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Recent demonstrations of modulators, polarization rotators and isolators have indicated the potential of graphene for photonic applications. The present study investigates the fundamental limits and near-optimal design of graphene modulators and non-reciprocal devices.

Photonic crystal microresonators permit precise control of nonlinear optical processes. By suppressing specific parasitic processes, they enable the efficient and robust generation of single-mode squeezed vacuum states of light.

Finding ways to accumulate electronic spins of a given polarization in a given location is important to the development of spintronics. Endres et al.demonstrate a device that uses light to drive the accumulation of spin using a similar principle that a solar cell uses to drive the accumulation of charge.

Researchers have demonstrated spontaneous soliton formation in an edgeless photonic crystal resonator.

By exploiting an optical thermodynamic framework, researchers demonstrate universal routing of light. Specifically, light launched into any input port of a nonlinear array is universally channelled into a tightly localized ground state. The principles of optical thermodynamics demonstrated may enable new optical functionalities.

Time-resolved measurements show that current-induced magnetization switching in ferrimagnetic devices is faster and more energy-efficient than in ferromagnet devices.

Magneto-ionics are a promising approach for controlling magnetism via electric fields, but most studies have been limited to thin films, rather than the nanostructures that would form the basis of a magneto-ionic memory unit. Here, Spasojevic et al demonstrate magneto-ionic control over transitions among paramagnetic, single domain, and vortex states in an array of nanodots.

Femtosecond laser pulses allow for extremely fast switching of magnetization in ferromagnetic films, but all examples so far contained gadolinium. Here the authors demonstrate room temperature all-optical toggle switching in a ferrimagnetic manganese-based half-metal without gadolinium.

Topological phases are challenging to identify in systems with general, strong nonlinearities. Here, the authors establish the analytic methodology that defines the topological invariant of nonlinear normal modes. Strongly nonlinear topological boundary modes are guaranteed by the nontrivial topological index.

Spin currents can be generated by passing electric currents through ferromagnets, but the process is too slow for ultrafast spintronics. Here, the authors show an approach for laser-driven thermal spin generation that has the potential to attain much higher speeds.

Chip-based frequency combs promise many applications, but full integration requires the electrical pump source and the microresonator to be on the same chip. Here, the authors show such integration of a microcomb with < 100 GHz mode spacing without additional filtering cavities or on-chip heaters.

At the ultrafast timescale the propagation of light pulses through a dielectric material is not only determined by the envelope, but also by nonlinear interactions that evolve within one optical cycle. Here, the authors demonstrate a method to determine the subcycle-resolved delay to a probe pulse in ultrafast, high-field pump–probe experiments.

Researcher demonstrate the line-by-line pulse shaping of frequency combs generated in silicon nitride ring resonators, and observe two distinct paths to comb formation that exhibit strikingly different time domain behaviours.

Adding tunable photon-photon nonlinearities to programmable photonic circuits would greatly extend their capabilities. Here, the authors demonstrate this by embedding a photonic-crystal waveguide nanostructure hosting an InAs quantum dot within a programmable linear optical circuit, and using it to realise a proof-of-concept quantum simulation of anharmonic molecular vibrational dynamics.

Superluminescent diodes, that provide a broadband spectrum are typically used in spectral domain coherence tomography. Here, the authors use chipscale silicon nitride resonators to generate soliton microcombs with a lower noise flor that could substitute the diode sources.

Boosting conversion efficiency, coherence and spectral bandwidth of optical signals generated in integrated photonic devices is an important current challenge. Here, the authors present their observations of two-colour dissipative solitons, breathers and frequency combs resulting from second-harmonic generation in lithium-niobate ring microresonators.

Homochirality, a key feature of life, has unknown origins. Magnetic mineral surfaces can act as chiral agents, but are only weakly magnetized by nature. Here, the authors report the uniform magnetization of magnetite by an RNA precursor that spreads across the surface like an avalanche.

Kagome materials, such as CsV3Sb5, a rich array of correlated phase, including a time-reversal symmetry breaking phase, which could possibly be the result of loop currents. Attempts to verify this with magneto-optical measurements have yielded mixed results. Here, Farhang et al show that the magneto-optical signals are due to specular optical rotation. ‘

Neuromorphic computing processes data faster and with less energy than electronics. Here, authors demonstrate a reconfigurable photonic reservoir computer that performs multiple machine learning tasks in parallel at ultrafast rates while using extremely low energy per operation.

The intrinsic Kerr nonlinearity in ring resonators is exploited to demonstrate passive isolation of a continuous-wave laser. Up to 35-dB isolation with 5-dB insertion loss was achieved on-chip.

Free-running stable optical dissipative solitons, called Nozaki–Bekki solitons, are created in a ring semiconductor laser; their spontaneous formation with tuning of laser bias eliminates the need for an external optical pump.

While the spin generation in topological insulators is well studied, little is known about the interaction of the spins with external stimuli. Here, Seifert et al. observe a helical, bias-dependent photoconductance at the lateral edges of topological Bi₂Te₂Se platelets for perpendicular incidence of light, distinct to common longitudinal photoconductance phenomena.

The propagation of high-intensity light beams through transparent media can lead to unusual non-linear effects. Here Panagiotopoulos et al.show that a high-intensity ring-Airy beam transforms into a robust non-linear light bullet.

Despite remarkable optical properties in lead halide perovskites, spin control in these materials is largely unexplored. Herein Belykh et al. study the coherent spin dynamics of electrons and holes in cesium lead bromide perovskites, and evidence interaction of electron and lattice nuclear spins.

Identifying jets originating from heavy quarks plays a fundamental role in hadronic collider experiments. In this work, the ATLAS Collaboration describes and tests a transformer-based neural network architecture for jet flavour tagging based on low-level input and physics-inspired constraints.

Despite larger nonlinear coefficients, waveguide losses have prevented using semiconductors instead of dielectric materials for on-chip frequency-comb sources. By significantly reducing waveguide loss, ultra-low-threshold Kerr comb generation is demonstrated in a high-Q AlGaAs-on-insulator microresonator system.

The use of electric fields to control the magnetization of ferromagnetic materials could enable more efficient electronics. Lei et al.show that by applying lateral strain to a magnetostrictive nanowire with a piezoelectric, voltage-controlled gating of magnetic domain wall motion in the wire can be achieved.

Using time-stretch dispersive Fourier transform, scientists directly observe the spectro-temporal dynamics of the mode-locking transition on a single-shot basis over long record lengths of ∼900,000 consecutive pulses.

Signatures of magnetism control by the flow of angular momentum are observed in Pt/Al/Fe/GaAs(001) multilayers by the application of an in-plane charge current in Pt.

The Landé factors govern all the spin-related basic phenomena and are the key parameters which guide spintronics applications. Here, Kirstein et al. demonstrate a universal dependence of the Landé factors on the bandgap energy of several perovskite materials.

In a ferromagnetic layer, an electric current parallel to the magnetization generates opposite spin–orbit torques on the two surfaces of the magnetic film, which is attributed to the generation of spin currents with a spin polarization transverse to the magnetization within the ferromagnet.

It is now shown that femtosecond optical excitation can be used as a tool to investigate the spin-polarization properties of half-metals, and provide a clear distinction between those and metals. Such knowledge is of fundamental importance for the use of these materials in spintronics applications.

The integration of 2D materials on photonic devices provides advanced functionalities in sensing applications. The authors demonstrate a graphene functionalized microcomb sensor by exploiting spectrally trapped Stokes solitons. They obtain both multispecies gas identification and individual molecule sensitivity.

Temporal dissipative solitons are observed in a nonlinear, high-finesse, optical microresonator driven by a continuous-wave laser. This approach enables ultrashort pulses to be generated in spectral regimes lacking broadband laser gain media and saturable absorbers, making it potentially useful for applications in broadband spectroscopy, telecommunications, astronomy and low-phase-noise microwave generation.

Whispering-gallery mode microresonators are powerful sensing tools, but spectrum acquisition has taken milliseconds or longer. Here, Rosenblum et al.introduce cavity ring-up spectroscopy, in which sharply rising detuned probe pulses capture spectra of microresonators on nanosecond timescales.

An all-optical method involving third-harmonic Faraday rotation is used to probe the breaking of time-reversal symmetry in mono- and bilayer transition metal dichalcogenide WS₂.

Nuclear spins in solid-state systems present a promising platform for quantum information applications. Here the authors report evidence of the long-predicted entangled dark nuclear spin state via optical polarization of localized hole spins coupled to the nuclear bath in a lead halide perovskite semiconductor.

Optical switching of ferromagnets has attracted interest for use in ultrafast spintronics but the physical origin of the effect remains unclear. Here the authors determine the contributions of two proposed mechanisms, the inverse Faraday effect and optical spin-transfer torque.

Microresonator frequency combs are versatile tools for sensing, data transmission and quantum applications. In this work the authors present the generation of low-noise frequency combs at repetition rates of 100 GHz by utilizing a cascaded forward-propagating Brillouin scattering process to seed soliton frequency comb generation.

Broken symmetry at the interface with a heavy metal gives rise to a chiral exchange interaction in ferromagnetic thin films, which may be used to control magnetic domain walls. Here, the authors demonstrate how this effect enforces topologically stable homochiral domain walls in a Pt/Co/AlO_xtrilayer.

Integration of ferromagnetic and semiconducting elements is important for future devices capable of both processing and storing information. Korenevet al. describe a novel spin-separation effect in a ferromagnet/semiconductor quantum well hybrid and show the optical readout of hysteresis loops.

One advantage of van der Waals materials is the ability to combine different materials in layers to form new heterostructures. Here, the authors investigate heterostructures of CrBr₃ and MoSe₂, and find that the ferromagnetism of CrBr₃ enhances the valley dependent optical response of the MoSe₂.

Broadband coherent light sources are crucial for numerous applications, such as imaging and spectroscopy. Using filamentation of mid-infrared laser pulses in bulk crystals, Silvaet al. generate supercontinuum spectra over three octaves, from 4.5 μm to 450 nm, with carrier-envelope phase stability.

McGrail and colleagues report that high intratumoral bacteria abundance is associated with an immunosuppressive microenvironment and resistance to immune checkpoint blockade in head and neck squamous cell carcinoma.

Negative coupling is an intriguing mechanism for linking lattice sites, enabling phenomena unattainable with positive coupling alone. Here, the authors introduce this unique coupling into the polariton system and demonstrate topological polariton condensation in lattices with negative coupling.

A strong Hall effect is observed in a material with spin textures and strong electron correlations. This hints that correlation effects can amplify real-space topological spin transport.

Optical frequency combs are a key technology in precision time keeping, spectroscopy and metrology. A theoretical proposal shows that introducing topological principles into their design makes on-chip combs more efficient and robust against fabrication defects.