Articles in 2008

Politics can be hard to swallow.

Detailed investigation of a single atomic spin on a surface reveals that its Kondo interaction with the substrate electrons depends strongly on the spin's relative orientation.

For nearly two decades physicists have been learning to incorporate spin into conventional electronics. Now they may be one step closer to devices that use only flow of spins, but not of charges.

A fresh take on perturbation theory allows quantum-mechanical interactions to be simplified, while preserving low-energy properties, and deepens understanding of the complexity of quantum systems.

Science once enjoyed a close and fruitful relationship with the White House and Capitol Hill — one that must now be rekindled, as a new president and Congress take office.

Entanglement swapping—a protocol for entangling remote quantum systems without the requirement of direct interaction between them—has been implemented in a completely deterministic fashion, allowing to prepare well-defined entangled states on demand.

Evidence for metal–insulator transitions in dilute 2D electron gases has sparked controversy and debate. A new model suggests such behaviour could arise from strong correlations driven by non-local Coulomb interactions, providing an alternative view to that which considers disorder to be the over-riding influence.

Optical lattice clocks, in which trapped atoms serve as a frequency reference, are promising candidates for next-generation atomic clocks. Depending on whether bosons or fermions are loaded into the lattice, fundamentally different design principles apply, as has now been shown.

The tendency of small objects to stick together as they come into contact is a commonly observed phenomenon. Yet the interactions that govern this behaviour can be complex. A systematic study of the variation in the force between a particle and a solid surface as they are brought together finds many parallels with the characteristics of glassy and granular systems.

Electron microscopes are regularly used to resolve atoms in solid samples. It turns out that they can also be used to image atoms in a Bose–Einstein condensate—remarkably, without destroying the coherent properties of the condensate.

A systematic study of the propagation of ultrasound through a random network of aluminium beads provides the first demonstration of the Anderson localization of classical waves in a 3D system.

Warm dense matter is a complex and little-explored state that is characterized by temperatures usually associated with plasmas but at densities similar to solids. A combination of inelastic X-ray scattering and ab initio simulations enables insight into its structure and behaviour.

The precision of various interferometric measurements can be enhanced by using entangled states of light. Now an experiment demonstrates that all the metrological advantages of the famed Hong–Ou–Mandel quantum interferometer can be realized even with purely classical light.

It is already known that the theory of quantum entanglement shares some analogies with the laws of thermodynamics. Now a rigorous and general link between the two fields has been established.

An experiment that demonstrates efficient absorption of light by a single atom residing in free space should be helpful for designing interfaces for the transfer of quantum information from ‘flying’ qubits to stationary quantum systems, without the need for optical cavities.

The computational capability of the brain remains a mystery. Some insight might come from a series of experiments in which cultures of living neurons are patterned in a way to form functional logic devices.

The 2008 Nobel Prize for physics has been awarded to Yoichiro Nambu “for the discovery of the mechanism of spontaneous broken symmetry in subatomic physics”, and to Makoto Kobayashi and Toshihide Maskawa “for the discovery of the origin of the broken symmetry which predicts the existence of at least three families of quarks in nature”.

A key element in spintronics is the spin-transfer effect, by which the magnetization in a nanomagnet can be switched. The effect has already been demonstrated using spin-polarized electrical currents, but now reversible magnetization switching has been achieved using a pure, chargeless spin current.

An array of 488 Josephson junctions that amplifies and squeezes noise beyond conventional quantum limits should prove useful in the study and development of superconducting qubits and other quantum devices.