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  • richardmitnick 8:59 am on July 30, 2019 Permalink | Reply
    Tags: A team of physicists at University of Illinois at Chicago and the University of Hamburg have taken a different approach., Entangled Majorana quasiparticles produced by splitting an electron into two halves are surprisingly stable., , , Majorana quasiparticles, , , , , , , They remember how they've been moved around a property that could be exploited for storing information., They've started with a rhenium superconductor a material that conducts electricity with zero resistance when supercooled to around 6 Kelvin (–267°C; 449°F)., , , U illinois Chicago   

    From University of Illinois and U Hamburg, via Science Alert: “An Elusive Particle That Acts as Its Own Antiparticle Has Just Been Imaged” 

    U Illinois bloc

    From University of Illinois Chicago

    and

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    U Hamburg

    via

    30 JULY 2019
    MICHELLE STARR

    3
    (Palacio-Morales et al. Science Advances, 2019)

    New images of the Majorana fermion have brought physicists a step closer to harnessing the mysterious objects for quantum computing.

    These strange objects – particles that acts as their own antiparticles – have a vast as-yet untapped potential to act as qubits, the quantum bits that are the basic units of information in a quantum computer.

    IBM iconic image of Quantum computer

    They’re equivalent to binary bits in a traditional computer. But, where regular bits can represent a 1 or a 0, qubits can be either 1, 0 or both at the same time, a state known as quantum superposition. Quantum superposition is actually pretty hard to maintain, although we’re getting better at it.

    This is where Majorana quasiparticles come in. These are excitations in the collective behaviour of electrons that act like Majorana fermions, and they have a number of properties that make them an attractive candidate for qubits.

    Normally, a particle and an antiparticle will annihilate each other, but entangled Majorana quasiparticles produced by splitting an electron into two halves are surprisingly stable. In addition, they remember how they’ve been moved around, a property that could be exploited for storing information.

    But the quasiparticles have to remain separated by a sufficient distance. This can be done with a special nanowire, but a team of physicists at the University of Illinois at Chicago and the University of Hamburg in Germany have taken a different approach.

    They’ve started with a rhenium superconductor, a material that conducts electricity with zero resistance when supercooled to around 6 Kelvin (–267°C; 449°F).

    On top of these superconductors, the researchers deposited nanoscale islands of single layers of magnetic iron atoms. This creates what is known as a topological superconductor – that is, a superconductor that contains a topological knot.

    “This topological knot is similar to the hole in a donut,” explained physicist Dirk Morr of the University of Illinois at Chicago.

    “You can deform the donut into a coffee mug without losing the hole, but if you want to destroy the hole, you have to do something pretty dramatic, such as eating the donut.”

    When electrons flow through the superconductor, the team predicted that Majorana fermions would appear in a one-dimensional mode at the edges of the iron islands – around the so-called donut hole. And that by using a scanning tunneling microscope – an instrument used for imaging surfaces at the atomic level – they would see this visualised as a bright line.

    Sure enough, a bright line showed up.

    It’s not the first time Majorana fermions have been imaged, but it does represent a step forward. And just last month, a different team of researchers revealed that they had been able to turn Majorana quasiparticles on and off.

    But being able to visualise these particles, the researchers said, brings us closer to using them as qubits.

    “The next step will be to figure out how we can quantum engineer these Majorana qubits on quantum chips and manipulate them to obtain an exponential increase in our computing power,” Morr said.

    The research has been published in Science Advances.

    See the full article here .

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    Please help promote STEM in your local schools.

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    The University

    Universität Hamburg is the largest institution for research and education in northern Germany. As one of the country’s largest universities, we offer a diverse range of degree programs and excellent research opportunities. The University boasts numerous interdisciplinary projects in a broad range of fields and an extensive partner network of leading regional, national, and international higher education and research institutions.
    Sustainable science and scholarship

    Universität Hamburg is committed to sustainability. All our faculties have taken great strides towards sustainability in both research and teaching.
    Excellent research

    As part of the Excellence Strategy of the Federal and State Governments, Universität Hamburg has been granted clusters of excellence for 4 core research areas: Advanced Imaging of Matter (photon and nanosciences), Climate, Climatic Change, and Society (CliCCS) (climate research), Understanding Written Artefacts (manuscript research) and Quantum Universe (mathematics, particle physics, astrophysics, and cosmology).

    An equally important core research area is Infection Research, in which researchers investigate the structure, dynamics, and mechanisms of infection processes to promote the development of new treatment methods and therapies.
    Outstanding variety: over 170 degree programs

    Universität Hamburg offers approximately 170 degree programs within its eight faculties:

    Faculty of Law
    Faculty of Business, Economics and Social Sciences
    Faculty of Medicine
    Faculty of Education
    Faculty of Mathematics, Informatics and Natural Sciences
    Faculty of Psychology and Human Movement Science
    Faculty of Business Administration (Hamburg Business School).

    Universität Hamburg is also home to several museums and collections, such as the Zoological Museum, the Herbarium Hamburgense, the Geological-Paleontological Museum, the Loki Schmidt Garden, and the Hamburg Observatory.
    History

    Universität Hamburg was founded in 1919 by local citizens. Important founding figures include Senator Werner von Melle and the merchant Edmund Siemers. Nobel Prize winners such as the physicists Otto Stern, Wolfgang Pauli, and Isidor Rabi taught and researched at the University. Many other distinguished scholars, such as Ernst Cassirer, Erwin Panofsky, Aby Warburg, William Stern, Agathe Lasch, Magdalene Schoch, Emil Artin, Ralf Dahrendorf, and Carl Friedrich von Weizsäcker, also worked here.
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    U Illinois campus

    The University of Illinois at Urbana-Champaign community of students, scholars, and alumni is changing the world.

    With our land-grant heritage as a foundation, we pioneer innovative research that tackles global problems and expands the human experience. Our transformative learning experiences, in and out of the classroom, are designed to produce alumni who desire to make a significant, societal impact.

    The University of Illinois at Chicago (UIC) is a public research university in Chicago, Illinois. Its campus is in the Near West Side community area, adjacent to the Chicago Loop. The second campus established under the University of Illinois system, UIC is also the largest university in the Chicago area, having approximately 30,000 students[9] enrolled in 15 colleges.

    UIC operates the largest medical school in the United States with research expenditures exceeding $412 million and consistently ranks in the top 50 U.S. institutions for research expenditures.[10][11][12] In the 2019 U.S. News & World Report’s ranking of colleges and universities, UIC ranked as the 129th best in the “national universities” category.[13] The 2015 Times Higher Education World University Rankings ranked UIC as the 18th best in the world among universities less than 50 years old.[14]

    UIC competes in NCAA Division I Horizon League as the UIC Flames in sports. The Credit Union 1 Arena (formerly UIC Pavilion) is the Flames’ venue for home games.

     
  • richardmitnick 2:55 pm on July 28, 2016 Permalink | Reply
    Tags: , , , U illinois Chicago   

    From U Illinois Chicago: “Breakthrough solar cell captures CO2 and sunlight, produces burnable fuel” 

    U Illinois bloc

    University of Illinois

    1

    July 28, 2016
    Bill Burton

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    Simulated sunlight powers a solar cell that converts atmospheric carbon dioxide directly into syngas.

    Researchers at the University of Illinois at Chicago have engineered a potentially game-changing solar cell that cheaply and efficiently converts atmospheric carbon dioxide directly into usable hydrocarbon fuel, using only sunlight for energy.

    The finding is reported in the July 29 issue of Science and was funded by the National Science Foundation and the U.S. Department of Energy. A provisional patent application has been filed.

    Unlike conventional solar cells, which convert sunlight into electricity that must be stored in heavy batteries, the new device essentially does the work of plants, converting atmospheric carbon dioxide into fuel, solving two crucial problems at once. A solar farm of such “artificial leaves” could remove significant amounts of carbon from the atmosphere and produce energy-dense fuel efficiently.

    “The new solar cell is not photovoltaic — it’s photosynthetic,” says Amin Salehi-Khojin, assistant professor of mechanical and industrial engineering at UIC and senior author on the study.

    “Instead of producing energy in an unsustainable one-way route from fossil fuels to greenhouse gas, we can now reverse the process and recycle atmospheric carbon into fuel using sunlight,” he said.

    While plants produce fuel in the form of sugar, the artificial leaf delivers syngas, or synthesis gas, a mixture of hydrogen gas and carbon monoxide. Syngas can be burned directly, or converted into diesel or other hydrocarbon fuels.

    The ability to turn CO2 into fuel at a cost comparable to a gallon of gasoline would render fossil fuels obsolete.

    Chemical reactions that convert CO2 into burnable forms of carbon are called reduction reactions, the opposite of oxidation or combustion. Engineers have been exploring different catalysts to drive CO2 reduction, but so far such reactions have been inefficient and rely on expensive precious metals such as silver, Salehi-Khojin said.

    “What we needed was a new family of chemicals with extraordinary properties,” he said.

    2
    Amin Salehi-Khojin (left), UIC assistant professor of mechanical and industrial engineering, and postdoctoral researcher Mohammad Asadi with their breakthrough solar cell that converts atmospheric carbon dioxide directly into syngas.

    Salehi-Khojin and his coworkers focused on a family of nano-structured compounds called transition metal dichalcogenides — or TMDCs — as catalysts, pairing them with an unconventional ionic liquid as the electrolyte inside a two-compartment, three-electrode electrochemical cell.

    The best of several catalysts they studied turned out to be nanoflake tungsten diselenide.

    “The new catalyst is more active; more able to break carbon dioxide’s chemical bonds,” said UIC postdoctoral researcher Mohammad Asadi, first author on the Science paper.

    In fact, he said, the new catalyst is 1,000 times faster than noble-metal catalysts — and about 20 times cheaper.

    Other researchers have used TMDC catalysts to produce hydrogen by other means, but not by reduction of CO2. The catalyst couldn’t survive the reaction.

    “The active sites of the catalyst get poisoned and oxidized,” Salehi-Khojin said. The breakthrough, he said, was to use an ionic fluid called ethyl-methyl-imidazolium tetrafluoroborate, mixed 50-50 with water.

    “The combination of water and the ionic liquid makes a co-catalyst that preserves the catalyst’s active sites under the harsh reduction reaction conditions,” Salehi-Khojin said.

    The UIC artificial leaf consists of two silicon triple-junction photovoltaic cells of 18 square centimeters to harvest light; the tungsten diselenide and ionic liquid co-catalyst system on the cathode side; and cobalt oxide in potassium phosphate electrolyte on the anode side.

    When light of 100 watts per square meter – about the average intensity reaching the Earth’s surface – energizes the cell, hydrogen and carbon monoxide gas bubble up from the cathode, while free oxygen and hydrogen ions are produced at the anode.

    “The hydrogen ions diffuse through a membrane to the cathode side, to participate in the carbon dioxide reduction reaction,” said Asadi.

    The technology should be adaptable not only to large-scale use, like solar farms, but also to small-scale applications, Salehi-Khojin said. In the future, he said, it may prove useful on Mars, whose atmosphere is mostly carbon dioxide, if the planet is also found to have water.

    “This work has benefitted from the significant history of NSF support for basic research that feeds directly into valuable technologies and engineering achievements,” said NSF program director Robert McCabe.

    “The results nicely meld experimental and computational studies to obtain new insight into the unique electronic properties of transition metal dichalcogenides,” McCabe said. “The research team has combined this mechanistic insight with some clever electrochemical engineering to make significant progress in one of the grand-challenge areas of catalysis as related to energy conversion and the environment.”

    Nanostructured transition metal dichalcogenide electrocatalysts for CO2 reduction in ionic liquid is online at http://www.eurekalert.org/jrnls/sci/ or by contacting scipak@aaas.org.

    Co-authors with Asadi and Salehi-Khojin are Kibum Kim, Aditya Venkata Addepalli, Pedram Abbasi, Poya Yasaei, Amirhossein Behranginia, Bijandra Kumar and Jeremiah Abiade of UIC’s mechanical and industrial engineering department, who performed the electrochemical experiments and prepared the catalyst under NSF contract CBET-1512647; Robert F. Klie and Patrick Phillips of UIC’s physics department, who performed electron microscopy and spectroscopy experiments; Larry A. Curtiss, Cong Liu and Peter Zapol of Argonne National Laboratory, who did Density Functional Theory calculations under DOE contract DE-ACO206CH11357; Richard Haasch of the University of Illinois at Urbana-Champaign, who did ultraviolet photoelectron spectroscopy; and José M. Cerrato of the University of New Mexico, who did elemental analysis.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    U Illinois campus

    The University of Illinois at Urbana-Champaign community of students, scholars, and alumni is changing the world.

    With our land-grant heritage as a foundation, we pioneer innovative research that tackles global problems and expands the human experience. Our transformative learning experiences, in and out of the classroom, are designed to produce alumni who desire to make a significant, societal impact.

     
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