Reviews & Analysis

One way of realizing controlled nuclear fusion reactions for the production of energy involves confining a hot plasma in a magnetic field. Here, the physics of magnetic-confinement fusion is reviewed, focusing on the tokamak and stellarator concepts.

The quest for energy production from controlled nuclear fusion reactions has been ongoing for many decades. Here, the inertial confinement fusion approach, based on heating and compressing a fuel pellet with intense lasers, is reviewed.

Simulating magnetically confined fusion plasmas is crucial to understand and control them. Here, the state of the art and the multi-physics involved are discussed: electromagnetism and hydrodynamics combined over vast spatiotemporal ranges.

The transition to widespread connectivity in networks is aptly described by concepts borrowed from percolation theory. Attempts to delay the transition with small interventions lead to explosive percolation, with drastic consequences for the system.

Magnons provide a route for information-processing technologies that are free from charge-related dissipations. Advances in the manipulation of magnons, and the conversion to charge currents, bring magnon-based computing closer to realization.

The discovery of spin-triplet Cooper pairs at superconductor/ferromagnet interfaces provides a route for combining superconducting and magnetic orders. Recent advances and challenges in the field of superconducting spintronics are now reviewed.

The task of integrating information into the framework of thermodynamics dates back to Maxwell and his infamous demon. Recent advances have made these ideas rigorous—and brought them into the laboratory.

Statistical mechanics is adept at describing the equilibria of quantum many-body systems. But drive these systems out of equilibrium, and the physics is far from clear. Recent advances have broken new ground in probing these equilibration processes.

Exciton–polaritons, resulting from the light–matter coupling between an exciton and a photon in a cavity, form Bose–Einstein-like condensates above a critical density. Various aspects of the physics of exciton–polariton condensates are now reviewed.

The superconducting energy gap is perhaps the best-known of the spectral gaps in a superconductor, but there are many other types, including density waves and the mysterious pseudogap. This Review Article surveys what angle-resolved photoemission spectroscopy has revealed about the various gaps.

Understanding the physics of two-dimensional materials beyond graphene is of both fundamental and practical interest. Recent theoretical and experimental advances uncover the interplay between real spin and pseudospins in layered transition metal dichalcogenides.

There are good reasons to consider nonlocality to be the defining feature of quantum mechanics, but stronger nonlocal correlations than those predicted by quantum theory could exist, which raises the intriguing question of what lies beyond.

Testing the limits of the quantum mechanical description of nature has become a subject of intense experimental interest. Recent advances in investigating macroscopic quantum superpositions are pushing these limits.

Starting with wave-particle duality, experiments with light have played a major role in the development of quantum theory. Advances in photonic technologies allow for improved tests of quantum complementarity, delayed-choice and nonlocality.

Nematic order in the iron-based superconductors breaks the symmetry between the x and y directions in the Fe plane. Beyond this, however, there is little consensus on how nematic order arises and whether it has an effect on superconductivity. This Review discusses the current theoretical and experimental state of the field.

Surface-plasmon polaritons are hybrid particles that result from strong coupling between light and collective electron motion on the surface of a metal. This Review presents an overview of the quantum properties of surface plasmons, their role in controlling light–matter interactions at the quantum level and potential applications.

Could biological systems have evolved to find the optimal quantum solutions to the problems thrown at them by nature? This Review presents an overview of the possible quantum effects seen in photosynthesis, avian magnetoreception and several other biological systems.

Experimental progress in controlling and manipulating trapped atomic ions has opened the door for a series of proof-of-principle quantum simulations. This article reviews these experiments, together with the methods and tools that have enabled them, and provides an outlook on future directions in the field.

Quantum optics has played an important role in the exploration of foundational issues in quantum mechanics, and in using quantum effects for information processing and communications purposes. Photonic quantum systems now also provide a valuable test bed for quantum simulations. This article surveys the first generation of such experiments, and discusses the prospects for tackling outstanding problems in physics, chemistry and biology.

Experiments with ultracold quantum gases provide a platform for creating many-body systems that can be well controlled and whose parameters can be tuned over a wide range. These properties put these systems in an ideal position for simulating problems that are out of reach for classical computers. This review surveys key advances in this field and discusses the possibilities offered by this approach to quantum simulation.