Review Articles

The past decade has witnessed remarkable progress in our understanding of equilibration, thermalization and prethermalization, due in large part to experimental breakthroughs in ultracold atomic gases. This Review discusses theoretical and experimental advances on these topics and the challenges ahead.

Axion fields provide a unique way to understand large quantized electromagnetic responses in topological insulators and dynamics in Weyl semimetals. This Review discusses the theory of axion fields in condensed matter, their experimental realization and their application in next-generation devices.

The charge radius of the proton is controversial because measurements by different methods disagree. Recent results indicate that these measurements might be reconciled. In this Review, we discuss the experimental techniques used to measure the proton radius and describe the current status of the field as well as forthcoming experiments.

Holographic duality is an equivalence relation between a gravitational system and a quantum many-body system. The Review discusses various insights obtained from the duality into properties of strongly coupled matter, quantum many-body chaos and deep connections between quantum information and geometry.

The coupling of photons to material quasiparticles such as plasmons, phonons and excitons opens new possibilities in light–matter interactions. This Review presents a generalized view of such quasiparticles and the technique that describes their interactions with matter: macroscopic quantum electrodynamics.

Topological Majorana bound states have potential for encoding, manipulating and protecting quantum information in condensed-matter systems. This Review discusses emergence and characterization of Majorana bound states in realistic devices based on hybrid semiconducting nanowires and their connection to more conventional Andreev bound states.

Ferroelectric and ferroelastic domain walls are 2D topological defects with thicknesses approaching the unit cell level and emergent functional properties. This Review discusses the exotic polarization profiles that arise at domain walls and the fundamental mechanisms responsible for domain-wall conduction.

2D materials host various collective excitations, which either mutate or cease to exist in the bulk. In this Review, we select the most striking properties of 2D plasmons, excitons, phonons and magnons, contrasting them with the bulk versions.

Understanding the behaviour of materials at high pressures and temperatures is of great importance to planetary science and the physics of warm dense matter. This Review addresses the close connection between modelling the interiors of gaseous planets and the high-pressure physics of hydrogen and helium.

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.

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.

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.

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.

Optical microscopy is limited to shallow in vivo imaging depths owing to the exponential extinction of single-scattered waves by multiple light scattering. In this Review, we survey methodologies for deep optical imaging that maintain microscopic resolution by making deterministic use of multiple-scattered waves.

The integration of gate-defined quantum dots with superconducting resonators results in a hybrid architecture that holds promise for quantum information processing. This Review discusses recent experimental results in the field, including the achievement of strong coupling between single microwave photons and the charge and spin degrees of freedom, and examines the underlying physics.

Cilia are hair-like organelles that enable cellular locomotion. This Review considers cilia from a dynamical systems perspective, discussing the nonlinear oscillations seen in the single cilia of microorganisms and the emergent topological phenomena seen in the ciliary arrays of animals.

Pseudo-electromagnetic fields emerge in inhomogeneous materials. This Review discusses the properties of such fields in the context of 3D topological semimetals, the origin and consequences of pseudo-fields in real materials and their field theory description.

Artificial spin ices are metamaterials displaying fascinating phenomena arising from the collective behaviour of nanoscale magnets. We review recent developments in terms of emergent magnetic monopoles, phase transitions, dynamics and geometries, and discuss future directions for research and potential applications.

The partonic (quark and gluon) structure of protons and neutrons is modified in heavy nuclei. This Review surveys how studies of photon-induced interactions reveal the density distribution of partons in nuclei, thereby probing quantum chromodynamics in high-density environments.