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  • richardmitnick 1:14 pm on June 27, 2017 Permalink | Reply
    Tags: , Expanding the capacity of underwater communications could open up new avenues for exploration the researchers said, High-speed communications under seas, , Physics, Remote probes in the oceans could send data without the need to surface   

    From LBNL: “Could This Strategy Bring High-Speed Communications to the Deep Sea?” 

    Berkeley Logo

    Berkeley Lab

    June 27, 2017
    Sarah Yang
    scyang@lbl.gov
    (510) 486-4575

    1
    Binary data representing the word “Berkeley” is converted by a digital circuit to information encoded in independent channels with different orbital angular momentum. The transducer array sends the information via a single acoustic beam with different patterns. The colors in the helical wavefront show different acoustic phases. (Credit: Chengzhi Shi/Berkeley Lab and UC Berkeley)

    A new approach to sending acoustic waves through water could potentially open up the world of high-speed communications to activities underwater, including scuba diving, remote ocean monitoring, and deep-sea exploration.

    By taking advantage of the dynamic rotation generated as acoustic waves travel, or the orbital angular momentum, researchers at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) were able to pack more channels onto a single frequency, effectively increasing the amount of information capable of being transmitted.

    They demonstrated this by encoding in binary form the letters that make up the word “Berkeley,” and transmitting the information along an acoustic signal that would normally carry less data. They describe their findings in a study published this week in the Proceedings of the National Academy of Sciences.

    “It’s comparable to going from a single-lane side road to a multi-lane highway,” said study corresponding author Xiang Zhang, senior faculty scientist at Berkeley Lab’s Materials Sciences Division and a professor at UC Berkeley. “This work has huge potential in high-speed acoustic communications.”

    While human activity below the surface of the sea increases, the ability to communicate underwater has not kept pace, limited in large part by physics. Microwaves are quickly absorbed in water, so transmissions cannot get far. Optical communication is no better since light gets scattered by underwater microparticles when traveling over long distances.

    Low frequency acoustics is the option that remains for long-range underwater communication. Applications for sonar abound, including navigation, seafloor mapping, fishing, offshore oil surveying, and vessel detection.

    2
    Chengzhi Shi checks the connections between the transducer array and the digital circuit. The experimental setup showed the potential of generating independent channels onto a single frequency to expand acoustic communications underwater. (Credit: Marilyn Chung/Berkeley Lab)

    However, the tradeoff with acoustic communication, particularly with distances of 200 meters or more, is that the available bandwidth is limited to a frequency range within 20 kilohertz. Frequency that low limits the rate of data transmission to tens of kilobits per second, a speed that harkens back to the days of dialup internet connections and 56-kilobit-per-second modems, the researchers said.

    “The way we communicate underwater is still quite primitive,” said Zhang. “There’s a huge appetite for a better solution to this.”

    The researchers adopted the idea of multiplexing, or combining different channels together over a shared signal. It is a technique widely used in telecommunications and computer networks, but multiplexing orbital angular momentum is an approach that had not been applied to acoustics until this study, the researchers said.

    As sound propagates, the acoustic wavefront forms a helical pattern, or vortex beam. The orbital angular momentum of this wave provides a spatial degree of freedom and independent channels upon which the researchers could encode data.

    “The rotation occurs at different speeds for channels with different orbital angular momenta, even while the frequency of the wave itself stays the same, making these channels independent of each other,” said study co-lead author Chengzhi Shi, a graduate student in Zhang’s lab. “That is why we could encode different bits of data in the same acoustic beam or pulse. We then used algorithms to decode the information from the different channels because they’re independent of each other.”

    3
    Letters are encoded onto independent channels, with the amplitudes and phases forming different patterns. (Credit: Chengzhi Shi/Berkeley Lab and UC Berkeley)

    The experimental setup, located at Berkeley Lab, consisted of a digital control circuit with an array of 64 transducers, together generating helical wavefronts to form different channels. The signals were sent out simultaneously via independent channels of the orbital angular momentum. They used a frequency of 16 kilohertz, which is within the range currently used in sonar. A receiver array with 32 sensors measured the acoustic waves, and algorithms were used to decode the different patterns.

    “We modulated the amplitude and phase of each transducer to form different patterns and to generate different channels on the orbital angular momentum,” said Shi. “For our experiment we used eight channels, so instead of sending just 1 bit of data, we can send 8 bits simultaneously. In theory, however, the number of channels provided by orbital angular momentum can be much larger.”

    The researchers noted that while the experiment was done in air, the physics of the acoustic waves is very similar for water and air at this frequency range.

    Expanding the capacity of underwater communications could open up new avenues for exploration, the researchers said. This added capacity could eventually make the difference between sending a text-only message and transmitting a high-definition feature film from below the ocean’s surface. Remote probes in the oceans could send data without the need to surface.

    “We know much more about space and our universe than we do about our oceans,” said Shi. “The reason we know so little is because we don’t have the probes to easily study the deep sea. This work could dramatically speed up our research and exploration of the oceans.”

    The other researchers on this team are co-lead author Marc Dubois and co-author Yuan Wang, both members of Zhang’s group.

    This research is supported by the UC Berkeley Ernest Kuh Chair Endowment, a UC Berkeley Graduate Student Fellowship, and the Gordon and Betty Moore Foundation.

    See the full article here .

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  • richardmitnick 12:22 pm on June 27, 2017 Permalink | Reply
    Tags: 1 billion suns: World’s brightest laser sparks new behavior in light, Diocles Laser, Extreme Light Laboratory, Focusing laser light to a brightness 1 billion times greater than the surface of the sun, , , Physics, U Nebraska,   

    From U Nebraska – Lincoln: “1 billion suns: World’s brightest laser sparks new behavior in light” 

    University of Nebraska -Lincoln

    6.26.17
    Scott Schrage

    1
    A rendering of how changes in an electron’s motion (bottom) alter the scattering of light (top), as measured in a new experiment that scattered more than 500 photons of light from a single electron. Previous experiments had managed to scatter no more than a few photons at a time. Donald Umstadter and Wenchao Yan

    4
    Brighter than a billion suns: A scientist at work in the Extreme Light Laboratory. Diocles Laser.
    University of Nebraska-Lincoln. COSMOS.

    Physicists from the University of Nebraska-Lincoln are seeing an everyday phenomenon in a new light.

    By focusing laser light to a brightness 1 billion times greater than the surface of the sun — the brightest light ever produced on Earth — the physicists have observed changes in a vision-enabling interaction between light and matter.

    Those changes yielded unique X-ray pulses with the potential to generate extremely high-resolution imagery useful for medical, engineering, scientific and security purposes. The team’s findings, detailed June 26 in the journal Nature Photonics, should also help inform future experiments involving high-intensity lasers.

    Donald Umstadter and colleagues at the university’s Extreme Light Laboratory fired their Diocles Laser at helium-suspended electrons to measure how the laser’s photons — considered both particles and waves of light — scattered from a single electron after striking it.

    Under typical conditions, as when light from a bulb or the sun strikes a surface, that scattering phenomenon makes vision possible. But an electron — the negatively charged particle present in matter-forming atoms — normally scatters just one photon of light at a time. And the average electron rarely enjoys even that privilege, Umstadter said, getting struck only once every four months or so.

    Though previous laser-based experiments had scattered a few photons from the same electron, Umstadter’s team managed to scatter nearly 1,000 photons at a time. At the ultra-high intensities produced by the laser, both the photons and electron behaved much differently than usual.

    “When we have this unimaginably bright light, it turns out that the scattering — this fundamental thing that makes everything visible — fundamentally changes in nature,” said Umstadter, the Leland and Dorothy Olson Professor of Physics and Astronomy.

    A photon from standard light will typically scatter at the same angle and energy it featured before striking the electron, regardless of how bright its light might be. Yet Umstadter’s team found that, above a certain threshold, the laser’s brightness altered the angle, shape and wavelength of that scattered light.

    “So it’s as if things appear differently as you turn up the brightness of the light, which is not something you normally would experience,” Umstadter said. “(An object) normally becomes brighter, but otherwise, it looks just like it did with a lower light level. But here, the light is changing (the object’s) appearance. The light’s coming off at different angles, with different colors, depending on how bright it is.”

    That phenomenon stemmed partly from a change in the electron, which abandoned its usual up-and-down motion in favor of a figure-8 flight pattern. As it would under normal conditions, the electron also ejected its own photon, which was jarred loose by the energy of the incoming photons. But the researchers found that the ejected photon absorbed the collective energy of all the scattered photons, granting it the energy and wavelength of an X-ray.

    The unique properties of that X-ray might be applied in multiple ways, Umstadter said. Its extreme but narrow range of energy, combined with its extraordinarily short duration, could help generate three-dimensional images on the nanoscopic scale while reducing the dose necessary to produce them.

    3
    Using a laser focused to the brightest intensity yet recorded, physicists at the Extreme Light Laboratory produced unique X-ray pulses with greater energy than their conventional counterparts. The team demonstrated these X-rays by imaging the circuitry of a USB drive. Extreme Light Laboratory | University of Nebraska-Lincoln.

    Those qualities might qualify it to hunt for tumors or microfractures that elude conventional X-rays, map the molecular landscapes of nanoscopic materials now finding their way into semiconductor technology, or detect increasingly sophisticated threats at security checkpoints. Atomic and molecular physicists could also employ the X-ray as a form of ultrafast camera to capture snapshots of electron motion or chemical reactions.

    As physicists themselves, Umstadter and his colleagues also expressed excitement for the scientific implications of their experiment. By establishing a relationship between the laser’s brightness and the properties of its scattered light, the team confirmed a recently proposed method for measuring a laser’s peak intensity. The study also supported several longstanding hypotheses that technological limitations had kept physicists from directly testing.

    “There were many theories, for many years, that had never been tested in the lab, because we never had a bright-enough light source to actually do the experiment,” Umstadter said. “There were various predictions for what would happen, and we have confirmed some of those predictions.

    “It’s all part of what we call electrodynamics. There are textbooks on classical electrodynamics that all physicists learn. So this, in a sense, was really a textbook experiment.”

    Umstadter authored the study with Sudeep Banerjee and Shouyuan Chen, research associate professors of physics and astronomy; Grigory Golovin and Cheng Liu, senior research associates in physics and astronomy; Wenchao Yan, Ping Zhang, Baozhen Zhao and Jun Zhang, postdoctoral researchers in physics and astronomy; Colton Fruhling and Daniel Haden, doctoral students in physics and astronomy; along with Min Chen and Ji Luo of Shanghai Jiao Tong University.

    The team received support from the Air Force Office for Scientific Research, the National Science Foundation, the U.S. Department of Energy’s Office of Science, the Department of Homeland Security’s Domestic Nuclear Detection Office, and the National Science Foundation of China.

    See the full article here .

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    The University of Nebraska–Lincoln, often referred to as Nebraska, UNL or NU, is a public research university in the city of Lincoln, in the state of Nebraska in the Midwestern United States. It is the state’s oldest university, and the largest in the University of Nebraska system.

    The state legislature chartered the university in 1869 as a land-grant university under the 1862 Morrill Act, two years after Nebraska’s statehood into the United States. Around the turn of the 20th century, the university began to expand significantly, hiring professors from eastern schools to teach in the newly organized professional colleges while also producing groundbreaking research in agricultural sciences. The “Nebraska method” of ecological study developed here during this time pioneered grassland ecology and laid the foundation for research in theoretical ecology for the rest of the 20th century. The university is organized into eight colleges on two campuses in Lincoln with over 100 classroom buildings and research facilities.

    Its athletic program, called the Cornhuskers, is a member of the Big Ten Conference. The Nebraska football team has won 46 conference championships, and since 1970, five national championships. The women’s volleyball team has won four national championships along with eight other appearances in the Final Four. The Husker football team plays its home games at Memorial Stadium, selling out every game since 1962. The stadium’s capacity is about 92,000 people, larger than the population of Nebraska’s third-largest city.

     
  • richardmitnick 7:36 pm on June 26, 2017 Permalink | Reply
    Tags: , Electromagnetic radiation [light], Hyperbolic metamaterials (HMMs), Molecular beam epitaxy, Nanoresonators, , , Physics, ,   

    From Notre Dame: “Notre Dame Researchers Open Path to New Generation of Optical Devices” 

    Notre Dame bloc

    Notre Dame University

    COLLEGE of ENGINEERING

    OFFICE of the PROVOST
    College of Engineering

    June 22, 2017
    Nina Welding

    1
    Sub-diffraction Confinement in All-semiconductor Hyperbolic Metamaterial Resonators was co-authored by graduate students Kaijun Feng and Galen Harden and Deborah L. Sivco, engineer-in-residence at MIRTHE+ Photonics Sensing Center, Princeton Univ.

    Cameras, telescopes and microscopes are everyday examples of optical devices that measure and manipulate electromagnetic radiation [light]. Being able to control the light in such devices provides the user with more information through a much better “picture” of what is occurring through the lens. The more information one can glean, the better the next generation of devices can become. Similarly, controlling light on small scales could lead to improved optical sources for applications that span health, homeland security and industry. This is what a team of researchers, led by Anthony Hoffman, assistant professor of electrical engineering and researcher in the University’s Center for Nano Science and Technology (NDnano), has been pursuing. Their findings were recently published in the June 19 issue of ACS Photonics.

    In fact, the team has fabricated and characterized sub-diffraction mid-infrared resonators using all-semiconductor hyperbolic metamaterials (HMMs) that confine light to extremely small volumes — thousands of times smaller than common materials.

    2
    The scanning electron microscope image here shows an array of 0.47 μm wide resonators with a 2.5 μm pitch. No image credit.

    HMMs combine the properties of metals, which are excellent conductors, and dielectrics, which are insulators, to realize artificial optical materials with properties that are very difficult, even impossible, to find naturally. These unusual properties may elucidate the quantum mechanical interactions between light and matter at the nanoscale while giving researchers a powerful tool to control and engineer these light-matter interactions for new optical devices and materials.

    Hoffman’s team engineered these desired properties in the HMMs by growing them via molecular beam epitaxy using III-V semiconductor materials routinely used for high-performance optoelectronic devices, such as lasers and detectors. Layers of Si-doped InGaAs and intrinsic AlInAs were placed on top of one another, with a single layer being 50 nm thick. The total thickness of the HMM was 1μm, about 100 times smaller than the width of a human hair.

    The nanoresonators were produced by Kaijun Feng, graduate student in the Department of Electrical Engineering, using state-of-the-art fabrication equipment in Notre Dame’s Nanofabrication Facility. The devices were then characterized in Hoffman’s laboratory using a variety of spectroscopic techniques.

    “What is particularly exciting about this work,” says Hoffman, “is that we have found a way to squeeze light into small volumes using a mature semiconductor technology. In addition to being able to employ these nanoresonators to generate mid-infrared light, we believe that these new sources could have significant application in the mid-infrared portion of the spectrum, which is used for optical sensing across areas such as medicine, environmental monitoring, industrial process control and defense. We are also excited about the possibility of utilizing these nanoresonators to study interactions between light and matter that previously have not been possible.”

    See the full article here .

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    Notre Dame Campus

    The University of Notre Dame du Lac (or simply Notre Dame /ˌnoʊtərˈdeɪm/ NOH-tər-DAYM) is a Catholic research university located near South Bend, Indiana, in the United States. In French, Notre Dame du Lac means “Our Lady of the Lake” and refers to the university’s patron saint, the Virgin Mary.

    The school was founded by Father Edward Sorin, CSC, who was also its first president. Today, many Holy Cross priests continue to work for the university, including as its president. It was established as an all-male institution on November 26, 1842, on land donated by the Bishop of Vincennes. The university first enrolled women undergraduates in 1972. As of 2013 about 48 percent of the student body was female.[6] Notre Dame’s Catholic character is reflected in its explicit commitment to the Catholic faith, numerous ministries funded by the school, and the architecture around campus. The university is consistently ranked one of the top universities in the United States and as a major global university.

    The university today is organized into five colleges and one professional school, and its graduate program has 15 master’s and 26 doctoral degree programs.[7][8] Over 80% of the university’s 8,000 undergraduates live on campus in one of 29 single-sex residence halls, each of which fields teams for more than a dozen intramural sports, and the university counts approximately 120,000 alumni.[9]

    The university is globally recognized for its Notre Dame School of Architecture, a faculty that teaches (pre-modernist) traditional and classical architecture and urban planning (e.g. following the principles of New Urbanism and New Classical Architecture).[10] It also awards the renowned annual Driehaus Architecture Prize.

     
  • richardmitnick 7:19 pm on June 26, 2017 Permalink | Reply
    Tags: , , It is a dream come true to follow in such detail how a glassy state of water transforms into a viscous liquid which almost immediately transforms to a different even more viscous liquid of much lower , , Physics, Stockholm University, The pioneer of X-ray radiation Wolfgang Röntgen himself speculated that water can exist in two different forms, Water exists as two different liquids   

    From phys.org: “Water exists as two different liquids” 

    physdotorg
    phys.org

    June 26, 2017

    1
    Artist’s impression of the two forms of ultra-viscous liquid water with different density. On the background is depicted the x-ray speckle pattern taken from actual data of high-density amorphous ice, which is produced by pressurizing water at very low temperatures. Credit: Mattias Karlén

    We normally consider liquid water as disordered with the molecules rearranging on a short time scale around some average structure. Now, however, scientists at Stockholm University have discovered two phases of the liquid with large differences in structure and density.

    2

    The results are based on experimental studies using X-rays, which are now published in Proceedings of the National Academy of Science (US).

    Most of us know that water is essential for our existence on planet Earth. It is less well-known that water has many strange or anomalous properties and behaves very differently from all other liquids. Some examples are the melting point, the density, the heat capacity, and all-in-all there are more than 70 properties of water that differ from most liquids. These anomalous properties of water are a prerequisite for life as we know it.

    “The new remarkable property is that we find that water can exist as two different liquids at low temperatures where ice crystallization is slow”, says Anders Nilsson, professor in Chemical Physics at Stockholm University. The breakthrough in the understanding of water has been possible through a combination of studies using X-rays at Argonne National Laboratory near Chicago, where the two different structures were evidenced and at the large X-ray laboratory DESY in Hamburg where the dynamics could be investigated and demonstrated that the two phases indeed both were liquid phases. Water can thus exist as two different liquids.


    ANL/APS

    DESY Petra III


    DESY Helmholtz Centres & Networks

    “It is very exciting to be able to use X-rays to determine the relative positions between the molecules at different times”, says Fivos Perakis, postdoc at Stockholm University with a background in ultrafast optical spectroscopy. “We have in particular been able to follow the transformation of the sample at low temperatures between the two phases and demonstrated that there is diffusion as is typical for liquids”.

    When we think of ice it is most often as an ordered, crystalline phase that you get out of the ice box, but the most common form of ice in our planetary system is amorphous, that is disordered, and there are two forms of amorphous ice with low and high density. The two forms can interconvert and there have been speculations that they can be related to low- and high-density forms of liquid water. To experimentally investigate this hypothesis has been a great challenge that the Stockholm group has now overcome.

    “I have studied amorphous ices for a long time with the goal to determine whether they can be considered a glassy state representing a frozen liquid”, says Katrin Amann-Winkel, researcher in Chemical Physics at Stockholm University. “It is a dream come true to follow in such detail how a glassy state of water transforms into a viscous liquid which almost immediately transforms to a different, even more viscous, liquid of much lower density”.

    “The possibility to make new discoveries in water is totally fascinating and a great inspiration for my further studies”, says Daniel Mariedahl, PhD student in Chemical Physics at Stockholm University. “It is particularly exciting that the new information has been provided by X-rays since the pioneer of X-ray radiation, Wolfgang Röntgen, himself speculated that water can exist in two different forms and that the interplay between them could give rise to its strange properties”.

    “The new results give very strong support to a picture where water at room temperature can’t decide in which of the two forms it should be, high or low density, which results in local fluctuations between the two”, says Lars G.M. Pettersson, professor in Theoretical Chemical Physics at Stockholm University. “In a nutshell: Water is not a complicated liquid, but two simple liquids with a complicated relationship.”

    These new results not only create an overall understanding of water at different temperatures and pressures, but also how water is affected by salts and biomolecules important for life. In addition, the increased understanding of water can lead to new insights on how to purify and desalinate water in the future. This will be one of the main challenges to humanity in view of the global climate change.

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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 5:11 pm on June 26, 2017 Permalink | Reply
    Tags: , , Electron beam lithography, Halide perovskites, , , Physics,   

    From LBNL: “New Class of ‘Soft’ Semiconductors Could Transform HD Displays” 

    Berkeley Logo

    Berkeley Lab

    June 26, 2017
    Sarah Yang
    scyang@lbl.gov
    (510) 486-4575

    A new type of semiconductor may be coming to a high-definition display near you. Scientists at the Department of Energy’s Lawrence Berkeley National Laboratory (LBNL) have shown that a class of semiconductor called halide perovskites is capable of emitting multiple, bright colors from a single nanowire at resolutions as small as 500 nanometers.

    1
    Single nanowires shown emitting different colors. The top panel shows a cesium lead bromide (CsPbBr3)-cesium lead chloride (CsPbCl3) heterojunction simultaneously emitting green and blue lights, respectively, under UV excitation. The bottom panel shows a cesium lead iodide (CsPbI3)-cesium lead bromide-cesium lead chloride configuration emitting red, green, and blue lights, respectively. (Credit: Letian Dou/Berkeley Lab and Connor G. Bischak/UC Berkeley)

    The findings, published online this week in the early edition of the Proceedings of the National Academy of Sciences, represent a clear challenge to quantum dot displays that rely upon traditional semiconductor nanocrystals to emit light. It could also influence the development of new applications in optoelectronics, photovoltaics, nanoscopic lasers, and ultrasensitive photodetectors, among others.

    The researchers used electron beam lithography to fabricate halide perovskite nanowire heterojunctions, the junction of two different semiconductors. In device applications, heterojunctions determine energy level and bandgap characteristics, and are therefore considered a key building block of modern electronics and photovoltaics.

    The researchers pointed out that the lattice in halide perovskites is held together by ionic instead of covalent bonds. In ionic bonds, atoms of opposite charges are attracted and transfer electrons to each other. Covalent bonds, in contrast, occur when atoms share their electrons with each other.

    “With inorganic halide perovskites, we can easily swap the anions in the ionic bonds while maintaining the single crystalline nature of the materials,” said study principal investigator Peidong Yang, senior faculty scientist at Berkeley Lab’s Materials Sciences Division. “This allows us to easily reconfigure the structure and composition of the material. That’s why halide perovskites are considered soft lattice semiconductors. Covalent bonds, in contrast, are relatively robust and require more energy to change. Our study basically showed that we can pretty much change the composition of any segment of this soft semiconductor.”

    2
    A 2-D plate showing alternating cesium lead chloride (blue) and cesium lead bromide (green) segments. (Credit: Letian Dou/Berkeley Lab and Connor G. Bischak/UC Berkeley)

    In this case, the researchers tested cesium lead halide perovskite, and then they used a common nanofabrication technique combined with anion exchange chemistry to swap out the halide ions to create cesium lead iodide, cesium lead bromide, and cesium lead chloride perovskites.

    Each variation resulted in a different color emitted. Moreover, the researchers showed that multiple heterojunctions could be engineered on a single nanowire. They were able to achieve a pixel size down to 500 nanometers, and they determined that the color of the material was tunable throughout the entire range of visible light.

    The researchers said that the chemical solution-processing technique used to treat this class of soft, ionic-bonded semiconductors is far simpler than methods used to manufacture traditional colloidal semiconductors.

    “For conventional semiconductors, fabricating the junction is quite complicated and expensive,” said study co-lead author Letian Dou, who conducted the work as a postdoctoral fellow in Yang’s lab. “High temperatures and vacuum conditions are usually involved to control the materials’ growth and doping. Precisely controlling the materials composition and property is also challenging because conventional semiconductors are ‘hard’ due to strong covalent bonding.”

    To swap the anions in a soft semiconductor, the material is soaked in a special chemical solution at room temperature.

    “It’s a simple process, and it is very easy to scale up,” said Yang, who is also a professor of chemistry at UC Berkeley. “You don’t need to spend long hours in a clean room, and you don’t need high temperatures.”

    The researchers are continuing to improve the resolution of these soft semiconductors, and are working to integrate them into an electric circuit.

    Other co-lead authors on this paper are Christopher Kley, UC Berkeley postdoctoral fellow, and Minliang Lai, UC Berkeley graduate student. Dou is now an assistant professor of chemical engineering at Purdue University.

    The DOE Office of Science supported this work.

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  • richardmitnick 1:09 pm on June 24, 2017 Permalink | Reply
    Tags: , , , , , It all started from humble beginnings, Physics, Scientists make waves with black hole research, , What is superradiance?   

    From U Nottingham : “Scientists make waves with black hole research” 

    1

    University of Nottingham

    14 Jun 2017
    Jane Icke
    Media Relations Manager (Faculty of Science)
    jane.icke@nottingham.ac.uk
    +44 (0)115 951 5751
    University Park

    Dr Silke Weinfurtner, in the School of Mathematicson
    +44 (0) 115 9513865,
    silke.weinfurtner@nottingham.ac.uk

    Lindsay Brooke
    Media Relations Managers for the Faculty of Science
    +44 (0)115 951 5751
    lindsay.brooke@nottingham.ac.uk

    1
    A groundbreaking experiment has allowed researchers to simulate the dissipation of energy around a black hole using waves generated in the lab. University of Nottingham

    Scientists at the University of Nottingham have made a significant leap forward in understanding the workings of one of the mysteries of the universe. They have successfully simulated the conditions around black holes using a specially designed water bath.

    Their findings shed new light on the physics of black holes with the first laboratory evidence of the phenomenon known as the superradiance, achieved using water and a generator to create waves.

    The research – Rotational superradiant scattering in a vortex flow – has been published in Nature Physics. It was undertaken by a team in the Quantum Gravity Laboratory in the School of Physics and Astronomy.

    The work was led by Silke Weinfurtner from the School of Mathematical Sciences. In collaboration with an interdisciplinary team she designed and built the black hole ‘bath’ and measurement system to simulate black hole conditions.

    Dr Weinfurtner said: “This research has been particularly exciting to work on as it has bought together the expertise of physicists, engineers and technicians to achieve our common aim of simulating the conditions of a black hole and proving that superadiance exists. We believe our results will motivate further research on the observation of superradiance in astrophysics.”

    What is superradiance?

    The Nottingham experiment was based on the theory that an area immediately outside the event horizon of a rotating black hole – a black hole’s gravitational point of no return – will be dragged round by the rotation and any wave that enters this region, but does not stray past the event horizon, should be deflected and come out with more energy than it carried on the way in – an effect known as superradiance.

    Superadiance – the extraction of energy from a rotating black hole – is also known as the Penrose Mechanism and is a precursor of Hawking Radiation – a quantum version of black-hole superradiance.

    What’s in the Black Hole Lab?

    Dr Weinfurtner said: “Some of the bizzare black hole phenomena are hard, if not, impossible to study directly. This means there are very limited experimental possibilities. So this research is quite an achievement.”

    The ‘flume’, is specially designed 3m long, 1.5m wide and 50cm deep bath with a hole in the centre. Water is pumped in a closed circuit to establish a rotating draining flow. Once at the desired depth waves were generated at varied frequenices until the supperadiant scattering effect is created and recorded using a specially designed 3D air fluid interface sensor.

    Tiny dots of white paper punched out by a specially adapted sewing machine were used to measure the flow field – the speed of the fluid flow around the analogue black hole.

    It all started from humble beginnings

    This research has been many years in the making. The initial idea for creating a supperradiant effect with water started with a bucket and bidet. Dr Weinfurtner said: “This research has grown from humble beginnings. I had the initial idea for a water based experiment when I was at the International School for Advanced Studies (SISSA) in Italy and I set up an experiment with a bucket and a bidet. However, when it caused a flood I was quickly found a lab to work in!

    After her postdoc, Dr Weinfurtner went on to work with Bill Unruh, the Canadian born physicist who also has a made seminal contributions to our understanding of gravity, black holes, cosmology, quantum fields in curved spaces, and the foundations of quantum mechanics, including the discovery of the Unruh effect.

    Her move to the University of Nottingham accelerated her research as she was able to set up her own research group with support from the machine shop in the School of Physics and Astronomy.

    This research is funded by the Engineering and Physical Sciences Research Council, the Royal Society and the University of Nottingham.

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    2

    “The University of Nottingham shares many of the characteristics of the world’s great universities. However, we are distinct not only in our key strengths but in how our many strengths combine: we are financially secure, campus based and comprehensive; we are research-led and recruit top students and staff from around the world; we are committed to internationalising all our core activities so our students can have a valuable and enjoyable experience that prepares them well for the rest of their intellectual, professional and personal lives.”

     
  • richardmitnick 4:16 pm on June 23, 2017 Permalink | Reply
    Tags: Broadband light harvesting and energy storage, broadband optical camouflaging (“invisibility cloaking”), Casting aside reciprocity, , Medicine and the environment and telecommunications, More electromagnetic energy can be stored in wave-guiding systems than previously thought, On-chip spectroscopy, Physics, Q factor at Western Electric, The trick was to create asymmetric resonant or wave-guiding systems using magnetic fields   

    From EPFL: “A 100-year-old physics problem has been solved at EPFL” 

    EPFL bloc

    École Polytechnique Fédérale de Lausanne EPFL

    1
    Generic image illustrating wave-interference and resonant energy transfer from
    one source to another distant source or object, pertaining to the fundamental concept of
    resonances. No image credit.

    23.06.17
    Laure-Anne Pessina

    EPFL researchers have found a way around what was considered a fundamental limitation of physics for over 100 years. They were able to conceive resonant systems that can store electromagnetic waves over a long period of time while maintaining a broad bandwidth. Their study, which has just been published in Science, opens up a number of doors, particularly in telecommunications.

    At EPFL, researchers challenge a fundamental law and discover that more electromagnetic energy can be stored in wave-guiding systems than previously thought. The discovery has implications in telecommunications. Working around the fundamental law, they conceived resonant and wave-guiding systems capable of storing energy over a prolonged period while keeping a broad bandwidth. Their trick was to create asymmetric resonant or wave-guiding systems using magnetic fields.

    The study, which has just been published in Science, was led by Kosmas Tsakmakidis, first at the University of Ottawa and then at EPFL’s Bionanophotonic Systems Laboratory run by Hatice Altug, where the researcher is now doing post-doctoral research.

    This breakthrough could have a major impact on many fields in engineering and physics. The number of potential applications is close to infinite, with telecommunications, optical detection systems and broadband energy harvesting representing just a few examples.

    Casting aside reciprocity

    Resonant and wave-guiding systems are present in the vast majority of optical and electronic systems. Their role is to temporarily store energy in the form of electromagnetic waves and then release them. For more than 100 hundred years, these systems were held back by a limitation that was considered to be fundamental: the length of time a wave could be stored was inversely proportional to its bandwidth. This relationship was interpreted to mean that it was impossible to store large amounts of data in resonant or wave-guiding systems over a long period of time because increasing the bandwidth meant decreasing the storage time and quality of storage.

    This law was first formulated by K. S. Johnson in 1914, at Western Electric Company (the forerunner of Bell Telephone Laboratories). He introduced the concept of the Q factor, according to which a resonator can either store energy for a long time or have a broad bandwidth, but not both at the same time. Increasing the storage time meant decreasing the bandwidth, and vice versa. A small bandwidth means a limited range of frequencies (or ‘colors’) and therefore a limited amount of data.

    Until now, this concept had never been challenged. Physicists and engineers had always built resonant systems – like those to produce lasers, make electronic circuits and conduct medical diagnoses – with this constraint in mind.

    But that limitation is now a thing of the past. The researchers came up with a hybrid resonant / wave-guiding system made of a magneto-optic material that, when a magnetic field is applied, is able to stop the wave and store it for a prolonged period, thereby accumulating large amounts of energy. Then when the magnetic field is switched off, the trapped pulse is released.

    With such asymmetric and non-reciprocal systems, it was possible to store a wave for a very long period of time while also maintaining a large bandwidth. The conventional time-bandwidth limit was even beaten by a factor of 1,000. The scientists further showed that, theoretically, there is no upper ceiling to this limit at all in these asymmetric (non-reciprocal) systems.

    “It was a moment of revelation when we discovered that these new structures did not feature any time-bandwidth restriction at all. These systems are unlike what we have all been accustomed to for decades, and possibly hundreds of years», says Tsakmakidis, the study’s lead author. “Their superior wave-storage capacity performance could really be an enabler for a range of exciting applications in diverse contemporary and more traditional fields of research.” Hatice Altug adds.

    Medicine, the environment and telecommunications

    One possible application is in the design of extremely quick and efficient all-optical buffers in telecommunication networks. The role of the buffers is to temporarily store data arriving in the form of light through optical fibers. By slowing the mass of data, it is easier to process. Up to now, the storage quality had been limited.+

    With this new technique, it should be possible to improve the process and store large bandwidths of data for prolonged times. Other potential applications include on-chip spectroscopy, broadband light harvesting and energy storage, and broadband optical camouflaging (“invisibility cloaking”). “The reported breakthrough is completely fundamental – we’re giving researchers a new tool. And the number of applications is limited only by one’s imagination,” sums up Tsakmakidis.

    —–

    Source: Breaking Lorentz reciprocity to overcome the time-bandwidth limit in physics and engineering

    Cover image capture: Generic image illustrating wave-interference and resonant energy transfer from
    one source to another distant source or object, pertaining to the fundamental concept of
    resonances.

    Study conducted by:

    Kosmas Tsakmakidis, lead author, former researcher at the University of Ottawa and currently an EPFL Fellow in EPFL’s Bionanophotonic Systems Laboratory
    Linfang Shen and collaborators, Institute of Space Science and Technology, Nanchang University, Nanchang, China and State Key Laboratory of Modern Optical Instrumentation, Zhejiang University, Hangzhou, China
    Prof. Robert Boyd and collaborators, University of Ottawa
    Prof. Hatice Altug, director of EPFL’s Bionanophotonic Systems Laboratory
    Prof. Alexandre Vakakis, University of Illinois at Urbana-Champaign

    See the full article here .

    Please help promote STEM in your local schools.

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    EPFL campus

    EPFL is Europe’s most cosmopolitan technical university with students, professors and staff from over 120 nations. A dynamic environment, open to Switzerland and the world, EPFL is centered on its three missions: teaching, research and technology transfer. EPFL works together with an extensive network of partners including other universities and institutes of technology, developing and emerging countries, secondary schools and colleges, industry and economy, political circles and the general public, to bring about real impact for society.

     
  • richardmitnick 1:35 pm on June 23, 2017 Permalink | Reply
    Tags: , , , , Magnetic materials, Magnetocaloric effect, , Physics   

    From Ames Lab- “Scientists’ surprising discovery: making ferromagnets stronger by adding non-magnetic element” 


    Ames Laboratory

    June 23, 2017
    Yaroslav Mudryk
    Division of Materials Science and Engineering
    (515) 294-2728
    slovkomk@ameslab.gov

    Durga Paudyal
    Division of Materials Science and Engineering
    (515)-294-2041
    durga@ameslab.gov

    Laura Millsaps
    Ames Laboratory Public Affairs
    (515) 294-3474
    millsaps@ameslab.gov

    1
    No image caption or credit.

    Researchers at the U.S. Department of Energy’s Ames Laboratory discovered that they could functionalize magnetic materials through a thoroughly unlikely method, by adding amounts of the virtually non-magnetic element scandium to a gadolinium-germanium alloy.

    It was so unlikely they called it a “counterintuitive experimental finding” in their published work on the research.

    “People don’t talk much about scandium when they are talking magnetism, because there has not been much reason to,” said Yaroslav Mudryk, an Associate Scientist at Ames Laboratory. “It’s rare, expensive, and displays virtually no magnetism.”

    “Conventional wisdom says if you take compound A and compound B and combine them together, most commonly you get some combination of the properties of each. In the case of the addition of scandium to gadolinium, however, we observed an abrupt anomaly.”

    Years of research exploring the properties of magnetocaloric materials, relating back to the discovery of the giant magnetocaloric effect in rare earth alloys in 1997 by Vitalij Pecharsky and the late Karl Gschneidner, Jr., laid the groundwork for computational theory to begin “hunting” for hidden properties in magnetic rare-earth compounds that could be discovered by introducing small amounts of other elements, altering the electronic structure of known materials.

    “From computations, we projected that scandium may bring something really unusual to the table: we saw an unexpectedly large magnetic moment developing on its lone 3d electron,” said Ames Laboratory Associate Scientist Durga Paudyal. “It is the hybridization between gadolinium 5d and the scandium 3d states that is the key that strengthens magnetism with the scandium and transforms it to a ferromagnetic state.”

    “Basic research takes time to bear fruit. This is an exemplary case when 20 years ago our team started looking into what are called the 5:4 compounds,” said Ames Laboratory group leader and Iowa State University Distinguished Professor Vitalij Pecharsky. “Only now we have learned enough about these unique rare earth element-containing materials to become not only comfortable but precise in predicting how to manipulate their properties at will.”

    The discovery could greatly change the way scandium and other ‘conventionally’ non-magnetic elements are considered and used in magnetic materials research and development, and possibly creates new tools for controlling, manipulating, and functionalizing useful magnetic rare-earth compounds.

    The research is further discussed in the paper, Enhancing Magnetic Functionality with Scandium: Breaking Stereotypes in the Design of Rare Earth Materials, authored by Yaroslav Mudryk, Durga Paudyal, Jing Liu, and Vitalij K. Pecharsky; and published in the Chemistry of Materials.

    The work was supported by the U.S. Department of Department of Energy’s Office of Science.

    Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.

    DOE’s Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit http://science.energy.gov.

    See the full article here .

    Please help promote STEM in your local schools.
    STEM Icon
    Stem Education Coalition

    Ames Laboratory is a government-owned, contractor-operated research facility of the U.S. Department of Energy that is run by Iowa State University.

    For more than 60 years, the Ames Laboratory has sought solutions to energy-related problems through the exploration of chemical, engineering, materials, mathematical and physical sciences. Established in the 1940s with the successful development of the most efficient process to produce high-quality uranium metal for atomic energy, the Lab now pursues a broad range of scientific priorities.

    Ames Laboratory is a U.S. Department of Energy Office of Science national laboratory operated by Iowa State University. Ames Laboratory creates innovative materials, technologies and energy solutions. We use our expertise, unique capabilities and interdisciplinary collaborations to solve global problems.

    Ames Laboratory is supported by the Office of Science of the U.S. Department of Energy. The Office of Science is the single largest supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.
    DOE Banner

    DOE Banner

     
  • richardmitnick 4:01 pm on June 22, 2017 Permalink | Reply
    Tags: , , , Physics, The history of the web at FNAL   

    From FNAL: “Fermilab celebrates its website’s 25th anniversary” 

    FNAL II photo

    FNAL Art Image
    FNAL Art Image by Angela Gonzales

    Fermilab is an enduring source of strength for the US contribution to scientific research world wide.

    June 21, 2017
    No writer credit found

    Twenty-five years ago this month, Fermilab stood up its first website — one of the earliest websites in the United States.

    The World Wide Web was born at CERN in Europe in 1989 as a tool for exchanging particle physics data. The first U.S. web server was created at Stanford Linear Accelerator Center in December 1991.

    In June 1992, Fermilab’s Computing Division installed its first web server. In late 1992, Computing Division staff created Fermilab’s first HTML page.
    1992
    1

    In 1992, the National Center for Supercomputing Applications at the University of Illinois launched Mosaic, a graphical interface web browser that made the web navigable for people without computer expertise. In February 1994, Fermilab created the laboratory’s first pages designed for the public.

    1994
    2

    In August 1996, the laboratory redesigned its growing volume of public webpages.

    1996
    3

    A complete overhaul of the Fermilab website appeared on March 1, 2001, and its design and the technology behind its webpages has been updated several times since then:

    2001
    3

    2004
    4

    2006
    5

    2009
    6

    2014
    7

    2017
    8

    See the full article here .

    Please help promote STEM in your local schools.

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    FNAL Icon
    Fermilab Campus

    Fermi National Accelerator Laboratory (Fermilab), located just outside Batavia, Illinois, near Chicago, is a US Department of Energy national laboratory specializing in high-energy particle physics. Fermilab is America’s premier laboratory for particle physics and accelerator research, funded by the U.S. Department of Energy. Thousands of scientists from universities and laboratories around the world
    collaborate at Fermilab on experiments at the frontiers of discovery.

     
  • richardmitnick 3:23 pm on June 22, 2017 Permalink | Reply
    Tags: African School works to develop local expertise, Physics, Symmetry, The African School of Fundamental Physics and Applications   

    From Symmetry: “African School works to develop local expertise” 

    Symmetry Mag

    Symmetry

    06/22/17
    Mike Perricone

    1
    Artwork by Sandbox Studio, Chicago

    Universities in sub-Saharan Africa are teaming up to offer free training to students interested in fundamental physics.

    Last Feremenga was born in a small town in Zimbabwe. As a high school student in a specialized school in the capital, Harare, he was drawn to the study of physics.

    “Physics was at the top of my list of potential academic fields to pursue,” he says.

    But with limited opportunities nearby, that was going to require a lot of travel.

    With help from the US Education Assistance Center at the American Embassy in Harare, Feremenga was accepted at the University of Chicago in 2007.

    As an undergraduate, he conducted research for a year at the nearby US Department of Energy’s Fermi National Accelerator Laboratory [FNAL].

    Then, through the University of Texas at Arlington, he became one of just a handful of African nationals to conduct research as a user at European research center CERN.

    1

    Feremenga joined the ATLAS experiment at the Large Hadron Collider.

    CERN/ATLAS detector

    He spent his grad-school years traveling between CERN and Argonne National Laboratory near Chicago, analyzing hundreds of terabytes of ATLAS data.

    “I became interested in solving problems across diverse disciplines, not just physics,” he says.

    “At CERN and Argonne, I assisted in developing a system that filters interesting events from large data-sets. I also analyzed these large datasets to find interesting physics patterns.”

    3
    The African School of Fundamental Physics and Applications. No image credit

    In December 2016, he received his PhD. In February 2017, he accepted a job at technology firm Digital Reasoning in Nashville, Tennessee.

    To pursue particle physics, Feremenga needed to spend the entirety of his higher education outside Zimbabwe. Only one activity brought him even within the same continent as his home: the African School of Fundamental Physics and Applications. Feremenga attended the school in the program’s inaugural year at South Africa’s Stellenbosch University.

    4

    The ASP received funding for a year from France’s Centre National de la Recherche Scientific (CNRS) in 2008.

    Since then, major supporters among 20 funding institutions have included the International Center for Theoretical Physics (ICTP) in Trieste, Italy; the South African National Research Foundation, and department of Science and Technology; and the South African Institute of Physics. Other major supporters have included CERN, the US National Science Foundation and the University of Rwanda.

    The free, three-week ASP has been held bi-annually since 2010. Targeting students in sub-Saharan Africa, the school has been held in South Africa, Ghana, Senegal and Rwanda. The 2018 School is slated to take place in Namibia. Thanks to outreach efforts, applications have risen from 125 in 2010 to 439 in 2016.

    5
    The African School of Fundamental Physics and Applications. No image credit

    The free, three-week ASP has been held bi-annually since 2010. Targeting students in sub-Saharan Africa, the school has been held in South Africa, Ghana, Senegal and Rwanda. The 2018 School is slated to take place in Namibia. Thanks to outreach efforts, applications have risen from 125 in 2010 to 439 in 2016.

    The 50 to 80 students selected for the school must have a minimum of a 3-year university education in math, physics, engineering and/or computer science. The first week of the school focuses on theoretical physics; the second week, experimental physics; the third week, physics applications and high-performance computing.

    School organizers stay in touch to support alumni in pursuing higher education, says organizer Ketevi Assamagan. “We maintain contact with the students and help them as much as we can,” Assamagan says. “ASP alumni are pursuing higher education in Africa, Asia, Europe and the US.”

    Assamagan, originally from Togo but now a US citizen, worked on the Higgs hunt with the ATLAS experiment. He is currently at Brookhaven National Lab in New York, which supports him devoting 10 percent of his time to the ASP.

    While sub-Saharan countries are just beginning to close the gap in physics, there is one well-established accelerator complex in South Africa, operated by the iThemba LABS of Cape Town and Johannesburg. The 30-year-old Separated-Sector Cyclotron, which primarily produces particle beams for nuclear research and for training at the postdoc level, is the largest accelerator of its kind in the southern hemisphere.

    7
    Separated-Sector Cyclotron

    Jonathan Dorfan, former Director of SLAC National Accelerator Laboratory and a native of South Africa, attended University of Cape Town.

    8

    Dorfan recalls that after his Bachelor’s and Master’s degrees, the best PhD opportunities were in the US or Britain. He says he’s hopeful that that outlook could one day change.

    Organizers of the African School of Fundamental Physics and Applications continue reaching out to students on the continent in the hopes that one day, someone like Feremenga won’t have to travel across the world to pursue particle physics.

    See the full article here .

    Please help promote STEM in your local schools.

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    Symmetry is a joint Fermilab/SLAC publication.


     
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