News & Views in 2019

Photonic circuits naturally implement boson sampling, a quantum algorithm that is classically hard to solve. Four photon pairs produced and processed within a single silicon chip have now been used to run it, a step towards besting classical computers.

The superconductor–insulator phase transition is a quantum phenomenon that reveals a competition between the superconducting phase order and charge localization. Now, microwave spectroscopy is shown to be a promising approach to investigate this effect in controllable one-dimensional Josephson arrays.

A demonstration that Michael Berry’s legacy can inform our understanding of Lamb waves in stratified fluids serves as a reminder of the reach of topological thinking — as well as its potential utility.

A rich pattern of fractional quantum Hall states in graphene double layers can be naturally explained in terms of two-component composite fermions carrying both intra- and interlayer vortices.

The detection of the quantum state of tens of neutral atoms arranged in arrays has reached a new record fidelity. This brings fault-tolerant quantum computation and simulation closer to reality.

A theoretical analysis of exotic superconductors suggests that it is possible to manipulate the state of their order parameter with light. This will help engineer devices from topological superconductors by patterning regions with different orders.

While Bose–Einstein condensates of atoms were achieved in the mid-1990s, extending the regime of quantum degeneracy to polar molecules took another two decades of dedicated work. The researchers that contributed to this achievement span many generations of students in many different laboratories around the world.

The transport properties of many two-dimensional systems are strongly affected by the proximity of a periodic pattern. Colloidal particles are now shown to have preferred sliding routes due to competing symmetries between two unmatched crystalline surfaces.

A measurement based on quantum entanglement of the parameter describing the asymmetry of the Λ hyperon decay is inconsistent with the current world average. This shows that relying on previous measurements can be hazardous.

A variety of magnetic structures based around ferromagnetic spin spirals have been the topic of intense study over the past decade. The discovery of spin spirals that arise from antiferromagnetic order has just broadened the horizons for magnetic possibilities even further.

Experiments and simulations show that trains of droplets in microfluidic networks undergo synchronized oscillations, and that strategies to prevent these oscillations can help maintain uniform distribution of red blood cells in microcirculation.

The measurement of the charge density wave energy gap in high-temperature superconducting cuprates uncovers new links between competing states.

An experimental study of living cells suggests that single myosin molecules are capable of generating unusually large forces. The observation is supported by a theoretical model — and demonstrates the complexity of in vivo force generation.

The mechanics of many materials can be modelled by a network of balls connected by springs. A bottom-up approach based on differential geometry now captures changes in mechanics upon network growth or merger, going beyond the linear deformation regime.

One of the fundamental radioactive decay modes of nuclei is β decay. Now, nuclear theorists have used first-principles simulations to explain nuclear β decay properties across a range of light- to medium-mass isotopes, up to ¹⁰⁰Sn.

Artificial magnetic fields have been constructed in 2D and 3D acoustic structures to manipulate sound, in much the same way as Dirac and Weyl fermions respond to magnetic fields in their quantum levels.

Ultrasonic radiation forces are harnessed to trap and then shake clusters of spheres — mimicking the effect of temperature on cluster formation in granular systems. This assembly process has applications from the nanoscale to the macroscale.

A two-state hopping experiment combined with a dynamical systems model reveals that cancer cells are deterministically driven across barriers, whereas normal cells cross only with the help of stochastic fluctuations.

An electrical interferometer device has detected interference patterns that suggest anyons could be conclusively demonstrated in the near future.

Kagome lattice materials combine a frustrated lattice with electron–electron and spin–orbit interactions. One of them, Co₃Sn₂S₂, now reveals magnetic properties that respond in the opposite way to what is expected.