Research articles

When current is passed through certain semiconductors or metals, spins of opposite sign accumulate on opposing boundaries. The phenomenon is known as the spin Hall effect, and now, for the first time, its dynamics has been measured directly.

Impurity centres in diamond have recently attracted attention in the context of quantum information processing. Now their use as magnetic-field sensors is explored, promising a fresh approach to single-spin detection and magnetic-field imaging at the nanoscale.

Interactions between photons are typically extremely weak. But when light pulses are confined to an optical waveguide and manipulated with nearby cold atoms, strongly interacting photons can be created that may even undergo crystallization, as is now shown theoretically.

The coupling of a quantum system to its environment is usually associated with the unwanted effect of decoherence. But theoretical work shows that with suitably engineered couplings, dissipation can drive a system of cold atoms into desired many-body states and quantum phases.

Maxwell’s equations describing electric and magnetic fields limit the shapes field lines can take. But exotic solutions exist where the field lines are linked and knotted. A proposal now shows how such solutions could be realized experimentally.

Superconducting quantum interference devices, or SQUIDs as they are better known, are capable of detecting minute variations in magnetic field. Embedding a suspended beam into the structure of d.c. SQUID enables this sensitivity to be exploited for measuring displacements.

Cells can change shape by reorganizing the actin filaments that make up the cytoskeleton, and this is usually achieved through protein interactions. But it seems that the cell membrane, by virtue of its elasticity, can also influence the bundling of actin filaments.

Analysis of how condensation of an ensemble of bilayer excitons reorganizes the low-energy degrees of freedom of its constituent fermions suggests it should be possible to generate a dissipationless superflow in such a system.

Coherent population trapping is a process by which a particle is induced to exist in a superposition of two ground states. This has now been demonstrated for an electron spin on a single quantum dot, which could prove useful in a variety of photonic and information-processing applications.

The integration of a micrometre-sized magnet with a semiconductor device has enabled the individual manipulation of two single electron spins. This approach may provide a scalable route for quantum computing with electron spins confined in quantum dots.

Improvements in the microwave output efficiency of MgO-based magnetic tunnel junctions brings them a step closer to practical applications and enables greater insight into the physics of spin transfer in such devices.

That the dynamical properties of a glass-forming liquid at high temperature are different from behaviour in the supercooled state has already been established. Numerical simulations now suggest that the static length scale over which spatial correlations exist also changes on approaching the glass transition.

A technique that controls electron spins using single optical pulses far detuned from the optical transition has been demonstrated. This approach may enable fast spin manipulation in a variety of solid-state systems.

When a superfluid—such as liquid helium—is set in rotation, vortices appear in which circulation around a closed loop can take only discrete values. Such quantized vortices have now been observed in a solid-state system—a Bose–Einstein condensate made of exciton polaritons.

State-of-the-art simulations of disorder-induced trapping of light in inverted opals provides a basis for a definitive identification, and potential use, of the three-dimensional Anderson localization of light.

The observation of so-called Bogoliubov excitations provides the first sign of possible superfluid behaviour in an exciton-polariton condensate.

The ability to control the velocity of molecules using time-varying electrical and magnetic fields has led to a renewed interest in molecular beams. This article reviews the technology of these decelerators and discusses applications.

Detailed analysis of multiscale structures and the identification of long-lived streamer-like wavemodes in a magnetically confined plasma provides new insight into the physics of plasma turbulence.

Analysis of the best available data on the behaviour of a large number of glass-forming organic liquids suggests that the widespread belief that a glass ceases to flow below its transition temperature could be wrong.

Disorder and geometric frustration usually lead to magnetic spins that point in random directions, as in a spin glass. So how can spin-glass behaviour emerge in a well-ordered system without static frustration? The presence of ‘dynamic frustration’ may explain the situation.