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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 particle is its own anti-particle, 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)., , ,   

    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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    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 5:07 pm on September 28, 2017 Permalink | Reply
    Tags: "New ’building material’ points toward quantum computers, , Ettore Majorana's Majorana particle, Explains Fabrizio Nichele: “We are now able to design the nano wire on a laptop – and include the details we go for, Majorana particle is its own anti-particle, , , , The quantum computer is by no means just around the corner   

    From Niels Bohr Institute: “New ’building material’ points toward quantum computers” 

    Niels Bohr Institute bloc

    Niels Bohr Institute

    28 September 2017
    Fabrizio Nichele
    fnichele@nbi.ku.dk

    A Danish-American research team has shown that it is possible to produce ‘Majorana particles’ in a new ‘building material’. The research, led by scientists from Niels Bohr institute, University of Copenhagen, paves the road for new types of experiments – and at the same time represents an important contribution to the construction of the information circuits of tomorrow.

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    Fabrizio Nichele in the lab at Center for Quantum Devices. The scientists keep their samples in the transparent ‘cabinet’ – in an oxygen-free environment. Photo: Ola Jakup Joensen

    Ever since Ettore Majorana – legendary and mythical Italian physicist – back in 1937 suggested the existence of a particle that is also its own anti-particle, scientists have been searching for the ‘Majorana particle’, as it is has come to be known.

    This far the search has been to no avail

    A team of scientists from Center for Quantum Devices at Niels Bohr Institute (NBI) and from Purdue University, USA, have – however – recently contributed to the advancement of Majorana research.

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    The blue part of the structure – one half of a wafer – is where the scientists start building the nano wire. Photo: Ola Jakup Joensen

    Not by finding the elusive particle itself, but by figuring out how to produce a material in which electrons behave in accordance with the theoretical predictions for Majorana particles.

    The results of the research project are published in this week issue of the scientific journal Physical Review Letters.

    No charge

    An anti-particle is an elementary particle – identical to its ‘counterpart’, but with opposite electrical charge. As seen in the relationship between negatively charged electrons and positively charged positrons.

    If a particle is also its own anti-particle – which, given it does indeed exist, will be the case with a Majorana particle – it will therefore have no charge at all.

    The properties that, according to Ettore Majorana´s calculations, will characterize a Majorana particle do for a number of reasons fascinate scientists. Obviously because such properties ‘packaged’ in one particle will represent new experimental possibilities. But also because Majorana-properties are thought to be useful when scientists are e.g. attempting to construct quantum computers – i.e. the information circuits of tomorrow that will have the capacity to process data loads far, far heavier than those dealt with by our present super computers.

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    The nano wire is embedded in spider shaped structures. These structures are here seen through the lense of an optical microscope. The structures sit in rows, two in each row. Photo: Ola Jakup Joensen

    All over the world scientists are trying to design quantum computers.

    It’s a race – Center for Quantum Devices at NBI is one of the contestants – and assistant professor Fabrizio Nichele and professor Charles Marcus, both representing the NBI-center, have been in charge of the Danish-American research project.

    “The condensed version is that it is possible to produce a material in which electrons behave like Majorana particles, as our experiments suggest – and that it is possible to produce this material by means of techniques rather similar to those used today when manufacturing computer circuits. On top of that we have shown how this material enables us to measure properties of Majorana particles never measured before – and carry out these measurements with great precision”, explains Fabrizio Nichele.

    Laptop design

    Two ultra thin sheets – combined in a ‘sandwich’ – are at the center of the Danish-American discovery, and it all has to do with producing a material based on this ‘sandwich’.

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    One of the optical microscopes available to the NBI-scientists. Photo: Ola Jakup Jensen

    The bottom layer of the ‘sandwich’ is made out of indium arsenide, a semiconductor, and the top layer is made out of aluminium, a superconductor. And the ‘sandwich’ sits on top of a so called wafer, one of the building blocks used in modern computer technology.

    If you carve out a nano wire from this ‘sandwich’-layer it is possible to create a state where electrons inside the wire display Majorana-properties – and the theory behind this approach has in part been known since 2010, says Fabrizio Nichele:

    “However, until now there has been a major problem because it was necessary to ‘grow’ the nano wire in special machines in a lab – and the wire was, literally, only available in the form of minute ‘hair-like’ straws. In order to build e.g. a chip based on this material, you therefore had to assemble an almost unfathomable number of single straws – which made it really difficult and very challenging to construct circuits this way”.

    And this is exactly where the Danish-American discovery comes in very handily, explains Fabrizio Nichele: “We are now able to design the nano wire on a laptop – and include the details we go for. Further down the road production capacity will no doubt increase – which will allow us to use this technique in order to construct computers of significant size”.

    5
    Signature of a Majorana particle, shown on a screen. “The horizontal stripe in the center of the figure shows that a zero energy particle appears in a magnetic field in our devices – as expected for a Majorana particle”, explains Fabrizio Nichele.

    Faster road to Majorana

    At Center for Quantum Devices at NBI, focus is very much on the construction of a quantum computer. Still it is a long haul – the quantum computer is by no means just around the corner, says Fabrizio

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    One of the nanowires central to the NBI-scientist’s research. The wire is made out of aluminum. It is approx. 1/1.000 millimeter long, and 1/20.000 wide. Illustration: NBI

    Nichele: “Materials with Majorana-properties obviously have a number of relevant qualities in this context – which is why we try to investigate this field through various experiments”.

    Some of these experiments are carried out at temperatures just above absolute zero (-273,15 C), explains Fabrizio Nichele: “When you do that – which naturally requires equipment tailored for experiments of this kind – you are able to study details related to quantum properties in various materials. When it comes to constructing a quantum computer, Majorana-particles do, however, represent just one of a number of possible and promising options. This field is very complex – and when, some day, a quantum computer has indeed been constructed and is up and running, it may very well be based on some form of integration of a number of different techniques and different materials, whereof some may be based on our research”, says Fabrizio Nichele.

    7
    Fabrizio Nichele. Photo: Ola Jakup Joensen

    Scientists working with Ettore Majoranas equations for entirely other reasons than the desire to build a quantum computer, can also benefit from the Danish-American research, explains Fabrizio Nichele:

    “Our technique makes it possible to conduct experiments that have up till now not been doable – which will also facilitate the understanding of the Majorana particle itself”.

    The research project has been funded by the Danish National Research Foundation, the Villum Foundation, Deutsche Forschungsgemeinschaft (DFG) and – representing the commercial donor side – Microsoft; the latter joining the project as part of a well established cooperation with NBI.

    In addition to cooperating with colleagues from Purdue University, the NBI-researchers have also recently studied Majorana properties working together with scientists from University of California, Santa Barbara, USA. The results of this project are published in a separate article in Physical Review Letters.

    See the full article here .

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    Niels Bohr Institute Campus

    The Niels Bohr Institute (Danish: Niels Bohr Institutet) is a research institute of the University of Copenhagen. The research of the institute spans astronomy, geophysics, nanotechnology, particle physics, quantum mechanics and biophysics.

    The Institute was founded in 1921, as the Institute for Theoretical Physics of the University of Copenhagen, by the Danish theoretical physicist Niels Bohr, who had been on the staff of the University of Copenhagen since 1914, and who had been lobbying for its creation since his appointment as professor in 1916. On the 80th anniversary of Niels Bohr’s birth – October 7, 1965 – the Institute officially became The Niels Bohr Institute.[1] Much of its original funding came from the charitable foundation of the Carlsberg brewery, and later from the Rockefeller Foundation.[2]

    During the 1920s, and 1930s, the Institute was the center of the developing disciplines of atomic physics and quantum physics. Physicists from across Europe (and sometimes further abroad) often visited the Institute to confer with Bohr on new theories and discoveries. The Copenhagen interpretation of quantum mechanics is named after work done at the Institute during this time.

    On January 1, 1993 the institute was fused with the Astronomic Observatory, the Ørsted Laboratory and the Geophysical Institute. The new resulting institute retained the name Niels Bohr Institute.

     
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