Browse Physics

Published July 21, 2008

Quantum Mechanics Statistical Mechanics

Theorists show that the quantum critical states of fermions may have fractal character and predict signatures of this result in liquid ³He, a fermionic fluid.

Published July 21, 2008

Biological Physics Statistical Mechanics

Molecular dynamics simulations show that thermal gradients – of order 10¹⁰ K over a meter - can polarize liquid water. The finding could have interesting implications for developing hyperthermal treatments that target cancer cells.

Published July 17, 2008

Superconductivity

The ability to grow single crystals of a compound in the family of iron-based superconductors will open the door to a wide range of experiments that were not previously possible.

Published July 17, 2008

Nuclear Physics

When an antiproton is fired into an atomic nucleus, will it live long enough for the nucleus to respond to the attractive strong force between the antiproton and the protons and neutrons? Calculations suggest that it would and predict the experimental signatures of an antiproton annihilating in a locally compressed nucleus.

David Voss, Physics 1, 1 (2008) – Published July 14, 2008

Anyone who has recently glanced at a library shelf of physics journals or browsed the literature online will instantly recognize both the increase in volume and the fragmentation of disciplines. How can a researcher stay on top of his or her own field, much less stay abreast of related areas that might harbor interdisciplinary gems? To address this, we begin a new publication, simply called Physics.

Miles Blencowe, Physics 1, 3 (2008) – Published July 14, 2008

Quantum Mechanics Gravitation

The longitudinal ringing mode of a metal bar resonator weighing approximately one metric ton has been cooled to submillikelvin temperatures with the use of active amplifier feedback. Further improvements may allow researchers to approach the quantum limit for cooling macroscopic objects.

Steve K. Lamoreaux, Physics 1, 4 (2008) – Published July 14, 2008

Quantum Mechanics Nanophysics

Modification of electromagnetic zero-point fluctuations by closely spaced conductors causes an interaction between them called the Casimir force. New experiments with nanostructured silicon substrates show that the geometry of the conducting surfaces has a large effect on this force.

Steven L. Rolston, Physics 1, 2 (2008) – Published July 14, 2008

Plasma Physics

Plasmas are normally thought of as high temperature ionized gases or fluids, such as those in the sun’s corona or those found in controlled nuclear fusion experiments. Many interesting plasma phenomena can occur, however, in plasmas at low temperature. With the help of laser trapping and cooling, atoms can be photoionized to form neutral plasmas at extremely low temperatures. These plasmas may exist in the so-called strong coupling regime, where the energy of the Coulomb interactions between particles is larger than their thermal energy. In addition to providing a test bed for studying the strongly coupled plasmas such as those found in Jovian planets and white dwarfs, ultracold plasmas play a critical role in understanding the formation of antihydrogen.

Published July 14, 2008

Plasma Physics

Magnetic field lines in moving plasmas can break and reform, releasing large amounts of energy. Simulations suggest this happens in a two stage process—one slow and smooth, the other rapid and chaotic.

Published July 14, 2008

Superconductivity

Theorists have developed a simple and intuitive model that could be the basis for explaining superconductivity in iron-arsenides.

Published July 14, 2008

Nanophysics Optics

Single photon emission is normally only observed in systems, such as atoms, that are quantum confined in all directions. Now, scientists have shown that carbon nanotubes, which are quasi-one-dimensional materials, can also act as single photon emitters.

Published July 14, 2008

Atomic & Molecular Physics

Lasers can confine atoms in one-dimensional traps. Now, the right superposition of lasers can act as one-way barriers that let atoms move in one direction, but not the other.

Published July 14, 2008

Quantum Mechanics

The Dirac and Klein-Gordon equations provide a full relativistic description for particles with spin ½ and 0, respectively. A calculation now shows how to extend this description to particles, such as nuclei, with spin greater than ½.