Papers

The need for atmospheric measurements with higher spatial and temporal resolution is driving the development of satellites and satellite constellations to complement existing flagship missions. We are developing an instrument concept based on photonic crystal filters with tailored spectral transmission for trace gas retrieval. These filters can be integrated directly with the detector module, enabling a highly compact system architecture. In this work, we present performance simulations for methane and carbon dioxide retrieval in the 1.6 um SWIR band for a medium-resolution global coverage mission with an approximately 250 m spatial resolution and a 150 km swath. We furthermore introduce an improved retrieval algorithm that substantially reduces retrieval bias. These results demonstrate the potential of the proposed architecture for medium-resolution global greenhouse-gas mapping, with retrieval performance comparable to state-of-the-art global mapping missions such as the planned CO2M mission at substantially finer spatial resolution. This measurement approach also inherently compresses the acquired spectral information, reducing the need for high downlink data rates. In the coming year, these filters will be fabricated by NIL Technology, followed by mechanical integration and experimental validation in a breadboard system.

Molecular docking is a vital computational task in drug discovery, wherein the objective is to efficiently identify optimal binding poses between a ligand and a target receptor protein. Due to the combinatorial explosion of possible binding configurations, docking of large and flexible molecules remains a computationally intensive problem, especially at scale. Early studies have revealed that the molecular docking can be re-cast as a maximum vertex-weighted clique problem (MVWCP) problem on a compatibility graph to be solved classically. In this work, we proposed a hybrid quantum-classical approach for molecular docking leveraging the MVWCP formalism with a variational full-basis encoding (FBE) strategy, which enables efficient encoding of classical binary variables with Bloch sphere vectors. We further prove that a global minimizer of the FBE objective can always be chosen to be a pure product state, thereby providing a rigorous justification for its optimization using a unitary variational circuit. The molecular docking problem is first mapped to a cost Hamiltonian that is minimized within a variational framework, optimized via a randomized imaginary time evolution (ITE)-inspired warm start, and gradient-based techniques. Finally, we also executed the circuit on an IBM quantum computer, underlying the feasibility and of quantum-assisted optimization for structure-based drug design and point towards the broader utility of advanced encoding techniques in quantum optimization for computational biology.

We investigate the skewness dependence of the pion generalized parton distribution (GPD) at different momentum transfers $-t$ within the covariant Nambu-Jona-Lasinio (NJL) model, employing the Schwinger proper-time regularization scheme to regulate ultraviolet divergences and implement an effective description of quark confinement. We evolve the pion GPDs for various values of $-t$ and $\xi$ to the scales $\mu^2=4$ and $27~\mathrm{GeV}^2$. We find that the valence-quark distributions are suppressed with increasing $-t$ and $\xi$, with the suppression becoming more pronounced at the lower scale, $\mu^2=4~\mathrm{GeV}^2$. In the forward limit, $\xi=0$ and $-t=0$, the predicted pion valence-quark distribution at $\mu^2=27~\mathrm{GeV}^2$ is in good agreement with the available experimental data and the global JAM analysis. The corresponding pion gluon distribution at $\mu^2=4~\mathrm{GeV}^2$, obtained through next-to-leading-order (NLO) DGLAP evolution, is also consistent with the JAM analysis. We further find that the pion and kaon valence-quark distributions exhibit a strong dependence on $-t$ but only a weak dependence on $\xi$, whereas the corresponding gluon distributions show weak dependence on both $-t$ and $\xi$. The generalized form factors of the pion and kaon at $\mu^2=4~\mathrm{GeV}^2$ are in good agreement with the corresponding lattice-QCD results.

Volatile resistive switching in correlated-electron systems, characterized by an abrupt resistance decrease under applied current, is crucial for developing next-generation electronics. Despite its technological significance, the underlying physics remains elusive. Inorganic thin films on substrates—the widely studied platform for resistive switching—usually exhibit broad temperature-induced metal-insulator transitions (MITs) and substantial heat dissipation. These factors complicate the nonlinear thermal effect induced by Joule heating, a key contributor to resistive switching, rendering it excessively complex and difficult to decipher. Here we investigate a resistive-switched state in the bulk organic conductor ($d$7-DMe-DCNQI)$_{2}$Cu, which undergoes an extremely sharp first-order MIT and exhibits weak heat dissipation, using resistance and $^{1}$H-NMR measurements. These extreme conditions make the Joule heating effect vivid, allowing us to observe peculiar phenomena, including temperature locking to the MIT and `inverse Ohm's law'—an inverse proportionality between voltage and current. These findings provide fundamental insights into the nonlinear thermal effect in resistive switching, offering a pathway to efficient resistive-switching technologies.

In previous work arXiv:2604.00160, we found soliton solutions in a deformation of the sine-Gordon theory in AdS spacetime that, in the infinite-radius limit, reduce to single-soliton solutions in flat space. In this paper, we find another single soliton solution that has no analog in flat space.

The unexpectedly small ordered moments of CeNiAsO, a candidate for correlated $p$-wave magnet, have posed a serious challenge to the precise determination of its magnetic structure, hindering the understanding of its fundamental properties. By leveraging the high sensitivity to local internal fields, our $^{75}$As nuclear quadrupole / magnetic resonance experiments reveal a commensurate antiferromagnetic order with a small out-of-plane moment $m_z\approx0.05$ $\mu_{\mathrm{B}}$. This tilted magnetic configuration not only rotates the spin polarization axis away from the crystallographic $\mathbf{c}$-axis, but also enhances the non-relativistic spin splitting. We refer to this rare paradigm as a \textit{tilted $p$-wave magnet}.

The stability and instability in the time dynamics of quantum fluctuation of the massive gauge field coupling to the nonlinear massive wave solution is studied. In particular, the instability in the transverse polarization and longitudinal polarization modes are obtained as the two dimensional plot of the initial field value parameter and the spatial momentum of the quantum massive gauge fields with the help of the theory of the Hill's equation. We present the formalism to analyze the massive gauge field by taking into account Proca constraint and we found that our formalism can predict the time dynamics of the unstable quantum mode by the Floquet index. The resulting polarization-resolved Floquet maps show that the transverse modes possess only narrow parametric-resonance bands, whereas the longitudinal modes exhibit substantially broader regions generated by both parametric and spinodal instabilities. We also find additional low-momentum instability regions for the $W$ boson that are absent or strongly suppressed in the $Z$ sector.

We identify CFT counterparts of Synge's identity for finite AdS geodesics in arbitrary dimensions. Starting from exact finite bulk–boundary pairs, the Synge equation induces endpoint scale equations for a Weyl-frame scalar two-point function and for the finite entanglement entropy between disjoint balls. In the planar frame, the common-scale correlator equation is the dilatation Ward identity. In the entanglement sector, the corresponding relative-scale equation is governed by a transverse hyperbolic area and reduces in two dimensions to the previously identified entanglement RG equation.

A spectral macroparticle simulation scheme is used to model non-neutral plasma dynamics in a Penning-Malmberg trap. This grid-free numerical scheme is well adapted to the specific geometry of trapped plasmas, with varying longitudinal and transverse profiles in a cylindrical conducting pipe. The cutoff spectral harmonics provide control over the trade-off between accuracy and noise smoothing, which is especially important in the three-dimensional case. We demonstrate the ability of this scheme to obtain the dispersion relation of the plasma modes from the inherent simulation noise, providing a valuable tool for understanding the plasma's behavior. In the presence of a rotating wall drive, we show that the numerical scheme can reproduce the time evolution of the driven eigenmodes, identify the onset of mode mixing with increasing drive amplitude and retrieve the compression rate dependency on the drive frequency, known from the weak drive regime of the rotating wall technique. To the authors' knowledge, such simulations have not been reported in the literature so far.

We present a new computational approach based on Nuclear-Electronic Orbital and Subsystem Density Functional Theory. The resulting NEO-sDFT methodology enables quantum chemical calculations of large molecular systems composed of thousands of atoms while also describing selected protons quantum mechanically. A key feature of the associated program implementation is its flexibility in assigning quantum protons to subsystems, allowing different embedding schemes to be employed within a unified framework. The accuracy of NEO-sDFT is assessed by computing water dimer interaction energies, which exhibit errors of only a few meV compared to reference Nuclear-Electronic Orbital Density Functional Theory results. The favorable computational scaling of NEO-sDFT is further showcased through calculations on water clusters of increasing size, with up to 303 protons being treated quantum mechanically. Our results demonstrate that NEO-sDFT is an accurate and efficient approach for incorporating nuclear quantum effects into large-scale simulations, providing a foundation for future applications to proton transfer processes in biochemical systems.

Variational Quantum Eigensolver requires many circuit executions, making it ideal for distributed parallelization. However, heterogeneous noise in NISQ devices can skew results and efficiency. Using the CUNQA platform for emulation of virtual QPUs, we evaluate three embarrassingly parallelization strategies (shot-level, circuit-level for gradients and observables and candidate level for population-based optimizers) across metrics like speedup and accuracy.

Objective. Joint assessment of tissue oxygenation and microvascular perfusion could offer valuable insights into vascular function across a wide range of biomedical applications. Multispectral photoacoustic imaging enables the evaluation of blood oxygenation, while ultrasound localization microscopy provides sub-diffraction visualization of the microvasculature and blood perfusion. Here, we combine these two complementary modalities to simultaneously generate co-registered, volumetric maps of blood oxygenation and perfusion. Approach. Photoacoustic imaging and ultrasound localization microscopy are both ultrasound-based techniques. We developed an imaging platform that integrates the two modalities using a single planar ultrasonic matrix array, a state-of-the-art array for 3D ultrasound localization microscopy. The bimodal platform was validated in vitro using vessel-mimicking phantoms, then in vivo in mice. Main results. In vitro bimodal images of tubes injected with contrast agents demonstrated a coregistration accuracy of 20 $\mu$m and revealed complementary structural and functional information. Multispectral photoacoustic imaging achieved oxygen saturation measurements spanning the physiological range (60-95 %) with 5 % accuracy using only five optical wavelengths. In vivo imaging of healthy mouse tissues with known vascular anatomy further demonstrated the ability of the proposed platform to jointly characterize blood oxygenation and microvascular perfusion. Significance. This work experimentally validates a bimodal photoacoustic imaging-ultrasound localization microscopy approach using a planar ultrasound array. We characterized the functional imaging performance of this platform and identified limited-view artifacts inherent to this array configuration in photoacoustic imaging. These findings establish a foundation for adopting the platform in future studies of murine models and for advancing this promising bimodal approach.

Freidlin–Wentzell theory converts weak-noise large deviations into a Hamiltonian variational problem. We study how a $k$-dimensional normally hyperbolic invariant manifold (NHIM) $N$ of the deterministic dynamics appears in this Hamiltonian system. Its zero-momentum copy $N_0=N\times\{0\}$ is invariant, but the Hamiltonian dynamics has $2k$ center directions near $N_0$: $k$ tangent to $N$ and $k$ conjugate covector directions. We construct the resulting local symplectic geometry and show that fluctuation extremals approaching $N_0$ backward in time at the strong normal rate form an $n$-dimensional exact Lagrangian invariant manifold carrying a single-valued action. A counterexample shows that a corresponding zero-energy section need not be normally hyperbolic within $H_{\mathrm{FW}}^{-1}(0)$. We then consider reaction dynamics. If a parameter moves a deterministic trajectory toward a codimension-one reactivity boundary, the minimum Freidlin–Wentzell action required to reach the boundary is quadratic in the distance from the threshold parameter. Its coefficient is determined by the relative motion of trajectory and boundary and by how effectively the available noise acts transversely. This deterministic boundary is distinct from a noise-dependent stochastic transition state or a committor surface. In a solvent–solute model, varying solvent mass moves the phase-space reactivity boundary while leaving the potential-energy surface fixed, changing the rare-event cost without changing the potential-energy barrier.

We consider the combined effect of a Duffing nonlinearity and the optomechanical interaction on the cavity density of states (DOS), which is directly observable in optomechanically induced transparency (OMIT) experiments. Both nonlinearities introduce the same type of interaction between polaritons, producing a distinct feature in the optical response. We derive the resonant condition that enhances the nonlinear scattering between polaritons and study the parameter dependence of the cavity DOS in detail. This allows us to characterize the typical strength and optimal conditions for observing the quantum effects of the Duffing nonlinearity in OMIT experiments.

The self-assembly of associative triblock copolymers composed of a central hydrophilic elastin-like polypeptide (ELP) block and short fatty acid end groups (C16) was investigated in aqueous solution. In one system, the ELP contains 80 pentapeptide units (C16-80-C16), whereas in the other two C16-ELP40 chains were oxidatively coupled through their terminal cysteine residues to form a central disulfide bond, yielding C16-(40)2-C16. Despite their nearly identical molecular weights and compositions, the two polymers exhibit markedly different self-assembly behaviors. C16-80-C16 forms large hydrophobic aggregates that remain kinetically trapped and do not develop a dynamically connected network. In contrast, C16-(40)2-C16 forms very small associative nodes with an aggregation number of only $\sim$3 chains. These nodes coexist with larger clusters and become dynamically interconnected at higher concentrations, leading to transparent hydrogels at concentrations as low as 2.5 wt %. Oscillatory rheology reveals a transient Maxwell network governed by a single relaxation process associated with the reversible association of the C16 end groups. SAXS, light scattering, cryo-TEM, and molecular modeling consistently support a model in which the central disulfide junction promotes transient network formation.

III-V semiconductor nanowires (NWs) are a promising platform for optoelectronic and photoelectrochemical applications, where device performance strongly depends on NW density and spatial arrangement. While ordered arrays provide precise control, their fabrication requires complex and costly lithographic techniques. Unordered growth offers a scalable alternative but is limited by insufficient control over catalyst distribution and particle agglomeration. Here, we investigate the density scaling of unordered III-V NW arrays using commercially available Au colloid solutions as catalysts for NW growth via vapor-liquid-solid growth mode. Repeated deposition cycles yield a near-linear increase in particle density, which is ultimately limited by non-linear agglomeration effects not captured by simple stochastic models. To address this limitation, a previously established pre-anneal growth concept is transferred from patterned catalyst arrays to randomly deposited Au colloids, thereby suppressing thermally induced coalescence and stabilizing the catalyst distribution. This approach enables up to a tenfold increase in NW density while improving uniformity and vertical yield. The method is demonstrated for colloid diameters between 100 and 200 nm. Overall, this work provides a scalable, lithography-free route toward high-density III-V NW ensembles and offers insight into the role of particle dynamics in colloid-based growth processes.

Quasi-periodic eruptions (QPEs) are recurrent soft X-ray flares from galactic nuclei, but their origin remains uncertain. The delayed ultraviolet (UV) counterpart detected in ZTF19acnskyy provides a new constraint on viable models. We present a two-channel model in which a satellite black hole (sBH) repeatedly crosses a nuclear accretion disk threaded by a large-scale magnetic field. Gravitational focusing and dynamical drag generate hot, optically thick ejecta whose expansion and photon diffusion power the soft X-ray QPE. For fiducial Bondi-scale parameters, the model yields a characteristic X-ray duration of $\sim10^3\ \mathrm{s}$ and luminosity of $\sim10^{42}\ \mathrm{erg\,s^{-1}}$. For ZTF19acnskyy, the model reproduces the observed day-scale X-ray duration and energetics. Simultaneously, the sBH motion compresses and bends the background magnetic field, triggering in-disk reconnection. The reconnection channel provides the energy budget and photon-diffusion delay required for the variable UV component. Unfavorable magnetic fields or diffusion times longer than the QPE recurrence period can weaken or smear out the UV signal, potentially explaining the lack of clear UV counterparts in other QPE sources.

Let $W_{\cal O}[J]$ and $W_{\cal C}[J]$ denote the connected generating functionals of an open system and its closed system counterpart, and define the environment-induced contribution $W_{\rm IF}[J]$ by the difference: $ W_{\rm IF}[J]\equiv W_{\cal O}[J]-W_{\cal C}[J].$ The corresponding Legendre transforms, $\Gamma_{\cal O}$, $\Gamma_{\cal C}$, and $\Gamma_{\rm IF}$, do not obey an analogous additive relation but satisfy a stationary composition law given by: \[ \Gamma_{\cal O}[\Phi] = \operatorname*{Stat}_{\Psi} \left\{ \Gamma_{\cal C}[\Psi] + \Gamma_{\rm IF}[\Phi-\Psi] \right\} \] where ${\rm Stat}$ denotes evaluation at a solution of the stationarity condition with respect to $\Psi$. This variational composition applies to both local and nonlocal Schwinger-Keldysh effective actions in nonequilibrium quantum field theory. We illustrate its linear and nonlinear realizations through quadratic theories and general time independent effective actions, respectively.

Open-porous materials exhibit pronounced compressibility, nonlinear densification, and power-law scaling of stiffness with density. In this work, we propose a thermodynamically consistent compressible neo-Hookean constitutive model for open-porous solids in which porosity serves as the primary governing variable. The strain-energy density is formulated to couple distortional elasticity of the solid skeleton with a volumetric response governed by deformation-induced porosity evolution, including a bounded representation of pore collapse. The formulation introduces a minimal set of parameters, namely the initial porosity, intrinsic skeleton moduli, and a scalar parameter controlling the onset of densification. A key feature of the model is a modified volumetric term in which the response is normalised by the current porosity, ensuring a physically consistent transition from a porous to a densified state without artificial stiffening. In the small-strain limit, the model recovers classical linear elasticity with effective moduli that may be chosen either from homogenisation bounds, such as the Hashin-Shtrikman estimates, or from Gibson-Ashby-type power-law scaling to capture topology-dependent behaviour. At finite strains, the formulation captures the characteristic nonlinear stiffening and convex stress-stretch response associated with progressive pore collapse. The proposed framework thus provides a compact, flexible, and extensible constitutive description that unifies effective-medium consistency with experimentally observed scaling behaviour, and is well suited for finite element implementation and multiscale modelling of highly compressible open-porous materials. The model is finally validated against available experimental data.

This memorial tribute to Mannque Rho follows a line of thoughts and ideas that he continuously inspired and shaped over many decades: from the two-scales picture of low-energy nucleon structure to dense and cold baryonic matter as it is realized in the cores of neutron stars. Early groundbreaking concepts are recalled and updated by recent advanced analyses of the `core' and `cloud' sizes of the nucleon. Implications for dense nuclear matter are then discussed and confronted with empirical information from Bayesian inference analyses of neutron star observables.

Developed as a workhorse for classical simulations of quantum algorithms and quantum many-body systems, Tensor Network methods have entered the scientific mainstream in quantum physics. Among various types of tensor networks, Tensor Trains (commonly know as Matrix Product States in the quantum computing community) have already found applications in machine learning. These methods often rely on a powerful linear algebra tool called the Singular Value Decomposition (SVD). Several conditional GAN architectures for image denoising incorporate SVD as a single-cut decomposition step applied to generator feature maps. In this work we introduce TT-Net, which replaces the per-channel SVD denoising block with a two-cut tensor-train decomposition capable of accessing cross-channel information directly, a capability absent from contemporary alternatives. In a controlled comparison differing only in this decomposition mechanism, TT-Net outperforms SVD-Net on PSNR and SSIM across all three noise types tested (Gaussian, motion blur, and salt-and-pepper), supporting the hypothesis that cross-channel access improves denoising quality. Training-dynamics analysis further shows that TT-Net's adversarial loss term consistently saturates to a stagnant state across all three noise types, more so than SVD-Net's, while reconstruction quality continues to improve regardless, raising an open question about the adversarial component's contribution that this work identifies but does not resolve. Furthermore, for Gaussian noise our method outperforms both the EigenGAN and the state of the art Pix2pix method which does not assume any linear algebra decompositions and does not retain any linear algebra information. Our manuscript shows how quantum inspired tools can be used as practical real world feature filters for deep learning applications.

We show that there exists a total function for which there is a polynomial gap between the randomized and the constant-round quantum communication complexity. Previously, such a separation was known only for quantum protocols using polynomially many rounds.

Nucleosynthetic isotope anomalies allow distinguishing between non-carbonaceous (NC) and carbonaceous (CC) type meteorites, and have revealed correlated isotope variations especially among NC bodies. Understanding the origin of this NC trend is important for identifying the processes that produced the NC isotope heterogeneity, and for using these isotope anomalies to reconstruct the early evolution of the solar protoplanetary disk. We report mass-independent Ti, Cr, and Mo isotope compositions for a comprehensive set of previously not or only poorly investigated meteorites, as well as acid leachates obtained from the sequential digestion of primitive ordinary chondrites. Some of the samples investigated in this study fill previously identified apparent gaps in the NC trend, suggesting these gaps reflect unrepresentative sampling of a more continuous isotopic trend. Bulk meteorites and leachates exhibit distinct isotope systematics, indicating that the NC isotope variability does not reflect selective thermal processing of presolar carriers in the disk. The NC trend also cannot reflect the continuous addition of CC dust from the outer to the inner disk, because early- and late-formed NC meteorites display largely overlapping isotopic compositions. Instead, we find that the NC isotope heterogeneity is best accounted for by fractionation and mixing among chemically and isotopically distinct dust components, similar to the processes that produced the isotopic variability among carbonaceous chondrites. On this basis we argue for the presence of substructures in the inner disk, which facilitated fractionation and mixing among distinct dust components, and helped preserve a long-lived dust reservoir from which NC planetesimals accreted over an extended period of time.

Quintessential $\alpha$-attractor models of single-field inflation and evolving dark energy were constructed about a decade ago. Recently, it was pointed out that some of them might be disfavored due to dark-radiation constraints on gravitational waves and the higher values of $n_s$ favored by ACT. Here we present a class of updated quintessential $\alpha$-attractor models in which a single field describes both inflation and evolving dark energy, yields higher values of $n_s$, and admits reheating scenarios consistent with the dark-radiation bound on $\Delta N_{\rm eff}$. Depending on the value of the cosmological constant $\Lambda$, these models interpolate between $\Lambda$CDM with $\Lambda > 0$ (future dS universe), dynamical dark energy with $\Lambda = 0$ (future Minkowski universe), and dynamical dark energy with $\Lambda < 0$ (future cosmological collapse). We also study quintessential $\alpha$-attractor models based on an axion-inflaton complex scalar field with hyperbolic geometry, which describe inflation and dark energy of a “phantom illusion” type compatible with DESI DR2.

World models provide digital simulacra of the true world, allowing agents to be trained and tested before costly real-world deployment. At each time step, they receive an action and generate an observation and reward matching the statistics of the true world. In complex environments where present outcomes depend on events far in the past, this requires memory. One might expect that, by increasing memory, we can always build a model accurately enough to align the optimal agent policies of the real and virtual worlds. We show that this is false for classical world models, even when the true world itself is classical. We construct true worlds for which every finite classical model fails along the same possible trajectory: it either loses the ability to distinguish actions when the true world clearly prefers one, or repeatedly assigns the highest expected reward to suboptimal actions. Its expected-reward estimates also retain a nonvanishing average error. In contrast, each such true world admits a quantum world model using a single qutrit that reproduces it exactly: its reward estimates and preferred actions always match those of the true world, ensuring that the optimal policies of the real and virtual worlds remain perfectly aligned.

We construct 2d $\mathcal{N}=(2,2)$ gauged linear sigma models with $\mathrm{U}(1|1)^N$ supergauge group possibly with superpotential. Despite being nonunitary, one can still study their space of supersymmetric states and explore their applications to mathematics. In particular, we find a relation between a nonlinear sigma model on a Calabi-Yau complete intersection of hypersurfaces in a super-Grassmannian and a supergauged Landau-Ginzburg orbifold, which can reduce to a regular Calabi-Yau/Landau-Ginzburg correspondence for complete intersections. This defines a super-Grassmannian/supergroup generalization of the correspondence proved by Clader [1] and Zhao [2]. Similarly, we find a relation between a nonlinear sigma model on a Calabi-Yau hypersurface in a product of super-Grassmannians and a hybrid NLSM/supergauged Landau-Ginzburg orbifold, which can reduce to a regular hybrid Calabi-Yau/Landau-Ginzburg correspondence for hypersurfaces in product space. This defines a super-Grassmannian/supergroup generalization of the correspondence proved by Fan-Jarvis-Ruan [3]. We also find that Calabi-Yau supervector bundles over a super-Grassmannian can undergo a physically related mild topology change which is reducible to a regular Atiyah-type flop transition. This defines a super-Grassmannian generalization of a birational equivalence of Calabi-Yau vector bundles in mathematics. Similarly, we find that a Calabi-Yau complete intersection of quadrics in a super-Grassmannian can also undergo a physically related topology change which is reducible to a regular conifold transition. This defines a super-Grassmannian generalization of a homological projective duality for Calabi-Yau quadrics by Kuznetsov-Perry [4] in mathematics.

We use physics-informed neural networks (PINNs) to solve the gravitational quasinormal-mode (QNM) eigenvalue problem for Kerr spacetime directly in the two-dimensional hyperboloidal formulation of the Teukolsky equation. This formulation does not require separation of variables and thus retains the coupled radial–angular structure. Such a scheme provides a prototype for calculating the QNMs of beyond-Kerr black holes for which the perturbation equations are non-separable. Sequences with increasing angular momentum are constructed, reaching close to the extremal limit. We focus on the fundamental modes $(\ell,m,n)=(2,0,0)$, $(2,1,0)$, $(2,2,0)$, $(3,3,0)$ and $(4,4,0)$, together with the first overtone $(2,2,1)$. Independent benchmark evaluation shows that every reported real and imaginary frequency component remains below $0.5\%$ error, with a median deviation of $0.1\%$. This accuracy is maintained in the near-extremal regime, where the damping rate becomes small and the modes are longest-lived. The results establish a non-spectral numerical route to multidimensional black-hole perturbation eigenproblems which does not match the substantially higher precision of dedicated Kerr solvers but offers greater flexibility and requires less analytical pre-processing. Non-separable rotating backgrounds and coupled systems, such as gravitational–electromagnetic Kerr–Newman perturbations, are natural extensions of the same construction.

Surface acoustic wave (SAW) sensors, owing to their high operating frequencies, compatibility with planar micro-fabrication, and exceptional sensitivity to surface perturbations, are widely used in lab -on-a-chip and biomedical diagnostic applications. However, conventional SAW sensors operating in liquid environments suffer from substantial energy dissipation, which markedly reduces their quality factors (Q factors) and limits sensing reliability. Here, we design and fabricate a topological SAW resonant sensor for surface liquid loading by exploiting interference coupling between topological interface states and resonant cavities. The band structures are validated using a semi-analytical plane wave expansion-finite element method. The device requires only 0.04 uL of sample and enables concentration sensing of NaCl and glucose solutions, with sensitivities of up to 190 kHz/% for NaCl and 101.8 kHz% for glucose, respectively, and a concentration resolution of 0.01%. This work offers a potential technological route towards high-performance SAW biomedical chips for micro-volume sample analysis.

We propose a gradient-flow method for quantum states in lattice models, generated by an action consisting of the quantum-metric and the square of the Berry curvature. These two terms drive the spectral projector toward Bogomolny saturation and uniform Berry curvature, respectively. We show that, due to a no-go theorem for finite-dimensional projectors, the two conditions cannot in general be satisfied simultaneously in lattice models. Hence the flow is expected to approach a nontrivial fixed point that balances the two geometric requirements. For the Wilson-Dirac model, we demonstrate that the flowed projector exhibits almost uniform Berry curvature while remaining close to the Bogomolny bound. We further construct a short-range truncated flattened Hamiltonian from the flowed projector and obtain a lattice model with nearly flat bands and nearly uniform Berry curvature. We also apply the method to the Hofstadter model and confirm the roles of the metric and Berry-curvature terms in a Chern band with higher Chern number.

The abundance of galaxy clusters is a powerful cosmological probe, but optical cluster cosmology is limited by selection systematics, in particular the projection effects that affect cluster finders based on galaxy populations such as the red sequence. The outer stellar mass ($M_\mathrm{out}$) of cluster central galaxies – e.g., the stellar mass in a 50-100 kpc annulus – offers an alternative selection that relies only on the central galaxy and is therefore largely free from projection effects. Its primary systematic is instead satellite contamination, since massive clusters can host more than one galaxy with high outer stellar mass. Using the IllustrisTNG300 simulation at $z=0.4$, we quantify this contamination and investigate a simple, proximity-based percolation method to mitigate it, in which galaxies with lower outer stellar mass lying within a given radius of a more massive galaxy are removed from the sample. We find that the satellite fraction defined by the friends-of-friends (FoF) algorithm is modest even without percolation ($\leq 15\%$ for $M_\mathrm{out} > 10^{10}\,\mathrm{M}_\odot$ and $<10\%$ for $M_\mathrm{out} > 10^{11}\,\mathrm{M}_\odot$), and that percolation reduces it further, with the improvement increasing for percolation radii up to $3.0\,R_{200c}$. For a moderately high outer stellar mass cut ($\sim 4\times10^{10}\,\mathrm{M}_\odot$) and percolation radius ($\sim 2.0\,R_{200c}$), we recover a cluster sample that is both highly complete and pure for halo masses $\gtrsim 10^{14}\,\mathrm{M}_\odot$. These results indicate that outer stellar mass, combined with simple percolation, has the potential to provide a clean and readily calibratable selection of massive galaxy clusters.