Waves & Packets
Dec. 10, 2012

Ultrafast light turns insulator into a conductor
Optics & Photonics News
In a duo of Nature papers, physicists have shown that very intense femtosecond laser pulses can induce electrical currents in fused silica prism without doing damage to the material. Fused silica is normally an insulator. That it can quickly be changed into conductors (and back into insulators again) could be used for signal switching. Today's fastest semiconductor switching is measured in terahertz. But light-induced switching in insulators, such as demonstrated in these papers, could work at petahertz rates. Results in the first Nature paper demonstrate that a strong-field femtosecond pulse can induce a current in the dielectric on a very short timescale. But demonstration that the current can be turned off on the same time scale is shown in the second paper. Taken together the results show that the current-producing effect is nonlinear, but predictable, and that it is reversible and producible on interesting timescales.More

Photovoltaic materials that you can wear
Laser Focus World
Imagine a garment that can provide you with on-board power generation. Militaries, for instance, are especially interested in designing wearable power sources for soldiers in the field. But such a garment could be transformative for people who live and work in remote locations. An international team of researchers has created a silicon-based optical fiber with solar-cell capabilities that is scalable to many meters in length and has a bend radius of about 400 microns. The fiber has its own embedded electronic components, bypassing the need to integrate fiber-optics with chip-based electronics. This was achieved using chemical vapor deposition of semiconducting material into the fiber's lattice. The semiconductors can serve any number of purposes, including power generation, sensing or even neuro-stimulation. This research is reported in Advanced Materials.More

Astronomers see hydrogen gas just after Big Bang
Physics World
Looking at the farthest known quasar from Earth, astronomers have determined the chemical composition of gas from the first billion years of the universe's life when only the elements hydrogen and helium existed. The gas consists mostly of neutral hydrogen atoms, which means that it may mark the era before stellar radiation began ionizing the hydrogen gas, i.e, before the epoch of reionization. These observations, reported in Nature, may also be of early galaxy formation when it is taking in molecular hydrogen gas, but the galaxy is not yet massive enough for the formation of significant amounts of elements with higher atomic numbers.More

Increase your options for graduate or REU program admissions
The NSBP GradApps and REUApps services are open to all students and allows them to upload all the elements of an admissions application, including academic and work history, transcripts, letters of recommendation and a personal statement. Graduate and REU programs can subscribe to these databases to increase the programs' applicant pool, while at the same time allowing students can put their credentials in front of more programs than to which they would otherwise apply. More

Astronomers observe protostar before it has started fusion reactions
Ars Technica
Stars form through the agglomeration of mass from surrounding gas clouds. As mass comes together from gas clouds, it heats up, emitting infrared radiation and sometimes forming planets. At a critical point of mass density and temperature, self-sustaining nuclear fusion reactions are triggered. Protostars are structures that are before this point in their development. Astronomers have recently discovered the youngest protostar ever observed. Relying on 13CO rotational spectrum, the observations fit the agglomeration-thermal emission theory of star formation. But almost none of the mass in the protostar's surrounding envelope has been transformed into what will eventually be the star and its planets. This new observation, reported in Nature, gives a glimpse therefore into the common question of "how do the stars and planets form?"More

Enhanced measurements reveal anisotropy in electron-pairing
American Physical Society
Angle-resolved photoemission spectroscopy (ARPES) is the most direct way to probe the energy and momentum of a material's electrons. To date, ARPES has mostly revealed an isotropic gap in iron superconductors, which is consistent with electron pairing mediated by a combination of spin fluctuations and phonons. Conventional ARPES, however, is only sensitive to electrons near the surface, which may not represent those in the bulk of the material. Using an enhanced ARPES technique that is more sensitive to bulk electrons, physicists have reported in Physical Review Letters that they have observed a pronounced gap anisotropy in FeTe0.6Se0.4. The gap's shape suggests that phonons likely do not play a role in the pairing mechanism, but at least for this material, long-range magnetic interactions between the iron atoms should be taken into account.More

77 year old Einstein, Podolsky, and Rosen proposition extended to 3 particles
In a 1935 Physical Review paper, Einstein, Podolsky, and Rosen proposed a thought experiment that pondered what happens with two initially interacting systems are allowed to separate and not interact. Their conclusion was that there was some lingering interaction between the systems, encoded in some hidden variables, and that the wave function is an incomplete description of reality. Debate on the so-called 'EPR paradox' continues to this day. In work recently published in Nature Physics, physicists have extended the EPR experiment from two systems to three, and notably with continuous variables of those systems instead of discrete variables. To achieve this feat the researchers split a pump laser beam into two daughter beams, and then split one of the daughters. The total energy is conserved between the parent beam and the daughters. The emission times of the parents and daughters, which correspond to position, are also conserved. Thus energy and position, which are continuous variables, amongst the photons are correlated. This new demonstration will have several applications in quantum communications in addition to being a tool to further ponder the foundations of quantum mechanics.More

What lies beneath the surface of the Moon?
In a trio of papers published in Science researchers have presented the most detailed characterization of Moon's surface topography and gravitational field. The GRAIL mission consists of two satellites orbiting the moon. As they orbit the distance between them fluctuates. Those fluctuations are related to surface topography and material density below the surface. The first Science paper focuses on the Moon's overall gravity map. The data reveal previously unseen tectonic plates, volcanoes and craters. Material just below the lunar surface is almost completely pulverized, indicating that Moon was subject to more collisions that previously thought. In the second paper researchers show that the upper crust is much thinner, more porous and less dense than previously thought. The third paper then shows that the lunar crust appears inundated with cooled magma from the core. Overall the results tell a story of an an initially hot object rapidly expanding while cooling. All the while it was fracturing and taking heavy collisions.More

Rep. Rush Holt's advice to his fellow scientists on politics
Scientific America
Almost everyone would agree that policy decisions should follow a method of analysis of available evidence. This issue becomes what constitutes evidence, and who has the cognitive ability and unbiased agenda to give it a fair analysis. Placing more scientists in policy positions, or electing them to political office is long and hard. But getting involved in the political process is easy for scientists, and more should do it. Scientists must be better communicators, and be more active at all levels of government, from local school boards to the Federal government. Simply visiting and volunteering to advise your representatives in Congress are good ways to get started. As far as government spending on science, we have to figure out how to make science sound less like yet another special interest and more like a sound investment. More

Getting admitted into graduate school
Admission into a graduate program is a process that actually begins much earlier than your senior year. If you understand the actual criteria for admission, and develop and execute a plan to meet those criteria, you will be well ahead of the game before your applications are due. But if you're planning for the graduate admissions process has not been deliberate before your senior year, it is not too late to find a path to an advanced degree in physics. More

Internships 101
A focused research internship is an important part of a complete undergraduate physics curriculum. During an internship you can make contacts with new peers and mentors, and get a new perspective on your field of study. You can choose to go abroad and have a very different cultural experience. Importantly you can sharpen your baseline knowledge of physics and sharpen your skills in open-ended problem solving, information gathering and synthesizing, and communication. These are skills for which physicists are known, and they are useful no matter what ultimate career path you follow.More

National Society of Black Physicists jobs board postings
Assistant Professor of Physics - University of Idaho
REU summer program on complex materials
Assistant Professor of Physics-Tenure Track Bates College
REU Student
Tenure Track Experimentalist Specializing in the Physics of Organic Electronic Materials
Vacuum Equipment Group Leader
Assistant Professor, Department of Radiology at Stanford University
Condensed Matter Theory Faculty Positions
Two-Year Visiting Assistant Professor of Physics
Tenure-track Position Applied Physics - Cornell University
Assistant Professor - University of Wisconsin-Eau Claire
Faculty Position in Computational Science — Virginia Tech College of Science
Faculty Positions in Interdisciplinary Science/Science Education Research
Faculty Positions in Science, Technology, and Innovation
Postdoctoral Research Position in Stellar Astrophysics at the Space Telescope Science Institute
Faculty Position in Experimental Astrophysics and Cosmology
Tenure-track Assistant Professor of Physics — Duquesne University
National Radio Astronomy Observatory Research Experience for Undergraduates
Renewable Energy REU at Colorado School of Mines
Experimental Particle Physics FacultyMore

Latest research from European Journal of Physics
IOP Publishing
Modelling of phase transitions: do it yourself

Reflection from a moving mirror—a simple derivation using the photon model of light

Bohlin transformation: the hidden symmetry that connects Hooke to Newton

Classical Yang–Mills theory in condensed matter physics

Levitation of a magnet by an alternating magnetic field

Latest research from Tectonophysics
Transient crustal deformation in the South Iceland Seismic Zone observed by GPS and InSAR during 2000–2008

Implications of fracturing mechanisms and fluid pressure on earthquakes and fault slip data in the east Iceland rift zone

Fluid overpressure estimates from the aspect ratios of mineral veins

Observation and interpretation of fault activity in the Rochefort cave (Belgium)

Pseudotachylyte in the Tananao Metamorphic Complex, Taiwan: Occurrence and dynamic phase changes of fossil earthquakesMore