Volume 13 Issue 12, December 2017

A type of optics experiment called a boson sampler could be among the easiest routes to demonstrating the power of quantum computers. But recent work shows that super-classical boson sampling may be a long way off.

The spontaneous assembly of particulate or molecular 'building blocks' into larger architectures underlies structure formation in many biological and synthetic materials. Shape frustration of ill-fitting blocks holds a surprising key to more regular assemblies.

A classical algorithm solves the boson sampling problem for 30 bosons with standard computing hardware, suggesting that a much larger experimental effort will be needed to reach a regime where quantum hardware outperforms classical methods.

Traditionally quantum state tomography is used to characterize a quantum state, but it becomes exponentially hard with the system size. An alternative technique, matrix product state tomography, is shown to work well in practical situations.

Combining micrometre-sized mechanical resonators with superconducting quantum circuits, quantum information encoded with photons now can be converted to the motion of a macroscopic object.

Experimental signatures of a Berry phase for composite fermions in the fractional quantum Hall effect provide support for the predictions that these composite fermions are Dirac particles.

Magneto-optical trapping and sub-Doppler cooling of atoms has been instrumental for research in ultracold atomic physics. This regime has now been reached for a molecular species, CaF.

Semiconductor nanowires with superconducting leads are considered promising for quantum computation. The current–phase relation is systematically explored in gate-tunable InAs Josephson junctions, and is shown to provide a clean handle for characterizing the transport properties of these structures.

Graphene systems are clean platforms for studying electron–electron (e–e) collisions. Electron transport in graphene constrictions is now found to behave anomalously due to e–e interactions: conductance values exceed the maximum free-electron value.

Understanding crack formation is important for improving the mechanical performance of materials. A new theory is now presented for the description of cracks propagating at high speeds, with elastic nonlinearity as the underlying principle.

A photonic experiment demonstrates protective measurements, a type of weak measurements. These make it possible to determine the expectation value of the polarization of a photon from a single measurement.

Ring-exchange interactions are basic elements needed for realizing topological quantum computation. These interactions and anyonic statistics have been engineered using ultracold atoms in an optical lattice.

A detailed resonant inelastic X-ray scattering (RIXS) study of a series of well-known cuprate superconductors reveals a correlation between the number of apical oxygens in these systems, and the strength of their in-plane exchange interaction.

Whether ballistic transport can occur in a system is usually governed by the number of impurities, but a ballistic transport regime is seen in charge-neutral graphene that is limited not by impurities or phonons, but electron–hole collisions.

Spontaneous formation of a half-skyrmion lattice is observed in a thin-film chiral liquid crystal. The dynamics are shown to be thermally driven — presenting a platform to study the thermal fluctuations of topological defects.

Determining how cellular activity affects the collective properties of growing tissues is key to understanding morphogenesis. An epithelial tissue model shows how active tension can give rise to striking mechanical behaviours seen in experiments.

Nuclear reactions taking place in stars are not straightforward to study in laboratories on Earth. Now, inertial-confinement fusion implosion experiments are reported that mimic the conditions for the hydrogen-burning phase in main-sequence stars.

The arrival of a new type of timekeeper heralds the end of the second as we know it, as Helen Margolis explains.