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A topological phase of light emerges in dynamically driven nonlinear photonic crystals.

Using Floquet engineering, an ensemble of ytterbium-171 ions in an yttrium orthovanadate host crystal provides a platform for studying the dynamics of different quantum many-body models, including the realization of a time-crystalline phase.

Topological photonic structures can be understood by solving the eigenvalue problem of Maxwell’s equations in the static case. Here, the authors study Floquet topological phases in nonlinear photonic crystals under external drive and show how non-reciprocal transport can be achieved in a Floquet Chern insulator.

Vanishing Chern numbers usually mean that a system is topologically trivial, but this rule may be violated for periodically driven systems. Here, Maczewskyet al.report topologically protected edge modes in a periodically driven photonic lattice with all bands of zero Chern number.

Departing from common approaches to designing Floquet topological insulators, here the authors present a photonic realization of Floquet topological insulators revealing topological phases that simultaneously support Chern and anomalous topological states.

Information transfer between distant qubits suffers from spurious interactions and disorder. Here, the authors report up to an order of magnitude enhancement in the quality factor of a swap operation of eigenstates in a quantum dot chain, by using a periodic driving protocol inspired by discrete time crystals.

The build-up and dephasing of Floquet-–Bloch bands is visualized in both subcycle band-structure videography and quantum theory, revealing the interplay of strong-field intraband and interband excitations in a non-equilibrium Floquet picture.

Condensed matter research has seen prominent recent advances in ultrafast optical manipulation and topological materials. Here, Sentef et al. simulate the development of the photoemission-measured band structure of Floquet states in graphene excited by low-frequency circularly-polarized laser pulses.

Organic semiconductors employed in light-emitting diodes (OLEDs) allow for magnetic resonance studies that explore light-matter interactions in the ultrastrong-drive regime, where the Rabi frequency exceeds the Larmor frequency. The authors report the formation of Floquet spin states in OLEDs.

Digital quantum simulations of Kitaev’s honeycomb model are realized for two-dimensional fermionic systems using a reconfigurable atom-array processor and used to study the Fermi–Hubbard model on a square lattice.

Floquet physics occurs when a system is driven periodically in time and can be used to uncover phases absent in thermal equilibrium. Here, the authors theoretically investigate heating in a Floquet spin chain, demonstrating the existence and stability of long-lived π edge modes and determining their lifetime from exact diagonalization and Krylov techniques.

For solid-state experiments, exactly solvable quantum light matter models, where the quantum nature of light is relevant, are scarce. Here, the authors introduce an exactly solvable model, where a one-dimensional tight-binding chain is coupled to a single cavity mode and derive analytic expressions for the ground state, where the photons are squeezed due to the light-matter coupling.

Parity-time symmetric systems allow one to study new types of Hamiltonians which could have potential impact on our understanding of nonlinear physics. The authors investigate the energy stored in an electronic Floquet system and demonstrate that such a setup can be used to study the dynamics of dissipative parity-time symmetric systems.

Electronic interactions underlie the exchange interaction responsible for the magnetic ordering and dynamics of magnetic materials. Here, Mentink et al. theoretically demonstrate the ultrafast and reversible tuning of the exchange interaction in Mott insulators driven by a time-periodic electric field.

The authors propose a non-Hermitian topological insulator with a real-valued energy spectrum based on a periodically driven Floquet model implemented in a photonic platform where generalized parity–time symmetry is protected against spontaneous symmetry breaking under a spatiotemporal gain and loss distribution.

Electromagnetic oscillations are a key technological bottleneck that restricts the safe operation of power electronics-dominated power systems. Here, authors propose a generalized linear time-periodic participation factor and sensitivity theory within the eigenstructure-preserved framework for stability quantitative analysis.

Local integrals of motion are useful for understanding emergent integrability in many-body localized systems. Here the authors use a large-scale superconducting quantum processor with up to 124 qubits to simulate many-body dynamics in 1D and 2D systems and demonstrate extraction of local integrals of motion.

A time crystal is a state of matter that shows robust oscillations in time, and although forbidden in equilibrium, a discrete time crystal has now been observed in a periodically driven quantum system.

The lifting of valley degeneracy in the monolayer transition metal dichalcogenide WS₂ is now demonstrated by the optical Stark effect, showing that each valley can be selectively tuned by up to 18 meV.

Animal behaviour is characterized by repeated movements which can be difficult to analyse quantitatively. Here, the authors apply a data-driven framework based on theory of dynamical systems to characterize nematode behaviour and explain its complexity through deterministic chaotic dynamics.

Conical intersections, a hallmark of polyatomic molecules, can be induced with light, leading to new reaction pathways. Here, the authors show that intense fields can create complex, beyond-conical intersections even in diatomics, resulting in an unexpected angular distribution of fragment ions.

High-resolution microwave detection with NV centers in diamond is currently applicable to signals with frequencies below 10 MHz, thus limiting their range of applications. Here, the authors demonstrate detection of GHz signals with sub-Hz spectral resolution, not limited by the quantum sensor lifetime.

Spontaneous symmetry breaking can induce instabilities in natural and engineered systems. Nicolaou et al. show that such instabilities can be prevented by introducing suitable system asymmetry in the form of spatial heterogeneity, relevant for the development of novel control and design techniques.

Optical guiding by a synthetic gauge field is experimentally demonstrated through an array of evanescently coupled identical waveguides, opening the door to applications of artificial gauge fields in optical, microwave and acoustic systems and in cold atoms.

A transient topological response in graphene is driven by a short pulse of light. When the Fermi energy is in the predicted band gap the Hall conductance is around two conductance quanta. An ultrafast detection technique enables the measurement.

An experimental investigation of the dynamics of the spin ½ Floquet XXZ model finds bound states as predicted, and also robustness to noise and non-integrability when theoretical descriptions start to fail.

Many-body localization, which exhibits a fascinating interplay between disorder and interactions, can be studied using ultracold atoms in a quasiperiodic chain. Adding periodic driving makes things even more interesting.

Counter-propagating chiral edge states are demonstrated in a photonic structure able to effectively incorporate fermionic time-reversal symmetry, thus providing the photonic implementation of an electronic topological insulator.

Non-equilibrium signatures of topology—the appearance, movement and annihilation of vortices in a cold-atom system—are identified, showing that topological phase can emerge dynamically from a non-topological state.

Floquet theory describes transient states driven by a light-matter interaction and could potentially be used to engineer the band structure and the topology of solid-state systems. Here, the authors investigate coherent photoemission from a gold surface caused by a strong surface plasmon polariton excitation, which could be used to realize surface plasmon polariton driven Floquet effects in nanostructures.

It has long been suggested that the inverse Fourier transform of neutron scattering data gives access to space- and time-resolved spin-spin correlations. Scheie et al. perform this procedure on high-precision experimental data from a 1D quantum antiferromagnet and uncover new features in short-term quench dynamics.

Discrete time crystals are typically characterized by a period doubled response with respect to an external drive. Here, the authors predict the emergence of rich dynamical phases with higher-order and fractional periods in clean spin-1/2 chains with long-range interactions.

A study establishes a scalable approach to engineer and characterize a many-body-localized discrete time crystal phase on a superconducting quantum processor.

The Bose–Einstein condensation of ultracold atoms in a strong synthetic magnetic field in a cubic lattice realizes the Harper–Hofstadter model used in the study of topological states of matter.

Laser-driven ultrafast tranmission electron microscopy (UTEM) approaches such as stroboscopic UTEM enable the study of ultrafast reversible processes at time resolutions at the femtosecond scale and beyond. This Primer focuses on stroboscopic UTEM, describing its experimental set-up and variants, and covers the various applications of this technique in condensed matter physics, including imaging structural dynamics, photo-induced near-field electron microscopy, attosecond-scale imaging, dark-field imaging and beyond.

Researchers show that nonlinear polarization dynamics in a vertical-cavity surface-emitting laser inside an external cavity can result in the emission of temporal dissipative solitons.

Elementary excitations of electronic devices have potential use in quantum information but control and readout capabilities are not as developed as they are for more mature systems such as photonic qubits. Here the authors develop and demonstrate a tomographic protocol for electron and hole wavefunctions.

Disorder and device variability in hybrid superconductor-semiconductor devices pose challenges for their application in quantum technologies. Here, the authors show that Joule heating can provide a detailed fingerprint of such devices, uncovering different sources of inhomogeneities.

Artificial magnetic fields enable topological transport in metamaterials. Here, authors realize a programmable optomechanical metamaterial where laser-induced synthetic magnetism gives rise to chiral phonon edge states characteristic of quantum-Hall-like behavior.

Bubbles, long studied for their diverse dynamics across industrial, biological, and medical applications, continue to reveal unexpected behaviors. This study introduces galloping bubbles, a novel self-propulsion mechanism driven by shape oscillations in a vibrated fluid chamber, offering potential for applications in fluid transport, cleaning, and active matter.

By introducing a further modal dimension to transform a two-dimensional photonic waveguide array, a photonic topological insulator with protected topological surface states in three dimensions, enabled by a screw dislocation, is demonstrated.

Ultrathin laser-driven lightsails represent a unique vision for interstellar space exploration. Here, the authors show how spinning flexible membranes can be both shape- and trajectory-stable with multiphysics structural and nanophotonic engineering.

Deterministic control of the gain–loss balance in non-Hermitian systems remains challenging. A magnonic hybrid platform is now shown to enable this and, hence, coherently control excitations by leveraging an exceptional point.

Modifications of the effective band structure of MgO crystal is investigated on a timescale within one-quarter cycle of the electromagnetic-field oscillation. The high-harmonic generation spectra show a signature of laser-induced closing of the bandgap.