Volume 17 Issue 6, June 2021

Undergraduate labs are more effective and more positive for students if they encourage investigation and decision-making, not verification of textbook concepts.

A detailed analysis of a nucleon-knockout experiment has put forward a methodological roadmap for overcoming ambiguities in the interpretation of the data — promising access to the nuclear wave functions in unstable nuclei.

Excitations confined by long-range interactions between Ising spins may provide a way for systems to escape thermalization. A quantum simulator made of trapped ions has now made such confinement-induced enhancement possible.

Recent measurements of observables related to proton and neutron spin properties at low energies are in disagreement with the available theoretical predictions, and continue to challenge nuclear experimentalists and theorists alike.

Multiplexing increases the capacity of optical communication, but it is limited by the number of modes and their orbital angular momentum. A robust vortex laser now solves this problem by emitting several beams, all carrying large topological charges.

Most large quantum systems are ergodic, meaning that over time they forget their initial conditions and thermalize. This article reviews our understanding of seemingly ergodic systems that in fact have some long-lived, non-thermal states.

Measurements of observables sensitive to the neutron’s spin precession are extended to a regime that probes distances of the size of the nucleon. They are found to disagree with predictions from chiral effective field theory.

Initial- and final-state interactions distort the kinematics in particle knockout scattering experiments, complicating their interpretation. These effects are suppressed by detecting ¹¹B nuclei in quasi-free scattering of ¹²C ions from hydrogen.

A topological photonic crystal design directly 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.

Non-Hermitian concepts together with optical gain allow the tailoring of short- and long-range exchange interactions in integrated topological photonics, and an exact Haldane model can be realized in this way.

In magic-angle twisted bilayer graphene, topological Chern bands that are driven by electron–electron interactions appear at all the integer fillings of the moiré unit cell. The Rashba-like higher-energy bands also show Landau-level crossings.

Twisted bilayers of WS₂ and WSe₂ have correlated states that correspond to real-space ordering of the electrons on a length scale much longer than the moiré pattern.

The electrical potential created by a moiré pattern in twisted transition metal dichalcogenide bilayers can be surprisingly deep, trapping electrons that can possibly be used for opto-electronic or quantum simulation applications.

Quantum systems possessing conserved quantities are expected to show quantum fluid properties governed by hydrodynamic equations. This behaviour is now evidenced in a neutron scattering study on the one-dimensional Heisenberg antiferromagnet KCuF₃.

Quantum impurities immersed in a bosonic environment can evolve into polaronic quasiparticles, so-called polarons. Interferometric measurement reveals this transition, which involves three different regimes dominated by few-body and many-body dynamics.

Measurements of the proton’s spin structure in experiments scattering a polarized electron beam off polarized protons in regions of low momentum transfer squared test predictions from chiral effective field theory of the strong interaction.

Long-range Ising interactions present in one-dimensional spin chains can induce a confining potential between pairs of domain walls, slowing down the thermalization of the system. This has now been observed in a trapped-ion quantum simulator.

When strain is applied to strontium ruthenate, superconductivity emerges at a different temperature to the breaking of time-reversal symmetry. This indicates that the superconductivity could have a chiral d-wave order parameter.

A single equation can describe how fluids flow across a wide range of length scales, from ocean currents to swimming algae. The difference merely lies in the Reynolds number, says Julia Yeomans.