Articles in 2019

Skyrmions are topologically nontrivial spin textures which could be used as energy efficient carriers of information in future memory devices, but first reliable and efficient control of their movement is required. Here, the authors demonstrate a method to control the movement of individual skyrmions by making use of the magnetic interaction between a sample and a magnetic force microscopy probe.

Small-world networks describe mathematically many natural and man-made networks such as neurons, power grids or social networks, but a measure of how small a small-world network is, remains a subject of debate. The authors identify the limiting cases with the shortest and longest average path for a given number of nodes and edges, which can be used as benchmarks to evaluate the average shortest path length for both empirical and model networks.

Order-disorder structural transitions are a common occurrence for a number of everyday systems and play an important role in the vortex matter of a superconductor however their structure can be complex to understand. Here, the authors combine surface and bulk vortex imaging techniques to investigate the structural properties of the vortex glass phase in a type II superconductor and demonstrate the physics is relevant to other glass systems.

Accessing the non-equilibrium multi-pulse states arising from interactions between cavity pulses and the quasi-continuous-wave background has been hindered by the random nature of the background. Here, well-defined optoacoustic modulations to this noise-like background are proven able to control the positions of bunched pulses and soliton rains in the time domain.

Quantum key distribution allows ultimate security based on laws of physics, and its integration on the existing optical network is of worldwide interest. Exploiting the concept of space division multiplexing in a 37-cores multicore fibre, this work demonstrates efficient secret key generation and high compatibility with classical communication.

Understanding the effect of the subtle interplay between strong and weak coupling regimes on the properties of quasiparticles is key to understanding unconventional superconductivity. Here, X-ray spectroscopies reveal the partially localized and itinerant magnetic character of quasiparticles in a doped iron pnictide material.

Dispersive shock waves occur in a diverse range of non-viscous systems, from hydrodynamics to socioeconomics. Here, the authors demonstrate vectorial dispersive shock waves by employing orthogonally polarized light, revealing a testing ground for this ubiquitous, nonlinear phenomenon.

Fast and energy-efficient control of magnon transport in magnonic crystals is one of the main challenges of modern magnonics. High performances for voltage control are expected but have so far only been predicted theoretically and investigated numerically. In this paper, the authors report of the first experimental realization of voltage-controlled magnon currents in a dynamic electromagnonic crystal.

Superradiance, a collective light emission produced by an ensemble of excited atoms has been extensively investigated. The authors study the collective emission from ultracold strontium atoms trapped inside a hollow core fibre, which may offer a miniaturized platform for exploring superradiance.

Long-range Coulomb interactions play an important role in the non-equilibrium charge dynamics of Mott insulators, but are difficult to unravel experimentally. Here, transient spectroscopy and theoretical analyses reveal Coulomb interactions stabilize biexcitons over four lattice sites in a 1D Mott insulator.

Although characterizing the Seifert surface is central to the realization of novel phases in topological materials, this has been a purely mathematical construction so far. This paper proposes an experimentally realistic scheme for the realization and imaging of 4D-embedded Seifert surfaces, opening up a way for experimental topological characterization

Higher-order topological insulators are a class of systems where the relationship between the bulk and surface properties differ from that of conventional topological insulators. Here, the authors seek to demonstrate that these systems may be realized using acoustic systems.

The existence of Majorana zero modes have been potentially confirmed in superconductor-semiconductor nanowires but recent studies suggest the data can also be interpreted using Andreev bound states, throwing into doubt the conclusions regarding Majorana modes. To resolve this controversy the authors use non-Hermitian topology to determine the boundaries between the Majorana and Andreev states.

Quantum information provides a powerful method for improving imaging beyond classical limits, but the complexity typically scales non-linearly with the number of parameters. Here, the authors demonstrate a method to reduce the number of parameters required and identify an optimal degree of photon correlation for imaging.

The need to move away from silicon-based semiconductors for the electronic industry has yielded significant developments in the use of organic materials for devices. The authors present a method to enhance organic light-emitting diodes (OLEDs) performance by adding a common antibiotic, ampicillin into a common organic semiconductor and achieving a maximum external quantum efficiency of 35%.

Conventional multicolour metaholograms suffer from inherently low resolution and irreducible noise due to the single phase response of each unit structure. Here, a wavelength-decoupled multicolour metahologram is demonstrated overcoming the existing problems by a dual phase response in a single nanostructured unit.

Topological pumping and Aharonov–Bohm effect are fundamental effects enabled by the topological properties of a system. The authors combine these two concepts to study an interacting ring-lead system pierced by a synthetic magnetic field, finding that particle transport is substantially affected by entanglement and interaction.

The efficient generation of spin current in superconductors is an open problem in superconducting spintronics. Here, the authors predict that the spin supercurrent generation efficiency in two-dimensional non centrosymmetric superconductors with Rashba spin-orbit interaction can be greatly enhanced by tuning the chemical potential.

Skyrmions, Majorana fermions and topological superconductivity are active areas of research within the condensed matter physics community and each offer the promise of new physics and potential applications. Here, the authors theoretically demonstrate that by bringing skyrmions into close proximity with a superconductor topological superconductivity can be induced, as well as Majorana states localized at the edges of the skyrmions.