Reviews & Analysis

The Kondo insulator samarium hexaboride is the first experimentally demonstrated example of a strongly correlated topological insulator. This article reviews the topological theory and experimental evidence, including a mystery as to the origin of quantum oscillations and their relation to possible unconventional bulk in-gap states.

Magnetic skyrmions, two-dimensional nanometre-scale localized states, are promising candidates for new technological applications. This Perspective surveys the progress in this field and offers a brief, accessible guide to the basic physical principles of magnetic skyrmions.

Neuromorphic computing takes inspiration from the brain to create energy-efficient hardware for information processing, capable of highly sophisticated tasks. Including more physics in the algorithms and nanoscale materials used for computing could have a major impact in this field.

Over the past 40 years, the quantum Hall effect (QHE) has inspired new theories and led to experimental discoveries in a range of fields going beyond solid-state electronics to photonics and quantum entanglement. In this Viewpoint, physicists reflect on how the QHE has influenced their research.

Droplets in general are multicomponent and experience gradients in concentration, often leading to transport phenomena and phase transitions. This Perspective discusses recent progress on the physicochemical hydrodynamics of such droplet systems and their relevance for many important applications.

Despite comprising only about 15% of the known molecular inventory of the interstellar medium, molecular ions have an outsized role in driving chemical evolution. This Review examines the advances — and challenges — in laboratory spectroscopy that have enabled the study of ions in space.

Quantum simulation with ultracold atomic gases is an established platform for investigating complex quantum processes. Focusing on optical lattice experiments, this Technical Review overviews the available tools and their applications to the simulation of solid-state physics problems.

The study of higher-dimensional quantum states has seen numerous conceptual and technological developments. This review discusses various techniques for the generation and processing of qudits, which are stored in the momentum, path, time-/frequency-bins, or the orbital angular momentum of photons.

Chemical vapour deposition (CVD) enables the synthesis of high-purity, pinhole-free and conformal polymer thin films. This Review discusses the recent breakthroughs in mechanistically based CVD polymerization processes and designing CVD polymers for a diverse array of applications.

Quantum technologies require an extremely precise functioning of their components which is ensured by sophisticated tools for device characterization. This Technical Review surveys and assesses the currently available tools according to their overall complexity, information gain, and underlying assumptions.

Methods for measuring stress in living cells, tissues and organs are advancing steadily and are increasingly being used for biomedical applications. In this Review, we discuss the concept of tissue stress and the techniques available to measure it in 2D and 3D cell and tissue cultures and in vivo.

Ion traps enable the precise control and manipulation of the quantum state of a trapped ion. This Technical Review discusses the way in which ion-trap microchips can be fabricated and integrated with advanced on-chip features for implementing practical quantum technologies.

In the midst of the COVID-19 pandemic, science is crucial to inform public policy. At the same time, mistrust of scientists and misinformation about scientific facts are rampant. Six scientists, actively involved in outreach, reflect on how to build a better understanding and trust of science.

Non-line-of-sight (NLOS) imaging methods use light scattered from multiple surfaces to reconstruct images of scenes that are hidden by another object. This Perspective summarizes existing NLOS imaging techniques and discusses which directions show most promise for future developments.

As the COVID-19 pandemic continues, mathematical epidemiologists share their views on what models reveal about how the disease has spread, the current state of play and what work still needs to be done.

Time-periodic fields provide a versatile platform for inducing non-equilibrium topological phenomena in quantum systems. We discuss how such fields can be used for topological band structure engineering, and the conditions for observing robust topological behaviour in a many-body setting.

This Expert Recommendation provides a guide to identifying practical situations where the likelihood ratio test statistic cannot be approximated by a χ² distribution and proposes adequate solutions.

Plasmon-enhanced Raman spectroscopy (PERS) is a highly sensitive technique that can provide molecular fingerprint information. This Technical Review discusses the fundamental principles, advantages and limitations of PERS, key issues in using PERS and interpreting results, and state-of-the-art applications in materials characterization, bioanalysis and the study of surfaces.

Nine researchers, editors and science communicators share their views about the barriers that Asian scientists encounter in publishing their work and becoming more visible on the international level.

Due to their atomic structure, ultracold alkaline-earth atoms are well suited for quantum simulation and the study of quantum many-body physics. This Perspective overviews the ways to control the interactions between atoms and discusses the new physics that could be uncovered.