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  • richardmitnick 2:31 pm on June 23, 2018 Permalink | Reply
    Tags: , , , , phys.org, Researchers find last of universe's missing ordinary matter, University of Colorado Boulder   

    From University of Colorado Boulder via phys.org: “Researchers find last of universe’s missing ordinary matter” 

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    From University of Colorado Boulder

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    phys.org

    June 20, 2018
    No writer credit

    1
    A simulation of the cosmic web, or diffuse tendrils of gas connecting galaxies across the universe. Credit: NASA, ESA, E. Hallman (CU Boulder)

    Researchers at the University of Colorado Boulder have helped to find the last reservoir of ordinary matter hiding in the universe.

    Ordinary matter, or “baryons,” make up all physical objects in existence, from stars to the cores of black holes. But until now, astrophysicists had only been able to locate about two-thirds of the matter that theorists predict was created by the Big Bang.

    In the new research, an international team pinned down the missing third, finding it in the space between galaxies. That lost matter exists as filaments of oxygen gas at temperatures of around 1 million degrees Celsius, said CU Boulder’s Michael Shull, a co-author of the study.

    The finding is a major step for astrophysics. “This is one of the key pillars of testing the Big Bang theory: figuring out the baryon census of hydrogen and helium and everything else in the periodic table,” said Shull of the Department of Astrophysical and Planetary Sciences (APS).

    The new study, which will appear June 20 in Nature, was led by Fabrizio Nicastro of the Italian Istituto Nazionale di Astrofisica (INAF)—Osservatorio Astronomico di Roma and the Harvard-Smithsonian Center for Astrophysics.

    Researchers have a good idea of where to find most of the ordinary matter in the universe—not to be confused with dark matter, which scientists have yet to locate: About 10 percent sits in galaxies, and close to 60 percent is in the diffuse clouds of gas that lie between galaxies.

    In 2012, Shull and his colleagues predicted that the missing 30 percent of baryons were likely in a web-like pattern in space called the warm-hot intergalactic medium (WHIM). Charles Danforth, a research associate in APS, contributed to those findings and is a co-author of the new study.

    To search for missing atoms in that region between galaxies, the international team pointed a series of satellites at a quasar called 1ES 1553—a black hole at the center of a galaxy that is consuming and spitting out huge quantities of gas. “It’s basically a really bright lighthouse out in space,” Shull said.

    Scientists can glean a lot of information by recording how the radiation from a quasar passes through space, a bit like a sailor seeing a lighthouse through fog. First, the researchers used the Cosmic Origins Spectrograph on the Hubble Space Telescope to get an idea of where they might find the missing baryons. Next, they homed in on those baryons using the European Space Agency’s X-ray Multi-Mirror Mission (XMM-Newton) satellite.

    NASA/ESA Hubble Telescope

    ESA/XMM Newton

    The team found the signatures of a type of highly-ionized oxygen gas lying between the quasar and our solar system—and at a high enough density to, when extrapolated to the entire universe, account for the last 30 percent of ordinary matter.

    “We found the missing baryons,” Shull said.

    He suspects that galaxies and quasars blew that gas out into deep space over billions of years. Shull added that the researchers will need to confirm their findings by pointing satellites at more bright quasars.

    See the full article here .


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  • richardmitnick 3:46 pm on May 14, 2018 Permalink | Reply
    Tags: Harvard University and MIT, , Institute of Science and Technology Austria, phys.org, , University of Geneva,   

    From University of Leeds via phys.org: “Deeper understanding of quantum chaos may be the key to quantum computers” 

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    From University of Leeds

    phys.org

    May 14, 2018

    1
    Quantum systems can exist in many possible states, here illustrated by groups of spins, each pointing along a certain direction. Thermalization occurs when a system evenly explores all allowed configurations. Instead, when a “quantum scar” forms (as shown in the figure), some configurations emerge as special. This feature allows scarred systems to sustain memory of the initial state despite thermalization. Credit: Zlatko Papic, University of Leeds

    New research gives insight into a recent experiment that was able to manipulate an unprecedented number of atoms through a quantum simulator. This new theory could provide another step on the path to creating the elusive quantum computers.

    1
    Quantum computing – IBM

    An international team of researchers, led by the University of Leeds and in cooperation with the Institute of Science and Technology Austria and the University of Geneva, has provided a theoretical explanation for the particular behaviour of individual atoms that were trapped and manipulated in a recent experiment by Harvard University and MIT [Nature Physics]. The experiment used a system of finely tuned lasers to act as “optical tweezers” to assemble a remarkably long chain of 51 atoms.

    When the quantum dynamics of the atom chain were measured, there were surprising oscillations that persisted for much longer than expected and which couldn’t be explained.

    Study co-author, Dr. Zlatko Papic, Lecturer in Theoretical Physics at Leeds, said: “The previous Harvard-MIT experiment created surprisingly robust oscillations that kept the atoms in a quantum state for an extended time. We found these oscillations to be rather puzzling because they suggested that atoms were somehow able to “remember” their initial configuration while still moving chaotically.

    “Our goal was to understand more generally where such oscillations could come from, since oscillations signify some kind of coherence in a chaotic environment—and this is precisely what we want from a robust quantum computer. Our work suggests that these oscillations are due to a new physical phenomenon that we called ‘quantum many-body scar’.”

    In everyday life, particles will bounce off one another until they explore the entire space, settling eventually into a state of equilibrium. This process is called thermalisation. A quantum scar is when a special configuration or pathway leaves an imprint on the particles’ state that keeps them from filling the entire space. This prevents the systems from reaching thermalisation and allows them to maintain some quantum effects.

    Dr. Papic said: “We are learning that quantum dynamics can be much more complex and intricate than simply thermalisation. The practical benefit is that extended periods of oscillations are exactly what is needed if quantum computers are to become a reality. The information processed and stored on these computers will be dependent on keeping the atoms in more than one state at any time, it is a constant battle to keep the particles from settling into an equilibrium.”

    Study lead author, Christopher Turner, doctoral researcher at the School of Physics and Astronomy at Leeds, said: “Previous theories involving quantum scars have been formulated for a single particle. Our work has extended these ideas to systems which contain not one but many particles, which are all entangled with each other in complicated ways. Quantum many-body scars might represent a new avenue to realise coherent quantum dynamics.”

    The quantum many-body scars theory sheds light on the quantum states that underpin the strange dynamics of atoms in the Harvard-MIT experiment. Understanding this phenomenon could also pave the way for protecting or extending the lifetime of quantum states in other classes of quantum many-body systems.

    Read more at: https://phys.org/news/2018-05-deeper-quantum-chaos-key.html#jCp

    See the full article here.

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    The University, established in 1904, is one of the largest higher education institutions in the UK. We are a world top 100 university and are renowned globally for the quality of our teaching and research. The strength of our academic expertise combined with the breadth of disciplines we cover, provides a wealth of opportunities and has real impact on the world in cultural, economic and societal ways. The University strives to achieve academic excellence within an ethical framework informed by our values of integrity, equality and inclusion, community and professionalism.

     
  • richardmitnick 2:15 pm on March 12, 2018 Permalink | Reply
    Tags: A possible experiment to prove that gravity and quantum mechanics can be reconciled, , , phys.org, , ,   

    From phys.org: “A possible experiment to prove that gravity and quantum mechanics can be reconciled” 

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    phys.org

    March 12, 2018
    Bob Yirka

    1
    Credit: G. W. Morley/University of Warwick and APS/Alan Stonebraker

    Two teams of researchers working independently of one another have come up with an experiment designed to prove that gravity and quantum mechanics can be reconciled. The first team is a pairing of Chiara Marletto of the University of Oxford and Vlatko Vedral of National University of Singapore. The second is an international collaboration. In the papers, both published in Physical Review Letters, the teams describe their experiment and how it might be carried out Spin Entanglement Witness for Quantum Gravity and Gravitationally Induced Entanglement between Two Massive Particles is Sufficient Evidence of Quantum Effects in Gravity.

    Gravity is a tough nut to crack, there is just no doubt about it. In comparison, the strong, weak and electromagnetic forces are a walk in the park. Scientists still can’t explain the nature of gravity, though how it works is rather well understood. The current best theory regarding gravity goes all the way back to Einstein’s general theory of relativity, but there has been no way to reconcile it with quantum mechanics. Some physicists suggest it could be a particle called the graviton. But proving that such a particle exists has been frustrating, because it would be so weak that it would be very nearly impossible to measure its force. In this new effort, neither team is suggesting that their experiment could reconcile gravity and quantum mechanics. Instead, they are claiming that if such an experiment is successful, it would very nearly prove that it should be possible to do it.

    The experiment essentially involves attempting to entangle two particles using their gravitational attraction as a means of confirming quantum gravity. In practice, it would consist of levitating two tiny diamonds a small distance from one another and putting each of them into a superposition of two spin directions. After that, a magnetic field would be applied to separate the spin components. At this point, a test would be made to see if each of the components is gravitationally attracted. If they are, the researchers contend, that will prove that gravity is quantum; if they are not, then it will not. The experiment would have to run many times to get an accurate assessment. And while a first look might suggest such an experiment could be conducted very soon, the opposite is actually true. The researchers suggest it will likely be a decade before such an experiment could be carried out due to the necessity of improving scale and the sensitivity involved in such an experiment.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 2:20 pm on March 1, 2018 Permalink | Reply
    Tags: , , , How are hadrons born at the huge energies available in the LHC?, , , phys.org,   

    From phys.org: “How are hadrons born at the huge energies available in the LHC?” 

    physdotorg
    phys.org

    March 1, 2018
    The Henryk Niewodniczanski Institute of Nuclear Physics Polish Academy of Sciences

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    Particles produced during one of the collisions of two protons, each with energies of 7 TeV, registered by the detectors of the LHCb experiment in 2011; view from two different sides. Credit: CERN/LHCb

    CERN LHCb chamber, LHC


    CERN/LHCb detector

    Our world consists mainly of particles built up of three quarks bound by gluons. The process of the sticking together of quarks, called hadronisation, is still poorly understood. Physicists from the Institute of Nuclear Physics Polish Academy of Sciences in Cracow, working within the LHCb Collaboration, have obtained new information about it, thanks to the analysis of unique data collected in high-energy collisions of protons in the LHC.

    When protons accelerated to the greatest energy collide with each other in the LHC, their component particles – quarks and gluons – create a puzzling intermediate state. The observation that in the collisions of such relatively simple particles as protons this intermediate state exhibits the properties of a liquid, typical for collisions of much more complex structures (heavy ions), was a big surprise. Properties of this type indicate the existence of a new state of matter: a quark-gluon plasma in which quarks and gluons behave almost as free particles. This exotic liquid cools instantly. As a result, the quarks and gluons re-connect with each other in a process called hadronisation. The effect of this is the birth of hadrons, particles that are clumps of two or three quarks. Thanks to the latest analysis of data collected at energies of seven teraelectronvolts, researchers from the Institute of Nuclear Physics Polish Academy of Sciences (IFJ PAN) in Cracow, working within the LHCb Collaboration, acquired new information on the mechanism of hadronisation in proton-proton collisions.

    “The main role in proton collisions is played by strong interaction, described by the quantum chromodynamics. The phenomena occurring during the cooling of the quark-gluon plasma are, however, so complex in terms of computation that until now it has not been possible fully understand the details of hadronisation. And yet it is a process of key significance! It is thanks to this that in the first moments after the Big Bang, the dominant majority of particles forming our everyday environment was formed from quarks and gluons,” says Assoc. Prof. Marcin Kucharczyk (IFJ PAN).

    In the LHC, hadronisation is extremely fast, and occurs in an extremely small area around the point of proton collision: its dimensions reach only femtometres, or millionths of one billionth of a metre. It is no wonder then, that direct observation of this process is currently not possible. To obtain any information about its course, physicists must reach for various indirect methods. A key role is played by the basic tool of quantum mechanics: a wave function whose properties are mapped by the characteristics of particles of a given type (it is worth noting that although it is almost 100 years since the birth of quantum mechanics, there still exists various interpretations of the wave function!).

    “The wave functions of identical particles will effectively overlap, i.e. interfere. If they are enhanced as a result of interference, we are talking about Bose-Einstein correlations, if they are suppressed – Fermi-Dirac correlations. In our analyses, we were interested in the enhancements, that is, the Bose-Einstein correlations. We were looking for them between the pi mesons flying out of the area of hadronisation in directions close to the original direction of the colliding beams of protons,” explains Ph.D. student Bartosz Malecki (IFJ PAN).

    The method used was originally developed for radioastronomy and is called HBT interferometry (from the names of its two creators: Robert Hanbury Brown and Richard Twiss). When used with reference to particles, HBT interferometry makes it possible to determine the size of the area of hadronisation and its evolution over time. It helps to provide information about, for example, whether this area is different for different numbers of emitted particles or for their different types.

    The data from the LHCb detector made it possible to study the hadronisation process in the area of so-called small angles, i.e. for hadrons produced in directions close to the direction of the initial proton beams. The analysis performed by the group from the IFJ PAN provided indications that the parameters describing the source of hadronisation in this unique region covered by LHCb experiment at LHC are different from the results obtained for larger angles.

    “The analysis that provided these interesting results will be continued in the LHCb experiment for various collision energies and different types of colliding structures. Thanks to this, it will be possible to verify some of the models describing hadronisation and, consequently, to better understand the course of the process itself,” sums up Prof. Mariusz Witek (IFJ PAN).

    The work of the team from the IFJ PAN was financed in part by the OPUS grant from the Polish National Science Centre.

    Science paper:
    Bose-Einstein correlations of same-sign charged pions in the forward region in pp collisions at s√=7TeV
    Journal of High Energy Physics, December 2017, 2017

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 2:12 pm on February 19, 2018 Permalink | Reply
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    From phys.org: “Astronomers conduct a multi-frequency study of the Milky Way-like spiral galaxy NGC 6744” 

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    phys.org

    February 19, 2018
    Tomasz Nowakowski

    1
    WISE 3-color (W1+W2+W3) image of NGC 6744. Left panel shows the images before star subtraction, and the right panel after. Credit: Yew et al., 2018.

    NASA/WISE Telescope

    An international team of astronomers has conducted a multi-frequency study of NGC 6744, one of the most Milky Way-like spiral galaxies. The new research, published February 8 in a paper on arXiv.org, identifies radio and X-ray sources in NGC 6744 and estimates its star formation rate.

    Discovered in 1823, NGC 6744 is an intermediate spiral galaxy located some about 30 million light years away in the constellation Pavo. It is thought to be one of the most Milky Way-like spiral galaxies in our immediate vicinity, and is perceived by astronomers as a useful analogue to our own galaxy when it comes to studying objects such as supernova remnants and H II regions—clouds of glowing gas and plasma in which star formation takes place.

    When in 2005 a type Ic supernova was found in NGC 6744 at optical wavebands, astronomers started to observe this galaxy in detail across the electromagnetic spectrum with the aim of identifying more interesting objects there. One of the teams involved in the observations of NGC 6744 is an international group of astronomers led by Miranda Yew of the Western Sydney University, Australia, studying it as part of a wider research focused on nearby galaxies.

    Now, Yew’s team reports important results from their observations of NGC 6744, which include finding almost 400 radio and X-ray sources. The research is based on X-ray, radio and infrared data provided by NASA’s e Chandra X-Ray Observatory, the Australia Telescope Compact Array (ATCA), the GaLactic and Extragalactic All-sky Murchison Widefield Array (GLEAM) and NASA’s Wide-field Infrared Survey Explorer (WISE).

    NASA/Chandra Telescope

    CSIRO ATCA at the Paul Wild Observatory, about 25 km west of the town of Narrabri in rural NSW about 500 km north-west of Sydney, AU

    SKA Murchison Widefield Array, Boolardy station in outback Western Australia, at the Murchison Radio-astronomy Observatory (MRO)

    “We present a multi-frequency study of the intermediate spiral SAB(r)bc type galaxy NGC 6744, using available data from the Chandra X-Ray telescope, radio continuum data from the Australia Telescope Compact Array and Murchison Widefield Array, and Wide-field Infrared Survey Explorer infrared observations,” the researchers wrote in the paper.

    In an analysis of the available data, the astronomers identified 117 X-ray and 280 radio sources. One of these sources was classified as a supermassive black hole with a bolometric radio luminosity similar to the Milky Way’s central black hole. Two of the newly found sources are likely supernova remnants, five were classified as supernova remnant candidates and 17 as H II regions. The remaining sources were categorized as background objects.

    According to the study, the newly detected supernova remnants are particularly bright, but not as bright as Cassiopeia A, a supernova remnant in the constellation Cassiopeia. When it comes to the new H II regions, the researchers assume that 22-µm-dominated emission is likely to arise from the warm dust in the vicinity of these clouds.

    Moreover, the team calculated that the star formation rate of NGC 6744 is between 2.8 and 4.7 solar masses per year—at least two times greater than that of the Milky Way. This value indicates that NGC 6744 is still actively forming stars.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 10:41 am on February 19, 2018 Permalink | Reply
    Tags: , , phys.org, , Quantum computers, Topological superconductors   

    From phys.org: “Unconventional superconductor may be used to create quantum computers of the future” 

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    phys.org

    February 19, 2018

    1
    After an intensive period of analyses the research team led by Professor Floriana Lombardi, Chalmers University of Technology, was able to establish that they had probably succeeded in creating a topological superconductor. Credit: Johan Bodell/Chalmers University of Technology

    With their insensitivity to decoherence, Majorana particles could become stable building blocks of quantum computers. The problem is that they only occur under very special circumstances. Now, researchers at Chalmers University of Technology have succeeded in manufacturing a component that is able to host the sought-after particles.

    Researchers throughout the world are struggling to build quantum computers. One of the great challenges is to overcome the sensitivity of quantum systems to decoherence, the collapse of superpositions. One track within quantum computer research is therefore to make use of Majorana particles, which are also called Majorana fermions. Microsoft, among other organizations, is exploring this type of quantum computer.

    Majorana fermions are highly original particles, quite unlike those that make up the materials around us. In highly simplified terms, they can be seen as half-electron. In a quantum computer, the idea is to encode information in a pair of Majorana fermions separated in the material, which should, in principle, make the calculations immune to decoherence.

    So where do you find Majorana fermions? In solid state materials, they only appear to occur in what are known as topological superconductors. But a research team at Chalmers University of Technology is now among the first in the world to report that they have actually manufactured a topological superconductor.

    “Our experimental results are consistent with topological superconductivity,” says Floriana Lombardi, professor at the Quantum Device Physics Laboratory at Chalmers.

    To create their unconventional superconductor, they started with what is called a topological insulator made of bismuth telluride, Be2Te3. A topological insulator conducts current in a very special way on the surface. The researchers placed a layer of aluminum, a conventional superconductor, on top, which conducts current entirely without resistance at low temperatures.

    “The superconducting pair of electrons then leak into the topological insulator, which also becomes superconducting,” explains Thilo Bauch, associate professor in quantum device physics.

    However, the initial measurements all indicated that they only had standard superconductivity induced in the Bi2Te3 topological insulator. But when they cooled the component down again later, to routinely repeat some measurements, the situation suddenly changed—the characteristics of the superconducting pairs of electrons varied in different directions.

    “And that isn’t compatible at all with conventional superconductivity. Unexpected and exciting things occurred,” says Lombardi.

    “For practical applications, the material is mainly of interest to those attempting to build a topological quantum computer. We want to explore the new physics hidden in topological superconductors—this is a new chapter in physics,” Lombardi says.

    The results were recently published in Nature Communications in a study titled “Induced unconventional superconductivity on the surface states of Bi2Te3 topological insulator.”

    See the full article here .

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    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 9:22 am on February 12, 2018 Permalink | Reply
    Tags: , Forging a quantum leap in quantum communication, Homodyne detection, phys.org, Quantum communication   

    From phys.org: “Forging a quantum leap in quantum communication” 

    physdotorg
    phys.org

    February 9, 2018

    1
    In quantum communication, the participating parties can detect eavesdropping by resorting to the fundamental principle of quantum mechanics — a measurement affects the measured quantity. Thus, an eavesdropper can be detected by identifying traces his measurements of the communication channel leave behind. The major drawback of quantum communication is the slow speed of data transfer, limited by the speed at which the parties can perform quantum measurements. Researchers at Bar-Ilan University have devised a method that overcomes this, and enables an increase in the rate of data transfer by more than 5 orders of magnitude! This image illustrates their technique, in which they replaced electrical nonlinearity with a direct optical nonlinearity, transforming the quantum information into a classical optical signal. Credit: Bar-Ilan University.

    Quantum communication, which ensures absolute data security, is one of the most advanced branches of the “second quantum revolution”. In quantum communication, the participating parties can detect any attempt at eavesdropping by resorting to the fundamental principle of quantum mechanics – a measurement affects the measured quantity. Thus, the mere existence of an eavesdropper can be detected by identifying the traces that his measurements of the communication channel leave behind.

    The major drawback of quantum communication today is the slow speed of data transfer, which is limited by the speed at which the parties can perform quantum measurements.

    Researchers at Bar-Ilan University have devised a method that overcomes this “speed limit”, and enables an increase in the rate of data transfer by more than 5 orders of magnitude! Their findings were published today in the journal Nature Communications.

    Homodyne detection is a cornerstone of quantum optics, acting as a fundamental tool for processing quantum information. However, the standard homodyne method suffers from a strong bandwidth limitation. While quantum optical phenomena, exploited for quantum communication, can easily span a bandwidth of many THz, the standard processing methods of this information are inherently limited to the electronically accessible MHz-to-GHz range, leaving a dramatic gap between the relevant optical phenomena that is used for carrying the quantum information, and the capability to measure it. Thus, the rate at which quantum information can be processed is strongly limited.

    In their work, the researchers replace the electrical nonlinearity that serves as the heart of homodyne detection, which transforms the optical quantum information into a classical electrical signal, with a direct optical nonlinearity, transforming the quantum information into a classical optical signal. Thus, the output signal of the measurement remains in the optical regime, and preserves the enormous bandwidth optical phenomena offers.

    “We offer a direct optical measurement that conserves the information bandwidth, instead of an electrical measurement that compromises the bandwidth of the quantum optical information,” says Dr. Yaakov Shaked, who conducted the research during his Ph.D. studies in the lab of Prof. Avi Pe’er. To demonstrate this idea, the researchers perform a simultaneous measurement of an ultra-broadband quantum optical state, spanning 55THz, presenting non-classical behavior across the entire spectrum. Such a measurement, using standard method, would be practically impossible.

    The research was accomplished through a collaboration between the Quantum Optics Labs of Prof. Avi Pe’er and Prof. Michael Rosenbluh, together with Yoad Michael, Dr. Rafi Z. Vered and Leon Bello at the Department of Physics and Institute for Nanotechnology and Advanced Materials at Bar-Ilan University.

    This new form of quantum measurement is relevant also to other branches of the “second quantum revolution”, such as quantum computing with super powers, quantum sensing with super sensitivity, and quantum imaging with super resolution.

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
  • richardmitnick 1:17 pm on February 6, 2018 Permalink | Reply
    Tags: , , phys.org, , Researchers take terahertz data links around the bend   

    From Brown via phys.org: “Researchers take terahertz data links around the bend” 

    Brown University
    Brown University

    phys.org

    February 6, 2018
    Kevin Stacey

    1
    New research shows that non-line-of-site terahertz data links are possible because the waves can bounce off of walls without losing too much data. Credit: Mittleman lab / Brown University

    An off-the-wall new study by Brown University researchers shows that terahertz frequency data links can bounce around a room without dropping too much data. The results are good news for the feasibility of future terahertz wireless data networks, which have the potential to carry many times more data than current networks.

    Today’s cellular networks and Wi-Fi systems rely on microwave radiation to carry data, but the demand for more and more bandwidth is quickly becoming more than microwaves can handle. That has researchers thinking about transmitting data on higher-frequency terahertz waves, which have as much as 100 times the data-carrying capacity of microwaves. But terahertz communication technology is in its infancy. There’s much basic research to be done and plenty of challenges to overcome.

    For example, it’s been assumed that terahertz links would require a direct line of sight between transmitter and receiver. Unlike microwaves, terahertz waves are entirely blocked by most solid objects. And the assumption has been that it’s not possible to bounce a terahertz beam around—say, off a wall or two—to find a clear path around an object.

    “I think it’s fair to say that most people in the terahertz field would tell you that there would be too much power loss on those bounces, and so non-line-of-sight links are not going to be feasible in terahertz,” said Daniel Mittleman, a professor in Brown University’s School of Engineering and senior author of the new research published in APL Photonics. “But our work indicates that the loss is actually quite tolerable in some cases—quite a bit less than many people would have thought.”

    For the study, Mittleman and his colleagues bounced terahertz waves at four different frequencies off of a variety of objects—mirrors, metal doors, cinderblock walls and others—and measured the bit-error-rate of the data on the wave after the bounces. They showed that acceptable bit-error-rates were achievable with modest increases in signal power.

    “The concern had been that in order to make those bounces and not lose your data, you’d need more power than was feasible to generate,” Mittleman said. “We show that you don’t need as much power as you might think because the loss on the bounce is not as much as you’d think.”

    In one experiment, the researchers bounced a beam off two walls, enabling a successful link when transmitter and receiver were around a corner from each other, with no direct line-of-sight whatsoever. That’s a promising finding to support the idea of terahertz local-area networks.

    2
    In an effort to better understand the architecture needed for future terahertz data networks, Brown University researchers investigate how terahertz waves propagate and bounce off of objects both indoors and out. Credit: Mittleman Lab / Brown University

    “You can imagine a wireless network,” Mittleman explained, “where someone’s computer is connected to a terahertz router and there’s direct line-of-sight between the two, but then someone walks in between and blocks the beam. If you can’t find an alternative path, that link will be shut down. What we show is that you might still be able to maintain the link by searching for a new path that could involve bouncing off a wall somewhere. There are technologies today that can do that kind of path-finding for lower frequencies and there’s no reason they can’t be developed for terahertz.”

    The researchers also performed several outdoor experiments on terahertz wireless links. An experimental license issued by the FCC makes Brown the only place in the country where outdoor research can be done legally at these frequencies. The work is important because scientists are just beginning to understand the details of how terahertz data links behave in the elements, Mittleman says.

    Their study focused on what’s known as specular reflection. When a signal is transmitted over long distances, the waves fan out forming an ever-widening cone. As a result of that fanning out, a portion the waves will bounce off of the ground before reaching the receiver. That reflected radiation can interfere with the main signal unless a decoder compensates for it. It’s a well-understood phenomenon in microwave transmission. Mittleman and his colleagues wanted to characterize it in the terahertz range.

    They showed that this kind of interference indeed occurs in terahertz waves, but occurs to a lesser degree over grass compared to concrete. That’s likely because grass has lots of water, which tends to absorb terahertz waves. So over grass, the reflected beam is absorbed to a greater degree than concrete, leaving less of it to interfere with the main beam. That means that terahertz links over grass can be longer than those over concrete because there’s less interference to deal with, Mittleman says.

    “The specular reflection represents another possible path for your signal,” Mittleman said. “You can imagine that if your line-of-site path is blocked, you could think about bouncing it off the ground to get there.”

    Mittleman says that these kinds of basic studies on the nature of terahertz data transmission are critical for understanding how to design the network architecture for future terahertz data systems.

    See the full article here .

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    Welcome to Brown

    Brown U Robinson Hall
    Located in historic Providence, Rhode Island and founded in 1764, Brown University is the seventh-oldest college in the United States. Brown is an independent, coeducational Ivy League institution comprising undergraduate and graduate programs, plus the Alpert Medical School, School of Public Health, School of Engineering, and the School of Professional Studies.

    With its talented and motivated student body and accomplished faculty, Brown is a leading research university that maintains a particular commitment to exceptional undergraduate instruction.

    Brown’s vibrant, diverse community consists of 6,000 undergraduates, 2,000 graduate students, 400 medical school students, more than 5,000 summer, visiting and online students, and nearly 700 faculty members. Brown students come from all 50 states and more than 100 countries.

    Undergraduates pursue bachelor’s degrees in more than 70 concentrations, ranging from Egyptology to cognitive neuroscience. Anything’s possible at Brown—the university’s commitment to undergraduate freedom means students must take responsibility as architects of their courses of study.

     
  • richardmitnick 1:27 pm on February 1, 2018 Permalink | Reply
    Tags: phys.org, , ,   

    From Technion vis phys.org: “Speed of light drops to zero at ‘exceptional points'” 

    Technion bloc

    Israel Institute of Technology

    phys.org

    January 31, 2018
    Lisa Zyga

    1
    (Pixabay)

    Light, which travels at a speed of 300,000 km/sec in a vacuum, can be slowed down and even stopped completely by methods that involve trapping the light inside crystals or ultracold clouds of atoms. Now in a new study, researchers have theoretically demonstrated a new way to bring light to a standstill: they show that light stops at “exceptional points,” which are points at which two light modes come together and coalesce, in waveguides that have a certain kind of symmetry.

    Unlike most other methods that are used to stop light, the new method can be tuned to work with a wide range of frequencies and bandwidths, which may offer an important advantage for future slow-light applications.

    The researchers, Tamar Goldzak and Nimrod Moiseyev at the Technion – Israel Institute of Technology, along with Alexei A. Mailybaev at the Instituto de Matemática Pura e Aplicada (IMPA) in Rio de Janeiro, have published a paper on stopping light at exceptional points in a recent issue of Physical Review Letters.

    As the researchers explain, exceptional points can be created in waveguides in a straightforward way, by varying the gain/loss parameters so that two light modes coalesce (combine into one mode). Although light stops at these exceptional points, in most systems much of the light is lost at these points. The researchers showed that this problem can be fixed by using waveguides with parity-time (PT) symmetry, since this symmetry ensures that the gain and loss are always balanced. As a result, the light intensity remains constant when the light approaches the exceptional point, eliminating losses.

    To release the stopped light and accelerate it back up to normal speed, the scientists showed that the gain/loss parameters can simply be reversed. The most important feature of the new method, however, is that the exceptional points can be adjusted to work with any frequency of light, again simply by tuning the gain/loss parameters. The researchers also expect that this method can be used for other types of waves besides light, such as acoustic waves. They plan to further investigate these possibilities in the future.

    See the full article here .

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    Technion Campus

    A science and technology research university, among the world’s top ten,
    dedicated to the creation of knowledge and the development of human capital and leadership,
    for the advancement of the State of Israel and all humanity.

     
  • richardmitnick 2:30 pm on January 19, 2018 Permalink | Reply
    Tags: , , phys.org, U Texas San Antonio   

    From phys.org: “New research challenges existing models of black holes” 

    physdotorg
    phys.org

    January 19, 2018
    Joanna Carver, University of Texas at San Antonio

    1
    Credit: University of Texas at San Antonio

    Chris Packham, associate professor of physics and astronomy at The University of Texas at San Antonio (UTSA), has collaborated on a new study [Science] that expands the scientific community’s understanding of black holes in our galaxy and the magnetic fields that surround them.

    “Dr. Packham’s collaborative work on this study is a great example of the innovative research happening now in physics at UTSA. I’m excited to see what new research will result from these findings,” said George Perry, dean of the UTSA College of Sciences and Semmes Foundation Distinguished University Chair in Neurobiology.

    Packham and astronomers lead from the University of Florida observed the magnetic field of a black hole within our own galaxy from multiple wavelengths for the first time. The results, which were a collective effort among several researchers, are deeply enlightening about some of the most mysterious objects in space.

    A black hole is a place in space where gravity pulls so strongly that even light cannot escape its grasp. Black holes usually form when a massive star explodes and the remnant core collapses under the force of intense gravity. As an example, if a star around 3 times more massive than our own Sun became a black hole, it would be roughly the size of San Antonio. The black hole Packham and his collaborators featured in their study, which was recently published in Science, contains about 10 times the mass of our own sun and is known as V404 Cygni.

    “The Earth, like many planets and stars, has a magnetic field that sprouts out of the North Pole, circles the planet and goes back into the South Pole. It exists because the Earth has a hot, liquid iron rich core,” said Packham. “That flow creates electric currents that create a magnetic field. A black hole has a magnetic field as it was created from the remnant of a star after the explosion.”

    As matter is broken down around a black hole, jets of electrons are launched by the magnetic field from either pole of the black hole at almost the speed of light. Astronomers have long been flummoxed by these jets.

    These new and unique observations of the jets and estimates of magnetic field of V404 Cygni involved studying the body at several different wavelengths. These tests allowed the group to gain a much clearer understanding of the strength of its magnetic field. They discovered that magnetic fields are much weaker than previously understood, a puzzling finding that calls into question previous models of black hole components. The research shows a deep need for continued studies on some of the most mysterious entities in space.

    “We need to understand black holes in general,” Packham said. “If we go back to the very earliest point in our universe, just after the big bang, there seems to have always been a strong correlation between black holes and galaxies. It seems that the birth and evolution of black holes and galaxies, our cosmic island, are intimately linked. Our results are surprising and one that we’re still trying to puzzle out.”

    See the full article here .

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    About Phys.org in 100 Words

    Phys.org™ (formerly Physorg.com) is a leading web-based science, research and technology news service which covers a full range of topics. These include physics, earth science, medicine, nanotechnology, electronics, space, biology, chemistry, computer sciences, engineering, mathematics and other sciences and technologies. Launched in 2004, Phys.org’s readership has grown steadily to include 1.75 million scientists, researchers, and engineers every month. Phys.org publishes approximately 100 quality articles every day, offering some of the most comprehensive coverage of sci-tech developments world-wide. Quancast 2009 includes Phys.org in its list of the Global Top 2,000 Websites. Phys.org community members enjoy access to many personalized features such as social networking, a personal home page set-up, RSS/XML feeds, article comments and ranking, the ability to save favorite articles, a daily newsletter, and other options.

     
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