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  • richardmitnick 9:13 am on September 14, 2017 Permalink | Reply
    Tags: , Laser Technology, , Optical information processing, , Plasmonic cavity,   

    From Sandia: “Nanotechnology experts at Sandia create first terahertz-speed polarization optical switch” 


    Sandia Lab

    A Sandia National Laboratories-led team has for the first time used optics rather than electronics to switch a nanometer-thick thin film device from completely dark to completely transparent, or light, at a speed of trillionths of a second.

    The team led by principal investigator Igal Brener published a Nature Photonics paper this spring with collaborators at North Carolina State University. The paper describes work on optical information processing, such as switching or light polarization control using light as the control beam, at terahertz speeds, a rate much faster than what is achievable today by electronic means, and a smaller overall device size than other all-optical switching technologies.

    Electrons spinning around inside devices like those used in telecommunications equipment have a speed limit due to a slow charging rate and poor heat dissipation, so if significantly faster operation is the goal, electrons might have to give way to photons.

    To use photons effectively, the technique requires a device that goes from completely light to completely dark at terahertz speeds. In the past, researchers couldn’t get the necessary contrast change from an optical switch at the speed needed in a small device. Previous attempts were more like dimming a light than turning it off, or required light to travel a long distance.

    The breakthrough shows it’s possible to do high contrast all-optical switching in a very thin device, in which light intensity or polarization is switched optically, said Yuanmu Yang, a former Sandia Labs postdoctoral employee who worked at the Center for Integrated Nanotechnologies, a Department of Energy user facility jointly operated by Sandia and Los Alamos national laboratories. The work was done at CINT.

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    Former Sandia National Laboratories postdoctoral researcher Yuanmu Yang, left, and Sandia researcher Igal Brener set up to do testing in an optical lab. A team led by Brener published a Nature Photonics paper describing work on optical information processing at terahertz speeds, a rate much faster than what is achievable today by electronic means. (Photo by Randy Montoya)

    “Instead of switching a current on and off, the goal would be to switch light on and off at rates much faster than what is achievable today,” Yang said.

    Faster information processing important in communications, physics research

    A very rapid and compact switching platform opens up a new way to investigate fundamental physics problems. “A lot of physical processes actually occur at a very fast speed, at a rate of a few terahertz,” Yang said. “Having this tool lets us study the dynamics of physical processes like molecular rotation and magnetic spin. It’s important for research and for moving knowledge further along.”

    It also could act as a rapid polarization switch — polarization changes the characteristics of light — that could be used in biological imaging or chemical spectroscopy, Brener said. “Sometimes you do measurements that require changing the polarization of light at a very fast rate. Our device can work like that too. It’s either an absolute switch that turns on and off or a polarization switch that just switches the polarization of light.”

    Ultrafast information processing “matters in computing, telecommunications, signal processing, image processing and in chemistry and biology experiments where you want very fast switching,” Brener said. “There are some laser-based imaging techniques that will benefit from having fast switching too.”

    The team’s discovery arose from research funded by the Energy Department’s Basic Energy Sciences, Division of Materials Sciences and Engineering, that, among other things, lets Sandia study light-matter interaction and different concepts in nanophotonics.

    “This is an example where it just grew organically from fundamental research into something that has an amazing performance,” Brener said. “Also, we were lucky that we had a collaboration with North Carolina State University. They had the material and we realized that we could use it for this purpose. It wasn’t driven by an applied project; it was the other way around.”

    The collaboration was funded by Sandia’s Laboratory Directed Research and Development program.

    Technique uses laser beams to carry information, switch device

    The technique uses two laser beams, one carrying the information and the second switching the device on and off.

    The switching beam uses photons to heat up electrons inside semiconductors to temperatures of a few thousand degrees Fahrenheit, which doesn’t cause the sample to get that hot but dramatically changes the material’s optical properties. The material also relaxes at terahertz speeds, in a few hundred femtoseconds or in less than one trillionth of a second. “So we can switch this material on and off at a rate of a few trillion times per second,” Yang said.

    Sandia researchers turn the optical switch on and off by creating something called a plasmonic cavity, which confines light within a few tens of nanometers, and significantly boosts light-matter interaction. By using a special plasmonic material, doped cadmium oxide from North Carolina State, they built a high-quality plasmonic cavity. Heating up electrons in the doped cadmium oxide drastically modifies the opto-electrical properties of the plasmonics cavity, modulating the intensity of the reflected light.

    Traditional plasmonic materials like gold or silver are barely sensitive to the optical control beam. Shining a beam onto them doesn’t change their properties from light to dark or vice versa. The optical control beam, however, alters the doped cadmium oxide cavity very rapidly, controlling its optical properties like an on-off switch.

    The next step is figuring out how to use electrical pulses rather than optical pulses to activate the switch, since an all-optical approach still requires large equipment, Brener said. He estimates the work could take three to five years.

    “For practical purposes, you need to miniaturize and do this electrically,” he said.

    The paper’s authors are Yang, Brener, Salvatore Campione, Willie Luk and Mike Sinclair at Sandia Labs and Jon-Paul Maria, Kyle Kelley and Edward Sachet at North Carolina State.

    See the full article here .

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    Sandia National Laboratory

    Sandia National Laboratories is a multiprogram laboratory operated by Sandia Corporation, a wholly owned subsidiary of Lockheed Martin Corporation, for the U.S. Department of Energy’s National Nuclear Security Administration. With main facilities in Albuquerque, N.M., and Livermore, Calif., Sandia has major R&D responsibilities in national security, energy and environmental technologies, and economic competitiveness.
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  • richardmitnick 8:05 am on September 14, 2017 Permalink | Reply
    Tags: , atom by atom, ’ physicists create a new type of molecule, , Experiments like these pave the way for developing new methods for controlling chemistry, Help scientists understand how certain complex molecules including some that could be precursors to life came to exist in space, In step toward ‘controlling chemistry, Integrated ion-trap-time-of-flight mass spectrometer, Ion traps, Laser Technology, Narrow the gap between physics and chemistry, Octet Rule - each atom in a molecule that is produced by a chemical reaction will have eight outer orbiting electrons, , , Ultra-cold atom traps   

    From UCLA: “In step toward ‘controlling chemistry,’ physicists create a new type of molecule, atom by atom” 


    UCLA Newsrooom

    September 13, 2017
    Stuart Wolpert

    1
    By working in extremely controlled conditions, Eric Hudson and his colleagues could observe properties of atoms and molecules that have previously been hidden from view. Stuart Wolpert/UCLA

    UCLA physicists have pioneered a method for creating a unique new molecule that could eventually have applications in medicine, food science and other fields. Their research, which also shows how chemical reactions can be studied on a microscopic scale using tools of physics, is reported in the journal Science.

    For the past 200 years, scientists have developed rules to describe chemical reactions that they’ve observed, including reactions in food, vitamins, medications and living organisms. One of the most ubiquitous is the “octet rule,” which states that each atom in a molecule that is produced by a chemical reaction will have eight outer orbiting electrons. (Scientists have found exceptions to the rule, but those exceptions are rare.)

    But the molecule created by UCLA professor Eric Hudson and colleagues violates that rule. Barium-oxygen-calcium, or BaOCa+, is the first molecule ever observed by scientists that is composed of an oxygen atom bonded to two different metal atoms.

    Normally, one metal atom (either barium or calcium) can react with an oxygen atom to produce a stable molecule. However, when the UCLA scientists added a second metal atom to the mix, a new molecule, BaOCa+, which no longer satisfied the octet rule, had been formed.

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    Michael Mills, Prateek Puri, Eric Hudson and Christian Schneider. Stuart Wolpert/UCLA

    Other molecules that violate the octet rule have been observed before, but the UCLA study is among the first to observe such a molecule using tools from physics — namely lasers, ion traps and ultra-cold atom traps.

    Hudson’s laboratory used laser light to cool tiny amounts of the reactant atoms and molecules to an extremely low temperature — one one-thousandth of a degree above absolute zero — and then levitate them in a space smaller than the width of a human hair, inside of a vacuum chamber. Under these highly controlled conditions, the scientists could observe properties of the atoms and molecules that are otherwise hidden from view, and the “physics tools” they used enabled them to hold a sample of atoms and observe chemical reactions one molecule at a time.

    The ultra-cold temperatures used in the experiment can also be used to simulate the reaction as it would occur in outer space. That could help scientists understand how certain complex molecules, including some that could be precursors to life, came to exist in space, Hudson said.

    The researchers found that when they brought together calcium and barium methoxide inside of their system under normal conditions, they would not react because the atoms could not find a way to rearrange themselves to form a stable molecule. However, when the scientists used a laser to change the distribution of the electrons in the calcium atom, the reaction quickly proceeded, producing a new molecule, CaOBa+.

    The approach is part of a new physics-inspired subfield of chemistry that uses the tools of ultra-cold physics, such as lasers and electromagnetism, to observe and control how and when single-particle reactions occur.

    UCLA graduate student Prateek Puri, the project’s lead researcher, said the experiment demonstrates not only how these techniques can be used to create exotic molecules, but also how they can be used to engineer important reactions. The discovery could ultimately be used to create new methods for preserving food (by preventing unwanted chemical reactions between food and the environment) or developing safer medications (by eliminating the chemical reactions that cause negative side effects).

    “Experiments like these pave the way for developing new methods for controlling chemistry,” Puri said. “We’re essentially creating ‘on buttons’ for reactions.”

    Hudson said he hopes the work will encourage other scientists to further narrow the gap between physics and chemistry, and to demonstrate that increasingly complex molecules can be studied and controlled. He added that one key to the success of the new study was the involvement of experts from various fields: experimental physicists, theoretical physicists and a physical chemist.

    A key player in the research is already making a name for itself in Hollywood. A device called the integrated ion-trap-time-of-flight mass spectrometer, which was invented by Hudson’s lab and which was used to discover the reaction — was featured on a recent episode of the sitcom “The Big Bang Theory.”

    “The device enables us to detect and identify the products of reactions on the single-particle level, and for us, it has really been a bridge between chemistry and physics,” said Michael Mills, a UCLA graduate student who worked on the project. “We were delighted to see it picked up by the show.”

    Co-authors of the study are Christian Schneider, a UCLA research scientist; Ionel Simbotin, a University of Connecticut physics postdoctoral scholar; John Montgomery Jr., a University of Connecticut research professor of physics; Robin Côté, a University of Connecticut professor of physics; and Arthur Suits, a University of Missouri professor of chemistry.

    The research was funded by the National Science Foundation and Army Research Office.

    See the full article here .

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    For nearly 100 years, UCLA has been a pioneer, persevering through impossibility, turning the futile into the attainable.

    We doubt the critics, reject the status quo and see opportunity in dissatisfaction. Our campus, faculty and students are driven by optimism. It is not naïve; it is essential. And it has fueled every accomplishment, allowing us to redefine what’s possible, time after time.

    This can-do perspective has brought us 12 Nobel Prizes, 12 Rhodes Scholarships, more NCAA titles than any university and more Olympic medals than most nations. Our faculty and alumni helped create the Internet and pioneered reverse osmosis. And more than 100 companies have been created based on technology developed at UCLA.

     
  • richardmitnick 7:35 am on September 1, 2017 Permalink | Reply
    Tags: , , , Laser Technology, MEC- Matter in Extreme Conditions, , , ,   

    From SLAC: “Newly Upgraded Laser Allows Scientists to Peer Further Into the Extreme Universe at SLAC’s LCLS” 


    SLAC Lab

    August 15, 2017
    Miyuki Dougherty

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    Highly reflective mirrors and telescope lenses in the Matter in Extreme Conditions (MEC) optical laser system are carefully positioned to propagate the instrument’s high-quality laser beams. The laser beams create extreme pressure and temperature conditions in materials that are instantaneously probed using hard X-rays from SLAC’s Linac Coherent Light Source (LCLS). (Dawn Harmer/SLAC National Accelerator Laboratory)

    Tripling the energy and refining the shape of optical laser pulses at the Matter in Extreme Conditions instrument allows researchers to create higher-pressure conditions and explore unsolved fusion energy, plasma physics and materials science questions.

    Scientists at the Department of Energy’s SLAC National Accelerator Laboratory recently upgraded a powerful optical laser system used to create shockwaves that generate high-pressure conditions like those found within planetary interiors. The laser system now delivers three times more energy for experiments with SLAC’s ultrabright X-ray laser, providing a more powerful tool for probing extreme states of matter in our universe.

    Together, the optical and X-ray lasers form the Matter in Extreme Conditions (MEC) instrument at the Linac Coherent Light Source (LCLS).

    SLAC/LCLS

    The high-power optical laser system creates extreme temperature and pressure conditions in materials, and the X-ray laser beam captures the material’s response.

    With this technology, researchers have already examined how meteor impacts shock minerals in the Earth’s crust and simulated conditions in Jupiter’s interior by turning aluminum foil into a warm, dense plasma.

    Higher Intensity and More Controlled Pulse Shapes

    The MEC instrument team received funding from the Office of Fusion Energy Sciences (FES) within the DOE’s Office of Science to double the amount of energy the optical beam can deliver in 10 nanoseconds, from 20 to 40 joules.

    But they went even further.

    “The team exceeded our expectations, an exciting accomplishment for the DOE High Energy Density program and future MEC instrument users,” says Kramer Akli, program manager for High Energy Density Laboratory Plasma at FES.

    The team tripled the amount of energy the laser can deliver in 10 nanoseconds to a spot on a target no bigger than the width of a few human hairs. When focused down to that small area, the laser provides users with intensities up to 75 terawatts per square centimeter.

    “In other terms, the upgraded laser has the same power as 17 Teslas discharging their 100 kilowatt-hour batteries in one second,” says Eric Galtier, a MEC instrument scientist.

    A portion of the energy upgrade can be attributed to the optical laser’s new, homemade diode pumped front-end, designed with the help of Marc Welch, a MEC laser engineer. The scientists also built and automated a system for shaping the laser pulses with extraordinary precision, allowing users substantially greater flexibility and control over the pulse shapes used in their experiments.

    A more powerful and reliable laser means that researchers can study higher pressure regimes and reach conditions relevant to fusion energy studies.

    Simulating the Core of Planets

    The MEC upgrade is promising for many researchers, including Shaughnessy Brennan Brown, a doctoral student in Mechanical Engineering, whose research focuses on high energy density science, which spans chemistry, materials science, and physics. Brennan Brown uses the MEC experimental hutch to drive shock waves through silicon and generate high-pressure conditions that occur in the Earth’s interior.

    “The MEC upgrade at LCLS enables researchers like me to generate exciting, previously-unexplored regimes of exotic matter – such as those found on Mars, our next planetary stepping stone – with crucial reliability and repeatability,” Brennan Brown says.

    Brennan Brown’s research examines the processes by which silicon in Earth’s core rearranges atomically under high temperature and pressure conditions. The thermodynamic properties of these high-pressure states affect our magnetic field, which protects us from the solar wind and allows us to survive on Earth. The laser upgrade will permit Brennan Brown to reach higher pressure and temperature conditions inside her samples, a long-standing goal.

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    Inside the MEC vacuum target chamber where researchers create transient states of matter using high-power optical lasers, which are then examined with SLAC’s Linac Coherent Light Source (LCLS) X-rays. (Matt Beardsley/SLAC National Accelerator Laboratory)

    Intensity Plus Precision

    The optical laser amplifies a low-power beam in stages and reaches increasingly high energies. However, the quality of the laser beam and ability to control it diminish during amplification. A low-quality pulse may start and end with a significantly different shape, which is not useful for researchers trying to recreate specific conditions.

    “The initial low energy pulse must have a pristine spatial mode and the properly configured temporal shape – that is, a precise sculpting of the pulse’s power as a function of time – before amplification to produce the laser pulse characteristics needed to enable each users’ experiment,” says Michael Greenberg, the MEC Laser Area Manager.

    Each target is unique and requires a specific energy and pulse shape, making manual tests and adjustments time-consuming. Prior to the upgrade, the team optimized the pulse shape by hand, taking anywhere from a few hours to a few days to properly calibrate it.

    To resolve this issue, Eric Cunningham, a laser scientist at MEC, developed an automated control system to shape the low-powered beam before amplification.

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    To demonstrate the MEC laser system’s enhanced ability to tailor the shape of laser pulses, scientists generated pulse shapes that spell out “M-E-C” in a plot of laser intensity vs. time. (Eric Cunningham and Michael Greenberg/SLAC National Accelerator Laboratory)

    “The new system allows for precise tailoring of the pulse shape using a computerized feedback loop system that analyzes the pulses and automatically re-calibrates the laser,” Cunningham said. The new optimizer is a promising system for generating many high-quality pulses in the most accurate and timely manner possible.

    In addition to the improved pulse shapes, the upgraded system deposits energy on samples more consistently from shot to shot, which allows researchers to very closely reproduce extreme states of matter in their samples. As a result, both the data quality and operational efficiency are improved.

    Brennan Brown says it’s the people and technology that make the instrument so successful: “The capability and competency of the laser scientists and engineers at the MEC experimental station offer researchers the technological resources they need to explore unanswered questions of the universe and bring their theories to life.”

    LCLS is a DOE Office of Science User Facility.

    See the full article here .

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    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
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  • richardmitnick 8:36 pm on July 14, 2017 Permalink | Reply
    Tags: A high Mach number shock wave, High-energy plasma, Laser Technology, , , The first high-energy shock waves in a laboratory setting, U Rochester OMEGA EP Laser System   

    From PPPL: “Scientists create first laboratory generation of high-energy shock waves that accelerate astrophysical particles” 


    PPPL

    July 14, 2017
    John Greenwald

    1
    Physicist Derek Schaeffer. (Photo by Elle Starkman/Office of Communications).

    Throughout the universe, supersonic shock waves propel cosmic rays and supernova particles to velocities near the speed of light. The most high-energy of these astrophysical shocks occur too far outside the solar system to be studied in detail and have long puzzled astrophysicists. Shocks closer to Earth can be detected by spacecraft, but they fly by too quickly to probe a wave’s formation.

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    No image credit or caption.

    Opening the door to new understanding

    Now a team of scientists has generated the first high-energy shock waves in a laboratory setting, opening the door to new understanding of these mysterious processes. “We have for the first time developed a platform for studying highly energetic shocks with greater flexibility and control than is possible with spacecraft,” said Derek Schaeffer, a physicist at Princeton University and the U.S. Department of Energy’s (DOE) Princeton Plasma Physics Laboratory (PPPL), and lead author of a July paper in Physical Review Letters that outlines the experiments.

    Schaeffer and colleagues conducted their research on the Omega EP laser facility at the University of Rochester Laboratory for Laser Energetics.

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    U Rochester OMEGA EP Laser System

    U Rochester Omega Laser

    Collaborating on the project was PPPL physicist Will Fox, who designed the experiment, and researchers from Rochester and the universities of Michigan and New Hampshire. “This lets you understand the evolution of the physical processes going on inside shock waves,” Fox said of the platform.

    To produce the wave, scientists used a laser to create a high-energy plasma — a form of matter composed of atoms and charged atomic particles — that expanded into a pre-existing magnetized plasma. The interaction created, within a few billionths of a second, a magnetized shock wave that expanded at a rate of more than 1 million miles per hour, congruent with shocks beyond the solar system. The rapid velocity represented a high “magnetosonic Mach number” and the wave was “collisionless,” emulating shocks that occur in outer space where particles are too far apart to frequently collide.

    Discovery by accident

    Discovery of this method of generating shock waves actually came about by accident. The physicists had been studying magnetic reconnection, the process in which the magnetic field lines in plasma converge, separate and energetically reconnect. To investigate the flow of plasma in the experiment, researchers installed a new diagnostic on the Rochester laser facility. To their surprise, the diagnostic revealed a sharp steepening of the density of the plasma, which signaled the formation of a high Mach number shock wave.

    To simulate the findings, the researchers ran a computer code called “PSC” on the Titan supercomputer, the most powerful U.S. computer, housed at the DOE’s Oak Ridge Leadership Computing Facility.

    ORNL Cray XK7 Titan Supercomputer

    The simulation utilized data derived from the experiments and results of the model agreed well with diagnostic images of the shock formation.

    Going forward, the laboratory platform will enable new studies of the relationship between collisionless shocks and the acceleration of astrophysical particles. The platform “complements present remote sensing and spacecraft observations,” the authors wrote, and “opens the way for controlled laboratory investigations of high-Mach number shocks.”

    Support for this research came from the DOE Office of Science, the DOE INCITE Leadership Computing program, and the National Nuclear Security Administration, a semi-autonomous agency within the DOE.

    See the full article here .

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    Princeton Plasma Physics Laboratory is a U.S. Department of Energy national laboratory managed by Princeton University. PPPL, on Princeton University’s Forrestal Campus in Plainsboro, N.J., is devoted to creating new knowledge about the physics of plasmas — ultra-hot, charged gases — and to developing practical solutions for the creation of fusion energy. Results of PPPL research have ranged from a portable nuclear materials detector for anti-terrorist use to universally employed computer codes for analyzing and predicting the outcome of fusion experiments. The Laboratory is managed by the University for the U.S. Department of Energy’s Office of Science, which is the largest single supporter of basic research in the physical sciences in the United States, and is working to address some of the most pressing challenges of our time. For more information, please visit science.energy.gov.

     
  • richardmitnick 9:24 am on July 13, 2017 Permalink | Reply
    Tags: , extraterrestrial ice can form in just billionths of a second, Laser Technology, , , Stanford scientists discover how dense, ,   

    From Stanford: “Stanford scientists discover how dense, extraterrestrial ice can form in just billionths of a second” 

    Stanford University Name
    Stanford University

    July 12, 2017
    Adam Hadhazy

    1
    At the Linac Coherent Light Source, Stanford scientists used the world’s most powerful X-ray laser to create an extraterrestrial form of ice. (Image credit: Brad Plummer).

    Stanford researchers have for the first time captured the freezing of water, molecule-by-molecule, into a strange, dense form called ice VII (“ice seven”), found naturally in otherworldly environments, such as when icy planetary bodies collide.

    In addition to helping scientists better understand those remote worlds, the findings – published online July 11 in Physical Review Letters – could reveal how water and other substances undergo transitions from liquids to solids. Learning to manipulate those transitions might open the way someday to engineering materials with exotic new properties.

    “These experiments with water are the first of their kind, allowing us to witness a fundamental disorder-to-order transition in one of the most abundant molecules in the universe,” said study lead author Arianna Gleason, a postdoctoral fellow at Los Alamos National Laboratory and a visiting scientist in the Extreme Environments Laboratory of Stanford’s School of Earth, Energy & Environmental Sciences.

    Scientists have long studied how materials undergo phase changes between gas, liquid and solid states. Phase changes can happen rapidly, however, and on the tiny scale of mere atoms. Previous research has struggled to capture the moment-to-moment action of phase transitions, and instead worked backward from stable solids in piecing together the molecular steps taken by predecessor liquids.

    “There have been a tremendous number of studies on ice because everyone wants to understand its behavior,” said study senior author Wendy Mao, an associate professor of geological sciences and a Stanford Institute for Materials and Energy Sciences (SIMES) principal investigator. “What our new study demonstrates, and which hasn’t been done before, is the ability to see the ice structure form in real time.”

    Catching ice in the act

    Those timescales became achievable thanks to the Linac Coherent Light Source, the world’s most powerful X-ray laser located at the nearby SLAC National Accelerator Laboratory. There, the science team beamed an intense, green-colored laser at a small target containing a sample of liquid water. The laser instantly vaporized layers of diamond on one side of the target, generating a rocket-like force that compressed the water to pressures exceeding 50,000 times that of Earth’s atmosphere at sea level.

    As the water compacted, a separate beam from an instrument called the X-ray Free Electron Laser arrived in a series of bright pulses only a femtosecond, or a quadrillionth of a second, long. Akin to camera flashes, this strobing X-ray laser snapped a set of images revealing the progression of molecular changes, flip book–style, while the pressurized water crystallized into ice VII. The phase change took just 6 billionths of a second, or nanoseconds. Surprisingly, during this process, the water molecules bonded into rod shapes, and not spheres as theory predicted.

    The platform developed for this study – combining high pressure with snapshot images – could help researchers probe the myriad ways water freezes, depending on pressure and temperature. Under the conditions on our planet’s surface, water crystallizes in only one way, dubbed ice Ih (“ice one-H”) or simply “hexagonal ice,” whether in glaciers or ice cube trays in the freezer.

    Delving into extraterrestrial ice types, including ice VII, will help scientists model such remote environments as comet impacts, the internal structures of potentially life-supporting, water-filled moons like Jupiter’s Europa, and the dynamics of jumbo, rocky, oceanic exoplanets called super-Earths.

    “Any icy satellite or planetary interior is intimately connected to the object’s surface,” Gleason said. “Learning about these icy interiors will help us understand how the worlds in our solar system formed and how at least one of them, so far as we know, came to have all the necessary characteristics for life.”

    Other co-authors on the study include Cindy Bolme of Los Alamos National Laboratory; Eric Galtier, Hae Ja Lee and Eduardo Granados of the SLAC National Accelerator Laboratory; Dan Dolan, Chris Seagle and Tom Ao of Sandia National Laboratories; and Suzanne Ali, Amy Lazicki, Damian Swift and Peter Celliers of Lawrence Livermore National Laboratory.

    Funding was provided by the National Science Foundation, the Los Alamos National Laboratory, the U.S. Department of Energy Office of Science, Fusion Energy Science and the SLAC National Accelerator Laboratory.

    See the full article here .

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    Leland and Jane Stanford founded the University to “promote the public welfare by exercising an influence on behalf of humanity and civilization.” Stanford opened its doors in 1891, and more than a century later, it remains dedicated to finding solutions to the great challenges of the day and to preparing our students for leadership in today’s complex world. Stanford, is an American private research university located in Stanford, California on an 8,180-acre (3,310 ha) campus near Palo Alto. Since 1952, more than 54 Stanford faculty, staff, and alumni have won the Nobel Prize, including 19 current faculty members

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  • richardmitnick 7:30 pm on July 11, 2017 Permalink | Reply
    Tags: , Laser Technology, ,   

    From Northwestern: “New laser design offers more inexpensive multi-color output” 

    Northwestern U bloc
    Northwestern University

    July 11, 2017
    Kristin Samuelson

    1
    Photo courtesy of John Krzesinski, 2011, Flickr

    From checkout counters at supermarkets to light shows at concerts, lasers are everywhere, and they’re a much more efficient light source than incandescent bulbs. But they’re not cheap to produce.

    A new Northwestern University study has engineered a more cost-effective laser design that outputs multi-color lasing and offers a step forward in chip-based lasers and miniaturization. The findings could allow encrypted, encoded, redundant and faster information flow in optical fibers, as well as multi-color medical imaging of diseased tissue in real time.

    The study was published July 10 in Nature Nanotechnology.

    “In our work, we demonstrated that multi-modal lasing with control over the different colors can be achieved in a single device,” said senior author Teri W. Odom, a Charles E. and Emma H. Morrison Professor of Chemistry in the Weinberg College of Arts and Sciences at Northwestern. “Compared to traditional lasers, our work is unprecedented for its stable multi-modal nanoscale lasing and our ability to achieve detailed and fine control over the lasing beams.”

    This work offers new insights into the design and mechanism of multi-modal nanoscale lasing based on structural engineering and manipulating the optical band structures of nanoparticle superlattices. Using this technology, the researchers can control the color and intensity of the light by simply varying its cavity architecture.

    See the full article here .

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    South Campus

    On May 31, 1850, nine men gathered to begin planning a university that would serve the Northwest Territory.

    Given that they had little money, no land and limited higher education experience, their vision was ambitious. But through a combination of creative financing, shrewd politicking, religious inspiration and an abundance of hard work, the founders of Northwestern University were able to make that dream a reality.

    In 1853, the founders purchased a 379-acre tract of land on the shore of Lake Michigan 12 miles north of Chicago. They established a campus and developed the land near it, naming the surrounding town Evanston in honor of one of the University’s founders, John Evans. After completing its first building in 1855, Northwestern began classes that fall with two faculty members and 10 students.
    Twenty-one presidents have presided over Northwestern in the years since. The University has grown to include 12 schools and colleges, with additional campuses in Chicago and Doha, Qatar.

    Northwestern is recognized nationally and internationally for its educational programs.

     
  • richardmitnick 12:29 pm on July 9, 2017 Permalink | Reply
    Tags: , Laser Technology, ,   

    From APS Physics: “Cooperating Lasers Make Topological Defects” 

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    Physics

    July 7, 2017
    David Ehrenstein

    1
    A circle of ten interacting lasers (left) can cleanly synchronize their phases, as shown by the sharp distinctions between light and dark rings near the center. But using 20 lasers (right) leads to a 20% likelihood for topological defects, where each laser’s phase is offset from its neighbors’, leading to light and dark rings that are less sharply defined. V. Pal et al., Phys. Rev. Lett. (2017).

    If you cool molten iron slowly, the electron spins can gradually align in a single direction and produce a strong magnetic field. But rapid cooling leads to magnetic domains aligned in various directions, separated by thin boundaries called topological defects. A similar phenomenon may have occurred as the Universe rapidly cooled after the big bang. To study topological defect formation in the lab without the challenges of temperature control, Nir Davidson and colleagues at the Weizmann Institute, Israel, have now developed an experimental model involving interacting laser beams.

    Weizmann Institute Campus

    Imaging the laser intensities allows them to measure the likelihood for topological defects to form for a range of parameters such as the effective “cooling rate.”

    To create their experimental model, Davidson and colleagues placed a disk containing between 10 and 30 holes arranged in a circle inside a laser cavity. This “mask” produced a set of laser beams, each emerging from a different hole and leaking a bit into its two neighboring beams, generating interactions. These interactions caused the phase differences among the beams to change over time. The evolution was so rapid that the team simply observed the final state, by recording the resulting pattern of laser intensities.

    This state represented the combined effects of about 1000 different longitudinal modes in the cavity—essentially 1000 independent experiments running simultaneously, each with a different set of initial phase relationships among the lasers. In many cases, the beams quickly synchronized their phases, but for some initial phase relationships, the beams would get “stuck” in a state where each beam was a fixed phase away from its neighbors. The team showed that, with ten lasers, there are exactly eight of these topological defect states.

    Analysis of the laser patterns allowed the researchers to measure the likelihood of topological defect formation as they varied parameters such as the number of lasers in the ring and the power of the pump light inside the cavity. They found that, with increasing pump power, topological defects became increasingly likely. The team explains this result with simulations showing that the variations in intensity among the beams drop rapidly in time when the pump power is high, whereas low power is associated with slower intensity equilibration. They say that the slower equilibration is the equivalent of a slower cooling rate, and thus, a lower likelihood for topological defects.

    This research is published in Physical Review Letters

    See the full article here .

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    Physicists are drowning in a flood of research papers in their own fields and coping with an even larger deluge in other areas of physics. How can an active researcher stay informed about the most important developments in physics? Physics highlights a selection of papers from the Physical Review journals. In consultation with expert scientists, the editors choose these papers for their importance and/or intrinsic interest. To highlight these papers, Physics features three kinds of articles: Viewpoints are commentaries written by active researchers, who are asked to explain the results to physicists in other subfields. Focus stories are written by professional science writers in a journalistic style and are intended to be accessible to students and non-experts. Synopses are brief editor-written summaries. Physics provides a much-needed guide to the best in physics, and we welcome your comments (physics@aps.org).

     
  • richardmitnick 8:17 am on July 7, 2017 Permalink | Reply
    Tags: , , , Laser Technology, , Scientists Get First Direct Look at How Electrons ‘Dance’ with Vibrating Atoms,   

    From SLAC: “Scientists Get First Direct Look at How Electrons ‘Dance’ with Vibrating Atoms” 


    SLAC Lab

    July 6, 2017
    No writer credit

    A precise new way to study materials shows this ‘electron-phonon coupling’ can be far stronger than predicted, and could potentially play a role in unconventional superconductivity.

    1
    In this illustration, an infrared laser beam (orange) triggers atomic vibrations in a thin layer of iron selenide, which are then recorded by ultrafast X-ray laser pulses (white) to create an ultrafast movie. The motion of the selenium atoms (red) changes the energy of the electron orbitals of the iron atoms (blue), and the resulting electron vibrations are recorded separately with a technique called ARPES (not shown). The coupling of atomic positions and electronic energies is much stronger than previously thought and may significantly impact the material’s superconductivity. (Greg Stewart/SLAC National Accelerator Laboratory)

    Scientists at the Department of Energy’s SLAC National Accelerator Laboratory and Stanford University have made the first direct measurements, and by far the most precise ones, of how electrons move in sync with atomic vibrations rippling through an exotic material, as if they were dancing to the same beat.

    The vibrations are called phonons, and the electron-phonon coupling the researchers measured was 10 times stronger than theory had predicted – making it strong enough to potentially play a role in unconventional superconductivity, which allows materials to conduct electricity with no loss at unexpectedly high temperatures.

    What’s more, the approach they developed gives scientists a completely new and direct way to study a wide range of “emergent” materials whose surprising properties emerge from the collective behavior of fundamental particles, such as electrons. The new approach investigates these materials through experiments alone, rather than relying on assumptions based on theory.

    The experiments were carried out with SLAC’s Linac Coherent Light Source (LCLS) X-ray free-electron laser and with a technique called angle-resolved photoemission spectroscopy (ARPES) on the Stanford campus. The researchers described the study today in Science.

    SLAC/LCLS

    See the full article here .

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    SLAC Campus
    SLAC is a multi-program laboratory exploring frontier questions in photon science, astrophysics, particle physics and accelerator research. Located in Menlo Park, California, SLAC is operated by Stanford University for the DOE’s Office of Science.
    i1

     
  • richardmitnick 4:13 pm on July 5, 2017 Permalink | Reply
    Tags: An attosecond is to a second what a second is to 32 billion years: this is how fast the short pulses of light operated by a Free Electron Laser (FEL) particle accelerator could be operating at in the , Free Electron Lasers, Laser Technology, , STFC CLARA: (Compact Linear Accelerator for Research and Applications   

    From STFC: “CLARA milestone beams light on next generation laser technology” 

    STFC

    5 July 2017
    No writer credit found.

    An attosecond is to a second what a second is to 32 billion years. This is how fast the short pulses of light operated by a Free Electron Laser (FEL) particle accelerator could be operating at in the not too distant future, unlocking new windows of scientific exploration.

    A brand new research facility that is currently under construction at the Science and Technology Facilities Council’s (STFC) Daresbury Laboratory in Cheshire is ready to become the world’s first facility designed to develop, test and advance new technologies for this next generation of FEL accelerator. CLARA (Compact Linear Accelerator for Research and Applications) has just successfully generated its first electrons, a significant milestone in its development, as it aims to bring the UK’s world leading expertise and experience of FELs to a whole new level.

    CLARA Image 1[Compact Linear Accelerator for Research and Applications] at STFC_s Daresbury Laboratory

    CLARA Image 2 [Compact Linear Accelerator for Research and Applications] at STFC_s Daresbury Laboratory

    A FEL is unparalleled in its capability as a light source and is poised to be responsible for significant scientific breakthroughs in areas ranging from healthcare and new materials to sustainable energy. Scientists have already demonstrated its capabilities in a number of areas, from developing materials for the aero industry, to understanding new ways of controlling mosquito-borne diseases, to name a couple. But FEL technology is still at a relatively early stage and the potential for improvements is enormous. With very few FEL research capabilities in existence, new ideas and developments are extremely difficult to model and test experimentally.

    CLARA will provide the vital stepping stone between the development and testing of multiple new FEL technologies and their implementation onto any existing or planned FEL facility, in the UK or internationally.

    Professor Jim Clarke, Head of Science Division at STFC’s Accelerator Science and Technology Centre at Daresbury, said: “The next generation of FEL light sources will be a game changer in science research, and it is vital that we have the skills and facilities in place to be able to develop and test new FEL technologies. The design and development of CLARA has been particularly complex, so the generation of first electrons is a particularly exciting milestone. The impact of this is huge and will ensure that the UK has all the vital capabilities required should it choose to develop its own future FEL facility, whilst simultaneously contributing to R&D on an international scale, such as at the European XFEL in Germany.”

    CLARA’s first electrons were generated at around 4 million electron volts (MeV) and, over the next few months will go through a steady conditioning process, eventually ramping up to 50 MeV to be ready for use by the end of the year. It will also benefit from a new electron gun source that has been tested on VELA – another particle accelerator at Daresbury dedicated for research by industry. CLARA and VELA will be linked at source so that CLARA can also help support research on VELA. Once fully constructed CLARA will extend to 90 metres and its beam will reach a staggering 250 MeV – 99.99% of the speed of light! Its flexibility and tuneability means that it will be able to test out numerous FEL technologies for use in future FEL facilities, both in the UK and internationally.

    Professor Susan Smith, Head of STFC’s Daresbury Laboratory, said: “This milestone is a fantastic achievement for all STFC’s scientists, engineers and collaborators who are working on CLARA. Reaching this milestone is confirming the UK’s ability to build, develop and demonstrate its scientific skills and techniques in X-ray Free Electron Laser technology, which brings us exciting prospects for the future of next generation light sources. This is technology that will change people’s lives for the better.”

    Read further information about STFC’s Accelerator Science and Technology Centre.

    About Free Electron Lasers

    Free Electron Lasers (FELs) are an increasingly important kind of light source. Standard lasers can be very bright sources of visible light but they soon fade away in the deep ultra-violet and x-ray regions of the spectrum. FELs represent a radical alternative to conventional lasers, being the most flexible, high power and efficient generators of tuneable coherent radiation from the infra-red to the X-ray. FELs can have the optical properties that are characteristic of conventional lasers such as high spatial coherence and a near diffraction limited radiation beam, but FELs combine a high energy electron beam and a magnet called an undulator in such a way that all of the electrons emit light of the same wavelength at the same time, producing huge bursts of light. The latest FELs produce pulses of X-ray light that are powerful and fast enough for scientists to take stop-motion pictures of atoms and molecules in motion.

    See the full article here .

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    STFC Hartree Centre

    Helping build a globally competitive, knowledge-based UK economy

    We are a world-leading multi-disciplinary science organisation, and our goal is to deliver economic, societal, scientific and international benefits to the UK and its people – and more broadly to the world. Our strength comes from our distinct but interrelated functions:

    Universities: we support university-based research, innovation and skills development in astronomy, particle physics, nuclear physics, and space science
    Scientific Facilities: we provide access to world-leading, large-scale facilities across a range of physical and life sciences, enabling research, innovation and skills training in these areas
    National Campuses: we work with partners to build National Science and Innovation Campuses based around our National Laboratories to promote academic and industrial collaboration and translation of our research to market through direct interaction with industry
    Inspiring and Involving: we help ensure a future pipeline of skilled and enthusiastic young people by using the excitement of our sciences to encourage wider take-up of STEM subjects in school and future life (science, technology, engineering and mathematics)

    We support an academic community of around 1,700 in particle physics, nuclear physics, and astronomy including space science, who work at more than 50 universities and research institutes in the UK, Europe, Japan and the United States, including a rolling cohort of more than 900 PhD students.

    STFC-funded universities produce physics postgraduates with outstanding high-end scientific, analytic and technical skills who on graduation enjoy almost full employment. Roughly half of our PhD students continue in research, sustaining national capability and creating the bedrock of the UK’s scientific excellence. The remainder – much valued for their numerical, problem solving and project management skills – choose equally important industrial, commercial or government careers.

    Our large-scale scientific facilities in the UK and Europe are used by more than 3,500 users each year, carrying out more than 2,000 experiments and generating around 900 publications. The facilities provide a range of research techniques using neutrons, muons, lasers and x-rays, and high performance computing and complex analysis of large data sets.

    They are used by scientists across a huge variety of science disciplines ranging from the physical and heritage sciences to medicine, biosciences, the environment, energy, and more. These facilities provide a massive productivity boost for UK science, as well as unique capabilities for UK industry.

    Our two Campuses are based around our Rutherford Appleton Laboratory at Harwell in Oxfordshire, and our Daresbury Laboratory in Cheshire – each of which offers a different cluster of technological expertise that underpins and ties together diverse research fields.

    The combination of access to world-class research facilities and scientists, office and laboratory space, business support, and an environment which encourages innovation has proven a compelling combination, attracting start-ups, SMEs and large blue chips such as IBM and Unilever.

    We think our science is awesome – and we know students, teachers and parents think so too. That’s why we run an extensive Public Engagement and science communication programme, ranging from loans to schools of Moon Rocks, funding support for academics to inspire more young people, embedding public engagement in our funded grant programme, and running a series of lectures, travelling exhibitions and visits to our sites across the year.

    Ninety per cent of physics undergraduates say that they were attracted to the course by our sciences, and applications for physics courses are up – despite an overall decline in university enrolment.

     
  • richardmitnick 1:19 pm on July 1, 2017 Permalink | Reply
    Tags: Boulder, JILA, Laser Technology, , PTB,   

    From PTB: “The sharpest laser in the world” 

    PTB – The National Metrology Institute of Germany

    29.06.2017

    Erika Schow
    +49 531 592-9314
    erika.schow@ptb.de

    Imke Frischmuth
    +49 531 592-9323imke.frischmuth@ptb.de
    Secretariat
    Karin Conring
    Tel+49 531 592-3006
    Fax: +49 531 592-3008
    karin.conring@ptb.de

    Address
    Physikalisch-Technische Bundesanstalt
    Bundesallee 100
    38116 Braunschweig

    Contact
    Dr. Thomas Legero,
    PTB Department 4.3,
    Quantum Optics and Unit of Length
    +49 (0)531 592-4306,
    thomas.legero@ptb.de

    The Physikalisch-Technische Bundesanstalt has developed a laser with a linewidth of only 10 mHz.

    1
    One of the two silicon resonators (photo: PTB)

    No one had ever come so close to the ideal laser before: theoretically, laser light has only one single color (also frequency or wavelength). In reality, however, there is always a certain linewidth. With a linewidth of only 10 mHz, the laser that researchers from the Physikalisch-Technische Bundesanstalt (PTB) have now developed together with US researchers from JILA, a joint institute of the National Institute of Standards and Technology (NIST) and the University of Colorado, Boulder, has established a new world record. This precision is useful for various applications such as optical atomic clocks, precision spectroscopy, radioastronomy and for testing the theory of relativity. The results have been published in the current issue of Physical Review Letters.

    Lasers were once deemed a solution without problems – but that is now history. More than 50 years have passed since the first technical realization of the laser, and we cannot imagine how we could live without them today. Laser light is used in numerous applications in industry, medicine and information technologies. Lasers have brought about a real revolution in many fields of research and in metrology – or even made some new fields possible in the first place.

    One of a laser’s outstanding properties is the excellent coherence of the emitted light. For researchers, this is a measure for the light wave’s regular frequency and linewidth. Ideally, laser light has only one fixed wavelength (or frequency). In practice, the spectrum of most types of lasers can, however, reach from a few kHz to a few MHz in width, which is not good enough for numerous experiments requiring high precision.

    Research has therefore focused on developing ever better lasers with greater frequency stability and a narrower linewidth. Within the scope of a nearly 10-year-long joint project with the US colleagues from JILA in Boulder, Colorado, a laser has now been developed at PTB whose linewidth is only 10 mHz (0.01 Hz), hereby establishing a new world record. “The smaller the linewidth of the laser, the more accurate the measurement of the atom’s frequency in an optical clock. This new laser will enable us to decisively improve the quality of our clocks”, PTB physicist Thomas Legero explains.

    In addition to the new laser’s extremely small linewidth, Legero and his colleagues found out by means of measurements that the emitted laser light’s frequency was more precise than what had ever been achieved before. Although the light wave oscillates approx. 200 trillion times per second, it only gets out of sync after 11 seconds. By then, the perfect wave train emitted has already attained a length of approx. 3.3 million kilometers. This length corresponds to nearly ten times the distance between the Earth and the moon.

    Since there was no other comparably precise laser in the world, the scientists working on this collaboration had to set up two such laser systems straight off. Only by comparing these two lasers was it possible to prove the outstanding properties of the emitted light.

    The core piece of each of the lasers is a 21-cm long Fabry-Pérot silicon resonator. The resonator consists of two highly reflecting mirrors which are located opposite each other and are kept at a fixed distance by means of a double cone. Similar to an organ pipe, the resonator length determines the frequency of the wave which begins to oscillate, i.e., the light wave inside the resonator. Special stabilization electronics ensure that the light frequency of the laser constantly follows the natural frequency of the resonator. The laser’s frequency stability – and thus its linewidth – then depends only on the length stability of the Fabry-Pérot resonator.

    The scientists at PTB had to isolate the resonator nearly perfectly from all environmental influences which might change its length. Among these influences are temperature and pressure variations, but also external mechanical perturbations due to seismic waves or sound. They have attained such perfection in doing so that the only influence left was the thermal motion of the atoms in the resonator. This “thermal noise” corresponds to the Brownian motion in all materials at a finite temperature, and it represents a fundamental limit to the length stability of a solid. Its extent depends on the materials used to build the resonator as well as on the resonator’s temperature.

    For this reason, the scientists of this collaboration manufactured the resonator from single-crystal silicon which was cooled down to a temperature of -150 °C. The thermal noise of the silicon body is so low that the length fluctuations observed only originate from the thermal noise of the dielectric SiO2/Ta2O5 mirror layers. Although the mirror layers are only a few micrometers thick, they dominate the resonator’s length stability. In total, the resonator length, however, only fluctuates in the range of 10 attometers. This length corresponds to no more than a ten-millionth of the diameter of a hydrogen atom. The resulting frequency variations of the laser therefore amount to less than 4 × 10–17 of the laser frequency.

    The new lasers are now being used both at PTB and at JILA in Boulder to further improve the quality of optical atomic clocks and to carry out new precision measurements on ultracold atoms. At PTB, the ultrastable light from these lasers is already being distributed via optical waveguides and is then used by the optical clocks in Braunschweig.

    “In the future, it is planned to disseminate this light also within a European network. This plan would allow even more precise comparisons between the optical clocks in Braunschweig and the clocks of our European colleagues in Paris and London”, Legero says. In Boulder, a similar plan is in place to distribute the laser across a fiber network that connects between JILA and various NIST labs.

    The scientists from this collaboration see further optimization possibilities. With novel crystalline mirror layers and lower temperatures, the disturbing thermal noise can be further reduced. The linewidth could then even become smaller than 1 mHz.

    See the full article here .

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    The Physikalisch-Technische Bundesanstalt, the National Metrology Institute of Germany, is a scientific and technical higher federal authority falling within the competence of the Federal Ministry for Economic Affairs and Energy.

    PTB is Germany’s highest authority when it comes to correct and reliable measurements. It is the supreme technical authority of the Federal Ministry for Economic Affairs and Energy (BMWi) and employs a total of approx. 1900 staff members. PTB operates an integrated Opens internal link in current windowquality management system which covers the four interlinked field of business.

     
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