The formation of sintering bridges in amorphous powders affects both flow behavior and perceived material quality. When sintering is driven by surface tension, bridges emerge sequentially, favoring contacts between smaller particles first. Predicting the connectivity percolation threshold is key to understanding and controlling the onset of sintering. We investigate ranked percolation in granular packings, where particles connect based on contact number. While the percolation threshold defined by the fraction of connected particles is non-universal and highly sensitive to particle size dispersion, we find that the critical number of sintered bridges per particle provides a robust estimator across different size distributions. Through numerical simulations and a mean-field approach, we link this robustness to the spatial distribution of contacts. Our results have broader implications for understanding the resilience of spatially embedded networks under targeted attacks.

We present sum-of-squares spectral amplification (SOSSA), a framework for improving quantum simulation relevant to low-energy problems. We show how SOSSA can be applied to problems like energy and phase estimation and provide fast quantum algorithms for these problems that significantly improve over prior art. To illustrate the power of SOSSA in applications, we consider the Sachdev-Ye-Kitaev model, a representative strongly correlated system, and demonstrate asymptotic speedups over generic simulation methods by a factor of the square root of the system size. Our results reinforce those observed in [G. H. Low et al., arXiv:2502.15882], where SOSSA was used to achieve state-of-the-art gate costs for phase estimation of real-world quantum chemistry systems.

Microwave (MW) field sensing is foundational to modern technology, yet its evolution, reliant on classical antennas, is constrained by fundamental physical limits on field, temporal, and spatial resolutions. Here, we demonstrate a MW electrometry that simultaneously surpasses these constraints by using individual Rydberg atoms in an optical tweezer array as coherent sensors. This approach achieves a field sensitivity within 1.0 dB (13%) of the standard quantum limit, a response time that exceeds the Chu limit by more than 11 orders of magnitude, and in situ near-field mapping with $\lambda /3000$ spatial resolution. This Letter establishes Rydberg-atom arrays as a powerful platform that unites quantum-limited sensitivity, nanosecond-scale response time, and submicrometer resolution, opening new avenues in quantum metrology and precision electromagnetic field imaging.

Quantum mechanics and general relativity are the foundational pillars of modern physics, yet experimental tests that combine the two frameworks remain rare. Measuring optical phase shifts of massless photons in a gravitational potential provides a unique quantum platform to probe gravity beyond Newtonian descriptions, but laboratory-based interferometers have not yet reached the sensitivity needed to access this regime. Here, we report the realization of a 50-km table-top Mach-Zehnder fiber interferometer operating at the single-photon level, achieving a phase sensitivity of $4.42\times {10}^{-6}\mathrm{rad}\mathrm{rms}$ within the frequency range of 0.01–5 Hz. We demonstrate that this sensitivity is sufficient to resolve a phase-shift signal of $6.18(44)\times {10}^{-5}\mathrm{rad}\mathrm{rms}$ at 0.1 Hz, associated with a modulated gravity-induced signal. Our results establish a milestone for quantum sensing with large-scale optical interferometry, demonstrating the capability to detect gravitational redshifts in a local laboratory, thereby paving the way for testing quantum phenomena within general relativistic frameworks.

We discover a rare structural manifestation of the Goldstone paradigm in a hexagonal polytype of the prototypical ferroelectric ${\mathrm{BaTiO}}_3$. First-principles calculations confirm the Goldstone character of the order parameter, while our high-resolution diffraction measurements unveil an unusual reentrant Goldstone regime manifesting as a quasicontinuous domain texture in the vicinity of the ferroelectric transition. We develop a minimal Landau model that encapsulates these observations, illustrating how U(1) symmetry can be restored at the ferroelectric transition. Our findings demonstrate how exotic Goldstone physics can be unlocked in systems dominated by highly anharmonic interactions, presenting a promising pathway to stabilize emergent polar topologies in bulk materials.

Topological materials hold immense promise for exhibiting exotic quantum phenomena, yet achieving controllable topological phase transitions remains challenging. Here, we demonstrate a structurally driven, reversible topological phase transition in the distorted square net material GdPS, induced via in situ potassium dosing. Using angle-resolved photoemission spectroscopy and first principles calculations, we demonstrate a cascade of topological phases in the subsurface P layer: from a large, topologically trivial band gap to a gapless Dirac cone state with a 2 eV dispersion, and finally to a two-dimensional topological insulator as inferred from theory. This evolution is driven by subtle structural distortions in the first P layer caused by potassium adsorption, which in turn contribute to the band gap closure and topological phase transition. Furthermore, the ability to manipulate the topology of a subsurface layer in GdPS offers a unique route for exploring and controlling topological states in bulk materials.

Grain boundary (GB) premelting, the formation of liquid layers along GBs below the melting point, can significantly alter material properties. However, the phenomenon remains poorly understood due to observational challenges. We study GB premelting through both experiments using temperature-sensitive microgel colloids and simulations of hard spheres. We observe that the premelted liquid layer thickens logarithmically before being interrupted by melting at each GB. Additionally, the onset and ending volume fractions of premelting depend on GB misorientation, consistent with a simple theoretical model, and coincide with the equilibrium melting and freezing volume fractions of a single crystal. Simulations further reveal that premelting of GBs with different misorientation angles exhibits mutual influence for finite grain sizes. These findings advance our understanding of premelting and can be applied to determine liquid distribution in polycrystals, which is critical for mechanical stability and materials processing.

The impact of a liquid droplet on a solid surface generates a cylindrical air cavity along the droplet’s central axis and entraps a thin air film underneath, with a liquid film potentially sandwiched in between. We observe that the air cavity produced by impacting a water droplet on superhydrophobic nanoporous surfaces evolves via two distinct pathways within a narrow Weber number range ($We\approx 2–5$): bulk-bubble entrapment or air-cushion development. Ultrafast synchrotron x-ray imaging reveals three air-cavity pinch-off mechanisms: (i) inertia-dominated axial implosion due to rapid droplet recoiling, (ii) capillary-wave-driven necking triggered by liquid film rupture, and (iii) hybrid pinch-off. We demonstrate that the stability of the sandwiched liquid film critically determines the pathway selection. Whereas intact liquid films enable isolation of the air cavity and air film, leading to bulk-bubble entrapment, submillisecond liquid film rupture ($\lesssim 0.5\mathrm{ms}$) redirects the air-cavity pinch-off dynamics, developing an air cushion underneath the droplet.

Acoustic imaging is widely used in biomedicine and industrial nondestructive testing, yet its spatial resolution remains fundamentally limited by acoustic diffraction. Despite significant progress in nonlinear harmonic imaging, localization microscopy, and acoustic metamaterials, these approaches face intrinsic trade-offs between efficiency, invasiveness, structural complexity, and scalability. Here, we introduce a far-field super-resolution ultrasound imaging strategy based on composite orbital angular momentum (OAM). By synthesizing vortex beams spanning multiple topological charges, the collective angular spectrum converges toward a Dirac delta function, enabling the recovery of high spatial frequencies from far-field scattered fields. Numerical simulations and underwater experiments demonstrate robust subdiffraction imaging of metallic wires, complex steel structures, and blood vessels, achieving resolutions down to $0.2\lambda$ in simulation and $0.24\lambda$ in experiment at 1 MHz, well beyond the Rayleigh limit. Moreover, tailored OAM spectra enable functional imaging capabilities such as chirality discrimination, offering sensitivity to structural handedness. Our results establish composite OAM as a powerful new degree of freedom for ultrasound imaging.

The Berry phase—a fundamental quantum geometric phase given by the integral of the Berry curvature over a closed trajectory in momentum space—underlies a wide range of quantum topological phenomena. Recent advances have demonstrated the potential of tuning the Berry phase to access exotic quantum states, primarily by modifying the integration path. However, its definition also suggests an alternative, yet largely unexplored route: the direct control of the Berry curvature itself. Here, we realize continuous modulation of the Berry curvature in the Bernal-stacked bilayer graphene quantum dot by applying a vertical displacement field. This tuning alters the Berry phase accumulated along confined electron orbits, leading to a distinct energy splitting between the $M=0$ and $M=1$ angular momentum states. Moreover, we demonstrate that the split states exhibit characteristics of atomic collapse states, finally resolving a long-standing academic debate about their existence in Bernal-stacked bilayer graphene. These observations establish the Berry curvature as a robust, magnetic field-free control parameter for manipulating confined states, unveiling a previously unobserved link between band topology and the evolution of quantum-confined states.

The quantum Hall effect (QHE) is a cornerstone of topological physics, inspiring extensive explorations of its high-dimensional generalizations such as experimental realizations in synthetic systems including cold atoms, photonic lattices, and metamaterials. However, the many-body effect in the higher dimensional QHE system remains poorly understood. We explore this problem by formulating the microscopic wave functions on a four-dimensional sphere inspired by Laughlin’s seminal work. Employing a generalized pseudopotential framework, we derive an exact microscopic Hamiltonian consisting of two-body projection operators that annihilate the microscopic wave functions. Diagonalizations on finite system sizes show that the quasihole states remain zero energy while the quasiparticle states exhibit a finite gap, in consistency with an incompressible state. Furthermore, the pair distribution is calculated to substantiate the liquidlike nature of the wave function. Our Letter provides a preliminary understanding to the fractional quantum Hall states in high dimensions.

Strong correlation, when combined with dissipation in open systems, can lead to a variety of exotic quantum phenomena. Here, we study nontrivial interplays between non-Fermi liquid behaviors emerging from strong correlation and non-Hermiticity arising from open systems. We propose a practical physical setup that realizes a non-Hermitian multichannel Kondo model. We identify a weak-coupling local moment fixed point and a strong-coupling non-Fermi liquid fixed point under $\mathcal{P}\mathcal{T}$ symmetry, both are enriched by the non-Hermitian effect. Remarkably, universal unconventional Kondo conductance behaviors are found for both cases, which are distinct from all previously studied Kondo systems. Particularly, we show that an anomalous upturn of conductance could take place with increasing the temperature, originating from the interplay between non-Fermi liquid and non-Hermiticity. Our results identify a novel class of transport phenomena unrecognized before, driven by intertwined effects of correlation and dissipation.

The Berry phase and quantum distance characterize the geometry of wave functions in Hilbert space. We uncover a quantum analog of the classical isoperimetric inequality, revealing a fundamental link between the Berry phase and quantum distance along closed paths. For two-band systems, we establish a strong inequality analogous to the spherical isoperimetric problem. For multiband systems, we prove a weak inequality showing that the Berry phase never exceeds the quantum distance. These results introduce new quantum geometric principles, placing fundamental bounds on physical quantities such as the Wannier function spread, quantum speed, electron-phonon coupling, and superfluid weight, with broad implications across condensed matter, quantum information, and beyond.

The study of the geometric properties of quantum states in Hilbert space—particularly through the lens of the quantum geometric tensor (QGT)—has profoundly advanced the fields of condensed matter physics and materials science. The real and imaginary parts of the QGT, the quantum metric and Berry curvature, characterize the distance and phase variation of two adjacent quantum states, respectively. Here, we unveil a fundamental global inequality rooted in these two local quantities between the Fubini-Study quantum distance ($d_{\mathrm{FS}}$) and the Berry phase (${\varphi }_{\mathrm{B}}$), $d_{\mathrm{FS}}\ge {\varphi }_{\mathrm{B}}$, for any closed momentum path. Interestingly, the equality occurs when the closed path is mapped to a great circle on the Bloch sphere, i.e., $d_{\mathrm{FS}}={\varphi }_{\mathrm{B}}=\pi$ for a topologically nontrivial path, qualifying quantum distance as an alternative probe for nontrivial band topology. Experimentally, using acoustic metamaterials, we measure the full QGT of concrete models and provide compelling evidence for this quantum geometric inequality. Our findings shed new light on the geometric characteristics of quantum matter.

Long-range propagation of equal-spin triplet Cooper pairs typically occurs in ferromagnet-$s$-wave superconductor junctions, where net magnetization plays a crucial role. Here, we propose a fundamentally different scenario in which Josephson supercurrents mediated exclusively by spin-triplet pairings emerge in systems with zero net magnetization. We identify collinear altermagnets, particularly a subclass termed nodeless altermagnets, as ideal platforms to realize this phenomenon. These materials host spin-split Fermi surfaces that do not intersect altermagnetic nodal lines and support maximal spin-valley polarization, yielding fully spin-polarized electronic states at each valley. Consequently, Josephson junctions based on nodeless altermagnets sustain supercurrents solely through spin-polarized triplet pairing correlations, simultaneously contributed by spin-up Cooper pairs from one valley and spin-down Cooper pairs from the other. Furthermore, controlling the relative local inversion-symmetry breaking at the two interfaces enables a robust $0-\pi$ transition without fine tuning, while adjusting the junction orientation allows a crossover between pure triplet and mixed singlet-triplet states. Our Letter thus establishes nodeless altermagnets as a unique platform for altermagnetic superconductors with magnetization-free spin-polarized supercurrents.