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Ultrafast photoexcitation stabilizes new states of matter with rich out-of-equilibrium behaviours. Here, Lantzet al. report a transient non-thermal phase developing immediately after photoexcitation in V₂O₃, shedding a light on optical manipulation of strongly correlated systems.

The transport measurements of an interacting fermionic quantum gas in an optical lattice provide a direct experimental realization of the Hubbard model—one of the central models for interacting electrons in solids—and give insights into the transport properties of many-body phases in condensed-matter physics.

Atomically precise artificial lattices of dopant-based quantum dots offer a tunable platform for simulations of interacting fermionic models. By leveraging advances in fabrication and atomic-state control, Wang et al. report quantum simulations of the 2D Fermi-Hubbard model on a 3 × 3 few-dopant quantum dot array.

Confining semiconductor dipolar excitons using an artificial two-dimensional square lattice emulates extended Bose–Hubbard Hamiltonians, thus enabling control of boson-like arrays in lattices with programmable geometries and more than 100 sites.

An antiferromagnet with a correlation length that encompasses the whole system is created with the aid of quantum gas microscopy of cold atoms in an optical lattice.

Ferromagnetic insulator (FM) materials are rare due to the challenge of stabilizing the ferromagnetic insulating phase. By exploiting the recently proposed interorbital-hopping mechanism, the authors show how such mechanism stabilizes FM insulators in broad classes of materials, largely extending the FM platforms to support spintronic applications.

The two-dimensional Fermi-Hubbard model is central to understanding stripe order and high-Tc superconductivity. Here, the authors use tensor network methods to show forestalled phase separation at finite temperatures in the two-dimensional Fermi-Hubbard model.

Spin excitations are implicated in the emergence of high-temperature superconductivity in the cuprates but the details are unclear. Calculations performed by Jia et al.resolve a seeming contradiction presented by recent X-ray measurements and suggest that the role played by high-energy spin excitations is nominal for pairing.

This study of magic-angle twisted trilayer graphene moiré superconductors using scanning tunnelling microscopy and spectroscopy identifies two energy gaps that develop from many-body resonance in this highly tunable class of materials.

The formation of exciton crystals is challenging because excitons possess short lifetimes and exhibit weaker interactions than electrons. Now, an exciton Wigner crystal is observed in a moiré electron–hole bilayer.

Unconventional quasiparticles carrying spin but not electric charge emerge in quantum spin liquid phases. The Kondo interaction of these spinon quasiparticles with magnetic impurities may now have been observed.

Understanding the mechanism of ferromagnetism in strongly correlated systems is an ongoing theoretical challenge and the Hubbard model is typically adopted to investigate such systems. Here, the authors numerically investigate the doped triangular Fermi-Hubbard model and show ferromagnetism at intermediate coupling and finite doping, which results from the interplay of kinetic doublon-singlon exchange and lattice geometry.

Recent experiments reported charge order with a stripe pattern in parent compounds of infinite-layer nickelate superconductors. Chen et al. use first principles and effective model calculations to propose an electronic, charge-transfer-driven mechanism of the charge order.

The authors consider the changing sensitivity of the leaf-onset date to temperature (S_T) for boreal deciduous broadleaf forests. S_T increased between 1982–1996 and 1998–2012—potentially linked to enhanced chilling accumulation—but this increase is underestimated in phenology models.

Using quantum gas microscopy, Hilbert space fragmentation and fractonic excitations are observed in a two-dimensional tilted Bose–Hubbard model.

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.

The integration of strong electron correlations into topological systems is advancing the exploration of topological materials. Here, abnormal Mott physics emerges in weakly correlated 4f fermions through their interplay with topological singularity.

Fluctuations arising from Heisenberg's uncertainty principle enable quantum systems to exhibit phase transitions even at zero temperature. For example, a superfluid-to-insulator transition has been observed for weakly interacting bosonic atomic gases. Here the authors report a novel type of quantum phase transition in a strongly interacting, one-dimensional quantum gas of bosonic caesium atoms. The results open up the experimental study of ultracold gases in a new regime.

The existence of a long-lived, prethermal regime in many-body systems with tunable heating rates, driven by structured random protocols, is observed using a 78-qubit superconducting quantum processor.

Dielectric breakdown in Mott insulators induced by strong electric fields is thought to take place via a Zener mechanism. Guiot et al. show that the breakdown characteristics are instead similar to the avalanche breakdown in conventional semiconductors, although with much longer delay times.

How quantum many-body systems relax from an initial non-equilibrium state is one of the outstanding problems in quantum statistical physics. A study combining an experimental approach for monitoring the dynamics of strongly correlated cold atoms with theoretical analysis now provides quantitative insights into the problem.

A Mott insulator forms when strong interactions between particles cause them to become localized. A cold atom simulator has now been used to realize a selective Mott insulator in which atoms are localized or propagating depending on their spin state.

Quantum correlated materials offer a promising platform for the study of unconventional heat transport. Here the authors theoretically investigate heat transport in a layered correlated material, triggered by an ultrafast excitation, and predict various transport regimes controlled by correlations.

Nonlinear multidimensional spectroscopy that can image the sub-cycle dynamics of strongly correlated systems on the sub-femtosecond timescale is demonstrated by using the carrier–envelope-phase dependence of the correlated multielectron response to decode the complex interplay between different many-body states.

The control of a material's state via external stimuli is the basis of modern information storage technology. Here, the authors use pulsed currents to induce fast switching between Mott insulator and metallic states in the charge density wave system 1T-TaS₂, presenting an all-electronic storage mechanism.

Painful bone growth after injury or surgery often goes undetected until it is advanced and treatment options are limited. Here, authors demonstrate that a blood test detecting gene expression profiles in isolated circulating mesenchymal progenitor cells could detect early signs of this condition and track treatment success.

Some quantum spin liquids are expected to have an effective Fermi surface of fractionalized spinon excitations. The two-dimensional spin liquid candidate 1T-TaSe₂ has charge density modulations that may be caused by an unstable spinon Fermi surface.

Topological states may emerge in nonequilibrium but the mechanisms are much less understood. Here Topp et al. propose a nonequilibrium route to obtain the magnetic Weyl semimetallic phase in pyrochlore iridates by ultrafast modification of the effective electron-electron interactions with short laser pulses.

Coupled semiconductor microcavities constitute a model system where the hopping, interaction, and decay of exciton polaritons can be engineered. Here, Rodriguez et al. show how the phase acquired by polaritons hopping between cavities can be controlled through polariton-polariton interactions.

Altermagnetic materials have zero magnetization, like collinear antiferromagnets, however, due to the underlying crystal and spin symmetry, have spin-split Fermi surfaces. This combination grants them significant technological potential. Here, Yu, Suh, Roig and Agterberg propose a mechanism for stabilizing altermagnetism in two dimensions.

Manganese-based oxides are promising cathodes for sodium-ion batteries. Here, authors design a titanium substituted oxide cathode with an optimized structure, achieving long cycle life, good air/water stability, and validation in pouch cells, supported by theory and experiments.

A quantum spin liquid is a hypothetical system of spins (such as those carried by electrons), the orientations of which continue to fluctuate even at absolute zero. Theoretical and experimental evidence for the existence of such states at the microscopic level is elusive, but these authors have modelled correlated electrons arranged on a honeycomb lattice (such as in graphene), and identified the conditions under which a microscopic quantum spin liquid would be realized in two dimensions.

A detailed resonant inelastic X-ray scattering (RIXS) study of a series of well-known cuprate superconductors reveals a correlation between the number of apical oxygens in these systems, and the strength of their in-plane exchange interaction.

Recently, a discrepancy arose in predicting the pairing symmetry of high-temperature superconductor La₃Ni₂O₇. Xia et al. find that a slight increase in Ni-e_g crystal field splitting sensitively alters the pairing symmetry of La₃Ni₂O₇ from d-wave to s-wave.

The study shows that the spin state of a single titanium atom on an insulating surface can be reversibly switched by its local environment, without chemical changes (no hydrogenation), using advanced microscopy, spectroscopy, and theory.

Hidden orders involve phase transitions without obvious order parameters, challenging experimental detection and conventional theories. This Review summarizes recent advances in modelling hidden-order phases in correlated insulators, highlighting the role of material-specific theories in the interpretation and prediction of the experimental signatures of hidden orders.

Recently the Kondo effect has been observed in transition metal dichalcogenide heterobilayers, but the evidence for low-temperature coherent state has been missing. Wan et al. observe signatures of such state in the form of a split Kondo peak with a characteristic magnetic-field dependence by STM at 340 mK.

Adatoms on the surface of silicon can create two-dimensional superconductivity, the order parameter symmetry of which is currently not known. Now, evidence suggests it might be a topological chiral d-wave state.