Volume 17 Issue 4, April 2021

Scientific progress has always been driven by the ability to build an instrument to answer a specific question. But spreading the news of how to replicate that tool is an evolving art, ripe for an open-source revolution.

With increasing neutron number, the size of a nucleus grows, subject to subtle effects that act as fingerprints of its internal structure. A fresh look at potassium calls for theory to decipher the details.

A clever application of nuclear magnetic resonance techniques offers a glimpse at a quantum system driven at high frequency, resulting in Floquet prethermalization — a quasi-steady state that persists for a very long time.

Two experiments using entangled photons have successfully generated more randomness than consumed — at a level of security that is all but certain. They did so by exploiting non-locality, one of the most counterintuitive aspects of quantum mechanics.

Among the many reasons a signal may deviate from perfect periodicity, quantum-limited jitter is arguably the most fundamental. A clever experiment has now stripped away technical noise to unveil quantum-limited jitter of ultrafast soliton frequency combs.

The magnetic properties of intercalated metal dichalcogenides are dramatically affected by small crystal imperfections, potentially providing design principles and materials for spintronic devices.

Biophysicists have long sought to probe the physical properties of the cell nucleus, but the sheer size of this tiny organelle puts limits on its exploration. The coarsening of biomolecular droplets looks set to give us the inside scoop.

The unavoidable effects of noise make quantum error correction necessary to realize the full potential of quantum computers. Devices that correct errors autonomously can avoid the computational and hardware overheads of traditional approaches.

The charge radii of potassium isotopes up to ⁵²K are measured, and show no sign of magicity at 32 neutrons as previously suggested in calcium. The observations are interpreted with coupled cluster and density functional theory calculations.

A periodically driven Floquet quantum many-body system initially prepared in a far-from-equilibrium state may exhibit prethermalization: that is, before reaching its thermal equilibrium the system first relaxes to a long-lived quasistationary state.

Device-independent randomness expansion is demonstrated in an experiment that is secure against quantum adversaries as established by the entropy accumulation theorem.

Device-independent randomness expansion is demonstrated in an experiment that is secure in the presence of a classical eavesdropper who does not share any entanglement with the setup.

Momentum-space transport behaviour studied in a quench-cooled isolated atomic Bose gas shows a self-similar scaling character, implying the existence of a far-from-equilibrium universality class.

Quantum jitter fundamentally limits the performance of microresonator frequency combs. The timing jitter of the solitons that generate the comb spectra is analysed, reaching the quantum limit and establishing fundamental limits for soliton microcombs.

Neutron-scattering measurements on the magnetically ordered triangular-lattice compound FeI₂ reveal a dispersive band of mixed dipolar–quadrupolar fluctuations just above its ground state—a quantum excitation without a classical counterpart.

Measurements of a superconducting infinite-layer nickelate show that its upper critical field is largely isotropic despite its quasi-two-dimensional structure. This indicates that, unusually for layered oxides, the superconductivity is Pauli-limited.

In twisted bilayer graphene, the moiré potential, strong electron–electron interactions and a magnetic field conspire to split the flat band into topologically non-trivial subbands.

Majorana bound states should appear at both ends of a nanowire if it is in the topological regime. This paper reports that, in many cases, zero-bias conduction peaks only occur on one end of the wire, which casts doubt on whether they are Majoranas.

Resonant excitation of phonons by a laser pulse switches the magnetization of a thin yttrium iron garnet film. This particular combination of longitudinal optical phonons results in a quadrupolar pattern, but this could be tailored in the future.

Branching microtubule nucleation plays a major part in cellular processes driving eukaryotic cell division. A combination of microscopy approaches and hydrodynamic theory is used to show how the condensed protein TPX2 on a microtubule reorganizes according to the Rayleigh–Plateau instability.

In a beam-driven plasma wakefield accelerator, the energy spread of an electron bunch is reduced with respect to the plasma entrance, which is achieved through setting a positive energy chirp that rotates the bunches’ longitudinal phase space.

Characterizing the epithelial tissue of a shape-shifting marine animal as an integrated composite material reveals a ductile-to-brittle phase transition that captures how the tissue responds to failure.

Self-referenced attosecond streaking enables in situ measurements of Auger emission in atomic neon excited by femtosecond pulses from an X-ray free-electron laser with subfemtosecond time resolution and despite the jitter inherent to X-ray free-electron lasers.

Two monolayers of bismuth-containing cuprate will form a high-temperature topological superconductor when stacked with an approximately 45° rotation between the layers.

Coexistence of a spin-glass phase with antiferromagnetism in an intercalated crystal produces a large exchange bias effect. This is due to the interplay of disorder and frustration.

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.

What does it mean for an individual to be ‘important’ or for a connection to be ‘outstanding’? The answer depends on context, as Sarah Shugars and Samuel V. Scarpino explain.