Volume 11 Issue 5, May 2015

Granting access to publications and data may be a step towards open science, but it's not enough to ensure reproducibility. Making computer code available is also necessary — but the emphasis must be on the quality of the programming.

Writing efficient scientific software that makes best use of the increasing complexity of computer architectures requires bringing together modelling, applied mathematics and computer engineering. Physics may help unite these approaches.

Research in high-energy physics produces masses of data, demanding extensive computational resources. The scientists responsible for managing these resources are now turning to cloud and high-performance computing.

Classically, it is impossible to infer causal dependencies from the correlations between two variables alone, but in the quantum world causal relationships exist that can be completely characterized by observing the correlations between two systems.

Laser tweezers can be used to control particles in a colloidal glass, thereby influencing the dynamics of their neighbours. The range of this influence — and how it changes — may provide a structural mechanism to explain the solidity of glasses.

Quantum entanglement is as confounding as it is potentially useful. A paper in 2006 suggested that its utility might extend to making sense of a fundamental puzzle in statistical mechanics.

Topological insulators are often considered to be one-band problems that are easy to solve. However, strongly correlated topological insulators cannot be described by band theory because the electrons fractionalize into other degrees of freedom.

Squeezed states make it possible to circumvent the standard quantum limit. Using stroboscopic measurements one can create squeezed states of a rather unusual oscillator: the collective spin of an atomic ensemble precessing in a magnetic field.

Nitrogen–vacancy centres offer significant promise as nanoscale magnetometers. A light-trapping diamond waveguide is demonstrated, enhancing the temperature and magnetic field sensitivity of such centres by three orders of magnitude.

Charge transfer from adsorption is shown to provide an electrical method for probing the collective behaviour of atoms and small molecules confined to the surface of a carbon nanotube.

As a liquid relaxes towards the glass transition, its dynamics is thought to become more cooperative. Experiments using holographic optical tweezers support a contested thermodynamic picture, claiming this cooperation involves morphology changes.

In laboratory experiments, strong magnetic fields at the boundary of a plasma can be generated by means of laser-wakefield acceleration, enabling the study of magnetization processes in scaled versions of astrophysical plasmas.

It is impossible to distinguish between causal correlation and common cause based on classical correlations alone. An experiment now shows that for quantum variables it is sometimes possible to infer the causal structure just from observations.

By pushing both time and frequency resolution in optical spectroscopy it is now possible to resolve antiferromagnetic fluctuations in a copper oxide superconductor, which are believed to mediate the pairing of charge carriers.

Perovskite photovoltaics are the fastest-advancing solar technology but the mechanisms responsible for their performance are not clear. The observation of magnetic field effects in hybrid perovskites may help to explain their high efficiencies.

An identity crisis.

Physicists have always been quick to adopt computing technologies, and computers have likewise played a key role in physics research. This Focus examines physicists' response to the challenges—and opportunities—posed by recent advances in computing.