Volume 10 Issue 8, August 2014

Our perception of colour has always been a source of fascination, so it's little wonder that studies of the phenomenon date back hundreds of years. What, though, can modern scientists learn from medieval literature — and how do we go about it?

When a bubble bursts at a liquid–gas interface, a portion of gas is released from the liquid. Now, another, counterintuitive process is reported: rapid motion generated by bubble-bursting transports oil droplets from the surface into the interior of a volume of water.

The origins of the spin Hall effect are difficult to probe, largely because experiments typically characterize electrons near the Fermi surface. Quantum tunnelling spectroscopy now provides access to its energy dependence.

The ionization of atoms and molecules by strong laser fields has become a core technique in modern laser physics. Now, the electrons emerging from ionized molecules are shown to exhibit a memory of the ionization process, resulting in a spatial phase that may influence the interpretation of imaging data.

Measurements of laser-induced magnetization dynamics suggest that spin currents can be generated on ultrafast timescales. Now it is shown that such currents may be capable of exerting ultrafast spin-transfer torques.

Trapping rubidium atoms in narrow lattices provides insight into the quantum mechanics of collections of interacting particles. This innovative approach reveals a phase transition similar to one found in superconductors.

The jury's still out on how glasses and other disordered materials form. However, a new framework suggests that we can understand their mechanical properties without this information, by using the physics of jamming.

From the manner of its discovery in 2012, it was apparent that the 125 GeV Higgs boson couples to bosons, but does it couple to fermions too? Yes, says the CMS Collaboration at CERN, who present combined evidence of Higgs decay to pairs of bottom quarks and pairs of tau leptons.

The spin Hall effect, which arises from the spin–orbit interaction, is expected to be energy dependent, but experiments typically only characterize electrons near the Fermi surface. A tunnelling spectroscopy method has now been developed to probe the energy dependence.

The dissipation-less flow of supercurrent through a wire is a well-known property of superconductors. But in some cases, a normal current can flow in the presence of superconductivity. This may be due to non-equilibrium physics.

In crystalline topological insulators, the combination of an insulating bulk with conducting surface states is due to particular crystal symmetry. The associated Dirac cones—linear crossings in the electronic band structure—exhibit non-trivial orbital textures that have now been probed by means of scanning tunnelling spectroscopy.

Jammed systems are typically thought of as being amorphous. Simulations of packings with varying disorder reveal a crossover from crystalline behaviour, which suggests the physics of jamming also applies to highly ordered systems—providing a new framework for understanding amorphous solids.

A proposed network of atomic clocks—using non-local entangled states—could achieve unprecedented stability and accuracy in time-keeping, as well as being secure against internal or external attack.

Laser-assisted tunnelling allows quantum gases in optical lattices to be exposed to tunable artificial magnetic fields. Using such fields to confine a bosonic gas to an array of one-dimensional ladders, a low-dimensional equivalent of the Meissner effect has been observed.

Intense lasers can both ionize atoms and subsequently drive the recollision of the released electrons with their ionized parents. Holography experiments now show that the orientation of the parent can change the recollision process, requiring a refinement of the commonly used strong-field approximation.

Isotope production is usually associated with nuclear reactors, but there are alternative approaches. One such proposal is based on the well-known atomic physics experimental techniques of optical pumping and magnetic guiding, and its viability for isotope separation is now experimentally demonstrated.

When a bubble bursts on reaching a surface, mass transfer from the liquid to the gas phase can occur—aerosol dispersion. Now, the inverse transport process is reported: submicrometre-sized oil droplets, formed during bubble-bursting, are zipped across the interface to the liquid phase.

Chance encounter.