Browse Physics

Published September 2, 2008

Atomic & Molecular Physics

When an atom is bombarded with just enough energy to fully ionize it, how do the electrons and nucleus break apart from each other? Experimentalists are now able to study such a four-body breakup by bombarding a helium atom with an electron.

Published September 2, 2008

Biological Physics Interdisciplinary Physics

Given that vaccine supplies are often limited, a quantitative understanding of how the number and frequency of vaccinations can affect the growth rate of disease would be useful. Physicists show that even a small number of randomly vaccinated individuals can exponentially increase the extinction rate of a disease.

Published August 25, 2008

Graphene Mesoscopics

By adsorbing and desorbing nitrogen dioxide, it is possible to add and remove charge carriers from graphene and induce a reversible metal-insulator transition.

Published August 25, 2008

Optics Quantum Information

Squeezed states can enhance the sensitivity of a detector and the storage capability of quantum memory devices. Because these features improve with an increase in system size, researchers are exploring ways to produce squeezed states in large ensembles of atoms.

Published August 18, 2008

Nuclear Physics

The long-held belief that nuclear states of very heavy elements that carry a large angular momentum would be unstable has been shattered in recent years. Now, a new experiment that can probe the outermost nuclear orbitals in ²⁵⁰Fm studies these states and poses a challenge to theory.

Published August 18, 2008

Mesoscopics

Researchers find that tunneling between the two layers of a bilayer two-dimensional electron gas is proportional to their area. Although the result may seem intuitive it poses a challenge to current theory.

Published August 18, 2008

Nanophysics Optics

The response of nanostructured metal strips to an electromagnetic field may turn out to be similar to that of atomic gases. Periodic arrays of these artificial metal “molecules” could in principle form a metamaterial that slows light pulses and is easily integrated into optical circuits.

Published August 11, 2008

Superconductivity

The ability to tune the onset of superconductivity in a single crystal with other means than chemical doping makes the interpretation of results much cleaner. Now, scientists demonstrate pressure-induced superconductivity in undoped crystals of the pnictide CaFe₂As₂.

Published August 11, 2008

Interdisciplinary Physics Nonlinear Dynamics

Acoustic vortices that interact in a nonlinear medium may be one route to a new kind of robust arithmetic computation.

Published August 6, 2008

Mesoscopics

The formation of Landau levels in a magnetic field is the hallmark of a two-dimensional electron system, such as graphene. Experiments now suggest that Landau levels can also form in carbon nanotubes.

Published August 5, 2008

Quantum Mechanics

Bell showed that quantum entanglement cannot be modeled with local hidden variables alone. Now, physicists argue that only models based exclusively on nonlocal hidden variables can reproduce all possible quantum correlations.

Published August 5, 2008

Mesoscopics

Measurements show that the tunneling of electrons through a quantum dot has a complex dependence on magnetic field and the shape of the dot. These results challenge existing pictures of spin-dependent tunneling in quantum dot devices.

Published July 28, 2008

Gravitation

A “simple” closed-form Hamiltonian for a relativistic system of n gravitating particles, which depends only on the particles’ momenta and coordinates, is developed.

Published July 28, 2008

Quantum Information Spintronics

Spin decoherence is a fundamental obstacle in quantum computation and spintronics. Scientists show they can increase the lifetime of a localized spin in a diamond lattice up to 100 times by polarizing the surrounding spins on the lattice.

Published July 28, 2008

Atomic & Molecular Physics

The atoms in highly excited vibrational states of a diatomic molecule can be quite far apart near their maximum excursion. Physicists are now using laser spectroscopy to carefully measure the long-range effective interaction between potassium atoms in these states—an essential parameter to understanding ultracold atomic collisions.

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.

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.