Papers

We study the general form of meromorphic amplitudes that are compatible with unitarity, analyticity, crossing symmetry, polynomial boundedness and the hidden-zero and corresponding splitting conditions. These amplitudes are infinite-spin-tower (IST) amplitudes and are characterized by the distribution of poles. With infinitely many equidistant poles, the IST amplitudes reduce to Veneziano amplitudes. We construct such unitary amplitudes in a primal way (rule in) and find the bounds analytically. The allowed region we derive is smaller than, but close to, the region allowed by the positivity bounds (rule out). We argue that, with the conditions imposed, the analytic boundary we derive is the largest possible boundary in the primal construction of meromorphic amplitudes. This type of IST amplitude can also be extended to the fully crossing-symmetric case related to the Virasoro-Shapiro amplitude. We found from the IST amplitudes that graviton pole imposes unitarity constraints on UV spectrum.

Information engines exploit feedback to extract work from thermal fluctuations, extending the second law of thermodynamics through information-theoretic bounds. While several such bounds have been proposed, their relative performance under realistic conditions—where measurements are noisy and feedback is temporally correlated—remains largely unclear. Here, we experimentally and theoretically investigate this problem in an underdamped feedback-controlled system with Markovian measurements but non-Markovian control sequences. We compare three representative bounds derived from transfer entropy, unavailable information, and Markovian mutual information, and find that none is universally optimal. Instead, measurement noise preferentially affects information measures that rely on detailed trajectory statistics, while leaving quantities based on instantaneous correlations comparatively robust. As a consequence, trajectory-dependent bounds deteriorate rapidly, giving rise to a crossover in which the Markovian mutual-information bound becomes tighter than the unavailable-information bound over a broad range of measurement noise. Our results reveal a general limitation of information-theoretic descriptions that rely on detailed trajectory statistics in realistic settings and provide a unified perspective on information thermodynamics beyond idealised feedback protocols.

What is a Faddeev–Popov ghost? The textbook answer is that it is a trick: a way of writing a functional determinant as a term in the action, and nothing more. Dougherty 2021 and Dougherty and Read 2026 have argued that this undersells the ghost, which on their account encodes classical structure of the configuration space, viz. the degree-one generators of the Chevalley–Eilenberg complex of the action Lie algebroid. I agree with them that the ghost encodes classical structure. But I think the structure is bigger than they say. The ghost, I argue, is a principal connection $\varpi$ on the bundle $F \to F/G$ of gauge potentials over physical configurations; the BRST operator is the exterior derivative along the orbits; and the Chevalley–Eilenberg ghost coincides with $\varpi$ restricted to the orbits (and every $\varpi$ has the same restriction). The restriction drops the horizontal complement, and I show that gauge-fixed quantisation needs that complement. A gauge-fixing installs it as a pairing of configurations across orbits (a counterpart relation, in Lewis's sense); dressed observables and local counterfactuals rely on this pairing, but it is discarded by the quotient $\F/\G$. In the non-Abelian case Singer's theorem forbids a flat $\varpi$, and there the pairing exists only as parallel transport. Finally, BRST survives gauge-fixing because it is vertical and rigid, and so leaves any such pairing unchanged.

The rational design of photocatalysts for environmental remediation and CO2 conversion remains limited by the high computational cost and sparse experimental data describing multi-parameter photocatalytic behavior. This work presents an integrated machine-learning framework that couples reinforcement learning-based metal-organic framework (MOF) generation with a multi-stage Crystal Graph Convolutional Neural Network (CGCNN) prediction funnel to identify photocatalysts optimized across multiple electronic and structural features. 120,000 MOF candidates were generated and screened using 13 key descriptors, including band-gap suitability, CO2/H2O selectivity, adsorption energy, and structural stability. The funnel approach reduced computational cost by 4.13-fold while maintaining predictive robustness. Two top candidates, a Cr-based and a Zn-based MOF, exhibited predicted photocatalytic fitness values of 1.70 +/- 0.25 and 1.20 +/- 0.05 fold higher respectively than benchmark materials such as PCN-224(Zr), demonstrating simultaneous improvements in light absorption, redox energetics, and framework durability. Simulated X-ray diffraction patterns confirmed strong structural agreement with experimentally synthesized MOFs, indicating high synthesizability. Post-hoc analysis revealed recurring structural motifs, such as the N262 metal cluster, that correlated strongly with high predicted photocatalytic activity. These results highlight the potential of data-driven methods to accelerate discovery of efficient and durable photocatalysts for environmental and energy-related transformations, providing a foundation for experimental realization and large-scale implementation of computationally designed MOFs.

Analytical solutions encompassing the so-called Hubble tension problem are revisited through the framework of Weyl–Wigner quantum mechanics and discussed in the context of generalized phase-space scenarios of quantum cosmology. After reviewing the nature of the problem and its recent developments, an extended formulation constructed within the quantum phase-space framework to address the Hubble tension is proposed. For the quantum cosmology described in the minisuperspace framework through (generic) localized phase-space quantum states, when residual quantum corrections to the Einstein–Friedmann equation are analytically derived, quantum effects are shown to suppress the Hubble tension divergence between early- and late-time predictions. Besides addressing the Hubble tension problem within the standard $\Lambda$CDM cosmological model, our approach encompasses generalized quantum cosmological scenarios that also include curvature and dark sector modifications.

A study of the production of the Higgs boson in association with either a top-quark pair ($t\bar{t}H$) or a single top quark ($tH$) in the $\tau$-lepton-pair decay channel is presented. The analysis relies on final states featuring fully hadronic decays of the top quarks and the $\tau$-leptons. It employs data samples of proton–proton collisions at $\sqrt{s}=13$ and 13.6 TeV recorded with the ATLAS detector at the CERN Large Hadron Collider and corresponding to integrated luminosities of 140 fb$^{-1}$ and 161 fb$^{-1}$, respectively. The measured signal strength ($\mu$), defined as the measured cross-section normalised to the Standard Model prediction, is $\mu_{t\bar{t}H}=1.51^{+0.71}_{-0.62}$ for $t\bar{t}H$ and $\mu_{tH}=-0.4^{+5.6}_{-5.1}$ for $tH$. Additionally, the $t\bar{t}H$ cross-section is measured differentially in three bins of the Higgs boson transverse momentum in the simplified template cross-section framework.

Most benchmarks for causal inference over time series are observational, small, or domain-specific, leaving interventional and counterfactual estimation under-served exactly where it matters most, such as in healthcare, policy evaluation, and climate science. We introduce DoTime, an open, scalable, and theoretically grounded generator of multivariate temporal structural causal models (TSCMs) with interventions, released as the \code{dotime} PyPI package together with four frozen evaluation suites. Beyond existing work, it adds capabilities absent from prior generators: continuous-time intervention windows, counterfactual sampling modes with a positivity guard, regime-switching SCMs as a strict generalization of interrupted time series, non-stationary dynamics by construction with switching SCM parameters, and deterministic ramp and sinusoidal intervention profiles that place trends and structural breaks inside the evaluation window. Moreover, it demonstrates the suitability of the generator as a prior for a causal foundation model reference implementation. The released suites span a training-scale snapshot of $100{,}000$ trajectories and eight named identification structures, each with exact ground truth: paired interventional trajectories from the same SCM throughout, and shared-noise counterfactuals in the continuous-time suite. We ship reference baseline implementations with an evaluation harness, and pose a falsifiable claim: interventional training buys a measurable direction-accuracy advantage over an observational model of identical capacity. It is tested across three training seeds per arm. Under structure-matched evaluation on held-out episodes, the interventional prior-fitted network's (PFN) gap is positive in every structure, trajectory length, and seed tested.

Variational quantum algorithms often encounter barren plateaus, where cost gradients decay rapidly with increasing circuit depth, undermining the trainability of parameterized quantum circuits. This paper evaluates AdaInit (Adaptive Initialization), proposed by Zhuang and Cunningham, which uses large language models to propose initial parameters for quantum neural networks. We study a simplified single-query AdaInit variant paired with GPU-accelerated simulation in NVIDIA CUDA-Q and apply it to binary classification on the DMR-IR mammography dataset. AdaInit delivers 14.6 times higher gradient variance at initialization than random initialization (0.0095 vs. 0.0006), producing 160 times faster convergence (1.1s vs. 176 s) while maintaining the same classification accuracy of 61.4 percent. We provide theoretical analysis grounded in the geometry of parameterized circuit landscapes and show empirically that LLM-guided initialization places the optimizer in trainable regions of parameter space. Beyond performance, our results indicate that a single LLM query can yield informative parameters without iterative refinement, suggesting a low-overhead path to improved trainability. The findings validate AdaInit in a medical imaging setting and demonstrate its compatibility with GPU-accelerated quantum backends for practical speedups.

We investigate magnetic breakdown near Van Hove singularities (VHSs) in the electron-doped rhombohedral tetralayer graphene, where chiral superconductivity has recently been reported. Using the noninteracting band structure and Kubo formula, we identify anomalous Shubnikov-de Haas effects: Ring-like structures in the Landau fan and anomalous high-frequency peaks in the frequency spectra. These anomalous quantum oscillations can be understood by the reconstruction from magnetic breakdown among three nearby Fermi pockets separated by VHSs. Remarkably, these qualitative anomalous features persist into a stronger-VHS regime, where the semiclassical picture breaks down. The temperature and (weak) disorder dependence of the oscillations are also investigated. Our results establish that the magnetic-breakdown-induced anomalous quantum oscillation provides a general distinctive probe for the underlying Fermi-surface geometry associated with VHSs and may explain the recent quantum oscillation experiment in rhombohedral tetralayer graphene [arXiv:2606.05356].

Topological data analysis (TDA) provides a powerful framework for extracting information about the shape of complex, unstructured data, but the classical cost of computing high dimensional topological features limits its application. Quantum algorithms for TDA offer a route around this bottleneck, yet existing approaches typically focus on exact or high precision Betti number estimation, making the regime for practical quantum advantage appear narrow. Here, we instead frame quantum TDA as a feature-extraction method for downstream data analysis by extracting low-order spectral information from the combinatorial Laplacian as a proxy for high-dimensional topology. We support this perspective from both the application and algorithmic sides. First, we show that higher-order TDA features improve predictive performance in two time-series applications: functional MRI analysis for neurodegenerative disease classification and financial time-series analysis for identifying market instability. Second, we develop a moment-based quantum algorithm and show that low-order moments, including the relative trace, are strongly correlated with high-dimensional Betti information, even when the relative Betti number is small. Finally, we present circuit constructions, resource estimates, quantum-classical crossover projections, and experimental results from a Barium development system similar to the forthcoming IonQ Tempo line, extracting Laplacian-derived observables from graph instances and quantitatively comparing them with exact Betti information. Together, these results establish quantum TDA as a practical approach for extracting topological features from classically challenging data

Modular quantum computing is a leading paradigm for scaling quantum computation beyond the resource limitations of monolithic devices. In this architecture, multiple quantum processing units (QPUs), employing identical or distinct qubit modalities, are interconnected via shared entanglement. Here, we investigate how errors at module interfaces and within individual QPUs affect fault-tolerant computation when qubits are encoded using the rotated surface code. Going beyond the logical-memory benchmark, we perform circuit-level simulations of fault-tolerant nonlocal CNOT gates implemented via lattice surgery between QPUs connected by noisy Bell pairs, and analyze the resulting logical error rates. Our results show that interfaces can tolerate noise up to an order of magnitude higher than intra-QPU noise, with only a minor reduction in the fault-tolerance threshold. We further develop an efficient protocol for preparing distributed fault-tolerant logical GHZ states, reducing ancilla overhead, time, and nonlocal Bell-pair consumption. We show that ancilla minimization in this setting is equivalent to a vertex-cover problem on an associated graph, and introduce a polynomial-time heuristic algorithm for finding low-overhead solutions. Our results provide quantitative evidence that distributed quantum error correction can enable scalable, fault-tolerant quantum computation in modular architectures.

Recently, a fit of charmless $B\to PP$ decays ($B \in \{B^0, B^+, B_s^0\}$, $P \in \{ \pi, K, \eta, \eta' \}$) to the latest data was performed under the assumption of flavour SU(3) symmetry [SU(3)$_F$]. It was found that there is a $4.1\sigma$ disagreement with the SU(3)$_F$ limit of the Standard Model [$\rm SM_{SU(3)_F}$]. In this paper, we extend this analysis to charmless $B \to VV$ decays ($V \in \{\rho, K^*, \phi, \omega\}$). The fit examining $B \to \rho K^*$ decays, assuming only isospin symmetry, is found to be acceptable. When we fit to $B \to VV$ decays with $V \in \{ \rho, K^* \}$ within SU(3)$_F$, we find a $5.2\sigma$ discrepancy with SM$_{SU(3)_F}$. Finally, when $B \to VV$ decays with $V \in \{ \rho, K^*, \phi, \omega \}$ are considered, the discrepancy grows to $>7\sigma$. The theoretical input in this analysis is modest, so our results are quite rigorous, group theoretically, and hold almost exactly in the SU(3)$_F$ limit. Although it seems unlikely that the introduction of $\sim 30$% SU(3)$_F$-breaking effects can account for this discrepancy, this must be verified.

Flat-band materials host rich collective phenomena, yet a complete theory of their signatures in inelastic light scattering remains lacking. While naive theories of interacting flat bands would predict that Raman scattering vertices vanish identically in the limit of vanishing dispersion, we show that this picture is incomplete upon including the multiorbital character of such systems. We show that virtual interband processes generate a finite subgap Raman vertex controlled by the quantum geometric tensor even in the strict flat-band limit. We develop a systematic perturbative theory for Raman scattering from flat bands in the limit where the photon energy is far from resonance with interband transitions. Treating interband Coulomb scattering and light-matter coupling on equal footing, we decompose the Raman scattering vertices into an interaction-independent geometric term expressible directly in terms of the quantum geometric tensor, together with effective resonant and non-resonant pieces generated by virtual interband Coulomb scattering. We then study the polarization-resolved Raman response from collective excitations of an interacting flat band with nontrivial quantum geometry, and demonstrate quantitative agreement of our framework with a full multi-orbital calculation at large photon detuning from interband transitions. These results establish quantum geometry as an intrinsic contribution to inelastic light scattering in flat-band systems, and suggest polarization-resolved Raman spectroscopy as a quantum geometry-sensitive probe of the collective excitations of correlated flat-band platforms.

We exhibit a configuration of five point charges in Euclidean space whose electrostatic potential admits at least 24 critical points all of which are non-degenerate. Maxwell's conjecture that the field of \(n\) point charges has at most \((n-1)^2\) critical points which are all non-degenerate is therefore false.

The manipulation of quantum entanglement is fundamentally irreversible: some mixed entangled states require pure entanglement for their preparation, although no pure entanglement can be recovered from them by local operations and classical communication. This irreversibility is known to persist even under the maximal class of operations that do not generate entanglement, revealing a fundamental distinction between entanglement theory and thermodynamics. We construct cases for which any attempt to restore reversibility necessarily incurs an error that increases exponentially with the number of copies. Technically, we demonstrate a strict separation between the exponential strong-converse distillable entanglement and the exponential strong-converse entanglement cost. Our result resolves a conjecture posed by Lami and Regula (Nat. Phys. 19, 184-189 (2023)) and strengthens it by showing that the irreversibility of entanglement persists even at the level of polynomially (in the number of copies) growing error. We further derive a semidefinite-programming lower bound on the exponential strong-converse cost under non-entangling operations. Finally, for the class of completely PPT-preserving operations, we construct analytically solvable families of antisymmetric states exhibiting the exponential strong-converse irreversibility. Remarkably, to our knowledge, no analogous separation between exponential strong converse cost and the analogous distillable entanglement is currently known even under the more restrictive class of LOCC operations.

Chain inflation offers an alternative to standard slow-roll dynamics, with accelerated expansion proceeding through a sequence of rapid quantum tunneling events between metastable vacua. At the high energy scales relevant for the early Universe, scalar fields are generically expected to couple non-minimally to gravity via operators like $\xi R\phi^2$, allowed by symmetry and required as counterterms for interacting theories in curved spacetime. We study the dynamical and observational consequences of this coupling for chain inflation. We find the modifications to the model for arbitrary $\xi$ and focus on interesting phenomenology for $\xi ={\cal O}( 10)$. We show that, in the Einstein frame, the non-minimal coupling induces a field-dependent amplification of the Euclidean bounce action, thus modifying the tunneling rate across the chain. We develop an analytic framework connecting this modified tunneling dynamics to the scalar spectral index, its running, the primordial curvature power spectrum, and the stochastic gravitational wave background from bubble collisions. As one consequence, the non-minimal coupling breaks the rigid relation between the scalar tilt and inflationary scale that drives the minimally coupled pure tilted cosine model to very low energies ($V_*^{1/4}\lesssim 3\,\rm{GeV}$, where $V_*$ is the value of the inflationary potential when the CMB-relevant modes exit the horizon), allowing for viable high-scale chain inflation with $V_*^{1/4}\sim 10^{11}\,\rm{GeV}$. Furthermore, non-minimally coupled chain inflation at high scales produces a peaked stochastic gravitational wave signal in the dHz-kHz bands, accessible to upcoming interferometers such as the Einstein Telescope and Cosmic Explorer. Finally, the model predicts a distinct running of the spectral index that will be testable by the Simons Observatory, making it a prime target for multi-messenger cosmology.

Axions and axion-like particles are a compelling candidate for physics beyond the standard model. While many axion searches are focused on the linear coupling to photons $\theta F \tilde{F}$, the possibility of a quadratic coupling to the electromagnetic kinetic term, $\theta^2 F^2$, leads to novel phenomenology and new opportunities for testing axion-like particles. In this work we propose mechanisms for generating this coupling in string theory, which can be broadly classified as classical, perturbative, and non-perturbative. In benchmark examples, we find that both perturbative and non-perturbative quantum contributions such as instantons lead to couplings that are suppressed, $g \ll 1$ in units of $1/f^2$ where $f$ is axion decay constant, though easily larger than analogous coupling of the QCD axion that is generated through loops of charged pions. These analyses suggest that quadratic axion couplings to gauge fields are ubiquitous in string theory, and should be taken seriously as a probe of the string theory axiverse, both of string theory candidates for dynamical axions, such as dark matter or dark energy, and for spectroscopy of the string theory axiverse.

The debris disk orbiting the M star AU Microscopii has a series of large-scale clumps that move away from the star at high velocities above the mid-plane on the southeast side. Two more bright features lie on the northwest side of the disk, localized below the mid-plane and moving toward the star. These clumps are only observed in scattered light indicating that they affect small 0.2$\mu$m-sized grains. We present a mechanism for emitting periodic dust clumps by appealing to stellar forces and an inclined, eccentric planet interacting with an exterior debris disk. In our best-matching simulations, the planet exerts an impulse on the disk every orbital period, generating periodic enhancements in dust above the mid-plane. We assume that the stellar wind only acts on grains once they reach a height above the mid-planet that exceeds a threshold value (a free parameter in our model), at which point they are accelerated outward. The behavior of periodic particle ejections and trajectories depends significantly on the planet's mass, eccentricity, and inclination; separation between the planet and disk; and the ratio of stellar wind force to the star's gravitational force ($\beta$). We find a promising qualitative match to observations with simulations that include an as-yet-undiscovered and observationally allowed planet with mass $2 M_J$, semi-major axis between 3-4 au, eccentricity of 0.37, and inclination of 30$^\circ$, a ring of particles between 5-6 au, and a stellar wind height threshold of $z_h = hr$, where $h \approx 0.02$. We visualize our simulation with surface brightness maps to compare with existing observations of AU Mic. We find that a value of $\beta \approx 1.8$ accelerates the clumps radially outward at velocities that are comparable to the clumps seen in the AU Mic disk and produces features similar to those observed.

We study the Sachdev-Ye-Kitaev (SYK) Hamiltonian $H_{\operatorname{SYK}}$ on $n$ Majorana modes with $k$-body interactions, and prove that $\mathbb{E}\|H_{\operatorname{SYK}}\|_{\operatorname{op}} = (1 - o(1))\cdot\sqrt{2n}/k$ for super-constant $k\leq o(\sqrt{n})$, where the expectation is over the disorder variables in the Hamiltonian. This confirms predictions due to Garcia-Garcia, Jia and Verbaarschot and answers a question posed by Feng, Tian, and Wei. Our results extend to the sparse SYK Hamiltonian. As a corollary, we obtain that a dissipative quantum algorithm due to Basso, Chen, and Dalzell provably computes the ground state energy of the SYK Hamiltonian up to an $O(1)$-multiplicative factor for all $k < \sqrt{n}/4$. Our key technical idea is identifying an explicit, deterministic linear operator $\mathsf{x}$ such that a fixed quadratic form of $\mathsf{x}^{2\ell}$ exactly equals the expected trace moments of the SYK Hamiltonian for every $n$ and $k$. This linear operator can be naturally viewed as a twisted model of bosons on the space of hyperedges of a hypergraph. The problem thus reduces to identifying the spectral edge of $\mathsf{x}$, which we show is dominated by the spectrum of a natural ${n \choose k}$-dimensional matrix from the Johnson scheme and is straightforward to compute using known results. To show that our bound is sharp, we construct a witness state with a large quadratic form on $\mathsf{x}$ and transform it into a certificate of a lower bound on the largest quadratic form on $H_{\operatorname{SYK}}$. Beyond the SYK Hamiltonian, our techniques also apply to the $k-$local quantum spin glass (QSG), yielding $\mathbb{E}\|H_{k-\operatorname{QSG}}\|_{\operatorname{op}}\leq O(\sqrt{n/k})$ for all $1\leq k\leq\sqrt{n}/2$, thus improving the standard $O(\sqrt{n})$ bound by a factor of $\sqrt{k}$.

We show that nonadaptive single-qubit Pauli measurements suffice to test whether an unknown $n$-qubit state $\rho$ is $\varepsilon$-close to or $O(\varepsilon)$-far from an ideal target state $|\psi\rangle$, for all but a $2^{-\Omega(n)}$ fraction of target states. The test uses $O(\varepsilon^{-2}\log(1/\delta))$ copies of $\rho$ to achieve confidence $1-\delta$, which is information-theoretically optimal even among protocols with arbitrary joint measurements. The main technical innovation is an uncertainty principle for weighted generalizations of the total influence of Boolean functions. As a simple example, the unweighted variant states that $\mathbf{Inf}[f]+\mathbf{Inf}[\widehat{f}] = \Omega(n)$, which is a natural hypercube analogue of the Heisenberg uncertainty principle (here $\widehat{\,\cdot\,}$ denotes the $2^{-n/2}$-normalized Fourier transform). The weighted case generalizes $\mathbf{Inf}[\,\cdot\,]$ and $\mathbf{Inf}[\,\widehat{\,\cdot\,}\,]$ to Dirichlet energies associated with Glauber dynamics for certain dual measures on the cube.

Demonstrating a practical quantum advantage remains a central goal in quantum information science. While quantum computational supremacy is still technologically demanding, communication complexity offers a promising route to showcase quantum advantage with current photonic platforms. Here we introduce a reconfigurable optical platform for one-way quantum communication complexity based on multimode fibers and wavefront shaping. We experimentally validate it by implementing a genuine one-way quantum communication complexity problem for which an exponential quantum–classical communication separation is known. Complementary numerical simulations show that the same reconfigurable decoding architecture can support more general one-way communication tasks with comparable performance, while also offering a route to higher-dimensional implementations without increasing hardware complexity. Together, these results establish multimode-fiber wavefront shaping as a versatile hardware platform for one-way quantum communication complexity and provide a concrete roadmap toward more demanding protocols, where stronger quantum–classical separations could enable practical demonstrations of quantum advantage.

We investigate the cosmological imprints of massive fields during inflation through primordial non-Gaussianity (PNG). When these fields are sufficiently light, they produce a signal in galaxy clustering, $\propto f_{\rm NL,\Delta}k^{\Delta-2}$ with $\Delta\in(0,3/2]$, corresponding to a beyond-local PNG contribution to the scale-dependent bias. We use the angular correlation function to constrain $f_{\rm NL,\Delta}$ and $\Delta$ using imaging data used for the targeting of the Dark Energy Spectroscopic Instrument (DESI). For the most aggressive systematics treatment, there is no evidence for local PNG, hence no constraint on $\Delta$. However, when considering a less aggressive treatment, a hint is found with $f_{\rm NL}^{\rm loc}=27^{+10}_{-9}$, consistent with previous analyses. For beyond-local PNG, that signal gives a preference for $f_{\rm NL, \Delta}=5.12^{+6.13}_{-3.62}\times10^{3}$ and $\Delta=0.91^{+0.25}_{-0.19}$. This preference is not robust under decontamination choices, likely driven by residual systematics, and we present it as a showcase for future constraints. Additionally, we forecast the sensitivity of upcoming Stage-V surveys, the Wide-field Spectroscopic Telescope (WST), the MUltiplexed Survey Telescope (MUST), and the Spectroscopic Stage 5 Experiment (Spec-S5), to constrain $\Delta$ using Lyman-break galaxies. Around the local limit, $\Delta^{\rm fid}=0$, we find that they can reach uncertainties of $\sigma(\Delta)\simeq0.17-0.50$, depending on the survey, for a fiducial $f_{\rm NL,\Delta}^{\rm fid}=4$. The constraining power on $\Delta$ increases as we increase $f_{\rm NL,\Delta}^{\rm fid}$ and decreases for larger fiducial $\Delta$. Finally, we derive a relation between the detectability of $\Delta$ and the local PNG constraints, $\sigma(f_{\rm NL}^{\rm loc})$. This provides a tool to estimate the survey sensitivity required to resolve massive-field signatures.

The superradiant instability of rotating black holes can generate a significant overdensity of bosonic matter around them, together forming a gravitational atom. This mechanism allows one to probe a large part of the parameter space of scalars, axions and vectors that lies beyond the reach of traditional detection strategies. Modelling the dynamics of these systems in binaries is, however, subtle, due to the competing nature of the different perturbations. In this work, we provide a consistent scheme to treat these perturbations, including both the minimal set of internal ones (relativistic corrections and self-gravity) and the external tidal field. Within the worldline effective field theory framework, we then calculate the Love numbers of gravitational atoms, for the first time also for the most interesting case of spinning clouds. Certain spinning states are found to have negative (static) Love numbers, with a magnitude parametrically enhanced relative to the scaling for the non-spinning states – in phenomenologically relevant scenarios by a factor $\mathcal{O}(10^2\text{--}10^3)$. Finally, we consider the binary evolution in the early inspiral, assessing the impact of the competing perturbations on shifted resonances, which for dense clouds can alter the nature of some of the hyperfine and fine transitions (sinking instead of floating). This dynamical picture allows us to identify at which stages the permanent multipoles are the strongest indicators of new light bosons, and at which the induced ones take over, while keeping track of both types of finite-size effects even during the resonance. More broadly, our results demonstrate that gravitational atoms are a useful toy model for studying the theoretical aspects of tidal response in gravitational-wave physics.

Spin is the hidden engine behind the zoo of MacWilliams transforms in weight enumerator theories - not only for qubits and qudits, but even for classical codes. From nothing more than a split into trivial and nontrivial errors, we kinematically derive the MacWilliams transform as a Wigner-$D$ rotation between two canonical bases. Within each classical and quantum theory, changing the length $n$ leaves the rotation untouched: the same element simply reappears at spin $n/2$. And at fixed $n$, changing the rotation axis simply moves between the various classical and quantum theories.

Quantum query is a basic subroutine in many quantum algorithms, and Quantum Random Access Memory (QRAM) provides a natural way to realize such coherent query access. In delegated settings, however, a standard QRAM query interface can expose sensitive information to the server. This paper introduces oblivious QRAM, a cryptographic abstraction for privacy-preserving delegated coherent query access. The protocol consists of an offline refresh phase and an online protected query phase. The database is stored in an encrypted and shuffled layout, and each query is protected by coherent address masking using either a quantum-secure pseudorandom permutation (qPRP) based method or a quantum one-time pad (qOTP) based method. In the adopted client model, the online protection adds only modest quantum overhead beyond the query register, avoiding the exponential quantum resources that would otherwise be required by an equivalent local QRAM construction. The qPRP-based variant also supports multi-query use by distributing database refresh across multiple queries to reduce classical communication. To address malicious servers, decoy checks are further incorporated to strengthen privacy protection and enable probabilistic tampering detection. Compared with fully blind quantum computing, this framework provides a lighter abstraction tailored to private delegated QRAM access, significantly reducing quantum resource requirements on both the client and server sides and achieving an exponential reduction in quantum communication.

The Non-Equilibrium Green's Function (NEGF) is the standard formalism for nano-scale electron transport. By recasting the NEGF scattering problem as a linear system of equations whose solution encodes the transmission and reflection amplitudes, we present the first quantum computerized implementation of NEGF. We apply both the Harrow–Hassidim–Lloyd and Variational Quantum Linear Solver algorithms to compute the transmission coefficient $T(E)$ of quantum dragon nanodevices within the single-band tight-binding model. Quantum dragon devices exhibit perfect transmission across the full conducting band regardless of internal disorder. The problem maps onto compact circuits of 3 and 4 total physical qubits for the 2-site and 6-site dragon devices, respectively. A similarity transformation block-diagonalizes the NEGF linear system reducing the Pauli decomposition of the block-encoded matrix. We demonstrate the feasibility of quantum computation by performing ideal and noise-aware simulations and computations on physical IBM quantum processor.

Consider a material point in finite dimensions moving under the influence of a potential force according to Newton's laws. Suppose the potential energy function is a generalized well, strictly convex transverse to a smooth submanifold $M$ on which it is minimal. If the potential is steep, one expects the particle will oscillate rapidly about this submanifold and, if the initial displacement is not too great, should approximately move along $M$ as if it were ideally constrained (e.g. geodesic). This expectation is true if the initial conditions are very well prepared but may fail otherwise - additional potential forces determined by how the Hessian of the potential varies along $M$ may be present. The origin of this force is that the transversal motion acts as a simple harmonic oscillator with a slowly varying frequency, which approximately conserves action, not energy. In this work, we regard continuum mechanical systems such as the elastic thread or compressible fluid as material points moving in an infinite dimensional space according to Newton's laws for appropriate potential energy functionals. We show how to arrive at ideally constrained systems such as the inextensible thread and incompressible fluid as a limit of a strong potential force, computing also corrections to the naive predictions when the data is not very well prepared. For example, for the thread we find a resistance to bending emerge from a strong resistance to compression/expansion. For the fluid, the effective incompressible dynamics may be driven by a remnant acoustical wavefield. Both of these emergent features are nonlinear and non-local. Finally, we give examples of some limits for which the naive models robustly hold because the additional force is trivial. These include the homogeneous incompressible Euler, anelastic Euler, as well as the lake and great lake equations.

Materials behavior is often treated as a deterministic mapping from structure to properties, yet many important phenomena emerge from the conditional activation of multiple mechanisms across scales. This is especially evident in fatigue of metals, where crack growth is typically modeled as monotonic and irreversible process, despite evidence that local microstructure, loading history, and competing unit processes can shift the balance among propagation, arrest, and self-healing. Here we present a probabilistic framework that describes materials behavior as an ensemble of constituent mechanisms whose activation, interaction, and evolution determine emergent outcomes. The framework connects mechanism activation, state evolution, and macroscopic observables in a probabilistic way. In the case of fatigue crack propagation, it reframes damage tolerance as an inference problem over mechanism competition and provides a basis for integrating multiscale simulation, multimodal characterization, and machine learning. The same logic extends to other physical and chemical systems suggesting a portable framework for any system in which emergent behavior reflects mechanism competition under changing conditions. The broader ambition of this perspective review is a shift from correlating structure and performance after the fact to identifying, in advance, the conditions that make desired emergent behavior probable.

We observe that the apparent inhomogeneous broadening, as measured by two-dimensional coherent spectroscopy (2DCS), of the exciton resonance in transition-metal dichalcogenide monolayers depends on the excitation strength. A key strength of 2DCS is the ability to separate inhomogeneous broadening, which primarily contributes to the diagonal linewidth, from homogeneous broadening, which dominates the cross-diagonal linewidth. We show that the fluence dependence of the diagonal linewidth arises from the effective saturation fluence varying with the exciton's resonance energy, i.e., inhomogeneous saturation. These results are critical for interpreting the exciton linewidths, which are often used as a measure of sample quality.

We numerically study the outcome of symmetry breaking motivated by Grand Unified models. Our results show the formation of biased domain walls for a range of parameters together with magnetic monopoles. The interactions of walls and monopoles leads to novel processes such as the absorption of monopoles on walls, production of monopoles when domain walls annihilate, collapse of walls with magnetic charge that can, with gravity taken into account, produce magnetically charged black holes, and production of a stochastic gravitational wave background from biased domain walls. Our findings open new avenues for probing the grand unification epoch by cosmological observables.