Coherently coupled quantum mixtures can simulate the dynamics of magnetic materials. Here an inhomogeneous gas shows two different regions, one (top) where interactions dominate and the gas stays polarized in one spin state and another (bottom) where coupling prevails and the spin processes. Quantum torque leads to the breaking of the interface between the two magnetic regions, and spin shockwaves with strong anticorrelations are observed.

See Farolfi et al.

Form factors encode the structure of nucleons. Measurements from electron–positron annihilation at BESIII reveal an oscillating behaviour of the neutron electromagnetic form factor, and clarify a long-standing photon–nucleon interaction puzzle.

See The BESIII Collaboration and Pakhlova

Optical frequency combs are a key technology in communications, sensing and metrology. A theoretical proposal shows that introducing topological principles into their design makes on-chip combs more efficient and robust against fabrication defects.

See Mittal et al. and Peano

A class of synthetic microswimmer self-assembled from alkane oil drops in surfactant solution offers a rechargeable platform for studying how microorganisms exploit flagellar elasticity to move.

See Cholakova et al. and Ramananarivo

High-temperature superconductor Fe(Te,Se) transitions to an electronic nematic phase that breaks rotation symmetry of the lattice near the composition where the superconducting transition temperature reaches its peak. Scanning tunnelling microscopy reveals that this transition is characterized by the emergence of nanoscale nematic regions. These regions, observed as unidirectional modulations portrayed in the image, show a surprising suppression of superconductivity.

See Zhao et al.

Protein oscillations linked to cell division in Escherichia coli are shown to localize unrelated molecules on the cell membrane via a diffusiophoretic mechanism, in which an effective friction fosters cargo transport along the fluxes set up by the proteins.

See Ramm et al. and Bocquet and Palacci

A topological photonic crystal design generates light that carries orbital angular momentum with high quantum numbers. The beam contains several different states at the same time, promising integrated and multiplexed light sources. The image represents the self-interference of a beam with a quantum number of 156.

See Bahari et al. and Ma

By exploiting polarization entanglement between photons, quantum holography can circumvent the need for the first-order coherence required for classical holographic imaging. In this protocol, when one photon in an entangled pair is directed at a smiley-shaped object, the phase information of the object is instantaneously shared with the other photon, regardless of their separation. The object shape is then remotely reconstructed in the form of quantum holograms by detecting photons with separate cameras.

See Defienne et al.

Biomolecules in the cell nucleus form condensates at a rate slower than that predicted by the theory of droplet growth. Experiments on living cells attribute this anomalous coarsening behaviour to subdiffusive dynamics in the crowded nucleus. The image is a composite fluorescence micrograph of live human osteosarcoma cells, showing the co-localization of nuclear droplets and chromatin, using a spinning disk confocal microscope.

Brangwynne, Article

Molluscs are capable of assembling layers of material in the shells around them with exquisite control. Synchrotron-based nanotomographic imaging of the structural evolution of this layer formation has now prompted a model that draws analogy with topological defect dynamics in liquid crystals

Article → N&V

Combining concepts from knot theory and statistical mechanics leads to a method for distinguishing between physical networks with identical wiring but different layouts.

See Barabási et al.

In 1927, Sir Arthur Eddington coined the phrase ‘time’s arrow’ to express the fact that the time reversibility of events on a microscale does not necessarily exist in macroscopic processes, for which we can usually discern temporal order. Now, a machine learning algorithm trained to infer the direction of time’s arrow has identified entropy production as key to making this decision.

Seif, Article