In the heavy-fermion metal ${\mathrm{YbRh}}_2{\mathrm{Si}}_2$, quantum criticality at a suppressed antiferromagnetic order is governed by the interplay of local magnetic moments and itinerant conduction electrons. We demonstrate how this can be investigated by a new experimental approach that enables the observation of electron spin resonance (ESR) across a broad range of frequencies and fields at very low temperatures. This allowed us to cover a large part of the phase diagram from the paramagnetic Fermi-liquid phase to the phase with antiferromagnetic order and including the quantum-critical regime. Both the ESR $g$ factor and the linewidth present distinct behaviors in these three regimes, providing further insight into the physics across a quantum critical point. Notably, when cooling down at a field directly toward the quantum critical point, both $g$ factor and linewidth continuously decrease. Furthermore, we observe a very good matching of the $g$-factor behavior upon field tuning and temperature tuning toward the quantum-critical point. We analyze and discuss the results in the context of present theories on ESR in strongly correlated electron systems.

Topological insulators are typically characterized by particularly stable properties, such as global invariants, and can be identified by probing their robust surface states. A recently discovered novel form of band topology, delicate topology, challenges this paradigm: its defining property, multicellularity, can be removed by introducing a coupling to local orbitals anywhere in the spectrum, even far above the relevant band gap. This makes it hard to diagnose delicate topology with conventional probes that access only low-energy degrees of freedom. Here, we introduce strong local impurities as a spectroscopic probe of a delicate topological insulator which we realize in a phononic metamaterial. By tuning the impurity strength and performing orbital-resolved readout, we observe recently proposed indicators of topology: ring states, in-gap bound states whose frequencies remain pinned in the strong-impurity limit while avoiding the impurity site in real space. We find that these ring states persist even when the multicellularity in our system is removed by a weakly hybridizing additional orbital. Our results establish strong-impurity spectroscopy as a bulk probe of complex multiband physics, including delicate topological phases.

For over 30 years, a $\sim 20\%$ deficit, now exceeding $5\sigma$, has persisted between measured and predicted neutrino capture rates on ${}^{71}\mathrm{Ga}$, as observed in radioactive source experiments (namely GALLEX, SAGE, and more recently BEST) using ${}^{51}\mathrm{Cr}$ and ${}^{37}\mathrm{Ar}$. This long-standing discrepancy, referred to as the gallium anomaly, has posed a significant challenge to our understanding of both experimental methods and theoretical predictions. In this Letter, we revisit the theoretical calculation of the neutrino capture cross section by moving beyond the standard treatment of the leptonic wave functions, revealing limitations in the commonly used factorization approach based on the detailed balance principle. Incorporating phenomenologically constrained Gamow-Teller transition densities, able to correctly reproduce the precisely measured half-life of ${}^{71}\mathrm{Ge}$, we find that the revised cross section can be significantly reduced, potentially resolving the gallium anomaly without invoking new physics.

Characterizing quantum phases of matter at finite temperature is essential for understanding complex materials and large-scale thermodynamic phenomena. Here, we develop algorithmic protocols for simulating quantum thermodynamics on quantum hardware through quantum kernel function expansion (QKFE), producing the free energy as an analytic function of temperature with uniform convergence. These protocols are demonstrated by simulating transverse field Ising and XY models with superconducting qubits. In both analog and digital implementations of the QKFE algorithms, we exhibit quantitative agreement of our quantum simulation experiments with the exact results. Our approach provides a general framework for computing thermodynamic potentials on programmable quantum devices, granting access to key thermodynamic properties such as entropy, heat capacity, and criticality, with far-reaching implications for material design and drug development.

The spontaneous breaking of time-reversal symmetry is a hallmark of unconventional superconductivity, typically observed in type-II superconductors. Here, we report evidence of time-reversal symmetry breaking in the type-I superconductor ${\mathrm{YbSb}}_2$. Zero-field muon spin relaxation and rotation ($\mu \mathrm{SR}$) measurements reveal spontaneous internal magnetic fields emerging just below the superconducting transition, while transverse-field $\mu \mathrm{SR}$ confirms a fully gapped type-I superconducting state. Our first-principles calculations identify ${\mathrm{YbSb}}_2$ as a ${\mathbb{Z}}_2$ topological metal hosting a Dirac nodal line near the Fermi level. Symmetry analysis within the Ginzburg-Landau framework indicates an internally antisymmetric nonunitary triplet (INT) state as the most probable superconducting ground state. Calculations based on an effective low-energy model further suggest that this INT state may host gapless Majorana surface modes, pointing to the possibility of topological superconductivity in ${\mathrm{YbSb}}_2$. Our results highlight ${\mathrm{YbSb}}_2$ as a unique material platform where type-I superconductivity coexists with triplet pairing and nontrivial topology.

Odd-parity magnets (OPMs) have emerged as a fundamental class of unconventional magnetism, characterized by time-reversal-preserving nonrelativistic spin splitting (NSS). Despite growing interest, the fundamental understanding of OPMs remains critically incomplete, as previous studies have focused exclusively on NSS while overlooking the intrinsically broken time-reversal symmetry ($\mathcal{T}$) inherent to magnetic order. In this Letter, we demonstrate that OPMs universally host a hidden Zeeman field rooted in this $\mathcal{T}$ breaking, which profoundly reshapes their band structure. Through an analytical study of an $f$-wave magnet model, we reveal that the NSS microscopically originates from an emergent gauge field, manifesting as a real-space spin loop-current order in this model. Crucially, the large NSS (eV scale) enables conventional superconductivity to coexist robustly with the hidden Zeeman field, with the Zeeman splitting reaching hundreds of meV. This unique band structure establishes OPMs as an ideal platform for topological superconductors (TSCs), supporting large topological regions. Based on OPMs, we engineer a series of TSCs hosting distinct Majorana boundary modes, including unidirectional Majorana edge states. Our Letter corrects a fundamental misconception about OPMs and establishes them as a versatile platform for field-free and robust TSCs.

In type-II superconductors, magnetic fields modulate the amplitude and phase of the superconducting order parameter, forming quantized vortices where superconductivity is locally suppressed and exotic bound states or competing electronic orders emerge. Using spectroscopic-imaging scanning tunneling microscopy on epitaxial $\mathrm{Ba}{({\mathrm{Fe}}_{0.94}{\mathrm{Co}}_{0.06})}_2{\mathrm{As}}_2$ films, we discover an incommensurate charge-stripe order aligned with the Fe-Fe bond direction. These charge modulations become strongly enhanced at the vortex core and extend far into the vortex halo. Strikingly, the charge order modulates Andreev bound states of vortices at nonzero energies, producing Abelian vortices with half-odd-integer level quantization and non-Abelian vortices with integer-quantized core states that host a Majorana zero mode. The distinct vortex types are distinguished by the registry of their centers relative to the charge-stripe pattern and remain robust in ultrathin (2.5-unit-cell) films. Our findings reveal a density-wave-textured vortex matter and provide fresh insights into intertwined phenomena in iron-based superconductors.

Distinguishing an exciton condensate from an excitonic gas or insulator remains a fundamental challenge, as both phases feature bound electron-hole pairs but differ only by the emergence of macroscopic phase coherence. Here, we theoretically propose that a spin-orbit-coupled bilayer system can host a finite-momentum exciton condensate exhibiting a nonreciprocal perfect Coulomb drag—the coherent-exciton diode effect. This effect arises from the simultaneous breaking of inversion and time-reversal symmetries in the exciton condensate, resulting in direction-dependent critical counterflow currents. The resulting nonreciprocal perfect Coulomb drag provides a clear and unambiguous transport signature of phase-coherent exciton condensation, offering a powerful and experimentally accessible approach to identify, probe, and control exciton superfluidity in solid-state platforms.

Even-denominator fractional quantum Hall states (FQHSs) fall outside the standard Laughlin’s and Jain’s odd-denominator hierarchy. They are of intense current interest because they may exhibit non-Abelian topological order and therefore have applications in topological quantum computation. In this Letter, we study the FQHS at filling factor $\nu =1/2$, observed in a two-dimensional electron system confined to a wide GaAs quantum well. Unlike other even-denominator FQHSs, this state is stabilized at the lowest Landau level and has an energy gap about 10 times larger than the widely studied $\nu =5/2$ FQHS. Moreover, a recently observed pair of daughter FQHSs theoretically predicted the parent $\nu =1/2$ FQHS to be a non-Abelian state. Here, we report shot-noise measurements of partitioned quasiparticles at $\nu =1/2$ by an etch-defined quantum point contact (QPC). Our measurements were performed on two nominally identical devices in two independent experimental setups. Analysis of the shot noise in the weak-backscattering regime (of the QPC) reveals quasiparticles with charge $e/4$, consistent with a non-Abelian order, although it does not rule out an Abelian order. These observations provide a clear benchmark for future studies aimed at probing the topological order of the $\nu =1/2$ FQHS and its quasiparticles’ exchange statistics.

We present a comprehensive low-temperature ${}^1\mathrm{H}$ nuclear magnetic resonance (NMR) study of magnetic field–induced phases and spin fluctuations in an isotropic Haldane chain system $m\text{−}{\mathrm{NO}}_2\mathrm{PhBNO}$ (BoNO) in fields up to 34 T. NMR spectral and $T_1^{-1}$ relaxation rate data are used to map out the transition temperature $T_c(B)$ and we show that it defines a complete phase boundary between the field-induced Bose-Einstein condensate (BEC) and Tomonaga-Luttinger liquid (TLL) phases by reproducing its shape via quantum Monte Carlo calculations. We also observe the theoretical critical behavior $T_c(B)\propto (B-B_{\mathrm{c}2}{)}^{\nu }$ with $\nu =2/3$ and universal quasiparticle scaling in the low-temperature limit close to $B_{\mathrm{c}2}$. The extensive Bayesian inference analysis of the temperature and field dependence of $T_1^{-1}(T,B)$ reveals attractive interactions across the TLL phase of a Haldane chain. Our results are further corroborated by magnetostriction measurements in pulsed magnetic fields and density matrix renormalization group calculations.

Wave turbulence is a regime of interacting nonlinear waves occurring in most physical systems. Kelvin waves are helical distortions that propagate along vortex filaments and are believed to play a central role in quantum turbulence up to atmospheric vortices. Yet, Kelvin-wave turbulence has remained inaccessible to direct experimental observation. Here, we report the first direct experimental observation of Kelvin-wave turbulence along a single vortex filament in a classical fluid under controlled conditions. Using high-resolution spatiotemporal measurements, we resolve Kelvin-wave dynamics over a broad range of scales and obtain wave-amplitude spectra consistent with the predicted weak-turbulence cascade. We identify six-wave resonant interactions as the mechanism driving this energy transfer, providing direct experimental support for a long-standing prediction of weak-turbulence theory. These results establish an experimental platform for investigating energy transport along vortex filaments, with broader implications for both classical and quantum turbulent systems.

Intertwining intrinsic topological order with gapless collective modes remains a central challenge in many-body physics. We show that a quantum-Hall trilayer at ${\nu }_1={\nu }_2={\nu }_3=\frac{1}{3}$, tuned solely by the interlayer spacing $d$, realizes this goal. Large-scale density-matrix renormalization group calculations and a Chern-Simons field theory analysis reveal an intermediate “anyon-exciton condensate” separating the familiar ${\nu }_{\mathrm{tot}}=1$ exciton condensate ($d\to 0$) from three decoupled Laughlin liquids ($d\to \infty$). In this phase, neutral bi-excitons condense while a $\nu =\frac{2}{3}$ Laughlin topological order survives, yielding a Goldstone mode coexisting with fractionalized anyons. A Ginzburg-Landau analysis maps out the finite-temperature phase diagram. The anyon-exciton condensate can be experimentally verified through a vanishing double-counter-flow resistance and a fractional layer-resolved Hall resistance of $5h/2e^2$, both within reach of existing high-mobility trilayer devices.

We propose a laboratory-scale experiment to locally measure the general relativistic frame-dragging effect on Earth using the macroscopic quantum properties of a novel superfluid ${}^4\mathrm{He}$ single Josephson junction gyrometer. We derive the frame-dragging and related geodetic and Thomas effects in the superfluid gyrometer and present a procedure for their experimental measurement. We compute the expected thermal noise floor and find that very high sensitivity can be expected at millikelvin temperatures, where near-future Josephson junctions using nanoporous 2D materials are expected to operate. Assuming utilization of the lowest-mechanical-loss materials, we find a noise spectral density of $5\times {10}^{-17}\mathrm{rads}/\mathrm{s}/\sqrt{\mathrm{Hz}}$ at 10 mK, which is sufficient to resolve the frame-dragging rate to 0.2% within one second of measurement, giving a rotational sensitivity of 1 revolution in 4 Byrs. This extreme sensitivity to rotation corresponds to a measurement of proper time differences as small as ${10}^{-35}\mathrm{s}$.

Long-lived storage of single photons under the form of atomic excitations is at the foundation of long-distance entanglement distribution in quantum networks. To mitigate decoherence effects induced by the environment, rephasing of the hyperfine coherences using microwave pulses have been implemented in a variety of single-emitter and ensemble-based solid-state systems. However, the demonstration of storage of single photons in an absorptive quantum memory including such a spin-rephasing mechanism remains elusive. In this Letter, we show nonclassical storage of telecom-heralded single photons in a ${\mathrm{Pr}}^{3+}:{\mathrm{Y}}_2{\mathrm{SiO}}_5$ rare-earth ion doped crystal quantum memory using the atomic frequency comb spin-wave protocol combined with a XY4 spin-rephasing sequence. Long-lived atomic frequency comb photon echoes are first observed in the classical regime for storage times of up to approximately 3 ms. We then demonstrate nonclassical correlations between heralding photons and stored signal photons generated by a cavity-enhanced parametric photon-pair source for storage times of up to $180\mathrm{\mu }\mathrm{s}$ and with measured cross-correlation values as high as 4.6(4). Together with the capacity of ${\mathrm{Pr}}^{3+}:{\mathrm{Y}}_2{\mathrm{SiO}}_5$ quantum memories to support highly efficient and multiplexed storage, this result represents a significant step toward scalable long-distance quantum repeater links.

For ultrafast magnetization switching devices, critical slowing down in conventional ferromagnets near their Curie temperature constitutes a key challenge that must be overcome. In contrast to this typical behavior, we observe an anomalous acceleration of demagnetization in ${\mathrm{CaRuO}}_3/{\mathrm{SrTiO}}_3$ superlattices, which are moderately correlated weak itinerant ferromagnets. The demagnetization rate increases with rising temperature, pump fluence, and applied magnetic field. To explain these anomalous phenomena, we develop a phenomenological model integrating the three-temperature model with self-consistent renormalization theory. Because the intrinsic gradient magnetism of the superlattice suppresses the typical divergence of specific heat, the conventional thermodynamic bottleneck is bypassed. Our model reveals that this decoupling enables the ultrafast dynamics to be predominantly governed by the spin-fluctuation-driven enhancement of the electron-spin scattering vertex. This Letter demonstrates how spatial inhomogeneity can decouple macroscopic thermodynamic singularities from microscopic scattering processes, offering a new paradigm for manipulating ultrafast spin dynamics in correlated quantum materials. The pronounced sensitivity of the demagnetization rate to external parameters further suggests the potential for designing highly tunable ultrafast spintronic devices that leverage enhanced fluctuations near the magnetic instability.

Compact double neutron star (DNS) systems are unique laboratories for testing gravitational theories and studying DNS mergers. Here we report the properties of a new DNS system, PSR J1856–0039, discovered in the Five-hundred-meter Aperture Spherical radio Telescope (FAST). The pulsar is mildly recycled with a period of 23.4 ms in a compact eccentric orbit ($e=0.106$) with an orbital period of 2.36 hours. By following up FAST observations, we measured the relativistic effects, including the orbital period derivative ${\dot{P}}_{\mathrm{orb}}=-1.284\pm 0.019\times {10}^{-12}\mathrm{s}{\mathrm{s}}^{-1}$, periastron advance $\dot{\omega }=17.5859\pm 0.0007\mathrm{deg}{\mathrm{yr}}^{-1}$, and Einstein delay $\gamma =0.445\pm 0.011\mathrm{ms}$. This DNS system has a low orbital inclination of $i=133\stackrel{\circ }{.}2\pm 1\stackrel{\circ }{.}1$ and the lowest total mass of any known DNS, $M_{\mathrm{tot}}=2.48841\pm 0.00015M_{\odot }$, with a determined pulsar mass of $1.304\pm 0.022M_{\odot }$ and a companion mass of $1.185\pm 0.022M_{\odot }$, one of the lowest neutron-star masses. The observed orbital decay due to gravitational-wave emission ${\dot{P}}_{\mathrm{orb},\mathrm{obs}}^{\mathrm{GW}}$ and the orbital decay predicted by general relativity ${\dot{P}}_{\mathrm{orb},\mathrm{pred}}^{\mathrm{GW}}$ are consistent at a level of ${\dot{P}}_{\mathrm{orb},\mathrm{obs}}^{\mathrm{GW}}/{\dot{P}}_{\mathrm{orb},\mathrm{pred}}^{\mathrm{GW}}=1.009(14)$ (68% confidence). This DNS will merge after 82 Myr and may form a stable neutron star or collapse into a black hole after spin-down. Long-term monitoring could potentially probe the Lense-Thirring precession.

We uncover a dual mechanism by which oxygen defects suppress superconductivity in the bilayer nickelate ${\mathrm{La}}_3{\mathrm{Ni}}_2{\mathrm{O}}_{7+\delta }$ using density functional theory, dynamical mean-field theory, and functional renormalization group analysis. Apical vacancies and interbilayer interstitials emerge as the dominant low-energy defect species and are further stabilized by orthorhombic domain walls. These two defect classes drive the electronic structure in opposing directions. Vacancy-induced disorder generates local magnetic moments and promotes Anderson localization at moderate concentrations, whereas periodic interstitial ordering yields a coherent but weakly correlated metallic background that fails to support superconductivity. These findings highlight the decisive role of oxygen defects in shaping superconductivity and provide microscopic guidance for improving it through controlled defect engineering.

We show that excitons forming between moiré flat Chern bands possess a substantial electric dipole moment comparable to the moiré lattice parameter times the elementary charge ($\sim {10}^2\mathrm{D}$). At a hole filling factor of 1 in twisted ${\mathrm{MoTe}}_2$, the dipole moment of the lowest-energy exciton branch develops in-plane helical texture in momentum space from the intrinsic Berry curvature of electron and hole. By solving the Bethe-Salpeter equations, we demonstrate that an out-of-plane displacement field induces a Frenkel-to-Wannier exciton transition, accompanied by a reversal of the dipole texture helicity. The giant dipole produces an attractive dipole-dipole interaction channel, suggesting a possible quadrupolar biexciton measurable via two-photon spectroscopy. Our findings establish band topology as a tunable knob to engineer exciton dipole moments and pave the way to manipulate many-body interactions in the terahertz regime.

Deploying $N$ Brownian searchers reduces the mean search time for an immobile target merely by a factor $1/\ln N$. We show that this conclusion is highly sensitive to the short-time dynamics of individual searchers. Based on the telegrapher’s equation we demonstrate that the classical logarithmic scaling is only an intermediate asymptotic and ultimately crosses over to a much faster exponential decay with $N$. For anomalous diffusion with finite speed, we also show that superdiffusion leads to faster search than subdiffusion, as intuitively expected. Our findings provide a clear physical picture of redundancy and minimal search times in collective search relevant for many biological and physical systems.

We report numerical evidence for a wave-turbulent regime in dense suspensions of active phoretic disks with physicochemical hydrodynamic interactions. At low activity, the disks assemble into active Wigner solids, which melt into a hexatic phase with increasing activity. This phase transition in dense suspensions is accompanied by the destruction of standing waves in the solid phase and the onset of turbulent dynamics in the hexatic phase. Unlike canonical active turbulence typically characterized by large-scale advection of self-propelling constituents, our disks remain caged and perform local vibrations. This behavior mirrors the weak turbulence of bending waves in vibrating elastic plates. Moreover, the observed turbulence displays a self-similar, power-law energy spectrum at large wavenumbers, scale-dependent spatial intermittency but weak temporal intermittency, and statistically weak nonlinearity, consistent with reported signatures of wave turbulence. We therefore identify a new wave turbulence regime in active matter’s hexatic phase, which we call active wave turbulence.