An amendment to this paper has been published and can be accessed via a link at the top of the paper.

A class of biological matter including elongated cells and filaments can be understood in the framework of active nematic liquid crystals. Within these systems, topological defects emerge and give rise to remarkable collective behaviours.

The soil bacterium Myxococcus xanthus lives in densely packed groups that form dynamic three-dimensional patterns in response to environmental changes, such as droplet-like fruiting bodies during starvation1. The development of these multicellular structures begins with the sequential formation of cell layers in a process that is poorly understood2. Here, using confocal three-dimensional imaging, we

Bacteria commonly live attached to surfaces in dense collectives containing billions of cells1. While it is known that motility allows these groups to expand en masse into new territory2,3,4,5, how bacteria collectively move across surfaces under such tightly packed conditions remains poorly understood. Here we combine experiments, cell tracking and individual-based modelling to study the pathogen

Animal morphogenesis arises from the complex interplay between multiple mechanical and biochemical processes with mutual feedback. Developing an effective, coarse-grained description of morphogenesis is essential for understanding how these processes are coordinated across scales to form robust, functional outcomes. Here we show that the nematic order of the supracellular actin fibres in regenerating

Three-dimensional topological insulators are a phase of matter that hosts unique spin-polarized gapless surface states that are protected by time-reversal symmetry. They exhibit unconventional charge and spin transport properties1,2. Intense laser fields can drive ballistic charge dynamics in Dirac bands3,4 or they can coherently steer spin5 and valley pseudospin6. Similarly, high-harmonic generation

When molecular model systems, such as polycyclic aromatic hydrocarbons, are ionized by ultrashort extreme ultraviolet pulses, their relaxation path proceeds via electron–phonon scattering, linking molecules to typical solid-state matter behaviour.

Modern ultrashort X-ray/XUV (extreme ultraviolet) sources provide unique opportunities to investigate the primary reactions of matter upon energetic excitation. Understanding these processes in molecules on ultrafast timescales is required to improve bespoke high-energy radiation detectors, nanomedicine schemes or to study the molecular composition of interstellar media. However, current experiments

Antiferromagnets (AFMs) have the potential to push spintronic devices from a static condition or gigahertz frequency range to the terahertz range for the sake of high-speed processing. However, the insensitivity of AFMs to magnetic fields makes the manipulation of spin currents difficult. The ultrafast generation of the spin current in ferromagnet/heavy-metal (HM) structures has received a lot of attention

The contact formalism describes short-range correlations, which play a crucial role in nuclear systems. Initially introduced for ultracold atoms, its generalization to the nuclear case was now validated by ab initio calculations.

While mean-field approximations, such as the nuclear shell model, provide a good description of many bulk nuclear properties, they fail to capture the important effects of nucleon–nucleon correlations such as the short-distance and high-momentum components of the nuclear many-body wave function1. Here, we study these components using the effective pair-based generalized contact formalism2,3 and ab

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Scaling arguments provide valuable analysis tools across physics and complex systems yet are often employed as one generic method, without explicit reference to the various mathematical concepts underlying them. A careful understanding of these concepts empowers us to unlock their full potential.

In first-century China, emperor Wang Mang standardized weights and measures in his newly established dynasty. Noa Hegesh tells the story of sound as the basis for this standardization.

The Nobel Prize in Physics 2020 has been awarded to Roger Penrose for his work on black hole formation, and to Andrea Ghez and Reinhard Genzel for their observation of a supermassive compact object at the Galactic Centre.

Observing accreting black holes in the early Universe allows precise comparison of clocks over intercontinental distances on Earth. This is achieved with a novel observation strategy using the next generation of very long baseline interferometry systems.

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Quantum optical coherence can be quantified only by accounting for both the particle- and wave-nature of light. For an ideal laser beam1,2,3, the coherence can be thought of roughly as the number of photons emitted consecutively into the beam with the same phase. This number, \({\mathfrak{C}}\), can be much larger than the number of photons in the laser itself, μ. The limit for an ideal laser was thought

While the structural characteristics of a network are uniquely determined by its adjacency matrix1,2,3, in physical networks, such as the brain or the vascular system, the network’s three-dimensional layout also affects the system’s structure and function. We lack, however, the tools to distinguish physical networks with identical wiring but different geometrical layouts. To address this need, here

Quantum light–matter interactions of bound electron systems have been studied extensively. By contrast, quantum interactions of free electrons with light have only become accessible in recent years, following the discovery of photon-induced near-field electron microscopy (PINEM). So far, the fundamental free electron–light interaction in all PINEM experiments has remained weak due to its localized

Active matter composed of self-propelled interacting units holds a major promise for the extraction of useful work from its seemingly chaotic dynamics. Streamlining active matter is especially important at the microscale, where the viscous forces prevail over inertia and transport requires a non-reciprocal motion. Here we report that microscopic active droplets representing aqueous dispersions of swimming

Twisted van der Waals heterostructures with flat electronic bands have recently emerged as a platform for realizing correlated and topological states with a high degree of control and tunability. In graphene-based moiré heterostructures, the correlated phase diagram and band topology depend on the number of graphene layers and the details of the external environment from the encapsulating crystals

An amendment to this paper has been published and can be accessed via a link at the top of the paper.

Animals seem capable of an infinite variety of movement, yet also exhibit substantial stereotypy in repeated actions. A beautiful view of worm behaviour now shows that the worm’s state evolves deterministically but is bounced chaotically between unstable periodic orbits.

In RuCl3, inelastic neutron scattering and Raman spectroscopy reveal a continuum of non-spin-wave excitations that persists to high temperature, suggesting the presence of a spin liquid state on a honeycomb lattice. In the context of the Kitaev model, finite magnetic fields introduce interactions between the elementary excitations, and thus the effects of high magnetic fields that are comparable to

The comparison of distant atomic clocks is foundational to international timekeeping, global positioning and tests of fundamental physics. Optical-fibre links allow the most precise optical clocks to be compared, without degradation, over intracontinental distances up to thousands of kilometres, but intercontinental comparisons remain limited by the performance of satellite transfer techniques. Here

Animal behaviour is often quantified through subjective, incomplete variables that mask essential dynamics. Here, we develop a maximally predictive behavioural-state space from multivariate measurements, in which the full instantaneous state is smoothly unfolded as a combination of short-time posture sequences. In the off-food behaviour of the roundworm Caenorhabditis elegans, we discover a low-dimensional

The assembly of the more than a million single parts of the ITER tokamak requires large-scale three-dimensional precision metrology. John Villanueva Jr gives us insights into the complexity of this project.

As Nature Physics turns fifteen, we celebrate some of our favourite papers.

Over the last 15 years, the content of Nature Physics has covered an enormous breadth of subjects at the forefront of physics. The journal’s past and present editors recount their favourite papers and what made chaperoning them to publication special.

Populations of organisms can be regarded as clouds of genetic variants evolving passively in response to mutation and natural selection. Counterdiabatic driving — a tool borrowed from quantum control — now offers the possibility of actively controlling both the rate and route followed by an evolving population.

Transport experiments in twisted bilayer graphene have revealed multiple superconducting domes separated by correlated insulating states1,2,3,4,5. These properties are generally associated with strongly correlated states in a flat mini-band of the hexagonal moiré superlattice as was predicted by band structure calculations6,7,8. Evidence for the existence of a flat band comes from local tunnelling

Collective cell migration offers a rich field of study for non-equilibrium physics and cellular biology, revealing phenomena such as glassy dynamics, pattern formation and active turbulence. However, how mechanical and chemical signalling are integrated at the cellular level to give rise to such collective behaviours remains unclear. We address this by focusing on the highly conserved phenomenon of

The understanding of how spins move and can be manipulated at pico- and femtosecond timescales has implications for ultrafast and energy-efficient data-processing and storage applications. However, the possibility of realizing commercial technologies based on ultrafast spin dynamics has been hampered by our limited knowledge of the physics behind processes on this timescale. Recently, it has been suggested

The particle physics community refreshes the roadmap for the field in Europe, taking into account the worldwide context, in the so-called European Strategy for Particle Physics update, which happens every seven years.

An atomic spin oscillator coupled to a mechanical membrane resonator forms an effective negative-mass oscillator. Entanglement in this hybrid quantum system is created by a backaction-evading position measurement, despite the macroscopic separation.

Ultrasound experiments reveal a multicomponent superconducting order parameter in Sr2RuO4.

The quasi-two-dimensional metal Sr2RuO4 is one of the best characterized unconventional superconductors, yet the nature of its superconducting order parameter is still under debate1,2,3. This information is crucial to determine the pairing mechanism of Cooper pairs. Here we use ultrasound velocity to probe the superconducting state of Sr2RuO4. This thermodynamic probe is sensitive to the symmetry of

Sr2RuO4 has stood as the leading candidate for a spin-triplet superconductor for 26 years1. However, recent NMR experiments have cast doubt on this candidacy2,3 and it is difficult to find a theory of superconductivity that is consistent with all experiments. The order parameter symmetry for this material therefore remains an open question. Symmetry-based experiments are needed that can rule out broad

Entanglement is an essential property of multipartite quantum systems, characterized by the inseparability of quantum states of objects regardless of their spatial separation. Generation of entanglement between increasingly macroscopic and disparate systems is an ongoing effort in quantum science, as it enables hybrid quantum networks, quantum-enhanced sensing and probing of the fundamental limits

The asymmetry in the flow of events that is expressed by the phrase ‘time’s arrow’ traces back to the second law of thermodynamics. In the microscopic regime, fluctuations prevent us from discerning the direction of time’s arrow with certainty. Here, we find that a machine learning algorithm that is trained to infer the direction of time’s arrow identifies entropy production as the relevant physical

Many-body localization (MBL) describes a quantum phase where an isolated interacting system subject to sufficient disorder displays non-ergodic behaviour, evading thermal equilibrium that occurs under its own dynamics. Previously, the thermalization–MBL transition has been largely characterized with the growth of disorder. Here, we explore a new axis, reporting on an energy-resolved MBL transition

Crystallization under geometrical confinement is of fundamental importance in condensed matter physics, biophysics and material science. Even the influence of the simplest geometry, a sphere, on crystallization remains far from well understood, thereby making morphology control of the final superstructures challenging. Here, we employ charged colloids encapsulated in an emulsion droplet as a model

Physical systems powering motion and creating structure in a fixed amount of time dissipate energy and produce entropy. Whether living, synthetic or engineered, systems performing these dynamic functions must balance dissipation and speed. Here, we show that rates of energy and entropy exchange are subject to a speed limit—a time–information uncertainty relation—imposed by the rates of change in the

Superradiance is the anomalous radiance describing coherent photon emission from a gas. It plays a crucial role in atomic physics, quantum mechanics and astrophysics. Because the intensity of superradiant light beams is proportional to the number of particles squared, superradiance is also at the core of today’s most powerful light sources. Superradiant emission is intuitively expected when the distance

Quantum measurement remains a puzzle through its stormy history from the birth of quantum mechanics to state-of-the-art quantum technologies. Two complementary measurement schemes have been widely investigated in a variety of quantum systems: von Neumann’s projective ‘strong’ measurement and Aharonov’s weak measurement. Here, we report the observation of a weak-to-strong measurement transition in a

The flat bands that appear in some twisted van der Waals heterostructures provide a setting in which strong interactions between electrons lead to a variety of correlated phases1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20. In particular, heterostructures of twisted double bilayer graphene host correlated insulating states that can be tuned by both the twist angle and an external electric field11

Natural soils are host to a high density1 and diversity2 of microorganisms, and even deep-earth porous rocks provide a habitat for active microbial communities3. In these environments, microbial transport by disordered flows is relevant for a broad range of natural and engineered processes, from biochemical cycling to remineralization and bioremediation4,5,6,7. Yet, how bacteria are transported and

Although quantum mechanics is essential to understand microscopic systems, it has little effect on heavier objects. Experiments have now put strict constraints on theories that use gravity to explain the absence of large-scale quantum effects.

Roger Penrose proposed that a spatial quantum superposition collapses as a back-reaction from spacetime, which is curved in different ways by each branch of the superposition. In this sense, one speaks of gravity-related wave function collapse. He also provided a heuristic formula to compute the decay time of the superposition—similar to that suggested earlier by Lajos Diósi, hence the name Diósi–Penrose

Hydrogen metallization under stable conditions is a substantial step towards the realization of the first room-temperature superconductor. Recent low-temperature experiments1,2,3 report different metallization pressures, ranging from 360 GPa to 490 GPa. In this work, we simulate the structural properties and vibrational Raman, infrared and optical spectra of hydrogen phase III, accounting for proton

Glass is inherently unstable to crystallization. However, how this transformation occurs while the dynamics in the glass stay frozen at the particle scale is poorly understood. Here, through single-particle-resolved imaging experiments, we show that due to frozen-in density inhomogeneities, a soft colloidal glass crystallizes via two distinct pathways. In the poorly packed regions of the glass, crystallinity

Hybrid quantum materials allow for quantum phases that otherwise do not exist in nature1,2. For example, a one-dimensional topological superconductor with Majorana states bound to its ends can be realized by coupling a semiconductor nanowire to a superconductor in the presence of a strong magnetic field3,4,5. However, the applied magnetic fields are detrimental to superconductivity, and constrain device

The properties of anyons — two-dimensional particles that are neither fermions nor bosons — have been directly measured in a quantum Hall interferometer.

Anyons are quasiparticles that, unlike fermions and bosons, show fractional statistics when two of them are exchanged. Here, we report the experimental observation of anyonic braiding statistics for the ν = 1/3 fractional quantum Hall state by using an electronic Fabry–Perot interferometer. Strong Aharonov–Bohm interference of the edge mode is punctuated by discrete phase slips that indicate an anyonic

A remarkable property of quantum mechanics in two-dimensional space is its ability to support ‘anyons’, particles that are neither fermions nor bosons. Theory predicts that these exotic excitations can exist as bound states confined near topological defects, such as Majorana zero modes trapped in vortices in topological superconductors. Intriguingly, in the simplest cases the non-trivial phase that

Wolfgang Pauli introduced the Bohr magneton as a fundamental unit of magnetic moment during an effort to find a quantum basis for magnetism, as Davide Castelvecchi recounts.

The First Plasma discharge in the ITER tokamak is expected for 2025 with deuterium–tritium plasma operation ten years later. We spoke with ITER’s Director-General, Bernard Bigot, and Tim Luce, head of ITER’s Science & Operations Department, about the current status of the project and potential future directions in fusion research.