Computer Memory: New Material Could Dramatically Boost Data Storage, Save Energy

North Carolina State University engineers have created a new material that would allow a fingernail-size computer chip to store the equivalent of 20 high-definition DVDs or 250 million pages of text, far exceeding the storage capacities of today's computer memory systems.

Led by Dr. Jagdish "Jay" Narayan, John C.C. Fan Family Distinguished Professor of Materials Science and Engineering and director of the National Science Foundation Center for Advanced Materials and Smart Structures at NC State, the engineers made their breakthrough using the process of selective doping, in which an impurity is added to a material that changes its properties. The process also shows promise for boosting vehicles' fuel economy and reducing heat produced by semiconductors, a potentially important development for more efficient energy production.

Working at the nanometer level -- a pinhead has a diameter of 1 million nanometers -- the engineers added metal nickel to magnesium oxide, a ceramic. The resulting material contained clusters of nickel atoms no bigger than 10 square nanometers, a 90 percent size reduction compared to today's techniques and an advancement that could boost computer storage capacity.

"Instead of making a chip that stores 20 gigabytes, you have one that can handle one terabyte, or 50 times more data," Narayan says.

Information storage is not the only area where advances could be made. By introducing metallic properties into ceramics, Narayan says engineers could develop a new generation of ceramic engines able to withstand twice the temperatures of normal engines and achieve fuel economy of 80 miles per gallon. And since the thermal conductivity of the material would be improved, the technique could also have applications in harnessing alternative energy sources like solar energy.

The engineers' discovery also advances knowledge in the emerging field of "spintronics," which is dedicated to harnessing energy produced by the spinning of electrons. Most energy used today is harnessed through the movement of current and is limited by the amount of heat that it produces, but the energy created by the spinning of electrons produces no heat. The NC State engineers were able to manipulate the nanomaterial so the electrons' spin within the material could be controlled, which could prove valuable to harnessing the electrons' energy. The finding could be important for engineers working to produce more efficient semiconductors.

Working with Narayan on the study were Dr. Sudhakar Nori, a research associate at NC State, Shankar Ramachandran, a former NC State graduate student, and J.T. Prater, an adjunct professor of materials science and engineering. The research was sponsored by the National Science Foundation.

A Decade of Studying the Earth's Magnetic Shield, in 3-D

Space scientists around the world are celebrating ten years of ground-breaking discoveries by 'Cluster', a mission that is illuminating the mysteries of the magnetosphere, the northern lights and the solar wind.

Cluster is a European Space Agency mission, launched in summer 2000. It consists of a unique constellation of four spacecraft flying in formation around Earth, studying the interaction between the solar wind and the magnetosphere. The spacecraft each carry an identical set of 11 scientific instruments, which together capture 3D information about the magnetosphere -- Earth's 'magnetic shield'.

An artist's impression of the Cluster quartet. (Credit: ESA)

A key instrument -- PEACE -- was designed by a team led by space scientists at UCL.

The solar wind is a continuous outflow of hot, magnetised, electrified gas from the Sun. Earth is shielded from the solar wind by its magnetic field, which surrounds the planet in a zone called the magnetosphere, many times larger than the Earth.

The magnetosphere prevents the solar wind from stripping away the atmosphere and protects Earth from deadly energetic particles produced by storms on the Sun. However the magnetosphere is not a perfect shield. Energy and material from solar wind can get inside, to cause the northern lights, ionospheric disturbances, the generation of radiation belts and disturbances to the ground-level magnetic field. These "space weather effects" are important because they interfere with spacecraft operations, communications, GPS signals and electrical power systems on the ground. Cluster is being used to find out how transfer of solar wind energy to the magnetosphere leads to these diverse effects.

PEACE measures electrons and electric currents in the solar wind, magnetosphere and aurora. During Cluster's mission PEACE has been used to study huge bubbles of plasma three times the size of Earth jetting through the magnetosphere, very thin sheets of electric current flowing through space where explosive magnetic reconnection occurs, and grand waves on the edge of the magnetosphere, formed by the solar wind 'blowing' over the surface before breaking and forming tornado-like vortices.

Dr Andrew Fazakerley, from UCL's Mullard Space Science Laboratory, and Principal Investigator for PEACE, said: "Cluster is revolutionising the study of the solar wind and the magnetosphere because it is the first space mission to reveal what plasmas are like in 3D, which is crucial to testing our theoretical models."

Cluster is also the first multi-spacecraft mission to study the northern lights or aurora. The aurora are caused when electrons from the magnetosphere smash into the upper atmosphere, but it's a mystery how these electrons are accelerated to high enough energies. Cluster's simultaneous measurements at different locations have given scientists the first opportunity to test ideas about what could be the cause.

"Cluster was not designed to visit the aurora, but luckily the orbit of the four spacecraft has naturally evolved to allow us to explore the unexplained auroral acceleration region which is the key to the formation of the aurora," said Dr Forsyth.

"We are very excited at the coming opportunity to investigate how the magnetosphere responds in the near future, as solar activity increases to solar maximum," said Dr Fazakerley.

Researchers Create 'Quantum Cats' Made of Light

Researchers at the National Institute of Standards and Technology (NIST) have created "quantum cats" made of photons (particles of light), boosting prospects for manipulating light in new ways to enhance precision measurements as well as computing and communications based on quantum physics.

These colorized plots of electric field values indicate how closely the NIST "quantum cats" (left) compare with theoretical predictions for a cat state (right). The purple spots and alternating blue contrast regions in the center of the images indicate the light is in the appropriate quantum state. (Credit: Gerrits/NIST)

The NIST experiments, described in a forthcoming paper, repeatedly produced light pulses that each possessed two exactly opposite properties -- specifically, opposite phases, as if the peaks of the light waves were superimposed on the troughs. Physicists call this an optical Schrödinger's cat. NIST's quantum cat is the first to be made by detecting three photons at once and is one of the largest and most well-defined cat states ever made from light. (Larger cat states have been created in different systems by other research groups, including one at NIST.)

A "cat state" is a curiosity of the quantum world, where particles can exist in "superpositions" of two opposite properties simultaneously. Cat state is a reference to German physicist Erwin Schrödinger's famed 1935 theoretical notion of a cat that is both alive and dead simultaneously.

"This is a new state of light, predicted in quantum optics for a long time," says NIST research associate Thomas Gerrits, lead author of the paper. "The technologies that enable us to get these really good results are ultrafast lasers, knowledge of the type of light needed to create the cat state, and photon detectors that can actually count individual photons."

The NIST team created their optical cat state by using an ultrafast laser pulse to excite special crystals to create a form of light known as a squeezed vacuum, which contains only even numbers of photons. A specific number of photons were subtracted from the squeezed vacuum using a device called a beam splitter. The photons were identified with a NIST sensor that efficiently detects and counts individual photons. Depending on the number of subtracted photons, the remaining light is in a state that is a good approximation of a quantum cat says Gerrits -- the best that can be achieved because nobody has been able to create a "real" one, by, for instance, the quantum equivalent to superimposing two weak laser beams with opposite phases.

NIST conducts research on novel states of light because they may enhance measurement techniques such as interferometry, used to measure distance based on the interference of two light beams. The research also may contribute to quantum computing -- which may someday solve some problems that are intractable today -- and quantum communications, the most secure method known for protecting the privacy of a communications channel. Larger quantum cats of light are needed for accurate information processing.

Hubble Observations of Supernova Reveal Composition of 'Star Guts' Pouring out

Observations made with NASA's newly refurbished Hubble Space Telescope of a nearby supernova are allowing astronomers to measure the velocity and composition of "star guts" being ejected into space following the explosion, according to a new study led by the University of Colorado at Boulder.

The team detected significant brightening of the emissions from Supernova 1987A, which were consistent with some theoretical predictions about how supernovae interact with their immediate galactic environment. Discovered in 1987, Supernova 1987A is the closest exploding star to Earth to be detected since 1604 and resides in the nearby Large Magellanic Cloud, a dwarf galaxy adjacent to our own Milky Way Galaxy.

A team of astronomers led by the University of Colorado at Boulder is charting the interactions between Supernova 1987A and a glowing gas ring encircling the supernova remnant known as the "String of Pearls." (Credit: NASA)

The team observed the supernova in optical, ultraviolet and near-infrared light, charting the interplay between the stellar explosion and the famous "String of Pearls," a glowing ring 6 trillion miles in diameter encircling the supernova remnant that has been energized by X-rays. The gas ring likely was shed some 20,000 years before the supernova exploded, and shock waves rushing out from the remnant have been brightening some 30 to 40 pearl-like "hot spots" in the ring -- objects that likely will grow and merge together in the coming years to form a continuous, glowing circle.

"The new observations allow us to accurately measure the velocity and composition of the ejected 'star guts,' which tell us about the deposition of energy and heavy elements into the host galaxy," said CU-Boulder Research Associate Kevin France of the Center for Astrophysics and Space Astronomy, lead study author. "The new observations not only tell us what elements are being recycled into the Large Magellanic Cloud, but how it changes its environment on human time scales."

A paper on the subject was published in the Sept. 2 issue ofScience. The international study involved study co-authors from 15 other universities and institutes and included CU-Boulder astrophysicist Richard McCray, the Science paper's second author.

In addition to ejecting massive amounts of hydrogen, 1987A has spewed helium, oxygen, nitrogen and rarer heavy elements like sulfur, silicon and iron. Supernovae are responsible for a large fraction of biologically important elements, including oxygen, carbon and iron found in plants and animals on Earth today, he said. The iron in a person's blood, for example, is believed to have been made by supernovae explosions.

Hubble is the only observatory in the world that can observe the brightening of the String of Pearls in ultraviolet light, said France. Most of the data for the study was gathered by the Space Telescope Imaging Spectrograph, or STIS, which was installed on Hubble in 1997 and was one of the workhorse instruments before its power supply failed in 2004. A faulty circuit board on STIS was replaced by astronauts on the final Hubble repair mission in May 2009.

The team compared STIS observations in January 2010 with Hubble observations made over the past 15 years on 1987A's evolution. STIS has provided the team with detailed images of the exploding star, as well as spectrographic data -- essentially wavelengths of light broken down into colors like a prism that produce unique fingerprints of gaseous matter. The results revealed temperatures, chemical composition, density and motion of 1987A and its surrounding environment, said France.

Since the supernova is roughly 163,000 light-years away, the explosion occurred in roughly 161,000 B.C., said France. One light year is about 6 trillion miles.

"To see a supernova go off in our backyard and to watch its evolution and interactions with the environment in human time scales is unprecedented," he said. "The massive stars that produce explosions like Supernova 1987A are like rock stars -- they live fast, flashy lives and die young."

France said the energy input from supernovae regulates the physical state and the long-term evolution of galaxies like the Milky Way. Many astronomers believe a supernova explosion near our forming sun some 4 to 5 billion years ago is responsible for a significant fraction of radioactive elements in our solar system today, he said.

"In the big picture, we are seeing the effect a supernova can have in the surrounding galaxy, including how the energy deposited by these stellar explosions changes the dynamics and chemistry of the environment," said France. "We can use this new data to understand how supernova processes regulate the evolution of galaxies."

Some of the upcoming Hubble observations of Supernova 1987A will be made with the Cosmic Origins Spectrograph, a $70 million instrument designed by a team at CU-Boulder's Center for Astrophysics and Space Astronomy that was installed on Hubble during the 2009 servicing mission. The instrument is designed to help scientists better understand the "cosmic web" of material permeating the cosmos by gathering information from UV light from distant objects, allowing scientists to look back in time and space and reconstruct the condition and evolution of the early universe.

France became a member of the Cosmic Origins Spectrograph science team in 2007 and has been using data gathered by instrument to study topics ranging from the chemistry of the early universe about 2.5 billion years after the Big Bang occurred roughly 13.7 billion years ago, to the evaporation of the atmosphere around a planet that is orbiting another star. "COS has been extremely productive in the early phases of its mission and has great scientific breadth," said France.