varies from that time we know that it’s taken that long to go through the barrier. That’s how we can measure how long it takes.

    “It came out to agree with the theory within experimental uncertainty being consistent with instantaneous tunnelling.”

    The precision of the clock to measure the tunnelling event was driven by the ultra-fast pulse of light in the attosecond laser – just a billionth of a billionth of a second long. The energy emitted by the laser during such a tiny amount of time is greater than that of the entire US power grid.

    Sang notes about the attosecond timescale that “it’s hard to appreciate how short that is, but it takes an electron about a hundred attoseconds to orbit a nucleus in an atom”.

    Tunnelling may be an unfamiliar effect in our everyday lives, yet common devices from electron microscopes to computer transistors rely on it.

    “One limitation you might think of is how fast can I make a transistor work – the ultimate limit will be partly about how quickly quantum particles can tunnel,” says Sang.

    “For a classical computer, it implies a limit as to how quickly you can switch a transistor.”

    As we explore the realms, and limits, of these strange quantum mechanical processes, there may be a speed boost for personal computers, too.

    Griffith University Australian Attosecond Science Facility laser

    Griffith University a breakthrough ‘speed test’ in quantum tunnelling

    The researchers have demonstrated that the electron spends no measurable time “under the potential” as it tunnels through the barrier, but noted that these events “are only as ‘instantaneous’ as the electron wave-function collapse that orthodox interpretations of quantum mechanics” predicts.

    This, Sang adds, offers a tantalising possibility of future zeptosecond lasers – which would operate for a period of time a thousand times shorter than an attosecond – “obtaining information on the dynamics of the wave-function collapse itself”. Such a measurement would explore that most fundamental difference of the quantum to the classical world, where common sense expectations break down in the face of wave-functions describing particles.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Griffith U Campus

    In 1971, Griffith was created to be a new kind of university—one that offered new degrees in progressive fields such as Asian studies and environmental science. At the time, these study areas were revolutionary—today, they’re more important than ever.

    Since then, we’ve grown into a comprehensive, research-intensive university, ranking in the top 5% of universities worldwide. Our teaching and research spans five campuses in South East Queensland and all disciplines, while our network of more than 120,000 graduates extends around the world.

    Griffith continues the progressive traditions of its namesake, Sir Samuel Walker Griffith, who was twice the Premier of Queensland, the first Chief Justice of the High Court of Australia, and the principal author of the Australian Constitution.

     
  • richardmitnick 1:47 pm on November 5, 2018 Permalink | Reply
    Tags: , Griffith precision measurement takes it to the limit, Griffith University, Heisenberg limit, , Quantum computing algorithms, ,   

    From Griffith University via phys.org: “Griffith precision measurement takes it to the limit” 

    Griffith U bloc

    From Griffith University

    via

    phys.org

    November 5, 2018

    1
    Griffith University researchers have demonstrated a procedure for making precise measurements of speed, acceleration, material properties and even gravity waves possible, approaching the ultimate sensitivity allowed by laws of quantum physics. Credit: Griffith University

    Published in Nature Communications, the work saw the Griffith team, led by Professor Geoff Pryde, working with photons (single particles of light) and using them to measure the extra distance travelled by the light beam, compared to its partner reference beam, as it went through the sample being measured—a thin crystal.

    The researchers combined three techniques—entanglement (a kind of quantum connection that can exist between the photons), passing the beams back and forth along the measurement path, and a specially-designed detection technique.

    “Every time a photon passes through the sample, it makes a kind of mini-measurement. The total measurement is the combination of all of these mini-measurements,” said Griffith’s Dr. Sergei Slussarenko, who oversaw the experiment. “The more times the photons pass through, the more precise the measurement becomes.

    “Our scheme will serve as a blueprint for tools that can measure physical parameters with precision that is literally impossible to achieve with the common measurement devices.

    Lead author of the paper Dr. Shakib Daryanoosh said this method can be used to investigate and measure other quantum systems.

    “These can be very fragile, and every probe photon we send it would disturb it. In this case, using few photons but in the most efficient way possible is critical and our scheme shows how do exactly that,” he said.

    While one strategy is to just use as many photons as possible, that’s not enough to reach the ultimate performance. For that, it is necessary to also extract the maximum amount of measurement information per photon pass, and that is what the Griffith experiment has achieved, coming far closer?to the so-called Heisenberg limit of precision than any comparable experiment.

    The remaining error is due experimental imperfection, as the scheme designed by Dr. Daryanoosh and Professor Howard Wiseman, is capable of achieving the exact Heisenberg limit, in theory.

    “The really nice thing about this technique is that it works even when you don’t have a good starting guess for the measurement,” Prof. Wiseman said. “Previous work has mostly focused a lot on the case where it’s possible to make a very good starting approximation, but that’s not always possible.”

    A few extra steps are required before this proof-of-principle demonstration can be harnessed outside the lab.

    Producing entangled photons is not simple with current technology, and this means it is still much easier to use many photons inefficiently, rather than each set of entangled photons in the best way possible.

    However, according to the team, the ideas behind this approach can find immediate applications in quantum computing algorithms and research in fundamental science.

    The scheme can ultimately be extended to a larger number of entangled photons, where the difference of the Heisenberg limit over the usually achievable limit is more significant.

    See the full article here .

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

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Griffith U Campus

    In 1971, Griffith was created to be a new kind of university—one that offered new degrees in progressive fields such as Asian studies and environmental science. At the time, these study areas were revolutionary—today, they’re more important than ever.

    Since then, we’ve grown into a comprehensive, research-intensive university, ranking in the top 5% of universities worldwide. Our teaching and research spans five campuses in South East Queensland and all disciplines, while our network of more than 120,000 graduates extends around the world.

    Griffith continues the progressive traditions of its namesake, Sir Samuel Walker Griffith, who was twice the Premier of Queensland, the first Chief Justice of the High Court of Australia, and the principal author of the Australian Constitution.

     
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