The presence of a temporary singularity can allow violation of global charge conservation even though local charge conservation still holds. In article number 2000565, Gratus, Kinsler & McCall describe the conditions required and the fields necessary for this to occur.

This Review explores the current state-of-the-art of topological insulator (TI)-based saturable absorbers (SA) and their applications in different regimes of thulium modelocked fiber lasers (TMFL). Starting from crystal structures and density of states calculations, the fabrication of different TIs and their integation as an efficient passive SA in TMFL able to produce fundamental to high-harmonic pulse generation are described.

The ultrawide photonic bandgap and ultrastrong photonic localization produced by a series of periodic networks are investigated. The results indicate that with increasing generation, the gap–midgap ratio enlarges rapidly and tends to 200%. Furthermore, the ultrastrong photonic localization is generated when the electromagnetic wave with the frequency of the all-transmission peak in the passband propagates in the networks.

Using the definition of transpose in Fock space and normal ordering of operators, partial operator transformation is achieved by replacing creation operator with annihilation within the normal ordering form, rather than the c-number. Some relations before and after transpose are constructed. The degree of entanglement is obtained in this proposed way for a nonideal two-mode squeezed vacuum.

Is charge conservation sacrosact? If so, why? Even when local charge conservation remains in force, the presence of a temporary singularity can give rise to surprising results. This work shows how global charge conservation can be broken after the combined appearance of both new charge and an axion-like field from the singularity.

When propagating in free space, radially polarized odd-Pearcey Gaussian beams (RPOPGBs) present a central symmetric distribution, including two main lobes, which auto-focus to the central optical trap at first, and then separate after the end of auto-focusing. Intriguingly, the energy of RPOPGBs auto-focuses several times when the Gaussian beam waist radius increase to some certain extents.

Most higher-order topological insulators are known to have high crystalline symmetry with few exceptions. Here, it is theoretically demonstrated that square lattices with low symmetry can also exhibit second-order photonic topological insulating phases, provided that the intracell coupling is negligible compared with the intercell one, taking photonic crystals with asymmetric sublattices.

In contrast to previous work, the authors prove that the VCl₃ monolayer is an antiferromagnetic semiconductor rather than a Dirac half-metal. However, chalcogen-doped VCl₃ monolayers will change to be ferromagnetic semiconductors at a low doping concentration. The corresponding Curie temperature can reach 170 K. Meanwhile, chalcogen-doped VCl₃ monolayers have enhanced optical absorption in the visible regions compared with the intrinsic one.

A multipartite entanglement structure resolution analyzer is constructed from a new perspective of quantum-control-assisted variance-based multipartite uncertainty relation. The multipartite entanglement resolution analyzer obtained can delineate the detailed structure of multipartite entanglement of all pure states with only a polynomial number of incompatible measurements, without a complete prior knowledge of the quantum state.