Tagged: physicsworld.com Toggle Comment Threads | Keyboard Shortcuts

  • richardmitnick 9:38 pm on December 29, 2015 Permalink | Reply
    Tags: , , , physicsworld.com, The world of physics in 2016   

    From physicsworld.com: “The world of physics in 2016” 

    physicsworld
    physicsworld.com

    Dec 17, 2015
    Matin Durrani

    As another year draws to a close, it’s time for me to peer into my crystal ball and predict the key events in physics that could take place in 2016. I always find it simpler and easier to say what’s coming up in “big science” – dominated as it is by massive projects in particle physics, astronomy and cosmology that are planned years in advance. And next year is no exception.

    1
    Fresh direction: CERN’s new boss Fabiola Gianotti

    So let’s start at CERN, where physicists at the Large Hadron Collider (LHC) will spend 2016 continuing to smash protons together at an energy of 13 TeV as part of “Run II”, which began last year.

    CERN LHC Map
    CERN LHC Grand Tunnel
    CERN LHC particles
    LHC at CERN

    Fabiola Gianotti, who takes the reins from Rolf-Dieter Heuer next month as CERN’s 15th director-general, will be keen to ensure the lab gathers as many top-quality data as possible, even if the LHC’s unlikely to reach its planned collision energy of 14 TeV or get “new physics” beyond the Standard Model in 2016.

    7
    Rolf-Dieter Heuer

    8
    The Standard Model of elementary particles (more schematic depiction), with the three generations of matter, gauge bosons in the fourth column, and the Higgs boson in the fifth.

    Indeed, a presentation at CERN just before Christmas of the first Run II data from the ATLAS and CMS experiments already appears to limit the possibility of “supersymmetric” particles to yet higher energies.

    CERN ATLAS New
    CERN ATLAS Higgs Event
    ATLAS and a Higgs event in ATLAS.

    CERN CMS Detector
    CERN CMS Event
    CMS and a Higgs event in CMS

    Supersymmetry standard model
    Standard Model of Supersymmetry

    Up in space, NASA’s Juno mission is set to enter the orbit of Jupiter on 4 July, handily timed for a watching US public. After a five-year journey, Juno will be the first craft to visit Jupiter since Galileo in 1995.

    NASA Juno
    NASA/Juno

    NASA Galileo
    NASA/Galileo 1

    The Japanese Space Agency (JAXA) is set for a busy year, too. Its Akatsuki spacecraft entered orbit around Venus last month, and mission scientists expect to receive its first data in April.

    JAXA AKATSUKI
    JAXA/AKATSUKI

    JAXA also plans to launch the ASTRO-H X-ray telescope into low Earth orbit this year, to study everything from the large-scale structure of the universe,

    2MASS LSS chart-NEW Nasa
    2MASS LSS chart large-scale structure of the universe

    to the distribution of dark matter in galaxy clusters.

    Meanwhile, the European Space Agency will release the first data early next year from its Gaia mission, which seeks to create a 3D catalogue of about a billion astronomical objects.

    ESA Gaia satellite
    ESA/Gaia

    March will see the European Space Agency’s Lisa Pathfinder craft begin work to test the technology for a future space-based gravitational-wave observatory.

    ESA LISA Pathfinder
    ESA/Pathfinder 1

    Another tantalizing prospect for 2016 will be the Event Horizon Telescope imaging a black hole for the first time.

    Event Horizon Telescope map
    Event Horizon Telescope
    Event Horizon telescope and map

    Astroparticle physicists, meanwhile, are set to start work in 2016 on a $14m upgrade to the Pierre Auger Observatory – the world’s largest cosmic-ray observatory – in Argentina.

    Pierre Augur Observatory
    Pierre Auger Observatory

    The AugerPrime upgrade will involve installing scintillation detectors alongside the 1660 existing water Cherenkov detectors, allowing researchers to more efficiently separate the electrons and muons that are created in the cascade of secondary particles created when a comic ray hits the Earth’s atmosphere. This, in turn, should make it easier to identify cosmic rays that are high-energy protons.

    Ups and downs

    All is not entirely rosy in astronomy, though. Hawaii’s Supreme court recently ruled that the construction permit for the $1.4bn Thirty Meter Telescope (TMT) on top of Mauna Kea mountain is invalid.

    TMT
    The more than proposed TMT

    The ruling will force the telescope’s backers to restart the entire permit process, delaying the project and adding further uncertainty. Construction of the TMT has already been on hold since last April following protests by native Hawaiians, who see its construction on Mauna Kea as desecration of their spiritual and cultural pinnacle.

    In nuclear physics, the ITER tokomak fusion reactor, which is being built in Cadarache in southern France, faces another turbulent year.

    ITER Tokamak
    ITER tokamak

    After last November’s ITER council meeting, rumours surfaced that the project’s completion could slip by six years, from 2019 to 2025. The council will now carry out its own review to see if there is scope for tightening the timeline and cutting costs, with a new plan, or “baseline”, due out in June. On a related note, the Wendelstein 7-X stellerator in Greifswald, Germany, which switched on last week, is set to be put through its paces next year as researchers test this type of fusion device.

    Wendelstein 7-AS
    Wendelstein 7-X stellerator

    Quantum frontiers

    Predicting what will happen across the rest of physics and in physics-based industry is harder, where progress is vital but fragmented across myriad groups, sectors and businesses. My tip is seeing “Li-Fi” – a light-based alternative to radio-frequency Wi-Fi – gaining commercial traction. Work on graphene and other 2D materials will continue, with the focus on layering a few 2D materials to make novel “designer” heterostructures using, say, graphene layers as electrodes and boron nitride as insulators.

    6
    Graphene. The ideal crystalline structure of graphene is a hexagonal grid.

    Applications of physics are crucial, and it is thanks to them – and through the advocacy of organizations like the Institute of Physics (IOP), which publishes Physics World – that science funding in the UK survived cuts in the country’s recent Comprehensive Spending Review. There will be further positive developments for UK science in 2016, with the opening of the massive new £650m Francis Crick Institute in London. Named after the co-discoverer of the structure of DNA, the institute will be the country’s flagship biomedical-science lab, with as many as a fifth of the 1250 staff being physicists, chemists, mathematicians and engineers. Remember that biosciences and the environment dominate Altmetric’s list of the top 100 most popular scientific papers of 2015, as judged by how much they were shared and discussed in mainstream and social media.

    7
    Future tech: quantum physics will continue to throw up surprises

    The beauty of physics, however, is that even the most esoteric research can unleash unforeseen benefits – as the winners of the Physics World 2015 Breakthrough of the Year will concur. We picked Jian-Wei Pan and Chaoyang Lu of the University of Science and Technology of China in Hefei, for being the first to achieve the simultaneous quantum teleportation of two inherent properties of a fundamental particle – the photon. The researchers are already talking about applications, such as “long-distance quantum communications that provide unbreakable security, ultrafast quantum computers and quantum networks”. We can also look forward to further developments in 2016 from the UK’s ambitious £270m National Quantum Technologies Programme, which seeks to stimulate applications of quantum physics.

    Speaking of which, surely 2016 will be the year when Anton Zeilinger – the doyen of quantum communication, computation and information – will finally win a long-overdue Nobel Prize for Physics? I’ve backed the Austrian quantum guru for Nobel glory for a long time, and 2016 has to be his year, possibly with Alain Aspect and John Clauser for their Bell’s inequality experiments. The Nobel Committee for Physics take note.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

     
  • richardmitnick 11:27 am on November 17, 2015 Permalink | Reply
    Tags: , , , physicsworld.com   

    From physicsworld.com: “Astronomers gaze upon the oldest stars in the galaxy” 

    physicsworld
    physicsworld.com

    Nov 13, 2015
    Tushna Commissariat

    Temp 1
    Dark heart: the dusty heart of the Milky Way galaxy

    The oldest stars in our Milky Way galaxy have been discovered by an international team of researchers. These ancient stars could contain vital clues about how the first stars in the early universe died, and their discovery marks the first time that extremely metal-poor stars have been observed in the central region of the galaxy. The location of the stars suggests that they formed when the Milky Way underwent rapid chemical changes during the first 1–2 billion years of the universe.

    After the Big Bang, only elements such as hydrogen, helium and some trace amounts of lithium existed in the universe. Heavier elements such as oxygen, nitrogen, carbon and iron – referred to as “metals” by astronomers – were forged in the extremely high-pressure centres of the first massive stars, which are predicted to have formed within 200 million years after the Big Bang. The metals were scattered across the cosmos when these first stars, known as “population III” stars, quickly burned out and exploded in supernovae. These explosions seeded the universe with the metals to form “population II” stars, which are still “metal-poor” compared with “population I” stars like the Sun.

    Not the stars we are looking for?

    A true first population-III star has not yet been discovered, although the best evidence for them was found earlier this year in an extremely bright and distant galaxy in the early universe. Astronomers believe that old metal-poor stars would have formed in the central regions or the “bulges” of galaxies, where the effects of gravity were the strongest. The Milky Way bulge underwent a rapid chemical enrichment in the early universe, and this should have created a host of metal-poor stars – indeed, we should find them there even today. However, metal-poor stars have only been found in the outer regions or the “halo” of the Milky Way and not at its centre.

    Now, Louise Howes of the Australian National University in Canberra and an international team have used the SkyMapper telescope to identify nearly 500 extremely metal-poor stars in the Milky Way bulge.

    ANU Skymapper telescope
    ANU Skymapper telescope interior
    SkyMapper telescope

    The team also confirmed that most of these old stars are in tight orbits around the galactic centre, rather than being halo stars passing through the bulge. The researchers also found that the chemical compositions of these stars are, for the most part, similar to typical halo stars of the same metal content (or metallicity). However, some unexpected differences exist when it comes to the amount of carbon in such stars.

    Stars with a low metal content look slightly bluer than others, so the team could sift through the millions of stars at the centre and whittle the observations down to 14,000 promising candidates. From those, the researchers identified 500 stars that had less than 100th the amount of iron in the Sun, making it the first extensive catalogue of metal-poor stars in the bulge. Of these, Howse and colleagues focused on 23 candidates that were the most metal-poor, and from these data, they homed in on nine stars with a metal content less than 1000th of the amount seen in the Sun. This includes one star with an iron abundance 10,000 times lower than that of the Sun – now the record-breaker for the most metal-poor star in the centre of the galaxy.

    To and fro

    To ensure that these stars were truly old – and not those that had formed much later in other parts of the galaxy that were not as dense and are now merely passing through the centre – the researchers used precise measurements and computer simulations to plot the stars’ movement in the sky. This allowed them to predict where the stars came from and where they were moving to. The team found that while some stars were indeed just passing through, seven of them were formed in the bulge and had remained there since.

    “These pristine stars are among the oldest surviving stars in the universe, and certainly the oldest stars we have ever seen,” says Howes. “These stars formed before the Milky Way, and the galaxy formed around them.” While it is currently not possible to directly determine the ages of these ancient stars, the researchers say that it could be inferred from data collected by the extended Kepler mission or its successors.

    The team’s discovery also challenges current theories about the environment of the early universe from which these stars formed. “The stars have surprisingly low levels of carbon, iron and other heavy elements, which suggests the first stars might not have exploded as normal supernovae,” says Howes. “Perhaps they ended their lives as hypernovae – poorly understood explosions of probably rapidly rotating stars, producing 10 times as much energy as normal supernovae.” If true, such hypernovae would be one of the most energetic things in the universe, and very different from the kinds of stellar explosions that we see today.

    The research is published in Nature.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

     
  • richardmitnick 11:40 am on November 12, 2015 Permalink | Reply
    Tags: , , , , physicsworld.com   

    From physicsworld.com: “Gran Sasso steps up the hunt for missing particles” 

    physicsworld
    physicsworld.com

    Nov 11, 2015
    Edwin Cartlidge

    XENON1T
    XENON1T

    Physicists working at the Gran Sasso National Laboratory in central Italy, located 1400 m under the mountain of the same name, are soon to start taking data from two new experiments.

    INFN Gran Sasso ICARUS
    Gran Sasso

    Each facility will target a different kind of missing matter: one will search for dark matter while the other will try and detect absent neutrinos to prove that neutrinos are their own antiparticle.

    Dark flash

    The hunt for dark matter – the mysterious substance believed to make up about 80% of all matter in the universe but not yet detected directly – will be carried out using XENON1T. This experiment, which was inaugurated at an event at Gran Sasso today, consists of 3.5 tonnes of liquid xenon. It is designed to measure very faint flashes of light that are given off whenever particles from the dark matter halo of the Milky Way collide with the xenon nuclei. The xenon will be stored at a temperature of about –100 °C in a cryostat and surrounded by a tank containing some 700 tonnes of purified water to minimize background radioactivity.

    Run by an international collaboration of 120 students and scientists from more than 2 institutions, XENON1T is expected to be about 100 times more sensitive than its 160 kg predecessor experiment and around 40 times better than the world’s current leading dark-matter detector – the 370 kg Large Underground Xenon experiment in South Dakota, US.

    LUX Dark matter
    LUX

    Due to start taking data by the end of March next year, XENON1T will either detect dark matter or place severe constraints on the properties of theoretically-favoured weakly interacting massive particles (WIMPs), says collaboration spokesperson Elena Aprile of Columbia University in New York.

    Dark heart

    The other new experiment at Gran Sasso is the Cryogenic Underground Observatory for Rare Events (CUORE), which will look for an extremely rare nuclear process known as neutrinoless double beta decay.

    CUORE experiment
    CUORE

    That decay, if it exists, would involve two neutrons in certain nuclei decaying simultaneously into two protons while emitting two electrons but no antineutrinos (unlike normal beta decay), implying that the neutrino is its own antiparticle. Due to turn on early next year, CUORE will measure the energy spectrum of electrons emitted by 741 kg of tellurium dioxide surrounded by radioactively inert lead blocks recovered from a Roman ship that sank 2000 years ago.

    Meanwhile, towards the end of 2016 another group of scientists at Gran Sasso should take delivery of about a kilogram of cerium oxide powder, which they will place several metres below the Borexino neutrino detector.

    Borexino Solar Neutrino detector
    Borexino

    The Short Distance Neutrino Oscillations with BoreXino (SOX) experiment will look for a sinusoidal-like variation in the number of interactions generated within the detector by neutrinos from the radioactive cerium. SOX leader Marco Pallavicini of the University of Genoa says that such a variation would be a sure sign of “sterile” neutrinos – hypothetical particles outside the Standard Model of particle physics that would “oscillate” into ordinary neutrinos but would not interact with any other kind of matter.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

     
  • richardmitnick 8:40 am on September 26, 2015 Permalink | Reply
    Tags: , physicsworld.com, Underground laboratories   

    From physicsworld: “Why do physicists do experiments deep underground?” 

    physicsworld
    physicsworld.com

    Sep 23, 2015

    To those who crave natural daylight, the idea of spending large chunks of time deep underground may seem like hell. But to particle physicists, this subterranean lifestyle is a price worth paying for the excellent radiation shielding provided by the overlying rock.

    Art McDonald, who was a long-standing director of the Sudbury Neutrino Observatory (SNO), explains how these underground science labs are designed to detect the interesting particles that can make it through the layers of overlying rock.

    Sudbury Neutrino Observatory

    An example is the neutrinos produced in the core of the Sun, whose properties can help to verify solar dynamics models. “We also make the surrounding areas really clean, avoiding the radioactivity contained in any mine dust that would potentially get into our experiments,” McDonald adds.

    SNO has now expanded into SNOLAB, which covers a more diverse range of research. This includes the search for dark-matter particles and the hunt for a rare form of decay called neutrinoless double beta decay – a process that could help explain why the universe has significantly more matter than antimatter.

    To find out more about subterranean physics, check out this feature article from the May 2015 issue of Physics World that looks at how deep underground laboratories of the world are no longer the scientific realm of astroparticle physics alone.

    Access the video explaining Why Physicists Do Experiments Deep Underground in the full article.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

     
  • richardmitnick 10:25 am on April 8, 2015 Permalink | Reply
    Tags: , , physicsworld.com   

    From physicsworld.com: “Mysterious baryon resonance is a subatomic molecule, say physicists” 

    physicsworld
    physicsworld.com

    Apr 7, 2015
    Hamish Johnston

    1
    Does Λ(1405) comprise an anti-kaon and a nucleon?

    Physicists in Australia have produced further evidence that an excited state of the lambda baryon is a “subatomic molecule” – a meson and a nucleon that are bound together. While the physicists are not the first to suggest this exotic structure, they have done new computer simulations and calculations that they say “strongly suggest” that the lambda baryon can exist in this exotic configuration.

    The lambda baryon (Λ) has no electrical charge and comprises three quarks (up, down and strange). Its discovery in 1950 by physicists at the University of Melbourne played an important role in the development of the quark model of matter and ultimately quantum chromodynamics (QCD), which is the theory of the strong interaction that binds quarks together in baryons and mesons.

    Λ is a composite particle, and therefore it exists in a number of different energy states, much like an atom. Λ is the lowest-energy state and Λ(1405), which was discovered in 1961, is the lowest-lying excited state or resonance. As physicists developed the quark model in the 1960s, it became apparent that there was something not quite right about Λ(1405). In particular, the energy difference between Λ and Λ(1405) is much lower than expected, if Λ(1405) is assumed to be a “single particle” containing just three quarks.

    Growing evidence

    In the 1960s the Australian physicist Richard Dalitz and colleagues suggested that that Λ(1405) could comprise an anti-kaon meson bound to a nucleon (proton or neutron). This can occur in two ways: a negatively charged anti-kaon bound to a proton, or a neutral anti-kaon bound to a neutron. Working out the structure of Λ(1405) – or any baryon resonance for that matter – is extremely difficult because of the nonlinear nature of the strong interaction. However, over the past two decades theoretical support for molecular Λ(1405) has grown, with calculations done by several groups of physicists backing up the idea.

    Now, Ross Young and colleagues at the University of Adelaide and the Australian National University have used lattice QCD to gain further insights into the nature of Λ(1405). The team used a lattice QCD simulation that was first developed by the Japan-based PACS-CS collaboration. The most important result of the team’s calculation is that the strange quark appears to make no contribution to the magnetic moment of Λ(1405). This is expected if the strange quark is confined within an anti-kaon with zero spin and is consistent with a molecular model of Λ(1405).

    Energy levels

    The team also analysed the energy levels calculated by lattice QCD and concluded that the Λ(1405) resonance is dominated by the anti-kaon nucleon molecule with a much smaller contribution from the single-particle three-quark state (up, down, strange).

    José Antonio Oller of the University of Murcia in Spain calls the calculation of the strange quark’s magnetic contribution a “remarkable result”. However, he points out that while this zero magnetic contribution is a necessary condition for molecular Λ(1405), it is not sufficient to confirm the molecular nature of the resonance. He added that further calculations of the properties of Λ(1405) using other techniques are needed before the issue can be settled.

    The calculations are described in Physical Review Letters.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

     
  • richardmitnick 4:56 pm on November 28, 2014 Permalink | Reply
    Tags: , , , physicsworld.com   

    From physicsworld.com: “Medical-isotope breakthrough made at Canadian lab” 

    physicsworld
    physicsworld.com

    Nov 28, 2014
    Andrew Williams

    The first commercial shipment of medical isotopes produced using a new particle-accelerator-based technique has been made by scientists at the Canadian Light Source (CLS). Molybdenum-99 (Mo-99) decays to create technetium-99m (Tc-99m), which is used to tag radiopharmaceuticals and plays a unique and vital role in medical imaging. Unlike nuclear reactors, which currently make most of the world’s Mo-99, the system is small enough to be deployed within a large hospital and could thereby improve the supply of the short-lived isotopes.

    Canadian Light Source
    cls
    Canadian Light Source

    The material is made at the Medical Isotope Project (MIP) facility at the CLS, which is located at the University of Saskatchewan in Saskatoon. According to Mark de Jong, director of accelerators at the CLS, the facility is the first of its kind anywhere in the world, and uses a small high-power industrial electron linear accelerator to produce a flux of high-energy X-rays through bremsstrahlung radiation. The X-rays strike a target made of enriched Mo-100, in the process “knocking out” a neutron from the nuclei of some of the target atoms to produce Mo-99.

    m
    Isotope maker: Mark de Jong at MIP

    No fission required

    “The main advantage of this method is the complete avoidance of any use of uranium or fission, with all the problems that arise from both volatile short-lived isotopes, as well as disposing of the long-lived radioactive waste,” says De Jong.

    After several days of irradiation at the CLS facility, the target is shipped 800 km to the Winnipeg Health Sciences Centre’s Radio-Pharmacy Department, where it is dissolved and the Tc-99m is extracted. Transport across long distances is possible because Mo-100 has a half-life of 66 hours, but significant losses do occur. The half-life of Tc-99m is just 6 hours, so it must be produced as near as possible to where it will be used.

    De Jong says that future implementations will not necessarily require such long-distance shipping. “The electron linear accelerator is small enough to be located close to where the Mo-99 is required, possibly even within major hospitals, reducing the losses caused by decay in shipping Mo-99. In the present fission-based production, more than 80% of the Mo-99 produced has decayed before it reaches the hospitals,” he adds.

    Reactor shutdowns

    The MIP was created in the wake of serious Mo-99 shortages in 2007 and 2009, which were both related to two unscheduled shutdowns of the ageing NRU nuclear reactor at Atomic Energy of Canada’s Chalk River Laboratories. NRU provides most of Mo-99 for North America, and isotope production is an important industry in Canada. In 2010, fearful of damage to the industry, the Canadian government launched a call under its Non-nuclear-reactor-based Isotope Supply Program (NISP) to encourage alternative isotope production using either photo-neutron production of Mo-99, or direct production of Tc-99m using proton cyclotrons. The CLS proposal was one of two photo-neutron production projects funded, the other being run by Winnipeg-based Prairie Isotope Production Enterprise (PIPE).

    “Once the work to approve the processes involved – Mo-99 production, target dissolution and Tc-99m extraction – is completed by Health Canada, the facility should produce enough for the hospitals serving a population of more than two million people. The health approvals are the next phase that we are working on with our colleagues at PIPE. We hope to have the New Drug Application (NDA) submitted to the authorities by the end of 2015, with routine clinical use possible by the end of 2016,” says De Jong.
    Other options

    In 2012 scientists at the Vancouver-based TRIUMF national laboratory for particle and nuclear physics pioneered two methods for producing Tc-99m using Mo-100 targets and medical cyclotron-based accelerator technology. Cyclotrons are particle accelerators that rely on electricity and magnets to create isotopes by accelerating ions and bombarding non-radioactive materials.

    “Our process is suitable for large population bases, using medical cyclotrons already installed and operational in our major hospitals throughout the country. We have demonstrated that cyclotrons in Vancouver, London and Hamilton have sufficient capacity to supply their respective hospital catchments with Tc-99m,” says TRIUMF’s Melissa Baluk.

    See the full article here.

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

     
  • richardmitnick 7:27 am on September 30, 2014 Permalink | Reply
    Tags: , physicsworld.com,   

    From physicsworld: “Quantum data are compressed for the first time” 

    physicsworld
    physicsworld.com

    Sep 29, 2014
    Jon Cartwright

    A quantum analogue of data compression has been demonstrated for the first time in the lab. Physicists working in Canada and Japan have squeezed quantum information contained in three quantum bits (qubits) into two qubits. The technique could pave the way for a more effective use of quantum memories and offers a new method of testing quantum logic devices.

    image
    Three for two: physicists have compressed quantum data

    Compression of classical data is a simple procedure that allows a string of information to take up less space in a computer’s memory. Given an unadulterated string of, for example, 1000 binary values, a computer could simply record the frequency of the 1s and 0s, which might require just a dozen or so binary values. Recording the information about the order of those 1s and 0s would require a slightly longer string, but it would probably still be shorter than the original sequence.

    Quantum data are rather different, and it is not possible to simply determine the frequencies of 1s and 0s in a string of quantum information. The problem comes down to the peculiar nature of qubits, which, unlike classical bits, can be a 1, a 0 or some “superposition” of both values. A user can indeed perform a measurement to record the “one-ness” of a qubit, but such a measurement would destroy any information about that qubit’s “zero-ness”. What is more, if a user then measures a second qubit prepared in an identical way, he or she might find a different value for its “one-ness” – because qubits do not specify unique values but only the probability of measurement outcomes. This latter trait would seem to preclude the possibility of compressing even identical qubits, because there is no way of predicting what classical values they will ultimately manifest as.

    A way forward

    In 2010 physicists Martin Plesch and Vladimír Bužek of the Slovak Academy of Sciences in Bratislava realized that, while it is not possible to compress quantum data to the same extent as classical data, some compression can be achieved. As long as the quantum nature of a string of identically prepared qubits is preserved, they said, it should be possible to feed them through a circuit that records only their probabilistic natures. Such a recording would require exponentially fewer qubits, and would allow a user to easily store the quantum information in a quantum memory, which is currently a limited resource. Then at some later time, the user could decide what type of measurement to perform on the data.

    “This way you can store the qubits until you know what question you’re interested in,” says Aephraim Steinberg of the University of Toronto. “Then you can measure x if you want to know x; and if you want to know z, you can measure z – whereas if you don’t store the qubits, you have to choose which measurements you want to do right now.”

    Now, Steinberg and his colleagues have demonstrated working quantum compression for the first time with photon qubits. Because photon qubits are currently very difficult to process in quantum logic gates, Steinberg’s group resorted to a technique known as measurement-based quantum computing, in which the outcomes of a logic gate are “built in” to qubits that are prepared and entangled at the same source. The details are complex, but the researchers managed to transfer the probabilistic nature of three qubits into two qubits.

    A nice trick

    Plesch says that this is the first time that compression of quantum data has been realized, and believes Steinberg and colleagues have come up with a “nice trick” to make it work. “This approach is, however, hard to scale to a larger number of qubits,” Plesch adds. “Having said that, I consider the presented work as a very nice proof-of-concept for the future.”

    Steinberg thinks that larger-scale quantum compression might be possible with different types of qubits, such as trapped ions, which have so far proved easier to manage in large ensembles. A practical use for the process would be in testing quantum devices using a process known as quantum tomography, in which many identically prepared qubits are sent through a quantum device to check that it is functioning properly. With quantum compression, says Steinberg, one could perform the tomography experiment and then decide later what aspect of the device you wanted to test.

    But in the meantime, says Steinberg, the demonstration provides another perspective on the strangeness of the quantum world. “If you had a book filled just with ones, you could simply tell your friend that it’s a book filled with ones,” he says. “But quantum mechanically, that’s already not true. Even if I gave you a billion identically prepared photons, you could get different information from each one. To describe their states completely would require infinite classical information.”

    The research will be described in Physical Review Letters.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 4:10 pm on September 27, 2014 Permalink | Reply
    Tags: , , physicsworld.com,   

    From physicsworld.com: “Nuclear spins control electrical currents” 

    physicsworld
    physicsworld.com

    Sep 23, 2014
    Katherine Kornei

    An international team of physicists has shown that information stored in the nuclear spins of hydrogen isotopes in an organic LED (OLED) can be read out by measuring the electrical current through the device. Unlike previous schemes that only work at ultracold temperatures, this is the first to operate at room temperature, and therefore could be used to create extremely dense and highly energy-efficient memory devices.

    man
    Spin doctor: Christoph Boehme inserts an OLED into a spectrometer

    With the growing demand for ever smaller, more powerful electronic devices, physicists are trying to develop more efficient semiconductors and higher-density data-storage devices. Motivated by the fact that traditional silicon semiconductors are susceptible to significant energy losses via waste heat, scientists are investigating the use of organic semiconductors. These are organic thin films placed between two conductors and they promise to be more energy efficient than silicon semiconductors. Furthermore, the availability of many different types of organic thin film could help physicists to optimize the efficiency of these devices.

    Chip and spin

    Conventional memory chips store data in the form of electrical charge. Moving this charge around the chip generates a lot of waste heat that must be dissipated, which makes it difficult to miniaturize components and also reduces battery life. An alternative approach is to store information in the spins of electrons or atomic nuclei – with spin-up corresponding to “1” and spin-down to “0”, for example. This could result in memories that are much denser and more energy efficient than the devices used today.

    Atomic nuclei are particularly attractive for storing data because their spins tend to be well shielded from the surrounding environment. This means that they could achieve storage times of several minutes, which is billions of times longer than is possible with electrons. The challenge, however, is how to read and write data to these tiny elements.

    Now, Christoph Boehme and colleagues at the University of Utah, along with John Lupton of the University of Regensburg and researchers at the University of Queensland, have shown that the flow of electrical current in an OLED can be modulated by controlling the spins of hydrogen isotopes in the device. “Electrical current in an organic semiconductor device is strongly influenced by the nuclear spins of hydrogen, which is abundant in organic materials,” explains Lupton. The team has shown that the current flowing through a plastic polymer OLED can be tuned precisely, suggesting that inexpensive OLEDs can be used as efficient semiconductors.

    Just like MRI

    Boehme and his team applied a small magnetic field to their test OLED, which creates an energy difference between the orientations of the nuclear spins of protons and deuterium (both hydrogen isotopes). The researchers then used radio-frequency signals to alter the directions of the spins of the protons and deuterium nuclei – a process that is also done during a nuclear magnetic resonance (NMR) experiment.

    The changes to the nuclear spins affect the spins of nearby electrons, and this results in changes to the electrical current. The magnetic forces between the nuclear and electron spins are millions of times smaller than the electrical forces needed to cause a similar change in current. This suggests that the effect could be used to create energy-efficient semiconductor memories.

    This recent work follows on from research done in 2010, when Boehme and colleagues showed that the technique could be used to control current in a device made from phosphorus-doped silicon. However, this was only possible in the presence of strong magnetic fields and at temperatures within a few degrees of absolute zero. Such conditions are impractical for commercial devices, but the OLED-based device needs neither ultracold temperatures nor high magnetic fields.

    Time to relax

    “In organic semiconductors, the spin-relaxation time does not change significantly with temperature,” explains Lupton. “In contrast, the spin-relaxation time in phosphorus-doped silicon increases significantly when the temperature is lowered; so in phosphorus-doped silicon, the experiments had to be carried out at low temperatures and high magnetic fields.”

    The team believes that its technique should also work with other nuclei with non-zero spin, with some limitations. “Since protons and deuterium are both hydrogen isotopes, they can be interchanged in the synthesis without changing the chemical structure of the polymer, which may not be possible with other types of nuclei,” Lupton explains. “Tritium, the third hydrogen isotope, is radioactive, so would not be much good in experiments.”

    The research is described in Science.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 9:33 pm on September 25, 2014 Permalink | Reply
    Tags: , physicsworld.com,   

    From physicsworld: “Photons weave their way through a triple slit” 

    physicsworld
    physicsworld.com

    Sep 25, 2014
    Hamish Johnston

    A flaw in how quantum-interference experiments are interpreted has been quantified for the first time by a team of physicists in India. Using the “path integral” formulation of quantum mechanics, the team calculated the interference pattern created when electrons or photons travel through a set of three slits. It found that non-classical paths – in which a particle can weave its way through several slits – must be considered along with the conventional quantum superposition of three direct paths (one through each of the slits). The team says the effect should be measurable in experiments involving microwave photons, and that the work could also provide insights into potential sources of decoherence in some quantum-information systems.

    slits
    Road less travelled: a photon weaves its way through three slits

    One of the cornerstones of quantum theory is the fact that particles can also behave as waves. This can be demonstrated by the double-slit experiment with electrons, which was once voted as the most beautiful physics experiment of all time by Physics World readers. It involves firing electrons through two adjacent slits and observing the build-up of a wave-like interference pattern on a screen on the other side of the slits. However, each particle is detected as a tiny dot within the pattern, suggesting that the particles are discrete entities too.

    Physics students are taught that the double-slit pattern can be explained by treating the system as a superposition of waves that travel through one slit and waves that travel through the other slit. Although this description reproduces the pattern seen in experiments, the Japanese physicist Haruichi Yabuki pointed out in 1986 that this approach is approximate because it ignores the tiny possibility that a particle could take a non-classical path through the slits.

    Quantum weaving

    These non-classical paths are easier to think of with an arrangement of three slits. A particle could go through, say, the slit on its left, curve around, go back through the centre slit before turning again and emerging from the slit on the right (see figure). Now, Urbasi Sinha and colleagues at the Raman Research Institute and Indian Institute of Science in Bangalore have calculated the effect of these non-classical paths on the resulting interference pattern of such a triple slit. Using the path-integral formulation of quantum mechanics, the team looked at different combinations of slit width and slit separation for both incident photons and electrons.

    In the case of electrons, the researchers worked out that the non-classical paths would have a minuscule effect on the observed pattern, which would deviate from a simple superposition by a factor of about 10–8. For visible light, this change increases to about 10–5, but this is still too small to detect. Indeed, the calculations explain why Sinha and colleagues at the University of Waterloo in Canada did not see any deviations in an optical triple-slit experiment done in 2010 (see “Quantum theory survives its latest ordeal“).

    Microwaveable deviation

    It turns out, however, that the deviation should rise to about 10–3 for microwave photons, and the team believes that it could be measured in an experiment using photons of wavelength 4 cm, a slit width of 120 cm and a slit separation of 400 cm. Indeed, Sinha told physicsworld.com that her team at the Raman Research Institute has already set up a microwave experiment to look for the effect, but could not comment on the preliminary results.

    Such an experiment, if carried out, could provide a room-sized demonstration of the path-integral formulation of quantum mechanics – something that is normally associated with sub-atomic processes. Furthermore, understanding the role of non-classical paths in interferometer-based quantum-information systems could help physicists reduce the destructive effects of noise in these systems.

    The research is described in Physical Review Letters.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
  • richardmitnick 3:58 pm on September 17, 2014 Permalink | Reply
    Tags: , , physicsworld.com   

    From physicsworld: “New plasmonic nanolaser is cavity-free” 

    physicsworld
    physicsworld.com

    Sep 17, 2014
    Tim Wogan

    A new design for a cavity-free nanolaser has been proposed by physicists at Imperial College London. The design builds on a proposal from the same team earlier this year to reduce the group velocity of light of a particular frequency to exactly zero in a metal–dielectric–metal waveguide. The laser, which has yet to be built, makes use of two such zero-velocity regions, and would achieve population inversion and create a laser beam without the need for an optical cavity. The researchers suggest that the design could have important applications in optical telecommunications and computing, as well as theoretical implications in reconciling the physics of lasers with plasmonics.

    graph
    Slowing light to a stop: nanolaser has no cavity

    The traditional design for a laser involves encasing a gain medium such as a gas in a cavity containing two opposing mirrors. The gain medium contains two electronic energy levels, and, in the natural state, the lower energy level is the more populated. However, by injecting electrical or light energy into the cavity, some electrons can be “pumped” into the upper state. At low pumping levels, atoms pushed to the upper level decay spontaneously back to the ground state with the emission of a photon. However, above a certain threshold, transitions back to the ground state are predominantly caused by an excited atom’s absorption of a second photon. The two photons are emitted perfectly in phase, and go on to excite emission from more atoms. The resulting beam of phase-coherent photons is the laser beam.

    Lasers have revolutionized modern science and technology, with tiny lasers can be found everywhere from cheap pointers to state-of-the-art telecommunications systems. While much smaller nanoscale lasers would be useful for creating chip-based optical circuits, the need for a cavity limits means that it is difficult to miniaturize a conventional laser beyond the wavelength of the light it produces. This limit is about one micron for the light used in telecommunications technologies.

    Plasmonic interactions

    Now, Ortwin Hess and colleagues have devised a new way of producing a sub-wavelength laser by removing the cavity altogether. The researchers designed a layered metal–dielectric–metal waveguide structure that supports plasmonic interactions between light and conduction electrons at the metal–dielectric interfaces. Such a plasmonic waveguide supports two “zero-velocity singularities” at closely spaced but distinct frequencies. Light of other frequencies will propagate through the semiconductor very slowly – allowing it plenty of time to interact with the gain material. While slow and stopped light might sound like unphysical concepts, they can occur when light interacts with plasmons. Injecting a pulse of this slow light, the researchers calculated, will pump carriers from a lower energy state to a higher state. This higher state would then decay to an intermediate state, which would then decay to produce the laser light. The presence of the zero-velocity singularities causes the laser light to be trapped in the material, where it drives the desired coherent stimulated emission.

    To produce a laser beam, however, some of the laser light must be able to leave the device. In previous work (see “Plasmonic waveguide stops light in its tracks”), Hess and colleagues proposed exciting a zero-velocity mode by passing the light through the cladding in the form of an evanescent wave – a special type of wave the frequency of which is a complex number. Radiation incident on the cladding would excite an evanescent wave, which would in turn excite the stopped-light mode in the dielectric inside. In their new paper, Hess and colleagues turn this idea on its head and use the evanescent field to allow laser light to escape. By varying the precise properties and thickness of the cladding layer, the proportion of light allowed to escape could be tuned, producing a laser beam of variable intensity.

    Biomedical applications

    Nicholas Fang, a nanophotonics expert at the Massachusetts Institute of Technology, believes that, if such cavity-free nanolasers could be produced, they could have major practical implications not only in computation and signalling, but also in less-obvious fields such as prosthetics: he suggests they could be embedded in synthetic tissue to provide sensors with output signals detectable by the nervous system. “Here you’d have a laser source that could be directly implantable,” he explains.

    Hess, meanwhile, is excited by the potential theoretical implications of the work. While the current research focuses on using plasmonic interactions to produce coherent light, he believes that it should also be possible to keep the plasmons themselves confined within the waveguide to produce a miniature surface plasmon laser or “spaser”.

    The research is described in Nature Communications.

    See the full article here.

    PhysicsWorld is a publication of the Institute of Physics. The Institute of Physics is a leading scientific society. We are a charitable organisation with a worldwide membership of more than 50,000, working together to advance physics education, research and application.

    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.
    IOP Institute of Physics

    ScienceSprings relies on technology from

    MAINGEAR computers

    Lenovo
    Lenovo

    Dell
    Dell

     
c
Compose new post
j
Next post/Next comment
k
Previous post/Previous comment
r
Reply
e
Edit
o
Show/Hide comments
t
Go to top
l
Go to login
h
Show/Hide help
shift + esc
Cancel
Follow

Get every new post delivered to your Inbox.

Join 534 other followers

%d bloggers like this: