A solid case of entanglement

For the first time, physicists have convincingly demonstrated that physically separated particles in solid-state devices can be quantum-mechanically entangled. The achievement is analogous to the quantum entanglement of light, except that it involves particles in circuitry instead of photons in optical systems. Both optical and solid-state entanglement offer potential routes to quantum computing and secure communications, but solid-state versions may ultimately be easier to incorporate into electronic devices.

Topological insulators could help define fundamental constants

A newly discovered class of materials known as "topological insulators" could help physicists to obtain new ways of defining the three basic physical constants – the speed of light (c); the charge of the proton (e); and Planck’s constant (h). That’s the claim of a team of physicists in the US, which has proposed a new experiment to measure the fine-structure constant (α), which is a function of h, c and e, by scattering light from such a material. Topological insulators are unusual in that electrical current flows well on their surface, but not through their bulk.

Topological insulators: Star material

 A topological insulator sounds simple enough:  A block of material that lets electrons move along its surface, but not through its inside . In fact, it is far from straightforward. Ordinary metals conduct electrons all the way through, whereas ordinary insulators don't conduct electrons at all. A copper-plated block of wood conducts only on the surface, but that is two materials, not one. The idea of a topological insulator is so strange that for a long time, physicists had no reason to believe that such a material would exist .

 Researchers also believe that the collective motions of electrons inside topological insulators will mimic several of the never-before-seen particles predicted by high-energy physicists. Among them are axions, hypothetical particles predicted in the 1970s; magnetic monopoles, single points of north and south magnetism; and Majorana particles — massless, chargeless entities that can serve as their own antiparticles. 

Stretched molecule puts a new spin on electrons

Physicists in the US have invented a way of measuring the magnetic properties of a single molecule as it is being stretched. The technique provides a

new approach for studying quantum chemistry and how the spin of an electron affects its passage through tiny structures.

The technique could one day even be adapted for use in spintronic devices, which use the spin of the electron to process and store information.

Physicsts reveal how to cope with 'frustration'

For most people, frustration is a condition to be avoided. But for scientists studying certain "frustrated" ensembles of interacting components -that is, those which cannot settle into a state that minimizes each interaction-

 it may be the key to understanding a host of puzzling phenomena that affect systems from neural networks and social structures to protein folding and magnetism.

Electrical properties of glass at the nanoscale lead to a pump the size of a red blood cell

Researchers have devised a way to fabricate tiny electrodes from glass, harnessing a phenomenon by which nanoscale glass walls can be transformed from insulators to conductors and back again. At larger scales, that phenomenon, known as  dielectric breakdown , leads to excess heating and structural damage,  but at the nanoscale the process appears to be harmless and  reversible.

Global classical solutions of the Boltzmann equation with long-range interactions

Ludwig Boltzmann
1844-1906

This is a brief announcement of our recent proof of global existence and rapid decay to equilibrium of classical solutions to the Boltzmann equation without any angular cutoff, that is, for long-range interactions. We consider perturbations of the Maxwellian equilibrium states and include the physical cross-sections arising from an inverse-power intermolecular potential r ^-(p-1) with p > 2, and more generally. We present here a mathematical framework for unique global in time solutions for all of these potentials.  We consider it remarkable that this equation, derived by Boltzmann in 1872 and Maxwell in 1867, grants a basic example where a range of geometric fractional derivatives occur in a physical model of the natural world . Our methods provide a new understanding of the effects due to grazing collisions.

http://www.pnas.org/content/107/13/5744.abstract?sid=9d675b61-b4d1-4bc0-88d1-b450d0b4b5ca
 
Philip T. Gressman and Robert M. Strain
University of Pennsylvania, Department of Mathematics, Philadelphia, PA 19104-6395

Graphene transistor could advance nanodevices

For years, scientists and researchers have been looking into the properties of carbon nanotubes and graphene for use in nanoelectronics.  There is no real mass application of devices based on graphene and carbon nanotubes , Zhenxing Wang tells PhysOrg.com.  This is really an opportunity for them to show their capabilities .

Appl. Phys. Lett. 96, 173104 ( 2010 )

Unraveling the physics of DNA's double helix

 The stability of DNA is so fundamental to life that it's important to understand all factors , said Piotr Marszalek, a professor of mechanical engineering and materials sciences at Duke.  If you want to create accurate models of DNA to study its interaction with proteins or drugs, for example,  you need to understand the basic physics of the molecule . For that, you need solid measurements of the forces that stabilize DNA .

Laser technology provides a quantum leap (La tecnología láser da un salto cuántico)

En la Universidad de Innsbruck ( Austria ), un equipo de investigación financiado con fondos comunitarios ha creado un láser de átomo único que se rige por el mismo principio que los láseres clásicos pero que además presenta propiedades cuánticas en sus interacciones entre átomos y fotones. Los resultados de su investigación, publicados en la revista Nature Physics, ampliarán el conocimiento que se posee de las propiedades de los láseres y podrán utilizarse para medir composiciones de oligoelementos gaseosos e isótopos de carbono en el aire y el suelo.

At the University of Innsbruck ( Austria ), a team of private funded research has created a single atom laser which is governed by the same principle as lasers but also presents classical quantum properties in interactions between atoms and photons. The results of their research, published in the journal Nature Physics, expand the knowledge of the lasers properties and may be used to measure gas compositions of trace elements and isotopes of carbon in the air and soil.

Charging Ahead: Carbon Nanotubes Could Hold Long-Sought Battery Technology Breakthrough

With battery technology advances long overdue, researchers are racing to develop more efficient ways to store power. One hopeful option is in the use of carbon nanotubes,  which can store much more electricity by weight than lithium-ion batteries while keeping their charge and remain durable for far longer .

The Bose-Einstein Condensate

ATOMIC TRAP cools by means of two different mechanisms

First, six laser beams ( red ) cool atoms, initially at room temperature, while corralling them toward the center of an evacuated glass box.

Next, the laser beams are turned off, and the magnetic coils ( copper ) are energized. Current flowing through the coils generates a magnetic field that further confines most of the atoms while allowing the energetic ones to escape. Thus, the average energy of the remaining atoms decreases, making the sample colder and even more closely confined to the center of the trap.

Ultimately, many of the atoms attain the lowest possible energy state allowed by quantum mechanics and become a single entity known as a Bose-Einstein condensate.

Light Improvement: Could Quantum Dots Boost the Quality of Cell Phone Pix?

Semiconductor crystals known as quantum dots have long held the promise of improving solar cells, lasers and lighting fixtures, but the reality is that integrating these fluorescent nanoparticles into existing technologies has proved difficult. One Silicon Valley start-up now aims to change this by the end of next year using quantum dots to vastly improve the picture-taking quality of cell phone cameras.

Scanner scans a 200 page book in one minute (w/ Video)

A research team led by Professor Masatoshi Ishikawa of the University of Tokyo has developed a prototype scanner that allows users to scan a book simply by rapidly flipping its pages. A high-speed camera operating at 500 fps and producing pictures with a resolution of 1280 x 1024 pixels, takes pictures of the page and its contents of text and images under ordinary light. A laser then projects lines on the page, and the camera captures this image as well. The lines allow the system to adjust for the curvature and distortion of pages as they are being flipped, and the software reconstructs the image into a digitized picture of a flat, regular page.

A New Spin on Conductivity: Electric Signals Can Propagate through an Insulator: Scientific American

But that is precisely what a group of Japanese researchers has found, as detailed in a study in the March 11 issue of Nature. The electric current induces a collective excitation in the magnetic insulator that can travel relatively long distances before unloading its momentum to generate a voltage when it reaches an electric conductor.

The Quantum Physics of Photosynthesis

By hitting single molecules with quadrillionth-of-a-second laser pulses, scientists have revealed the quantum physics underlying photosynthesis, the process used by plants and bacteria to convert light into energy, at efficiencies unapproached by human engineers. The quantum wizardry appears to occur in each of a photosynthetic cell’s millions of antenna proteins. These route energy from electrons spinning in photon-sensitive molecules to nearby reaction-center proteins, which convert it to cell-driving charges Almost no energy is lost in between. That’s because it exists in multiple places at once, and always finds the shortest path.

Read More in
http://www.wired.com/wiredscience/2010/02/quantum-photosynthesis/#ixzz0eVrEvcho

Buscan crear super computadoras sin límite de velocidad

Un equipo de investigadores liderados por científicos de la Universidad de Yale ejecutó exitosamente operaciones simples de mecánica cuántica, lo cual podría significar la creación de hardware con potencial ilimitado de procesamiento.

Deconstructing the electron

Explaining the behavior of interacting electrons in a solid is one of the long-standing problems in condensed matter. For most systems, the problem has been masterfully addressed by Landau, who showed that even though interactions can be very large, excitations behaving essentially as free fermions still exist in the system. The Landau Fermi-liquid theory allows sweeping the interactions under the rug and saying that the properties of many materials will be very similar to those of free electrons. However, this theory fails spectacularly when an electron gas is confined to one dimension. In that case, a completely new universality class appears, and the Fermi liquid turns into a Luttinger liquid.

download .pdf ( free )

First images of a carbon atom's electron clouds

The images were captured by  Igor Mikhailovskij 's team at the Kharkov Institute of Physics and Technology, Ukraine.

The uncalculability of electron systems

The electric and magnetic properties of solids are impossible to calculate exactly: The complex interactions of the many electrons which underly these phenomena cannot be computed even by the most powerful classical computers. Here, the central task is to determine the ground state of the electrons moving in the field of the positively charged nuclei. The most widely used method for treating such systems is Density Functional Theory, which reduces the many-body problem to a single particle interaction. As Dr. Norbert Schuch, scientist in the theory division of Prof. Ignacio Cirac at the Max Planck Institute of Quantum Optics in Garching, and Prof. Frank Verstraete from the University of Vienna, report in Nature Physics ( DOI: 10.1038/NPHYS1370 ), there exist however fundamental limitations to the applicability of this theory. The scientists succeeded by using methods developed in Quantum Information Theory, demonstrating that these methods can give deep insights beyond the development of quantum computers.