Unraveling the microscopic mechanisms governing the physics of doped quantum magnets is key to advancing our understanding of strongly correlated quantum matter. Quantum simulation platforms, e.g., ultracold atoms in optical lattices or tweezer arrays, provide a powerful tool to investigate the interplay between spin and charge motion in microscopic detail. Here, in a twist, we disentangle the role of particle statistics from the physics of strong correlations by exploring the strong coupling limit of doped bosonic quantum magnets, specifically the antiferromagnetic (AFM) bosonic $t\text{−}J$ model. Using large-scale density matrix renormalization group calculations, we map out the phase diagram on the two-dimensional square lattice at finite doping. In the low-doping regime, bosonic holes form partially filled stripes, akin to those observed in high-$T_c$ cuprates. As doping increases, a transition occurs to a partially polarized ferromagnetic (FM) phase, driven by the motion of mobile bosonic charge carriers forming Nagaoka polarons. At high doping or large $t/J$, the system evolves into a fully polarized FM. These findings shed light on the role of particle statistics in strongly correlated many-body systems, revealing connections to stripe formation and the physics of kinetic (Nagaoka-type) ferromagnetism. Our results may be realized in state-of-the-art quantum simulation platforms, including bosonic quantum gas microscopes, Rydberg atom tweezer arrays, and ultracold polar molecules, paving the way for future experimental studies of doped bosonic quantum magnets.

Measurement-induced phase transitions have largely been explored for projective or continuous measurements of Hermitian observables, assuming perfect detection without information loss. Yet such transitions also arise in more general settings, including quantum-jump processes with non-Hermitian jump operators, and under inefficient detection. A theoretical framework for treating these broader scenarios has been missing. Here we develop a comprehensive replica Keldysh field theory for general quantum-jump processes in both bosonic and fermionic systems. Our formalism provides a unified description of pure-state quantum trajectories under efficient detection and mixed-state dynamics emerging from inefficient monitoring, with deterministic Lindbladian evolution appearing as a limiting case. It thus establishes a direct connection between phase transitions in nonequilibrium steady states of driven open quantum matter and in measurement-induced dynamics. As an application, we study imbalanced and inefficient fermion counting in a one-dimensional lattice system: monitored gain and loss of fermions occurring at different rates, with a fraction of gain and loss jumps undetected. For imbalanced but efficient counting, we recover the qualitative picture of the balanced case: entanglement obeys an area law for any nonzero jump rate, with an extended quantum-critical regime emerging between two parametrically separated length scales. Inefficient detection introduces a finite correlation length beyond which entanglement, as quantified by the fermionic logarithmic negativity, obeys an area law, while the subsystem entropy shows volume-law scaling. Numerical simulations support our analytical findings. Our results offer a general and versatile theoretical foundation for studying measurement-induced phenomena across a wide class of monitored and open quantum systems.

Utilizing density functional theory, we assess the propagation of interactions between Pb layers intercalated underneath graphene supported on SiC(0001) and Pb atoms adsorbed on top of graphene. Rather than just assessing the adsorption energy at the strongest binding site for the Pb adatom, we map out the entire potential energy surface (PES) for a Pb adatom on these surfaces. As expected, the propagation of Pb-Pb interactions is somewhat stronger through just one layer versus two layers of graphene. We find that for an intercalated Pb layer resembling a hexagonal close-packed Pb(111) layer, the PES does not reflect the periodicity of Pb(111), but rather that of graphene (for either one or two layers of graphene). This disfavors strict remote epitaxy where the intercalated Pb layer directs the formation of an in-registry epitaxial Pb(111) overlayer or thin film. However, this does not exclude the possibility that intercalated and overlayer Pb(111) can be in-registry due to interactions of each with the same graphene layer(s). We discuss the formation of Pb(111)-like islands and thin films by Pb deposition on SiC-supported graphene for cases with and without intercalated Pb. Analysis is based on our assessment of the dependence on Pb intercalation of the PES and of the surface diffusion barriers for adsorbed Pb, and also an assessment of the strength of attractive interactions between Pb adatoms, which control Pb thin film nucleation and growth.

A Mott insulator can lose its gap yet refuse to metallize. In the spin–orbit-entangled iridate $\mathrm{S}{\mathrm{r}}_3\mathrm{I}{\mathrm{r}}_2{\mathrm{O}}_7$, transport reveals an abrupt collapse of the effective activation gap (${\mathrm{\Delta }}_{\mathrm{eff}}$) from $\sim 0.1–0.2$ eV to ≲0.02 eV within 12–17 GPa, yet $R$($T$) remains nonmetallic down to 2.6 K. Above this window, the low-temperature conduction follows three-dimensional Mott variable-range hopping with a strongly reduced hopping scale $T_0$. A concurrent magnetoresistance sign reversal further characterizes the postcollapse localized regime, with possible contributions from spin-related scattering. Helium-medium x-ray diffraction shows no resolvable symmetry change, supporting a Mott-Anderson crossover picture where localization preempts metallization. This disorder-inclusive framework may apply broadly to bandwidth-tuned correlated systems where quenched disorder coexists with a pressure-suppressed correlation gap.

Many-body chaos is a default property of many-body systems; at the same time, near-integrable behavior due to weakly interacting quasiparticles is ubiquitous throughout condensed matter at low temperature. There must therefore be a, possibly generic, crossover between these very different regimes. Here, we develop a theory encapsulating the notion of a cascade of lightcones seeded by sequences of scattering of weakly interacting harmonic modes as witnessed by a suitably defined chaos diagnostic (classical decorrelator) that measures the spatiotemporal profile of many-body chaos. Our numerics deals with the concrete prototypical case of a classical Heisenberg chain, for either sign of the interaction, at low temperatures where the short-time dynamics are well captured in terms of noninteracting spin waves—characteristic to continuous symmetry breaking. To model low-temperature dynamics, we use ensembles of initial states with randomly embedded point defects in an ordered background, which provides a controlled setting for studying the scattering events. The decorrelator exhibits a short-time integrable regime followed by an intermediate “scarred” regime of the cascade of lightcones in progress; these then overlap, leading to an avalanche of scattering events which finally yields the standard long-time signature of many-body chaos.

The honeycomb-lattice system $\alpha \text{−}{\mathrm{RuI}}_3$ is isostructural to the widely studied $\alpha \text{−}{\mathrm{RuCl}}_3$ compound which was identified as a potential Kitaev system but exhibits, instead of spin liquid behavior, a magnetically ordered zigzag ground state which sets in below 14 K. Here we show experimentally that, in contrast, the spins in $\alpha \text{−}{\mathrm{RuI}}_3$ remain dynamic down to at least 50 mK. We study the spin dynamics using muon-spin relaxation methods and determine the presence of low-frequency fluctuations which are characteristic of a two-dimensional system.

The study of real-time dynamics of fermions remains one of the last frontiers beyond the reach of classical simulations and is key to our understanding of quantum behavior in chemistry and materials, with implications for quantum technology. Here we present a Heisenberg-picture algorithm that propagates observables expressed in a Majorana-string basis using a truncation scheme that preserves Trotter accuracy. The framework is exact for quadratic Hamiltonians, where it remains restricted to a fixed low-weight sector determined by the physical observable, it admits variational initial states, and extends to interacting regimes via systematically controlled truncations. We benchmark our approach on one- and two-dimensional Fermi-Hubbard quenches, comparing against tensor network methods and recent experimental data. The method achieves high accuracy on timescales comparable to state-of-the-art variational techniques and experiments, demonstrating that controlled Majorana-string truncation is a practical tool for simulating two-dimensional fermionic dynamics.

We present a comprehensive ${}^{31}\mathrm{P}$ and ${}^{65}\mathrm{Cu}$ nuclear magnetic resonance (NMR) study of the layered van der Waals magnet ${\mathrm{CuCrP}}_2{\mathrm{S}}_6$. The compound exhibits a sequence of structural and magnetic phase transitions: a high-temperature paraelectric state, followed by a quasiantiferroelectric (QAFE) state near 185 K, a long-range antiferroelectric (AFE) phase below 150 K, and finally, antiferromagnetic (AFM) order below $T_{\mathrm{N}}$ = 30 K. The evolution of the NMR spectra, NMR shift, and spin-lattice $\left(T_1^{-1}\right)$ and spin-spin $\left(T_2^{-1}\right)$ relaxation rates provide direct microscopic fingerprints of these transitions. The splitting of both the NMR line and $T_1^{-1}$ below the AFE transition demonstrates the emergence of two inequivalent P sites. From $K\text{−}\chi$ analysis, we extract nearly isotropic transferred hyperfine couplings and show that the NMR shift anisotropy originates primarily from the dipolar contribution, in contrast to ${\mathrm{Mn}}_2{\mathrm{P}}_2{\mathrm{S}}_6$ and ${\mathrm{Ni}}_2{\mathrm{P}}_2{\mathrm{S}}_6$. We determine the ferromagnetic intralayer exchange $J_{\mathrm{intra}}\approx -4.9$ K from the Curie-Weiss temperature, consistent with ferromagnetic layers antiferromagnetically stacked along the $c$ axis, and evaluate the Moriya high-temperature relaxation rate including cross-correlation effects of the P–P dimer. Critical divergence of $T_1^{-1}$ near $T_{\mathrm{N}}$ yields a critical exponent $\gamma \simeq$ 0.45(4), placing ${\mathrm{CuCrP}}_2{\mathrm{S}}_6$ in a three-dimensional Heisenberg universality regime.

At a generic volume- to area-law entanglement transition in a many-body system, quantum chaos is arrested. We argue that this tends to imply the vanishing of a certain “mass” term in the field theory of the measurement-induced phase transition (MIPT) for monitored, interacting fermions. To explore this idea, we consider the MIPT with no conserved quantities that describes one-dimensional monitored, interacting Majorana fermions in class DIII. This is the most general problem of interacting fermions with weak fermion parity measurements. Without interactions, it is known that a noninteracting MIPT separates the area-law phase from a log-enhanced “thermal metal” phase at sufficiently weak monitoring. We conjecture that the MIPT with interactions is the same as the noninteracting one in this case; the volume-law phase arises through the dangerously irrelevant mass. The physical picture is that the mass represents a local Fermi's golden rule interparticle scattering rate density that is tantamount to the entangling rate density. The latter must vanish continuously at a continuous MIPT. On the other hand, the field theory capturing the MIPT for monitored fermions with additional continuous symmetries is expected to be different, because the interactions introduce additional terms associated to conserved Noether currents. We propose numerical tests of our conjecture. In addition, we analytically identify a candidate noninteracting critical point representing the MIPT, using a controlled $\varepsilon$-expansion.

We prove that, for translationally invariant quantum spin chains with finite-range interactions, the existence of a specific conservation law implies the presence of infinitely many local conserved quantities, i.e., integrability. This shows that the standard hierarchy of local conserved quantities arising for nearest-neighbor Hamiltonians obtained via the canonical Yang-Baxter construction is already encoded in the lowest nontrivial conservation law, known as the Reshetikhin condition. Combined with recent rigorous results on nonintegrability, our theorem strongly restricts the possibility of partially integrable systems that admit only a finite but large number of local conserved quantities. Our work establishes a rigorous foundation for the systematic identification of new integrable models and deepens the algebraic understanding of conservation-law structures in quantum spin chains.

We present an exact solution for entanglement entropy for the real-time dynamics following a quench from a thermal pure quantum (TPQ) state in a free-fermion system. In contrast to the usual linear growth and saturation behavior, the entanglement entropy exhibits a characteristic double-plateau structure. We establish this behavior through three complementary approaches: an exact conformal field theory calculation on the Klein bottle, finite-size Gaussian-state simulations, and a quasiparticle picture that becomes quantitatively accurate in the scaling regime.

Magnetic skyrmions in chiral magnets typically arrange into hexagonal lattices, with their structural order influenced by factors such as temperature, external magnetic fields, and geometric constraints. While translational defects in skyrmion lattices such as dislocations have been extensively studied, individual angular defects, or disclinations, remain largely unexplored. Here, we report on the stabilization of fivefold and sevenfold disclinations in pentagon- and heptagon-shaped FeGe single-crystal nanostructures created using focused ion beam milling. The magnetic and elastic structures of the disclinated lattices are investigated using Fresnel imaging and off-axis electron holography in a transmission electron microscope. The results are supported by micromagnetic simulations and analytical models based on linear elasticity theory.

Two-dimensional quantum materials can host original electronic phases that arise from the interplay of electronic correlations, symmetry, and topology. In particular, breaking internal symmetry that acts simultaneously on the pseudospin and the spatial degree of freedom realizes a nematic phase ordering. Here, we report evidence of a quantum Hall nematic phase with an underlying SU(3) internal symmetry carried by the valley flavor of $\mathrm{P}{\mathrm{b}}_{1-x}\mathrm{S}{\mathrm{n}}_x\mathrm{Se}$ quantum wells. Under SU(3) symmetry, this two-dimensional Dirac system exhibits a spin-polarized ground Landau level that is threefold valley degenerated, giving a robust $h/3e^2$ resistance plateau. A control over the valley pseudospin is further obtained by means of an in-plane magnetic field that acts as a valley Zeeman field, in analogy with the spin Zeeman field. By revealing the emergence of a $h/2e^2$ resistance plateau under tilted magnetic field, we demonstrate a quantum Hall valley nematic phase and the concomitant SU(3) symmetry breaking. An explicit SU(3) flavor symmetry breaking is achieved. Such evidence is of fundamental interest to shape the rich quantum Hall physics of a unique SU(3) system.

Altermagnets are a newly identified class of magnets with nodal spin-split band structures, providing a fertile platform for studying unconventional superconductivity and intertwined orders. Here, we investigate multicomponent superconductivity and fluctuation-induced intertwined orders in an interacting $d$-wave metallic altermagnet that is invariant under a combination of a fourfold rotation $C_4$ and time-reversal symmetry $\mathcal{T}$. Within mean-field theory, the superconducting ground-state manifold is described in terms of two equal-spin, two-component $p$-wave gap functions $({\mathrm{\Delta }}_A^x,{\mathrm{\Delta }}_B^y)$ and $({\mathrm{\Delta }}_A^y,{\mathrm{\Delta }}_B^x)$, where $A$ and $B$ refer to the two spin-polarized Fermi surfaces related by $C_4\mathcal{T}$ symmetry. Because these two sets of gap functions condense at different temperatures, a rich phase diagram with multiple superconducting phase transitions emerges. Distinct fluctuations of sub-leading normal-state instabilities that compete with altermagnetism lift the degeneracy of the multicomponent pairing state in different ways. While nematic fluctuations enhance competition between distinct superconducting components and stabilize nematic superconducting phases, spin current-loop fluctuations promote coexistence and select a pair of chiral states. Our results uncover the pairing structure and elucidate how intertwined sub-leading fluctuations shape superconducting order in altermagnetic metals, suggesting a route toward realizing nematic and topological superconductivity.

Magnetic interactions have long served as the most robust and widely used approach for realizing nonreciprocity, with an externally applied magnetic field breaking time-reversal symmetry (TRS) and chiral photon–magnon interactions introducing spatial asymmetry. In this work, we investigate the chirality mechanisms essential for magnetic nonreciprocity from a unified experimental and theoretical perspective. We begin by examining conventional chiral interactions that generate chiral electromagnetic fields through specially designed structures and then place particular emphasis on synthetic chirality enabled by nontrivial phase accumulation in traveling-wave–mediated coupling systems. We establish a microscopic theoretical framework that maps field polarization onto the phase of a complex coupling strength and validate it with systematic experiments, thereby providing a consistent formalism that describes both conventional and synthetic chirality. Notably, we highlight the symmetry properties and the unique features of synthetic chirality that distinguish it from conventional nonreciprocal mechanisms.

We report a detailed investigation of phonon-assisted anti-Stokes photoluminescence (ASPL) of light-hole (LH) excitons under heavy-hole (HH) exciton resonant excitation within a single shallow $\mathrm{GaAs}/{\mathrm{Al}}_{0.03}{\mathrm{Ga}}_{0.97}\mathrm{As}$ quantum well (QW). The ASPL results from transitions between excitonic states within the same system, made possible by the design of a high-quality QW with a HH-LH excitonic splitting of only 4 meV. Maximum ASPL was observed at 25 K and a clearly detectable signal was still seen even at 4 K. Power- and temperature-dependent measurements confirm the phonon-assisted origin of the underlying intersubband scattering. Our findings provide direct insight into excitonic transitions between subband-resolved states in high-quality QWs, offering opportunities for optical cooling of semiconductors.

The fuzzy-sphere regularization is an emerging numerical and theoretical technique for studying conformal field theories (CFTs). In this paper, we apply it to the $O\left(N\right)$ vector model, one of the most prominent theories for critical behavior in three space-time dimensions. We construct a model that realizes the $O\left(N\right)$ Wilson-Fisher and free-scalar CFTs for general $N$. For $N=2,3,4$, we present numerical evidence including the operator spectra and correlation functions in agreement with conformal symmetry and conformal bootstrap results.

According to Anderson's theorem, the gap of a time-reversal symmetric weak-coupling superconductor is unaffected by nonmagnetic disorder. However, the superfluid weight (stiffness) is reduced in the disordered limit by a factor of $\mathrm{\Delta }\tau$, a product of the scattering time $\tau$ and the superconducting order parameter $\mathrm{\Delta }$. Here, we show that the opposite holds true in flat-band superconductors. While nonmagnetic disorder does reduce the order parameter, we find that its direct effect on superfluid weight is mostly negligible. We show analytically that the effect of disorder is to lowest order given in terms of the difference between the intraband and interband parts of the localization functional of impurity wave functions, finding it to be typically vanishing.

We report a magnetic and neutron diffraction study on the ground state magnetism and field evolution of single-crystal van der Waals multiferroic ${\mathrm{CuCrP}}_2{\mathrm{S}}_6$. The ordered moments align along the $b$ axis in the “$A$-type” antiferromagnetic configuration with a spin-flop transition along the same direction. Field application along $a$ introduces a smooth transition to a fully polarized ferromagnetic state via in-plane spin rotation. These findings resolve the ambiguity of the ground state magnetization direction in ${\mathrm{CuCrP}}_2{\mathrm{S}}_6$ and uncover its field responses, providing a firm basis for future magnetoelectric study. A magnetoelastic coupling effect connecting the interlayer spacing and the magnetic order was further revealed, highlighting the out-of-plane strain as an effective control knob for tuning magnetism both in this system and in related van der Waals magnets.

We report a quantitative calorimetric study of ${\mathrm{UTe}}_2$ under pressure with a direct measurement of the Sommerfeld $\gamma$ coefficient, showing a threefold enhancement of electronic effective mass when approaching the critical pressure where superconductivity is suppressed and ordered states occur. We analyze the evolution of $\gamma$ with the amplitude of the jumps in the specific heat at the two superconducting transitions, and the superconducting critical temperature with pressure. This analysis would suggest that the high pressure superconducting phase nucleates only on a fraction of the Fermi surface. It also points to the possible major role of a quantum critical point of the unidentified phase that has been called weak magnetic order, rather than to the critical pressure of the antiferromagnetic phase. Just at the border of long-range antiferromagnetic order, where superconductivity emerges from the weak magnetic order phase, a significant increase in the specific heat jump for both superconducting transitions is found, accompanied by a noticeable change of their shapes.