From Stanford: “Stanford physicists develop revolutionary low-power polariton laser”

Stanford University

May 20, 2013
Thomas Sumner

“Lasers are an unseen backbone of modern society. They’re integral to technologies ranging from high-speed Internet services to Blu-ray players.

Physicist Na Young Kim, at the optical bench, is a member of the international team that has demonstrated a revolutionary electrically driven polariton laser that could significantly improve the efficiency of lasers.

The physics powering lasers, however, has remained relatively unchanged through 50 years of use. Now, an international research team led by Stanford’s Yoshihisa Yamamoto, a professor of electrical engineering and of applied physics, has demonstrated a revolutionary electrically driven polariton laser that could significantly improve the efficiency of lasers.

The system makes use of the unique physical properties of bosons, subatomic particles that scientists have attempted to incorporate into lasers for decades.

‘We’ve solidified our physical understanding, and now it’s time we think about how to put these lasers into practice, said physicist Na Young Kim, a member of the Stanford team. ‘This is an exciting era to imagine how this new physics can lead to novel engineering.’
“

This is truly revolutionary. See the full article here.

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

From SLAC: “X-ray Laser Explores How to Write Data with Light”

March 19, 2013
Glenn Roberts Jr.

“Using laser light to read and write magnetic data by quickly flipping tiny magnetic domains could help keep pace with the demand for faster computing devices.

A look inside the RCI sample chamber while researchers close up the chamber for vacuum for an experiment at LCLS. (Credit: Diling Zhu/SLAC)

Now experiments with SLAC’s Linac Coherent Light Source (LCLS) X-ray laser have given scientists their first detailed look at how light controls the first trillionth of a second of this process, known as all-optical magnetic switching.

The experiments show that the optically induced switching of the magnetic regions begins much faster than conventional switching and proceeds in a more complex way than scientists had thought – a level of detail long sought by the data storage industry, which is eager to learn more about the key drivers of optical switching. The new insight could help guide efforts to engineer materials that better control and speed this process.

Group photo of researchers who participated in an all-optical magnetic switching experiment at the Linac Coherent Light Source. (Credit: SLAC)

http://www6.slac.stanford.edu/pictures/220×142-(news-article-main)/130319-nanoswitching-art-thumb.jpg

‘This is really one of the first examples of new materials science that can be done with LCLS, which allows you to look at very short time scales and very small length scales,’ said Hermann Dürr, a staff scientist for the Stanford Institute for Materials and Energy Sciences (SIMES) and a principal investigator of the multinational team that performed the experiment, detailed in the March 17 issue of Nature Materials. SIMES is a joint institute of SLAC and Stanford.”

See the full article here.

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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From Berkeley Lab: “Surprising Control over Photoelectrons from a Topological Insulator”

Berkeley Lab

Berkeley Lab scientists discover how a photon beam can flip the spin polarization of electrons emitted from an exciting new material

“Plain-looking but inherently strange crystalline materials called 3D topological insulators (TIs) are all the rage in materials science. Even at room temperature, a single chunk of TI is a good insulator in the bulk, yet behaves like a metal on its surface.

The interior bulk of a topological insulator is indeed an insulator, but electrons (spheres) move swiftly on the surface as if through a metal. They are spin-polarized, however, with their momenta (directional ribbons) and spins (arrows) locked together. Berkeley Lab researchers have discovered that the spin polarization of photoelectrons (arrowed sphere at upper right) emitted when the material is struck with high-energy photons (blue-green waves from left) is completely determined by the polarization of this incident light. (Image Chris Jozwiak, Zina Deretsky, and Berkeley Lab Creative Services Office)

Researchers find TIs exciting partly because the electrons that flow swiftly across their surfaces are ‘spin polarized’: the electron’s spin is locked to its momentum, perpendicular to the direction of travel. These interesting electronic states promise many uses – some exotic, like observing never-before-seen fundamental particles, but many practical, including building more versatile and efficient high-tech gadgets, or, further into the future, platforms for quantum computing.

A team of researchers from the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) and the University of California at Berkeley has just widened the vista of possibilities with an unexpected discovery about TIs: when hit with a laser beam, the spin polarization of the electrons they emit (in a process called photoemission) can be completely controlled in three dimensions, simply by tuning the polarization of the incident light.

‘The first time I saw this it was a shock; it was such a large effect and was counter to what most researchers had assumed about photoemission from topological insulators, or any other material,’ says Chris Jozwiak of Berkeley Lab’s Advanced Light Source (ALS), who worked on the experiment. ‘Being able to control the interaction of polarized light and photoelectron spin opens a playground of possibilities.’”

See the full article here.

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

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From Berkeley Lab: “A Clock Einstein Would Have Loved”

Berkeley Lab

January 10, 2013
Lynn Yarris

“A very special clock that can measure time on the basis of the mass of a single atomic or even subatomic particle holds promise not only for ultraprecise measurements of mass and time, but also for such exotic applications as testing Einstein’s general theory of relativity, or the effects of gravity on antimatter.

‘We have directly demonstrated the connection between time and mass,’ says Holger Müller, physics professor at the University of California (UC), Berkeley and guest scientist with Berkeley Lab’s Chemical Sciences Division, who led the team of Berkeley researchers who developed the clock and reported it in the journal Science.

Holger Müller

See the full article here. See the full UC Berkeley article on this work here.

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

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From Berkeley Lab: “Synchronized Lasers Measure How Light Changes Matter”

Berkeley Lab

Berkeley Lab scientists and their colleagues have successfully probed the effects of light at the atomic scale by mixing x-ray and optical light waves at the Linac Coherent Light Source

August 29, 2012
Paul Preuss

“Light changes matter in ways that shape our world. Photons trigger changes in proteins in the eye to enable vision; sunlight splits water into hydrogen and oxygen and creates chemicals through photosynthesis; light causes electrons to flow in the semiconductors that make up solar cells; and new devices for consumers, industry, and medicine operate with photons instead of electrons. But directly measuring how light manipulates matter on the atomic scale has never been possible, until now.

Pulses of 8,000-electron-volt x-rays from the LCLS are synchronized with 1.55 electron-volt pulses from an optical laser, so that both strike the diamond sample at the same time and mix to form upconverted pulses of 8,001.55 electron volts. The detector first sees the diffracted x‑ray pulse, and then, after the sample is gently “rocked,” the slightly more energetic mixed pulse. The optical pulse exerts localized force on the chemical bonds among the carbon atoms. No image credit.

Simulated valence-charge density from x-ray and optical wave mixing shows the nuclei of carbon atoms as dark spots revealed by diffracted x-rays and the peaks of some of the bonds between them as white and blue spots induced by the polarized optical pulse. In diamond, the optical pulse primarily wiggles the charge that makes up chemical bonds. No image credit.

An international team of scientists led by Thornton Glover of the U.S. Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) used the Linac Coherent Light Source (LCLS) at the SLAC National Accelerator Laboratory to mix a pulse of superbright x-rays with a pulse of lower frequency, ‘optical’ light from an ordinary laser. By aiming the combined pulses at a diamond sample, the team was able to measure the optical manipulation of chemical bonds in the crystal directly, on the scale of individual atoms.

The researchers report their work in the August 30, 2012 issue of the journal Nature.

See the full article here.

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

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From Livermore Lab: “Lawrence Livermore’s National Ignition Facility achieves record laser energy in pursuit of fusion ignition”

Breanna Bishop
03/21/2012

“The National Ignition Facility (NIF), the world’s most energetic laser, surpassed a critical milestone in its efforts to meet one of modern science’s greatest challenges: achieving fusion ignition and energy gain in a laboratory setting. NIF’s 192 lasers fired in perfect unison, delivering a record 1.875 million joules (MJ) of ultraviolet laser light to the facility’s target chamber center.

This historic laser shot involved a shaped pulse of energy 23 billionths of a second long that generated 411 trillion watts (TW) of peak power (1,000 times more than the United States uses at any instant in time).

The record-breaking shot was made March 15.

‘This event marks a key milestone in the National Ignition Campaign’s drive toward fusion ignition,’ said NIF Director Edward Moses. ‘While there have been many demonstrations of similar equivalent energy performance on individual beams or quads during the completion of the NIF project, this is the first time the full complement of 192 beams has operated at this sound barrier.’”

Control room staff at the National Ignition Facility monitor the progress of the world’s most energetic laser shot on March 15. From left: Rodrigo Miramontes-Ortiz, Dean LaTray, Scott Phillip Rogers, Dean Steven Felzkowski. Photos by Damien Jemison/NIF

See the full article here.

Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security Administration

From Berkeley Lab: “The Next Big Step Toward Atom-Specific Dynamical Chemistry”

Berkeley Lab

Paul Preuss
JANUARY 05, 2012

“For Ali Belkacem of Berkeley Lab’s Chemical Sciences Division, ‘What is chemistry?’ is not a rhetorical question.

‘Chemistry is inherently dynamical,’ he answers. ‘That means, to make inroads in understanding – and ultimately control – we have to understand how atoms combine to form molecules; how electrons and nuclei couple; how molecules interact, react, and transform; how electrical charges flow; and how different forms of energy move within a molecule or across molecular boundaries.’ The list ends with a final and most important question: ‘How do all these things behave in a correlated way, dynamically in time and space, both at the electron and atomic levels?’

Making the most of spectroscopy

Belkacem’s research focuses on creating better ways to track the evolution of energy and charge on the molecular level. For this purpose, one of the sharpest tools in his chemist’s kit goes by the jawbreaking name nonlinear multidimensional spectroscopy.”

An impressionistic look at photosynthesis: at left, the oxygen-evolving complex in photosystem II (Yachandra/Yano lab); at right, electronic energy transfer in photosystem II’s light harvesting complex as simulated by supercomputers at NERSC, the National Energy Research Scientific Computing Center (Graham Fleming group)

See the full and very dense article here.

A US Department of Energy National Laboratory Operated by the University of California

From SLAC News Center: “LCLS Teams Up with DESY on Shortest X-ray Exposure of a Protein Crystal Ever”

January 4, 2012
from Deutsches Elektronen-Synchrotron DESY

“An international research team headed by DESY scientists from the Center for Free-Electron Laser Science (CFEL) in Hamburg, Germany, has recorded the shortest X-ray exposure of a protein crystal ever achieved. The incredible brief exposure time of 30 femtoseconds (0.000 000 000 000 03 seconds) opens up new possibilities for imaging molecular processes with X-rays.

This is of particular interest to biologists, but can be employed in many fields, explain lead authors Dr. Anton Barty and Prof. Henry Chapman from the German accelerator centre Deutsches Elektronen-Synchrotron DESY. CFEL is a joint venture of DESY, the Max Planck Society and the University of Hamburg.

From X-ray diffraction the molecular structure of proteins can be determined. The shorter the X-ray pulse and the higher its intensity, the better the structural information gained. With the free-electron laser at the SLAC National Accelerator Laboratory’s Linac Coherent Light Source (LCLS), the research team fired the most intense X-ray beam at a protein crystal to date: The tiny crystal was bombarded with a whamming 100,000 trillion watts per square centimeter – sunlight for comparison comes in at a mere 0.1 watts per square centimeter on average.

‘This way we get the most information out of the smallest crystals’, Chapman explains. Having small crystals is important, as especially many biological substances aren’t easily crystallized.

The molecular structure of proteins is inferred by measurements of patterns of X-rays scattered from crystals formed from those proteins. The regular array of molecules in the crystal gives rise to strong peaks needed for measurement, shown here as balls in a three-dimensional space.

Image courtesy Thomas White, CEFL/DESY

Full announcement posted Dec. 19, 2011, on DESY website.”

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.

From Livermore Labs: “Proton beam experiments open new areas of research”

Anne M Stark
11-12-02

“By focusing proton beams using high-intensity lasers, a team of scientists have discovered a new way to heat material and create new states of matter in the laboratory.

Researchers from Lawrence Livermore National Laboratory; Jacobs School of Engineering at the University of California, San Diego; Los Alamos National Laboratory; Hemoltz-Zentrum Dresden-Rossendorf of Germany; Technische Universitat Darmstadt of Germany, and General Atomics of San Diego unveiled new findings about how proton beams can be used in myriad applications.

Using the Trident sub-picosecond laser at Los Alamos, the team generated and focused a proton beam using a cone-shaped target. The protons were found to have unexpectedly curved trajectories due to the large electric fields in the beam. A sheath electric field also channeled the proton beam through the cone tip, substantially improving the beam focus.

‘These results agree well with our particle simulations and provide the physics basis for many future applications,’ said Mark Foord, one of the LLNL scientists on the team.”

The Trident laser at Los Alamos National Laboratory.

See the full article here.

Operated by Lawrence Livermore National Security, LLC, for the Department of Energy’s National Nuclear Security
Administration