Volume 15 Issue 4, April 2019

The British Royal Mint has issued a commemorative coin in honour of Stephen Hawking.

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.

From disease proliferation to cell functioning, spreading dynamics on networks impact many collective phenomena. The joint contributions of the interaction structure and local dynamics have now been disentangled, revealing three distinct types of spreading pattern.

Through stochastic resonance, noise-driven fluctuations make an otherwise weak periodic signal accessible. Experiments have now reported quantum stochastic resonance, which arises from intrinsic quantum fluctuations rather than external noise.

An inspired experimental approach sheds light on the formation of active turbulence in a system of microtubules and molecular motors. The emergent scaling behaviour takes us a step closer to understanding how activity begets turbulence.

Rich data are revealing that complex dependencies between the nodes of a network may not be captured by models based on pairwise interactions. Higher-order network models go beyond these limitations, offering new perspectives for understanding complex systems.

The magnetic moment of the neutron-rich exotic ⁷⁵Cu nucleus is measured using rare isotope beams with a high spin alignment, clarifying how the evolution of the nuclear shell and the shape deformations are connected.

An atom in a superposition of two circular Rydberg states with huge opposite magnetic momenta is reported and demonstrated to be an extremely sensitive probe of the magnetic field.

Quantum stochastic resonance, in which the quantum fluctuation represents the noise needed to amplify an otherwise weak signal, is reported in the charging and discharging of a single-electron quantum dot.

A new form of charge ordering is observed in a cuprate superconductor. At low doping, a fully rotationally symmetric ordering appears before becoming locked to the Cu–O bond directions at high doping. The link between charge correlations and fermiology give a perspective on the phase diagram.

There has latterly been a renewed interest in collective excitations in condensed matter systems. Now, spectroscopic evidence for the so-called Leggett mode is revealed in the superconductor MgB₂.

Efficient spin injection across ferromagnet/semiconductor interfaces is a major goal for future spintronic approaches. Ultrafast spectroscopy now reveals strong spin currents to be inducible in monolayer MoS₂ by ultralow-intensity laser pulses.

A graphene-like two-dimensional sonic crystal, under uniaxial deformation, experiences a giant uniform pseudomagnetic field. This leads to the quantization of the cyclotron orbits—a kind of acoustic Landau level—that is observed here.

Axial fields couple to the states of different chiralities with opposite signs. In an acoustic Weyl system, the implementation of such fields induces chiral Landau levels, which is now observed experimentally.

Experiments on microtubule-based nematics, together with active gel theory, suggest that the length scale associated with active turbulence is selected at its onset—balancing activity with the stabilizing effects of nematic elasticity and geometry.

Observations reveal that electrons in Earth’s outer radiation belt possess a spectrum that partially rises with increasing energy, contrary to common beliefs. Plasma hiss waves scattered off electrons are found to be the origin of this phenomenon.

Efficient photon pair sources connecting visible and telecommunication spectral regions are essential for viable long-distance fibre optic quantum communication architectures. A nanophotonic device is presented that allows kilometre-scale time–energy entanglement as an application.

Parity-breaking antisymmetric spin exchange interaction is reported in clusters of five qubits within superconducting circuits. This allows the creation of chiral spin dynamics, with potential for future quantum simulations of chiral molecules.

A spectroscopic study of strontium titanate provides a method for transferring the vibrational energy of a low-frequency phonon mode to higher-frequency modes, with the potential to access elusive ‘silent’ modes.

Changes in membrane curvature influence how migrating cells navigate their environment. Experiments and modelling reveal that dynamic reorganization of the actin cytoskeleton in response to these changes provides cells with a sensing mechanism.

Complex networks with identical topology may exhibit different dynamics. A systematic analysis of signal propagation in networks reveals the existence of three specific dynamic regimes that connect topological features to dynamic patterns.

If you were ever puzzled about the fact that the detectors at the Large Hadron Collider record huge datasets despite the tiny probability of two protons colliding, this is for you. Steven Goldfarb and Katarina Anthony connect the dots.