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  • richardmitnick 9:24 am on April 13, 2019 Permalink | Reply
    Tags: A new photonic switch built with more than 50000 microscopic “light switches”, , Each switch directs one of 240 tiny beams of light to either make a right turn when the switch is on or to pass straight through when the switch is off, , , Photolithography, Server networks could be connected by optical fibers with photonic switches acting as the traffic cops Wu said, This could one day revolutionize how information travels through data centers and high-performance supercomputers that are used for artificial intelligence and other data-intensive applications., UC Berkeley   

    From insideHPC: “Berkeley Engineers build World’s Fastest Optical Switch Arrays” 

    From insideHPC

    April 12, 2019

    Engineers at the University of California, Berkeley have built a new photonic switch that can control the direction of light passing through optical fibers faster and more efficiently than ever.

    1
    The photonic switch is built with more than 50,000 microscopic “light switches” etched into a silicon wafer. (Younghee Lee graphic)

    This optical “traffic cop” could one day revolutionize how information travels through data centers and high-performance supercomputers that are used for artificial intelligence and other data-intensive applications.

    The photonic switch is built with more than 50,000 microscopic “light switches,” each of which directs one of 240 tiny beams of light to either make a right turn when the switch is on, or to pass straight through when the switch is off. The 240-by-240 array of switches is etched into a silicon wafer and covers an area only slightly larger than a postage stamp.

    “For the first time in a silicon switch, we are approaching the large switches that people can only build using bulk optics,” said Ming Wu, professor of electrical engineering and computer sciences at UC Berkeley and senior author of the paper, which appeared online April 11 in the journal Optica. “Our switches are not only large, but they are 10,000 times faster, so we can switch data networks in interesting ways that not many people have thought about.”

    Currently, the only photonic switches that can control hundreds of light beams at once are built with mirrors or lenses that must be physically turned to switch the direction of light. Each turn takes about one-tenth of a second to complete, which is eons compared to electronic data transfer rates. The new photonic switch is built using tiny integrated silicon structures that can switch on and off in a fraction of a microsecond, approaching the speed necessary for use in high-speed data networks.

    Traffic cops on the information highway

    Data centers — where our photos, videos and documents saved in the cloud are stored — are composed of hundreds of thousands of servers that are constantly sending information back and forth. Electrical switches act as traffic cops, making sure that information sent from one server reaches the target server and doesn’t get lost along the way.

    But as data transfer rates continue to grow, we are reaching the limits of what electrical switches can handle, Wu said.

    “Electrical switches generate so much heat, so even though we could cram more transistors onto a switch, the heat they generate is starting to pose certain limits,” he said. “Industry expects to continue the trend for maybe two more generations and, after that, something more fundamental has to change. Some people are thinking optics can help.”

    Server networks could instead be connected by optical fibers, with photonic switches acting as the traffic cops, Wu said. Photonic switches require very little power and don’t generate any heat, so they don’t face the same limitations as electrical switches. However, current photonic switches cannot accommodate as many connections and also are plagued by signal loss — essentially “dimming” the light as it passes through the switch — which makes it hard to read the encoded data once it reaches its destination.

    In the new photonic switch, beams of light travel through a crisscrossing array of nanometer-thin channels until they reach these individual light switches, each of which is built like a microscopic freeway overpass. When the switch is off, the light travels straight through the channel. Applying a voltage turns the switch on, lowering a ramp that directs the light into a higher channel, which turns it 90 degrees. Another ramp lowers the light back into a perpendicular channel.

    “It’s literally like a freeway ramp,” Wu said. “All of the light goes up, makes a 90-degree turn and then goes back down. And this is a very efficient process, more efficient than what everybody else is doing on silicon photonics. It is this mechanism that allows us to make lower-loss switches.”

    The team uses a technique called photolithography to etch the switching structures into silicon wafers. The researchers can currently make structures in a 240-by-240 array — 240 light inputs and 240 light outputs — with limited light loss, making it the largest silicon-based switch ever reported. They are working on perfecting their manufacturing technique to create even bigger switches.

    “Larger switches that use bulk optics are commercially available, but they are very slow, so they are usable in a network that you don’t change too frequently,” Wu said. “Now, computers work very fast, so if you want to keep up with the computer speed, you need much faster switch response. Our switch is the same size, but much faster, so it will enable new functions in data center networks.”

    Co-lead authors on the paper are Tae Joon Seok of the Gwangju Institute of Science and Technology and Kyungmok Kwon, a postdoctoral researcher and Bakar Innovation Fellow at UC Berkeley. Other co-authors are Johannes Henriksson and Jianheng Luo of UC Berkeley.

    See the full article here .

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    Founded on December 28, 2006, insideHPC is a blog that distills news and events in the world of HPC and presents them in bite-sized nuggets of helpfulness as a resource for supercomputing professionals. As one reader said, we’re sifting through all the news so you don’t have to!

    If you would like to contact me with suggestions, comments, corrections, errors or new company announcements, please send me an email at rich@insidehpc.com. Or you can send me mail at:

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  • richardmitnick 9:02 am on March 15, 2019 Permalink | Reply
    Tags: "Can entangled qubits be used to probe black holes?", JQI at UMD, , , , UC Berkeley   

    From UC Berkeley: “Can entangled qubits be used to probe black holes?” 

    From UC Berkeley

    March 6, 2019
    Robert Sanders
    rlsanders@berkeley.edu

    1
    Someday, entangled quantum bits, or qubits, may allow us to explore the mysterious interior of a black hole, as represented in this artistic rendering. (Graphic by E. Edwards/Joint Quantum Institute)

    Physicists have used a seven-qubit quantum computer to simulate the scrambling of information inside a black hole, heralding a future in which entangled quantum bits might be used to probe the mysterious interiors of these bizarre objects.

    Scrambling is what happens when matter disappears inside a black hole. The information attached to that matter — the identities of all its constituents, down to the energy and momentum of its most elementary particles — is chaotically mixed with all the other matter and information inside, seemingly making it impossible to retrieve.

    This leads to a so-called “black hole information paradox,” since quantum mechanics says that information is never lost, even when that information disappears inside a black hole.

    So, while some physicists claim that information falling through the event horizon of a black hole is lost forever, others argue that this information can be reconstructed, but only after waiting an inordinate amount of time — until the black hole has shrunk to nearly half its original size. Black holes shrink because they emit Hawking radiation, which is caused by quantum mechanical fluctuations at the very edge of the black hole and is named after the late physicist Stephen Hawking.

    Unfortunately, a black hole the mass of our sun would take about 10^67 years to evaporate — far, far longer than the age of the universe.

    2
    Can you extract information from a black hole? As part of a thought experiment, Alice, a physicist, drops a qubit into a black hole and asks whether Bob can reconstruct the qubit using only the outgoing Hawking radiation. (Graphic by Emily Elisa Edwards, University of Maryland)

    However, there is a loophole — or rather, a wormhole — out of this black hole. It may be possible to retrieve this infalling information significantly faster by measuring subtle entanglements between the black hole and the Hawking radiation it emits.

    Two bits of information — like the quantum bits, or qubits, in a quantum computer — are entangled when they are so closely linked that the quantum state of one automatically determines the state of the other, no matter how far apart they are. Physicists sometimes refer to this as “spooky action at a distance,” and measurements of entangled qubits can lead to the “teleportation” of quantum information from one qubit to another.

    “One can recover the information dropped into the black hole by doing a massive quantum calculation on these outgoing Hawking photons,” said Norman Yao, a UC Berkeley assistant professor of physics and a faculty scientist at Lawrence Berkeley National Laboratory. “This is expected to be really, really hard, but if quantum mechanics is to be believed, it should, in principle, be possible. That’s exactly what we are doing here, but for a tiny three-qubit `black hole’ inside a seven-qubit quantum computer.”

    By dropping an entangled qubit into a black hole and querying the emerging Hawking radiation, you could theoretically determine the state of a qubit inside the black hole, providing a window into the abyss.

    Yao, who is a member of Berkeley Lab’s Quantum Algorithms Team, and his colleagues at the University of Maryland and the Perimeter Institute for Theoretical Physics in Waterloo, Ontario, Canada, will report their results in a paper appearing in the March 7 issue of the journal Nature.

    Teleportation

    Yao, who is interested in understanding the nature of quantum chaos, learned from friend and colleague Beni Yoshida, a theorist at the Perimeter Institute, that recovering quantum information falling into a black hole is possible if the information is scrambled rapidly inside the black hole. The more thoroughly it is mixed throughout the black hole, the more reliably the information can be retrieved via teleportation. Based on this insight, Yoshida and Yao proposed last year an experiment to provably demonstrate scrambling on a quantum computer.

    3
    A seven-qubit quantum computer circuit built by University of Maryland physicists uses quantum teleportation to detect information scrambling. This is analogous to information propagation through a traversable wormhole, which would allow Bob to identify the qubit that Alice threw into the black hole. (Graphic by Emily Elisa Edwards, University of Maryland)

    “With our protocol, if you measure a teleportation fidelity that is high enough, then you can guarantee that scrambling happened within the quantum circuit,” Yao said. “So, then we called up my buddy, Chris Monroe.”

    Monroe, a physicist at the University of Maryland in College Park who heads one of the world’s leading trapped-ion quantum information groups, decided to give it a try. His group implemented the protocol proposed by Yoshida and Yao and effectively measured an out-of-time-ordered correlation function.

    Called OTOCs, these peculiar correlation functions are created by comparing two quantum states that differ in the timing of when certain kicks or perturbations are applied. The key is being able to evolve a quantum state both forward and backward in time to understand the effect of that second kick on the first kick.

    Monroe’s group created a scrambling quantum circuit on three qubits within a seven-qubit trapped-ion quantum computer and characterized the resulting decay of the OTOC. While the decay of the OTOC is typically taken as a strong indication that scrambling has occurred, to prove that they had to show that the OTOC didn’t simply decay because of decoherence — that is, that it wasn’t just poorly shielded from the noise of the outside world, which also causes quantum states to fall apart.

    Yao and Yoshida proved that the greater the accuracy with which they could retrieve the entangled or teleported information, the more stringently they could put a lower limit on the amount of scrambling that had occurred in the OTOC. This is because, if information is successfully teleported from one atom to another, it means that the state of the first atom is spread out across all of the atoms — something that only happens if the information is scrambled. If the information was lost, successful teleportation would not be possible. For an arbitrary process whose scrambling properties might not be known, this method could be used to test whether — or even how much — it scrambles.

    Monroe and his colleagues measured a teleportation fidelity of approximately 80 percent, meaning that perhaps half of the quantum state was scrambled and the other half decayed by decoherence. Nevertheless, this was enough to demonstrate that genuine scrambling had indeed occurred in this three-qubit quantum circuit.

    “One possible application for our protocol is related to the benchmarking of quantum computers, where one might be able to use this technique to diagnose more complicated forms of noise and decoherence in quantum processors,” Yao said. “The ability to diagnose how noise affects quantum simulations is key to building better fault-tolerant algorithms and getting accurate answers from current noisy quantum computers.”

    Yao is also working with a UC Berkeley group led by Irfan Siddiqi to demonstrate scrambling in a different quantum system, superconducting qutrits: quantum bits that have three, rather than two, states. Siddiqi is a UC Berkeley professor of physics and a faculty scientist at Berkeley Lab, where he is leading the effort to build an advanced quantum computing test bed.

    “At its core, this is a qubit or qutrit experiment, but the fact that we can relate it to cosmology is because we believe the dynamics of quantum information is the same,” he said. “The U.S. is launching a billion-dollar quantum initiative, and understanding the dynamics of quantum information connects many areas of research within this initiative: quantum circuits and computing, high energy physics, black hole dynamics, condensed matter physics and atomic, molecular and optical physics. The language of quantum information has become pervasive for our understanding of all these different systems.”

    “Regardless of whether real black holes are very good scramblers, studying quantum scrambling in the lab could provide useful insights for the future development of quantum computing or quantum simulation,” Monroe said.

    Aside from Yao, Yoshida and Monroe, other co-authors are graduate student Tommy Schuster of UC Berkeley and graduate student and first author Kevin Landsman, Caroline Figgatt and Norbert Linke of Maryland’s Joint Quantum Institute. The work was supported by the Department of Energy’s Office of Advanced Scientific Computing Research and Office of High Energy Physics and National Science Foundation.

    RELATED INFORMATION

    Ion experiment aces quantum scrambling test (JQI)
    Verified Quantum Information Scrambling (Nature) [above]
    Disentangling Scrambling and Decoherence via Quantum Teleportation (Physical Review X)
    Norman Yao’s website

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

    UC Berkeley Seal

     
  • richardmitnick 11:24 am on March 1, 2019 Permalink | Reply
    Tags: "Exiled planet linked to stellar flyby 3 million years ago", , , , Binary stars, , , The planet dubbed HD 106906 b, The star HD 106906, UC Berkeley   

    From UC Berkeley: “Exiled planet linked to stellar flyby 3 million years ago” 

    From UC Berkeley

    February 28, 2019
    Robert Sanders
    rlsanders@berkeley.edu

    1
    Simulation of a binary star flyby of a young planetary system. UC Berkeley and Stanford astronomers suspect that such a flyby altered the orbit of a planet (in blue) around the star HD 106906 so that it remained bound to the system in an oblique orbit similar to that of a proposed Planet Nine attached to our own solar system. (Paul Kalas animation)

    Some of the peculiar aspects of our solar system — an enveloping cloud of comets, dwarf planets in weird orbits and, if it truly exists, a possible Planet Nine far from the sun — have been linked to the close approach of another star in our system’s infancy that flung things helter-skelter.

    But are stellar flybys really capable of knocking planets, comets and asteroids askew, reshaping entire planetary systems?

    UC Berkeley and Stanford University astronomers think they have now found a smoking gun.


    A planet orbiting a young binary star may have been perturbed by another pair of stars that skated too close to the system between 2 and 3 million years ago, soon after the planet formed from a swirling disk of dust and gas.

    If confirmed, this bolsters arguments that close stellar misses help sculpt planetary systems and may determine whether or not they harbor planets with stable orbits.

    “One of the mysteries arising from the study of exoplanets is that we see systems where the planets are misaligned, even though they are born in a flat, circular disk,” said Paul Kalas, a UC Berkeley adjunct professor of astronomy. “Maybe a cosmic tsunami hit these systems and rearranged everything about them, but we haven’t had proof. Our paper gives rare observational evidence for one of these flybys gently influencing one of the planetary systems in the galaxy.”

    2
    Two binary stars, now far apart, skated by one another 2-3 million years ago, leaving a smoking gun: a disordered planetary system (left).

    Astronomers are already searching for a stellar flyby in our solar system’s past, but since that likely happened 4.6 billion years ago, most of the evidence has gone cold. The star system that the astronomers studied, identified only by the number HD 106906 and located about 300 light years from Earth in the direction of the constellation Crux, is very young, only about 15 million years old.

    Kalas and Robert De Rosa, a former UC Berkeley postdoc who is now a research scientist at Stanford’s Kavli Institute for Particle Astrophysics and Cosmology, describe their findings in a paper accepted for publication in The Astronomical Journal.

    Rogue stars

    Kalas, who studies young, newly formed planetary systems to try to understand what happened in the early years of our own solar system, first focused on HD 106906 in 2015 after it was found to have a massive planet in a highly unusual orbit. The planet, dubbed HD 106906 b, has a mass of about 11 Jupiters, and it orbits HD 106906 — recently revealed to be a binary star — in an orbit tipped about 21 degrees from the plane of the disk that contains all the other material around the star. Its current location is at least 738 times farther from its star than Earth is from the sun, or about 18 times farther from its star than Pluto is from the sun.


    Some 2 to 3 million years ago, in a young, newly formed planetary system, a planet was in danger of being kicked out of the system because of gravitaional interactions with the central, binary star (left panel). A close pass by another binary star (not shown) within the same cluster gave the planet an extra kick that stabilized the orbit and rescued it from certain ejection (right panel). (Video by Paul Kalas)

    Kalas used both the Gemini Planet Imager on the Gemini Telescope in the Chilean Andes and the Hubble Space Telescope to look more closely at HD 106906 and discovered that the star has a lopsided comet belt, as well. The planet’s strange orbit and the fact that the dust disk itself is asymmetrical indicated that something had disrupted the young system.

    NOAO Gemini Planet Imager on Gemini South


    Gemini/South telescope, Cerro Tololo Inter-American Observatory (CTIO) campus near La Serena, Chile, at an altitude of 7200 feet

    NASA/ESA Hubble Telescope

    Kalas and his colleagues, including De Rosa, proposed that the planet had been kicked out of its solar system by interactions with another as-yet-unseen planet in the system or by a passing star. Kalas and De Rosa now believe that both happened: The planet was kicked into an eccentric orbit when it came dangerously close to the central binary star, a scenario proposed in 2017 by theorist Laetitia Rodet and her collaborators from the Grenoble Observatory in France. Repeated gravitational kicks from the binary would have quickly ejected the planet into interstellar space, but the passing stars rescued the planet by nudging its orbit to a safer distance from the binary.

    The Gaia space observatory gave them the data they needed to test their hypothesis. Gaia, launched in 2012 by the European Space Agency, collects precise measurements of distance, position and motion for 1.3 billion stars in the Milky Way Galaxy, a catalog 10,000 times larger than Gaia’s predecessor, Hipparcos.

    ESA/GAIA satellite

    Kalas and De Rosa gathered Gaia information on 461 stars in the same cluster as HD 106906 and calculated their positions backward in time—reversed the cosmic clock, so to speak—and discovered that another binary star system may have approached close enough 3 million years ago to alter the planetary system.

    “What we have done here is actually find the stars that could have given HD 106906 b the extra gravitational kick, a second kick so that it became long-lived, just like a hypothetical Planet Nine would be in our solar system,” Kalas said.

    They also found also that the binary star came in on a trajectory that was within about 5 degrees of the system’s disk, making it even more likely that the encounter had a strong and lasting impact on HD 106906.

    Such double kicks may be important to stabilizing planets, asteroids and comets around stars, Kalas said.

    “Studying the HD 106906 planetary system is like going back in time to watch the Oort cloud of comets forming around our young sun,” he said. “Our own giant planets gravitationally kicked countless comets outward to large distances. Many were ejected completely, becoming interstellar objects like ʻOumuamua, but others were influenced by passing stars. That second kick by a stellar flyby can detach a comet’s orbit from any further encounters with the planets, saving it from the prospect of ejection. This chain of events preserved the most primitive solar system material in a deep freeze far from the sun for billions of years.”

    Kalas hopes that future observations, such as an updated catalog of Gaia measurements, will clarify the significance of the flyby on HD 106906.

    “We started with 461 suspects and discovered two that were at the scene of the crime,” he said. “Their exact role will be revealed as we gather more evidence.”

    The work was supported by the National Science Foundation (AST-1518332), National Aeronautics and Space Administration (NNX15AC89G) and Nexus for Exoplanet System Science (NExSS), a research coordination network sponsored by NASA’s Science Mission Directorate (NNX15AD95G).

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

    UC Berkeley Seal

     
  • richardmitnick 1:07 pm on December 3, 2018 Permalink | Reply
    Tags: , , , , MESO devices, , Multiferroics, UC Berkeley   

    From UC Berkeley: “New quantum materials could take computing devices beyond the semiconductor era” 

    UC Berkeley

    From UC Berkeley

    December 3, 2018
    Robert Sanders
    rlsanders@berkeley.edu

    1
    MESO devices, based on magnetoelectric and spin-orbit materials, could someday replace the ubiquitous semiconductor transistor, today represented by CMOS. MESO uses up-and-down magnetic spins in a multiferroic material to store binary information and conduct logic operations. (Intel graphic)

    Researchers from Intel Corp. and UC Berkeley are looking beyond current transistor technology and preparing the way for a new type of memory and logic circuit that could someday be in every computer on the planet.

    In a paper appearing online Dec. 3 in advance of publication in the journal Nature, the researchers propose a way to turn relatively new types of materials, multiferroics and topological materials, into logic and memory devices that will be 10 to 100 times more energy-efficient than foreseeable improvements to current microprocessors, which are based on CMOS (complementary metal–oxide–semiconductor).

    The magneto-electric spin-orbit or MESO devices will also pack five times more logic operations into the same space than CMOS, continuing the trend toward more computations per unit area, a central tenet of Moore’s Law.

    The new devices will boost technologies that require intense computing power with low energy use, specifically highly automated, self-driving cars and drones, both of which require ever increasing numbers of computer operations per second.

    “As CMOS develops into its maturity, we will basically have very powerful technology options that see us through. In some ways, this could continue computing improvements for another whole generation of people,” said lead author Sasikanth Manipatruni, who leads hardware development for the MESO project at Intel’s Components Research group in Hillsboro, Oregon. MESO was invented by Intel scientists, and Manipatruni designed the first MESO device.

    Transistor technology, invented 70 years ago, is used today in everything from cellphones and appliances to cars and supercomputers. Transistors shuffle electrons around inside a semiconductor and store them as binary bits 0 and 1.

    2
    Single crystals of the multiferroic material bismuth-iron-oxide. The bismuth atoms (blue) form a cubic lattice with oxygen atoms (yellow) at each face of the cube and an iron atom (gray) near the center. The somewhat off-center iron interacts with the oxygen to form an electric dipole (P), which is coupled to the magnetic spins of the atoms (M) so that flipping the dipole with an electric field (E) also flips the magnetic moment. The collective magnetic spins of the atoms in the material encode the binary bits 0 and 1, and allow for information storage and logic operations.

    In the new MESO devices, the binary bits are the up-and-down magnetic spin states in a multiferroic, a material first created in 2001 by Ramamoorthy Ramesh, a UC Berkeley professor of materials science and engineering and of physics and a senior author of the paper.

    “The discovery was that there are materials where you can apply a voltage and change the magnetic order of the multiferroic,” said Ramesh, who is also a faculty scientist at Lawrence Berkeley National Laboratory. “But to me, ‘What would we do with these multiferroics?’ was always a big question. MESO bridges that gap and provides one pathway for computing to evolve”

    In the Nature paper, the researchers report that they have reduced the voltage needed for multiferroic magneto-electric switching from 3 volts to 500 millivolts, and predict that it should be possible to reduce this to 100 millivolts: one-fifth to one-tenth that required by CMOS transistors in use today. Lower voltage means lower energy use: the total energy to switch a bit from 1 to 0 would be one-tenth to one-thirtieth of the energy required by CMOS.

    “A number of critical techniques need to be developed to allow these new types of computing devices and architectures,” said Manipatruni, who combined the functions of magneto-electrics and spin-orbit materials to propose MESO. “We are trying to trigger a wave of innovation in industry and academia on what the next transistor-like option should look like.”

    Internet of things and AI

    The need for more energy-efficient computers is urgent. The Department of Energy projects that, with the computer chip industry expected to expand to several trillion dollars in the next few decades, energy use by computers could skyrocket from 3 percent of all U.S. energy consumption today to 20 percent, nearly as much as today’s transportation sector. Without more energy-efficient transistors, the incorporation of computers into everything – the so-called internet of things – would be hampered. And without new science and technology, Ramesh said, America’s lead in making computer chips could be upstaged by semiconductor manufacturers in other countries.

    “Because of machine learning, artificial intelligence and IOT, the future home, the future car, the future manufacturing capability is going to look very different,” said Ramesh, who until recently was the associate director for Energy Technologies at Berkeley Lab. “If we use existing technologies and make no more discoveries, the energy consumption is going to be large. We need new science-based breakthroughs.”

    Paper co-author Ian Young, a UC Berkeley Ph.D., started a group at Intel eight years ago, along with Manipatruni and Dmitri Nikonov, to investigate alternatives to transistors, and five years ago they began focusing on multiferroics and spin-orbit materials, so-called “topological” materials with unique quantum properties.

    “Our analysis brought us to this type of material, magneto-electrics, and all roads led to Ramesh,” said Manipatruni.

    Multiferroics and spin-orbit materials

    Multiferroics are materials whose atoms exhibit more than one “collective state.” In ferromagnets, for example, the magnetic moments of all the iron atoms in the material are aligned to generate a permanent magnet. In ferroelectric materials, on the other hand, the positive and negative charges of atoms are offset, creating electric dipoles that align throughout the material and create a permanent electric moment.

    MESO is based on a multiferroic material consisting of bismuth, iron and oxygen (BiFeO3) that is both magnetic and ferroelectric. Its key advantage, Ramesh said, is that these two states – magnetic and ferroelectric – are linked or coupled, so that changing one affects the other. By manipulating the electric field, you can change the magnetic state, which is critical to MESO.

    The key breakthrough came with the rapid development of topological materials with spin-orbit effect, which allow for the state of the multiferroic to be read out efficiently. In MESO devices, an electric field alters or flips the dipole electric field throughout the material, which alters or flips the electron spins that generate the magnetic field. This capability comes from spin-orbit coupling, a quantum effect in materials, which produces a current determined by electron spin direction.

    In another paper that appeared earlier this month in Science Advances, UC Berkeley and Intel experimentally demonstrated voltage-controlled magnetic switching using the magneto-electric material bismuth-iron-oxide (BiFeO3), a key requirement for MESO.

    “We are looking for revolutionary and not evolutionary approaches for computing in the beyond-CMOS era,” Young said. “MESO is built around low-voltage interconnects and low-voltage magneto-electrics, and brings innovation in quantum materials to computing.”

    Other co-authors of the Nature paper are Chia-Ching Lin, Tanay Gosavi and Huichu Liu of Intel and Bhagwati Prasad, Yen-Lin Huang and Everton Bonturim of UC Berkeley. The work was supported by Intel.

    RELATED INFORMATION

    Beyond CMOS computing with spin and polarization Nature Physics

    See the full article here .

    five-ways-keep-your-child-safe-school-shootings

    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

    UC Berkeley Seal

     
  • richardmitnick 8:33 am on November 25, 2018 Permalink | Reply
    Tags: A magnetic field is helpful in protecting a planetary atmosphere from being blown away by the stellar winds, , , Earth and planetary science, Earth Might Have Once Had a Different Kind of Magnetic Field-one generated by oceans of magma on its surface instead of the rotation of its core, Electrochemistry of moving magma, , UC Berkeley   

    From UC Berkeley via Science Alert: “Earth Might Have Once Had a Different Kind of Magnetic Field, And It’s Good News For Life on Other Planets” 

    UC Berkeley

    From UC Berkeley

    1
    (dottedhippo/iStock)

    23 NOV 2018
    MIKE MCRAE

    A new study suggests that Earth might have once had a different kind of magnetic field – one generated by oceans of magma on its surface, instead of the rotation of its core.

    And that’s good news, because it means more exoplanets than we thought could have a protective magnetic shield sheltering them from the harsh radiation of space, and a chance of hosting life.

    According to the research, long before Earth had a skin, when its molten insides flowed on its outside and its heart was yet to harden, a magnetic cage was already beginning to bloom overhead.

    An analysis of the electrochemistry of moving magma has found sufficiently sized oceans of liquid rock can generate their own magnetic fields, helping us understand not just our own planet’s history, but the chances of life arising on other worlds.

    Two Earth and planetary scientists from UC Berkeley went back to first principles to simulate the surface conditions of young super-Earths – huge rocky worlds with sub-surface pressures and temperatures guaranteed to keep the planets toasty.

    They found the make-up of these molten crusts could give rise to an electrical conductivity large enough to form a planetary dynamo, and it would take a current of rock flowing at a speed of just 1 millimetre per second to manage it.

    “This is the first detailed calculation for higher temperature and pressure conditions, and it finds that the conductivities appear to be a little bit higher, so the fluid motions you would need to make this all work are maybe a little bit less extreme,” says planetary scientist Burkhard Militzer.

    Our own world has a powerful dynamo churning away deep underfoot in the form of a rotating core of liquid iron and nickel swirling amid a gooey soup of lighter minerals and charged particles.

    We should be super thankful for it – without it, we probably wouldn’t be here.

    “A magnetic field is helpful in protecting a planetary atmosphere from being blown away by the stellar winds,” says co-author François Soubiran, now at the École Normale Supérieure in Lyon, France.

    Not only do we need that atmosphere to keep the surface temperature constant and for life-sustaining chemical reactions, it shields the biosphere from lethal doses of radiation.

    Magnetic fields also do a pretty good job of forming an umbrella that deflects high energy particles from bombarding the crust. So it’s a safe bet that no magnetic field equals no life.

    Knowing which planets outside of our own Solar System can generate magnetic fields might help us sort those that are likely to be sterile from the handful that just might be worth studying for biology.

    What’s more, categorising the different ways planets create magnetic fields opens the way to studying the geology of a planet without needing to set down on its surface.

    “On Jupiter, it arises from the convection of liquid metallic hydrogen,” says Militzer.

    “On Uranus and Neptune, it is assumed to be generated in the ice layers. Now we have added molten rocks to this diverse list of field-generating materials.”

    Just how a surface dynamo might interact with core processes is still anybody’s guess, especially given we know so little about our planet’s interior.

    “The interaction between the liquid core magnetic field and the magma ocean is not easy to predict, but could result in a significant – or even dominant – dipolar component,” the authors write.

    Ideally, to form a protective bubble, a magnetic field should have a neat dipole shape, as opposed to a mess of loops like a poodle’s haircut.

    Magnetosphere of Earth, original bitmap from NASA. SVG rendering by Aaron Kaase

    This could be good news for anybody hoping to include super-Earths in their list of potential alien hotspots.

    Most of these insanely big planets – massive rocky bodies that fall short of Neptune’s girth – tend to be pulled close to their temper-prone stars, where solar eruptions and constant heat would make short work of any atmosphere.

    A sufficient dipole magnetic field would give some of them a fighting chance of holding onto precious air while shielding the surface from a scouring brush of solar activity.

    Unfortunately any close proximity to a star also increases the chances such a world would be tidally locked, making its day and year more or less the same length. The team’s analysis suggests a distinct dipole formation would require a relatively rapid rotation, ruling out those slower-spinning worlds.

    With the number of exoplanets in our library climbing into the thousands, and a number of Earth-like worlds among them, we’re going to need better ways to study them.

    Hunting for hints of magnetic fields from afar could help us prioritise our search for life among the stars.

    This research was published in Nature Communications.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

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  • richardmitnick 2:07 pm on November 12, 2018 Permalink | Reply
    Tags: A research team has adapted a powerful electron-based imaging technique to obtain an image of atomic-scale structure in a synthetic polymer., Before these high-resolution images the arrangement and variation of the different types of crystal structures was unknown, , Cryogenic electron microscopy, Images of individual atoms in polymers had only been realized in computer simulations and illustrations, , , Peptoids are synthetically produced molecules that mimic biological molecules including chains of amino acids known as peptides, , Researchers achieved resolution of about 2 angstroms which is two-tenths of nanometer (billionth of a meter), Scientists Bring Polymers Into Atomic-Scale Focus, There are still mysteries about polymers at the atomic scale, UC Berkeley   

    From Lawrence Berkeley National Lab and UC Berkeley: “Scientists Bring Polymers Into Atomic-Scale Focus” 

    Berkeley Logo

    From Lawrence Berkeley National Lab

    November 12, 2018
    Glenn Roberts Jr.
    geroberts@lbl.gov
    (510) 486-5582

    1
    This image shows a rendering (gray and pink) of the molecular structure of a peptoid polymer that was studied by a team led by Berkeley Lab and UC Berkeley. The successful imaging of a polymer’s atomic-scale structure could inform new designs for plastics, like those that form the water bottles shown in the background. (Credit: Berkeley Lab, Charles Rondeau/PublicDomainPictures.net)

    From water bottles and food containers to toys and tubing, many modern materials are made of plastics. And while we produce about 110 million tons per year of synthetic polymers like polyethylene and polypropylene worldwide for these plastic products, there are still mysteries about polymers at the atomic scale.

    Because of the difficulty in capturing images of these materials at tiny scales, images of individual atoms in polymers have only been realized in computer simulations and illustrations, for example.

    Now, a research team led by Nitash Balsara, a senior faculty scientist in the Materials Sciences Division at the Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and professor of chemical and biomolecular engineering at UC Berkeley, has adapted a powerful electron-based imaging technique to obtain an image of atomic-scale structure in a synthetic polymer. The team included researchers from Berkeley Lab and UC Berkeley.

    The research could ultimately inform polymer fabrication methods and lead to new designs for materials and devices that incorporate polymers.

    In their study, published in the American Chemical Society’s Macromolecules journal, the researchers detail the development of a cryogenic electron microscopy imaging technique, aided by computerized simulations and sorting techniques, that identified 35 arrangements of crystal structures in a peptoid polymer sample. Peptoids are synthetically produced molecules that mimic biological molecules, including chains of amino acids known as peptides.

    2
    The simulated atomic-scale structure (top) and the averaged atomic-scale imaging (bottom) of a peptoid polymer sample. The sale bar is 10 angstroms, or 1 billionth of a meter. (Credit: Berkeley Lab, UC Berkeley)

    The sample was robotically synthesized at Berkeley Lab’s Molecular Foundry, a DOE Office of Science User Facility for nanoscience research. Researchers formed sheets of crystallized polymers measuring about 5 nanometers (billionths of a meter) in thickness when dispersed in water.

    “We conducted our experiments on the most perfect polymer molecules we could make,” Balsara said – the peptoid samples in the study were extremely pure compared to typical synthetic polymers.

    The research team created tiny flakes of peptoid nanosheets, froze them to preserve their structure, and then imaged them using an electron beam. An inherent challenge in imaging materials with a soft structure, such as polymers, is that the beam used to capture images also damages the samples.

    The direct cryogenic electron microscopy images, obtained using very few electrons to minimize beam damage, are too blurry to reveal individual atoms. Researchers achieved resolution of about 2 angstroms, which is two-tenths of nanometer (billionth of a meter), or about double the diameter of a hydrogen atom.

    They achieved this by taking over 500,000 blurry images, sorting different motifs into different “bins,” and averaging the images in each bin. The sorting methods they used were based on algorithms developed by the structural biology community to image the atomic structure of proteins.

    “We took advantage of technology that the protein-imaging folks had developed and extended it to human-made, soft materials,” Balsara said. “Only when we sorted them and averaged them did that blurriness become clear.”

    Before these high-resolution images, Balsara said, the arrangement and variation of the different types of crystal structures was unknown.

    “We knew that there were many motifs, but they are all different from each other in ways we didn’t know,” he said. “In fact, even the dominant motif in the peptoid sheet was a surprise.”

    3
    Researchers developed a colorized map (right) to show the distribution of different types of crystal structures (left) that they found in the polymer peptoid sample. The scale bar in the map image is 50 nanometers, or 50 billionths of a meter. (Credit: Berkeley Lab, UC Berkeley)

    Balsara credited Ken Downing, a senior scientist in Berkeley Lab’s Molecular Biophysics and Integrated Bioimaging Division who passed away in August, and Xi Jiang, a project scientist in the Materials Sciences Division, for capturing the high-quality images that were central to the study and for developing the algorithms necessary to achieve atomic resolution in the polymer imaging.

    Their expertise in cryogenic electron microscopy was complemented by Ron Zuckermann’s ability to synthesize model peptoids, David Prendergast’s knowledge of molecular dynamics simulations needed to interpret the images, Andrew Minor’s expertise in imaging metals at the atomic scale, and Balsara’s experience in the field of polymer science.

    At the Molecular Foundry, Zuckermann directs the Biological Nanostructures facility, Prendergast directs the Theory facility, and Minor directs the National Center for Electron Microscopy and is also a professor of materials science and engineering at UC Berkeley. Much of the cryo-electron imaging was carried out at UC Berkeley’s Krios microscopy facility.

    Balsara said that his own research into using polymers for batteries and other electrochemical devices could benefit from the research, as seeing the position of polymer atoms could greatly aid in the design of materials for these devices.

    Atomic-scale images of polymers used in everyday life may need more sophisticated, automated filtering mechanisms that rely on machine learning, for example.

    “We should be able to determine the atomic-scale structure of a wide variety of synthetic polymers such as commercial polyethylene and polypropylene, leveraging rapid developments in areas such as artificial intelligence, using this approach,” Balsara said.

    Determining crystal structures can provide vital information for other applications, such as the development of drugs, as different crystal motifs could produce quite different binding properties and therapeutic effects, for example.

    The work was conducted within the Soft Matter Electron Microscopy Program at Berkeley Lab, which is supported by the U.S. Department of Energy’s Office of Science; and by the Bay Area Cryo-EM Consortium.

    See the full article here .

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    Bringing Science Solutions to the World

    In the world of science, Lawrence Berkeley National Laboratory (Berkeley Lab) is synonymous with “excellence.” Thirteen Nobel prizes are associated with Berkeley Lab. Seventy Lab scientists are members of the National Academy of Sciences (NAS), one of the highest honors for a scientist in the United States. Thirteen of our scientists have won the National Medal of Science, our nation’s highest award for lifetime achievement in fields of scientific research. Eighteen of our engineers have been elected to the National Academy of Engineering, and three of our scientists have been elected into the Institute of Medicine. In addition, Berkeley Lab has trained thousands of university science and engineering students who are advancing technological innovations across the nation and around the world.

    Berkeley Lab is a member of the national laboratory system supported by the U.S. Department of Energy through its Office of Science. It is managed by the University of California (UC) and is charged with conducting unclassified research across a wide range of scientific disciplines. Located on a 202-acre site in the hills above the UC Berkeley campus that offers spectacular views of the San Francisco Bay, Berkeley Lab employs approximately 3,232 scientists, engineers and support staff. The Lab’s total costs for FY 2014 were $785 million. A recent study estimates the Laboratory’s overall economic impact through direct, indirect and induced spending on the nine counties that make up the San Francisco Bay Area to be nearly $700 million annually. The Lab was also responsible for creating 5,600 jobs locally and 12,000 nationally. The overall economic impact on the national economy is estimated at $1.6 billion a year. Technologies developed at Berkeley Lab have generated billions of dollars in revenues, and thousands of jobs. Savings as a result of Berkeley Lab developments in lighting and windows, and other energy-efficient technologies, have also been in the billions of dollars.

    Berkeley Lab was founded in 1931 by Ernest Orlando Lawrence, a UC Berkeley physicist who won the 1939 Nobel Prize in physics for his invention of the cyclotron, a circular particle accelerator that opened the door to high-energy physics. It was Lawrence’s belief that scientific research is best done through teams of individuals with different fields of expertise, working together. His teamwork concept is a Berkeley Lab legacy that continues today.

    A U.S. Department of Energy National Laboratory Operated by the University of California.

    University of California Seal

    DOE Seal

     
  • richardmitnick 8:37 am on September 27, 2018 Permalink | Reply
    Tags: , , Biomedical research, CZ Biohub awards $13.7 million for new collaborative health research, , Priscilla Chan, UC Berkeley   

    From UC Berkeley: “CZ Biohub awards $13.7 million for new collaborative health research” 

    UC Berkeley

    From UC Berkeley

    September 26, 2018

    The Chan Zuckerberg Biohub (CZ Biohub), a nonprofit medical research organization, today announced that it is awarding $13.7 million over three years to support cutting-edge biomedical research from seven teams of scientists, physicians and engineers, with faculty members from UC Berkeley, UCSF and Stanford on each team.

    1
    Mark Zuckerberg and Priscilla Chan

    The awards will fund two new programs: the CZ Biohub Microbiome Initiative and the CZ Biohub Intercampus Research Awards.

    “We are thrilled by the extent to which these awards honor and support the notion that our most pressing challenges can only be surmounted by transcending the lines that have too long divided academic disciplines, departments and even institutions,” said UC Berkeley Chancellor Carol Christ. “The awards will also help support our efforts to extend the reach of world-class, fundamental research through initiatives that can speed the translation of discoveries into inventions and services for the benefit of all.”

    “For the first time, these new awards bring together highly talented investigators from all three campuses to collaborate on promising new approaches to major biomedical problems,” said Joe DeRisi, co-president of CZ Biohub. “By drawing on the strengths of all three institutions, we believe these teams will accomplish what is now beyond the reach of individual investigators.”

    Launched as a pilot program earlier this year, the CZ Biohub Microbiome Initiative provides $4 million over three years to carry out research on the community of microbes within the human body that influence many aspects of health, from nutrition and immune function to drug metabolism. The Microbiome Initiative brings together eight leading microbiome experts from all three campuses based on their complementary research interests.

    2
    No image caption or credit

    Assembling the Microbiome Initiative team inspired CZ Biohub to create the Intercampus Research Awards. The new competitive awards program promotes collaborative research by bringing together clinicians, biologists, chemists, data scientists, mathematicians, engineers and bioethicists in teams that each include faculty members from all three campuses. The competition drew applications from 83 teams. CZ Biohub initially planned to support three teams but was inspired to increase the number of awards to six, providing $9.7 million over three years.

    “This new collaborative team-based funding allows investigators across the three campuses to tackle demanding problems to enhance health,” said Steve Quake, co-president of CZ Biohub. “These research teams will shed new light on a diverse and challenging set of questions that will advance our understanding while developing technologies that open fresh avenues of research.”

    “We launched the Biohub to bring together some of the brightest scientific minds in the Bay Area with world-class engineering teams, in order to help accelerate the pace of discovery and make faster progress in the fight against disease,” said Priscilla Chan and Mark Zuckerberg, co-founders of the Chan Zuckerberg Initiative and a pediatrician and founder of Facebook, respectively. “Just two years after its launch, it is incredible to see how the Biohub has helped spark promising new collaborations, tools, and research to enable and empower the entire scientific community.”

    The CZ Biohub is an independent non-profit medical research organization collaborating with Stanford, UC Berkeley and UCSF to harness the power of science, technology and human capacity to cure, prevent or manage all disease during our children’s lifetime. For more information about the CZ Biohub, visit https://czbiohub.org.

    See the full article here .

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    Please help promote STEM in your local schools.

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

    UC Berkeley Seal

     
  • richardmitnick 6:53 pm on September 11, 2018 Permalink | Reply
    Tags: , , , , , , , , , The notorious repeating fast radio source FRB 121102, UC Berkeley   

    From Breakthrough Listen via Science Alert: “Astronomers Have Detected an Astonishing 72 New Mystery Radio Bursts From Space “ 

    From Breakthrough Listen Project

    via

    ScienceAlert

    Science Alert

    11 SEP 2018
    MICHELLE STARR

    A massive number of new signals have been discovered coming from the notorious repeating fast radio source FRB 121102 – and we can thank artificial intelligence for these findings.

    Researchers at the search for extraterrestrial intelligence (SETI) project Breakthrough Listen applied machine learning to comb through existing data, and found 72 fast radio bursts that had previously been missed.

    Fast radio bursts (FRBs) are among the most mysterious phenomena in the cosmos. They are extremely powerful, generating as much energy as hundreds of millions of Suns. But they are also extremely short, lasting just milliseconds; and most of them only occur once, without warning.

    This means they can’t be predicted; so it’s not like astronomers are able to plan observations. They are only picked up later in data from other radio observations of the sky.

    Except for one source. FRB 121102 is a special individual – because ever since its discovery in 2012, it has been caught bursting again and again, the only FRB source known to behave this way.

    Because we know FRB 121102 to be a repeating source of FRBs, this means we can try to catch it in the act. This is exactly what researchers at Breakthrough Listen did last year. On 26 August 2017, they pointed the Green Bank Telescope in West Virginia at its location for five hours.

    In the 400 terabytes of data from that observation, the researchers discovered 21 FRBs using standard computer algorithms, all from within the first hour. They concluded that the source goes through periods of frenzied activity and quiescence.

    But the powerful new algorithm used to reanalyse that August 26 data suggests that FRB 121102 is a lot more active and possibly complex than originally thought. Researchers trained what is known as a convolutional neural network to look for the signals, then set it loose on the data like a truffle pig.

    It returned triumphant with 72 previously undetected signals, bringing the total number that astronomers have observed from the object to around 300.

    “This work is only the beginning of using these powerful methods to find radio transients,” said astronomer Gerry Zhang of the University of California Berkeley, which runs Breakthrough Listen.

    “We hope our success may inspire other serious endeavours in applying machine learning to radio astronomy.”

    The new result has helped us learn a little more about FRB 121102, putting constraints on the periodicity of the bursts. It suggests that, the researchers said, there’s no pattern to the way we receive them – unless the pattern is shorter than 10 milliseconds.

    See the full article here .

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    Please help promote STEM in your local schools.

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    Listen

    Breakthrough Listen is the largest ever scientific research program aimed at finding evidence of civilizations beyond Earth. The scope and power of the search are on an unprecedented scale:

    The program includes a survey of the 1,000,000 closest stars to Earth. It scans the center of our galaxy and the entire galactic plane. Beyond the Milky Way, it listens for messages from the 100 closest galaxies to ours.

    The instruments used are among the world’s most powerful. They are 50 times more sensitive than existing telescopes dedicated to the search for intelligence.

    CSIRO/Parkes Observatory, located 20 kilometres north of the town of Parkes, New South Wales, Australia

    UCSC Lick Automated Planet Finder telescope, Mount Hamilton, CA, USA



    GBO radio telescope, Green Bank, West Virginia, USA

    The radio surveys cover 10 times more of the sky than previous programs. They also cover at least 5 times more of the radio spectrum – and do it 100 times faster. They are sensitive enough to hear a common aircraft radar transmitting to us from any of the 1000 nearest stars.

    We are also carrying out the deepest and broadest ever search for optical laser transmissions. These spectroscopic searches are 1000 times more effective at finding laser signals than ordinary visible light surveys. They could detect a 100 watt laser (the energy of a normal household bulb) from 25 trillion miles away.

    Listen combines these instruments with innovative software and data analysis techniques.

    The initiative will span 10 years and commit a total of $100,000,000.

     
  • richardmitnick 12:43 pm on April 11, 2018 Permalink | Reply
    Tags: , , , , UC Berkeley   

    From U Washington via UC Berkeley: “Start of most sensitive search yet for dark matter axion” 

    U Washington

    University of Washington

    UC Berkeley

    UC Berkeley

    April 9, 2018
    Robert Sanders
    rlsanders@berkeley.edu

    1
    The SQUID-based amplifier, which is about a millimeter square, is supercooled to be sensitive to faint signals from axions, should they convert into a microwave photon in the ADMX detector. Sean O’Kelley image

    Thanks to low-noise superconducting quantum amplifiers invented at UC Berkeley, physicists are now embarking on the most sensitive search yet for axions, one of today’s top candidates for dark matter.

    The Axion Dark Matter Experiment (ADMX) reported results today showing that it is the world’s first and only experiment to have achieved the necessary sensitivity to “hear” the telltale signs of dark matter axions.

    The milestone is the result of more than 30 years of research and development, with the latest piece of the puzzle coming in the form of a quantum device that allows ADMX to listen for axions more closely than any experiment ever built.

    John Clarke, a professor of physics in the graduate school at UC Berkeley and a pioneer in the development of sensitive magnetic detectors called SQUIDs (superconducting quantum interference devices), developed the amplifier two decades ago. ADMX scientists, with Clarke’s input, have now incorporated it into the ADMX detector at the University of Washington, Seattle, and are ready to roll.

    “ADMX is a complicated and quite expensive piece of machinery, so it took a while to build a suitable detector so that they could put the SQUID amplifier on it and demonstrate that it worked as advertised. Which it did,” Clarke said.

    The ADMX team published their results online today in the journal Physical Review Letters.

    “This result signals the start of the true hunt for axions,” said Andrew Sonnenschein at the Fermi National Accelerator Laboratory (Fermilab) in Batavia, Illinois, the operations manager for ADMX. “If dark matter axions exist within the frequency band we will be probing for the next few years, then it’s only a matter of time before we find them.”

    Dark matter: MACHOs, WIMPs or axions?

    U Washington ADMX cutaway rendering of the ADMX detector

    Dark matter is the missing 84 percent of matter in the universe, and physicists have looked extensively for many possible candidates, most prominently massive compact halo objects, or MACHOs, and weakly interacting massive particles, or WIMPs. Despite decades of searching for MACHOs and WIMPs, scientists have struck out; they can see the effects of dark matter in the universe, in how galaxies and stars within galaxies move, but they can’t see dark matter itself.

    Axions are becoming the favored alternative, in part because their existence would also solve problems with the standard model of particle physics today, including the fact that the neutron should have an electric dipole moment, but doesn’t.

    Like other dark-matter candidates, axions are everywhere but difficult to detect. Because they interact with ordinary matter so rarely, they stream through space, even passing through the Earth, without “touching” ordinary matter. ADMX employs a strong magnetic field and a tuned, reflective box to encourage axions to convert to microwave-frequency photons, and uses the quantum amplifier to “listen” for them. All this is done at the lowest possible temperature to reduce background noise.

    Clarke learned of a key stumbling block for ADMX in 1994, when meeting with physicist Leslie Rosenberg, now a professor at the University of Washington and chief scientist for ADMX, and Karl van Bibber, now chair of UC Berkeley’s Department of Nuclear Engineering. Because the axion signal would be very faint, any detector would have to be very cold and “quiet.” Noise from heat, or thermal radiation, is easy to eliminate by cooling the detector down to 0.1 Kelvin, or roughly 460 degrees below zero Fahrenheit. But eliminating the noise from standard semiconductor transistor amplifiers proved difficult.

    They asked Clarke, would SQUID amplifiers solve this problem?

    Supercold amplifiers lower noise to absolute limit

    Though he had built SQUID amplifiers that worked up to 100 MHz frequencies, none worked at the gigahertz frequencies needed, so he set to work to build one. By 1998, he and his collaborators had solved the problem, thanks in large part to initial funding from the National Science Foundation and subsequent funding from the Department of Energy (DOE) through Lawrence Berkeley National Laboratory. The amplifiers on ADMX were funded by DOE through the University of Washington.


    Listening for dark matter: How ADMX employs cold cavities and SQUID amplifiers to find the elusive axion. Courtesy of University of Washington, Seattle.

    Clarke and his group showed that, cooled to temperatures of tens of milliKelvin above absolute zero, the Microstrip SQUID Amplifier (MSA) could achieve a noise that was quantum limited, that is, limited only by Heisenberg’s Uncertainty Principle.

    “You can’t do better than that,” Clarke said.

    This much quieter technology, combined with the refrigeration unit, reduced the noise by a factor of about 30 at 600 MHz so that a signal from the axion, if there is one, should come through loud and clear. The MSA currently in operation on ADMX was fabricated by Gene Hilton at the National Institute of Standards and Technology in Boulder, Colorado, and tested, calibrated and packaged by Sean O’Kelley, a graduate student in Clarke’s research group at UC Berkeley.

    The ADMX team plans to slowly tune through millions of frequencies in hopes of hearing a clear tone from photons produced by axion decay.

    “This result plants a flag,” said Rosenberg. “It tells the world that we have the sensitivity, and have a very good shot at finding the axion. No new technology is needed. We don’t need a miracle anymore, we just need the time.”

    Clarke noted too that the high-frequency, low-noise quantum SQUID amplifiers he invented for ADMX have since been employed in another hot area of physics, to read out the superconducting quantum bits, or qubits, for quantum computers of the future.

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

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    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

    UC Berkeley Seal

    The University of Washington is one of the world’s preeminent public universities. Our impact on individuals, on our region, and on the world is profound — whether we are launching young people into a boundless future or confronting the grand challenges of our time through undaunted research and scholarship. Ranked number 10 in the world in Shanghai Jiao Tong University rankings and educating more than 54,000 students annually, our students and faculty work together to turn ideas into impact and in the process transform lives and our world. For more about our impact on the world, every day.

    So what defines us — the students, faculty and community members at the University of Washington? Above all, it’s our belief in possibility and our unshakable optimism. It’s a connection to others, both near and far. It’s a hunger that pushes us to tackle challenges and pursue progress. It’s the conviction that together we can create a world of good. Join us on the journey.

     
  • richardmitnick 8:08 am on April 11, 2018 Permalink | Reply
    Tags: Antihydrogen physics, , , , , UC Berkeley   

    From UC Berkeley: “An Improved Method for Antihydrogen Spectroscopy” Berkeley Physics 

    UC Berkeley

    UC Berkeley

    April 4, 2018

    1
    Professor Jonathan Wurtele, undergraduate students Helia Kamal, Nate Belmore, Carlos Sierra, Stefania Balasiu, Cheyenne Nelson, graduate student Celeste Carruth, and Professor Joel Fajans.No image credit

    Berkeley physicists Joel Fajans and Jonathan Wurtele, along with their students and postdocs, have spent over a decade working on antihydrogen physics as part of the ALPHA Collaboration. The quest for precision antihydrogen spectroscopy was realized in a new paper that just appeared in Nature (Characterization of the 1S–2S transition in antihydrogen, Ahmadi et al.)

    Much of the effort of the Berkeley group has been to invent and develop new plasma physics techniques for synthesizing antihydrogen.

    A recent paper in Physical Review Letters, part of the thesis work of Celeste Carruth, reports an improved method for controlling plasma density and temperature, which in turn enabled a factor-of-ten increase in trapping rates. These increased trapping rates enabled reduced statistical and systematic errors that previously limited ALPHA measurements.

    The future is very promising. Improvements to the infrastructure for antiproton generation at CERN will provide on-demand antiprotons after the upcoming two-year CERN accelerator shutdown.

    Further improvements in antihydrogen synthesis may result from very successful plasma cavity cooling experiments by graduate student Eric Hunter. The work, interesting in their own right as a study of coupled nonlinear oscillators, appeared in Physics of Plasmas (Low magnetic field cooling of lepton plasmas via cyclotron-cavity resonance, E. Hunter et al.)

    The research has benefited from nearly two-dozen undergraduate students who have spent a summer at CERN working on ALPHA and worked here on the related plasma physics.

    CERN ALPHA Antimatter Factory

    See the full article here .

    Please help promote STEM in your local schools.

    STEM Icon

    Stem Education Coalition

    Founded in the wake of the gold rush by leaders of the newly established 31st state, the University of California’s flagship campus at Berkeley has become one of the preeminent universities in the world. Its early guiding lights, charged with providing education (both “practical” and “classical”) for the state’s people, gradually established a distinguished faculty (with 22 Nobel laureates to date), a stellar research library, and more than 350 academic programs.

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