Fluid Dynamics
Macroscale vortex impingement at a porous-fluid interface induces local heat-transfer enhancement
Thibaut K. Kemayo, Vishal Srikanth, Justin Courter et al. (+2 more)
Externally generated wakes can impinge on porous layers in several practical heat transfer applications. However, the transport of these macroscale
vortices and their resulting influence on heat transfer in the porous layer remain unknown. In this paper, two-dimensional pore-resolved simulations are used to examine a square-bluff-body wake impinging on a porous layer composed of an in-line array of heated square obstacles at Re = 500-4000, Pr = 0.7 and 7.0, and porosities $\phi$ = 0.75, 0.85, and 0.95. The incident macroscale
vortices break down starting immediately at the porous-fluid interface. Following macroscale turbulent thermal transport in this entrance region, fluctuations farther downstream are aligned with the pore geometry and are generated at the microscale level by pore-throat shear, separation, and repeated obstacle wakes. Direct impact locally improves heat transfer at the porous-fluid interface by increasing the local Nusselt number relative to a non-impingement region. The interfacial heat-transfer enhancement varies with porosity, Reynolds number, and Prandtl number, with a peak enhancement of 18.2% observed for $\phi$ = 0.85, Pr = 7.0, and Re = 1000. The wake-associated macroscale turbulent heat-flux contribution decays within a consistence entrance region extending approximately 3-4 unit
cells into the porous layer across all investigated porosities, Reynolds numbers, and Prandtl numbers. For Re$\ge$1000, the persistent wake momentum deficit subsequently causes the heat-transfer contrast to become negative, resulting in lower heat transfer in the impingement region than in the non-impingement region.
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All authors Thibaut K. Kemayo, Vishal Srikanth, Justin Courter, Rodrigo R. Caballero, Andrey V. Kuznetsov
Instrumentation and Methods for Astrophysics
A pilot study on the CSST astrometric capability: Detecting astrometric binaries with Gaia synergy via simulated data
Shangyu Wen, Shilong Liao, Zhaoxiang Qi et al. (+8 more)
Context. The China Space-station Survey
Telescope (CSST) will provide deep, wide-field epoch astrometry during its 10-year mission. Astrometric binary orbits constrain the masses of
stellar and compact-object components. Orbital recovery depends on astrometric precision and temporal coverage. Combining CSST and
Gaia data extends the baseline and improves binary detection. Aims. We evaluate CSST,
Gaia, and joint astrometry for binary-candidate selection and 12-parameter (12p) orbit fitting at faint magnitudes ($g>17.8$). We also test how regular CSST cadences affect the yield of 12p fits satisfying our criteria. Methods. We constructed a mock catalog, simulated CSST and
Gaia epoch astrometry, and fitted five-parameter (5p) single-
star models to derive astrometric diagnostics, proper-motion anomaly features, and observational-sampling features. A four-stage histogram-based gradient-boosting classifier used these features to select candidates for 12p orbit fitting and assessment. Results. On the independent test set, the classifier reaches a precision of 0.802 and a recall of 0.181 among eligible true binaries. In the scenario-specific fitted samples, joint astrometry raises the fiducial fraction from 6.76% for
Gaia alone to 10.46%; for fitted binaries with $P_{\rm true}>15{\rm yr}$, it rises from 2.37% to 6.78%. The current CSST schedule yields few fiducial fits, while idealized regular cadences increase the yield mainly at $g\lesssim21$. Conclusions. In the simulation, joint CSST and
Gaia epoch astrometry yields higher fractions of fitted unresolved binaries satisfying the stated criteria than
Gaia-only solution. A practical strategy is to select candidates from 5p diagnostics and astrometric anomalies, obtain more regular CSST follow-up observations, and then fit 12p orbital models and apply the selection criteria.
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All authors Shangyu Wen, Shilong Liao, Zhaoxiang Qi, Zhensen Fu, Xiyan Peng, Ye Ding, Qiqi Wu, Qi Xu, Xun Sun, Keyu Zhu, Yong Yu
Quantum Physics
A Sum-of-Squares Hierarchy with Quadratic Convergence for Quantum Channel Coding
Hoang Ta and Hoang Anh Tran
Computing the optimal success probability for transmitting classical messages through a single use of a
quantum channel is NP-hard, even for two messages. An existing semidefinite programming hierarchy based on symmetric extensions provides convergent upper bounds with an a priori error estimate that decays as the inverse square root of the extension level. In this work, we construct a Hermitian sum-of-squares hierarchy for an arbitrary number of messages and prove quadratic convergence in its level. The error bound is proportional to the advantage over random guessing. Our approach combines state-discrimination duality with positive
polynomial kernels on products of spheres to construct feasible
polynomial dual certificates. For binary messages, the resulting bounds give a multiplicative approximation from above of the trace-norm contraction coefficient.
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Statistical Mechanics
Renewal process's guide to fractional Navier-Stokes equations
Hong Zhang
The Navier-Stokes equations, which remain unsolved, are crucial equations in fluid mechanics. Discovering the solutions to the Navier-Stokes equations is one of the challenging Millennium problems. In 1900,
Hilbert proposed a potential approach to tackle this problem by establishing the relationship between microscopic dynamics and the macroscopic continuum equations. The key bridge is the derivation of Boltzmann equation and the theory of probability. In this paper, we shall use the collision renewal process with arbitrarily distributed waiting times to derive the Boltzmann equation for the time
evolution of the probability of the velocity and the displacement of the particle, based on which we prove that the renewal process with exponential collision waiting time is equivalent to the classical Navier-Stokes equations, and that with power-law waiting time is equivalent to the fractional Navier-Stokes equations. Since the collision renewal process with arbitrarily distributed waiting times is a random process and is easy to perform the
stochastic simulations of trajectories to obtain the corresponding solution, we actually find a
stochastic approach to solve the classical and fractional Navier-Stokes equations.
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Solar and Stellar Astrophysics
Planetary Nebula Central Stars as Tracers of Planetary Nebula-Star Cluster Associations in the Galaxy
Vasiliki Fragkou, Luis Lomelí-Núñez, Dante Minniti et al. (+2 more)
Planetary nebulae (PNe) that are physically associated with
star clusters are rare but crucial for
stellar evolution studies because they allow their initial and final
stellar properties to be determined independently, contributing to constraints on the initial-to-final-mass relation (IFMR), which traces
stellar mass loss. Although the identification of such pairs is essential, most reported cases have been identified incidentally rather than through systematic searches. Here, we attempt to uncover new such associations in our
Galaxy employing literature PN central
stars (CSs) and
star cluster catalogues. Exploring relevant angular positions on the sky and kinematic
Gaia DR3 data, we identify 38 candidate CS-cluster pairs. The components of eight of these pairs present consistent interstellar extinctions, and their CS properties are compatible with
stellar evolution models. Two of these candidate pairs are already reported in the literature as true associations. We evaluate separately the remaining six pairs using literature PN observational data, assessing the likelihood of each pair being a true association. The initial and final masses of our best candidates are mostly consistent with the latest IFMR predictions and confirmed cluster-PNe points. An additional 46 CS-cluster pairs have components with compatible angular positions but lack kinematic CS data and are thus presented separately. More data are needed for a precise estimation of the physical parameters of most of our candidates and to confirm these associations, which will be addressed in future studies.
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All authors Vasiliki Fragkou, Luis Lomelí-Núñez, Dante Minniti, Arianna Cortesi, Denise R. Gonçalves
Mathematical Physics
Hadamard–Tetrahedral Symmetric Spacetime and Clifford-Like Factorizations of Dirac and Maxwell Operators
Farhad Aghili
A symmetric representation of Minkowski spacetime is constructed by combining a normalized fourth-order Hadamard transformation with an imaginary temporal coordinate. The resulting complex coordinates $q^a$ distribute time and space equally among four components and transform the Minkowski metric into a Euclidean-form complex bilinear metric. The four Hadamard spatial sign vectors form a regular tetrahedron and appear simultaneously in the transformed Dirac and Maxwell operators. The Dirac
matrices satisfy a Euclidean-form Clifford
algebra and contain tetrahedral combinations of Pauli
matrices, whereas the Riemann–Silberstein Maxwell
matrices realize the corresponding
spin-1 structure. A gauge-invariant QED Lagrangian is formulated in the same coordinates. In
Fourier space, the Dirac and Maxwell systems are governed by the common invariant $\kappa_a\kappa^a$, while the complete Maxwell operator admits an exact rectangular Clifford-like factorization. The formulation is further extended to the weak-field Einstein–Dirac–Maxwell system. In harmonic gauge, the linearized gravitational field is governed by the same scalar wave operator $\Box_q$, while gravitational corrections to the Dirac and Maxwell equations enter through the perturbed tetrad,
spin connection, and
curvature. This common principal-operator structure suggests shared spectral kernels and scalar-wave preconditioning for coupled field solvers.
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Superconductivity
Eight-unit-cell electronic modulations in cuprates originating from local molecular orbitals
Zhiheng Yao, Sixuan Chen, Jianfa Zhao et al. (+10 more)
The pair density wave (PDW) state with eight-unit-
cell (8a0) periodicity has been widely regarded as the primary order in cuprates, yet its existence and origin remain subjects of intense debate. Using spectroscopic imaging scanning tunneling microscopy, we observe spatial modulations of the electronic states with approximately 8a0 periodicity in both the superconducting and insulating regimes of hole-doped Ca2CuO2Cl2 cuprate. We find that the 8a0 spatial patterns are generated by the formation of molecular orbitals by doped holes, which organize into 4a0*4a0 plaquettes as the basic unit. Our results identify the 4a0 molecular orbital as the fundamental electronic building block in cuprates, while the 8a0 PDW represents a spatial subharmonic that emerges at sufficiently high doping.
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All authors Zhiheng Yao, Sixuan Chen, Jianfa Zhao, Shusen Ye, Weixiang Qu, Ning Xia, Yuling Dai, Luchuan Shi, Hongrui Zhang, Zhenqi Hao, Changqing Jin, Shuo Yang, Yayu Wang
General Relativity and Quantum Cosmology
Probing quantum chaos near a wormhole throat with a circular string
Ai-chen Li, Xin-Fei Li and Xuanting Ji
We investigate whether
quantum fluctuations of a circular probe string develop a
quantum-chaotic response while traversing a wormhole throat. The classical circular-string
embedding is periodic and radially stable, but its two physical transverse polarizations experience time-dependent
tidal potentials. Expanding the world-sheet action to quadratic order, we canonically quantize these modes and construct out-of-time-ordered correlator(OTOC) amplitudes from their unequal-time commutators. For the Ellis–Bronnikov wormhole, both polarizations exhibit finite intervals of approximately exponential OTOC growth associated with the first throat passage. The corresponding dimensionless rate measured with respect to physical time is positive over the parameter range studied and generally decreases as the probe energy is increased relative to the throat scale. In the global-monopole extension, increasing the solid-angle deficit narrows the band of locally amplifiable modes and suppresses the extracted rates; a sufficiently strong defect can nearly quench the radial signal, while the angular channel retains a polarization-dependent non-monotonic structure when the energy-to-throat-scale ratio is small. These quantities characterize finite-time dynamical sensitivity in the Gaussian fluctuation sector and should not be identified with asymptotic many-body chaos or a thermodynamic phase transition. Although the numerical analysis uses two representative wormhole geometries, the construction depends only on covariant world-sheet fluctuations and real-time commutators. It therefore provides a transferable, non-
holographic framework for applying
quantum-chaos diagnostics directly to
quantum probes in curved spacetimes.
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Materials Science
Twist and strain identification in moiré heterostructures
Zhen Zhan, Federico Escudero, Dong Wang et al. (+4 more)
The geometrical and electronic properties of moiré materials are highly sensitive to the twist and strain in the samples due to the moiré magnifying effect. Accurate identification of twist and strain in moiré materials is therefore essential. In this work, we establish a general framework to extract the twist and strain configurations from moiré images with either atomic or moiré scale resolution. With only moiré-wavelength information, we show that there is a continuous family of possible twist and strain configurations, each one accounting for different orientations of the moiré pattern. To estimate the most likely twist-strain configuration, we discuss additional constraints and methods involving the minimum elastic energy and the electronic spectra. The minimum elastic energy, in particular, reflects that shear configurations become much more favorable as the strain increases. As an example of the developed methodology, we discuss the formation and identification of strained triangular moiré patterns. Our framework provides a comprehensive approach to identify the twist and strain configurations in systems with moiré-scale resolution.
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All authors Zhen Zhan, Federico Escudero, Dong Wang, Yiwen Liu, Ambikesh Gupta, Pierre A. Pantaleón, Francisco Guinea
Quantum Physics
Convex-Gaussianity of fermionic Gibbs states in perturbation theory
Kaifeng Bu and Yuanjie Ren
We study the structure of Gibbs states in weakly perturbed interacting fermionic systems. First, for a sparse
Hamiltonian $H=H_0+V$ with a quadratic term $H_0$ and a non-quadratic perturbation $V$ of scale $\epsilon$, we show that the Gibbs state $\rho_{\beta}$ decomposes into a convex combination of Gaussian states whenever the inverse temperature satisfies $\beta \le O(\log(1/\epsilon))$. Moreover, we prove that this bound is asymptotically tight by establishing that $\beta \le \Theta(\log(1/\epsilon))$ is necessary for certain sparse
Hamiltonians. This general framework applies directly to the weak-coupling (small-$\vert{}U\vert{}$) regime of the
Fermi–Hubbard model with hopping $t$ and on-site interaction $U$ on any graph of maximum degree $D$. Complementarily, in the strong-coupling (small-$\vert{}t\vert{}$) regime, we show that the Gibbs state remains convex-Gaussian up to $\beta \le O\big(\vert{}U\vert{}^{-1}\log(\vert{}U\vert{}/(D\vert{}t\vert{}))\big)$, revealing a mechanism for convex-Gaussianity distinct from the weak-coupling setting.
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Physics and Society
Energy pathway variety and the progress of the energy transition in European countries
Noam Abadi, Rossana Mastrandrea, Franco Ruzzenenti et al. (+1 more)
The integration of new energy forms into existing energy infrastructure has emerged as a critical challenge in the context of the pursuit of a sustainable energy transition. One of the main challenges is understanding how this integration takes place not only from the introduction, but also as energy follows existing paths or creates new ones through which it is transformed and used by different activities. Here we introduce techniques from network science to analyse this process for the case of 29 European countries between 1992 and 2021. We study how new energy forms increase or decrease the variety (heterogeneity) of paths through the system of each country by establishing new ones and replacing or phasing out existing ones. We find that the transition to systems based on renewable energy is characterised by an initial increase in the variety of paths while the heterogeneity of paths decreases at the end of the transition, when the proportion of non-renewables in the system tends to zero. We then demonstrate that greater heterogeneity (complexity) is associated with larger annual fluctuations in the proportion of non-renewable sources in the system, establishing a direct relationship between the progress of the transition and the complexity of the energy system in which it occurs. This contributes to the understanding of general properties of the dynamics of the energy transition and effects that accelerate or deter it.
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All authors Noam Abadi, Rossana Mastrandrea, Franco Ruzzenenti, Andrea Diaz
Materials Science
Heteroepitaxial Growth of PbSe on InP Substrates via Lattice-Matched III-V Buffer Layers
Biridiana Rodriguez, Mark Martino, Brody Yeung et al. (+2 more)
Detector cost remains a barrier to the widespread adoption of mid-wave infrared (3-5 micron) technology. PbSe, an inexpensive narrow band gap IV-VI
semiconductor that has been used since the early 1940s, delivers high performance for infrared detection despite the abundance of grain boundaries in polycrystalline films. Epitaxial growth, however, could provide superior crystalline quality and interfaces, but suitable substrates remain limited for PbSe. Recent PbSe heteroepitaxy has focused primarily on III-V, II-VI and group-IV substrates that each offer a comparatively narrow range of
lattice-matched
alloys for
heterostructure engineering. Here we show that InP-based heteroepitaxy provides access to a broader materials platform while limiting the
lattice mismatch with PbSe to approximately 4%. We grow 150-nm thick PbSe films by molecular beam epitaxy on 200-nm thick In0.53Ga0.47As and In0.52Al0.48As buffers on (001) InP substrates. Reflection high-energy electron diffraction and X-ray diffraction show (001)-oriented rock-salt PbSe with an out-of-plane
lattice constant of 6.12 Angstrom on both buffers. Photoluminescence (PL) is observed from room-temperature down to 12 K and the peak wavelength red-shifts from 3.7 to 5.0 microns. Under identical measurement conditions, the room-temperature peak PL intensities from films on In0.53Ga0.47As and In0.52Al0.48As are approximately 1.9x and 1.3x that of a PbSe on GaAs substrate reference, respectively. These results establish an InP-compatible platform for integrating narrow band-gap PbSe with a broad range of ternary and quaternary III-V
alloys, including, for example, structures in which In0.53Ga0.47As serves as both a short-wave infrared absorber and a template for PbSe growth.
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All authors Biridiana Rodriguez, Mark Martino, Brody Yeung, Benjamin Sprenger, Leland Nordin
Quantum Physics
Information-geometric bounds on nonequilibrium relaxation in quantum Markov dynamics
Xiao-Kan Guo and Zhiqiang Huang
In this paper, we study the
quantum information-
geometric structure underlying short-time nonequilibrium relaxation in
quantum Markov dynamics, and derive bounds on the nonequilibrium correction to the short-time relaxation
curvature. These bounds generalize the information-
geometric structure underlying Auconi's classical nonequilibrium relaxation inequality to
quantum Markov dynamics. We consider the von Neumann relative
entropy as
quantum divergence, and parametrize perturbations through the Kubo-Mori map, which converts the second-order expansion of the relative
entropy into the Bogoliubov-Kubo-Mori (BKM) inner product at all temperatures. For a
quantum Markov
semigroup with full-rank stationary state, the induced tangent-space generator admits a canonical decomposition into a BKM-symmetric and a BKM-antisymmetric part, and the leading nonequilibrium
curvature correction takes the exact form of the expectation of the commutator between the dissipative and the transport part of the generator. This correction is bounded by the product of a BKM-symmetric dissipative activity and a transport-sector activity. The bound is verified on a noncommuting
qubit model and a driven-dissipative qutrit, and the full chain is confirmed numerically on a two-dimensional Fokker-Planck steady state. In the high-temperature and overdamped limit the
quantum formula reduces to the position-space Fokker-Planck expression and reproduces Auconi's
entropy-production bound with the correct temperature factor.
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Materials Science
An encoded asymmetric ligand for metal-selective topological assembly of two-dimensional metal-organic frameworks
Huimin Qi, Jinkun Guo, Xinyan Wu et al. (+12 more)
Two-dimensional metal-organic frameworks (2D MOFs), with diverse topological architectures, provide a powerful platform for exploring unconventional electronic and
lattice-dynamical responses. Yet their structural diversity remains fundamentally constrained by the fixed geometry of high-
symmetry ligands. Here, we introduce an encoded asymmetric ligand, benzo[b]triphenylene-2,3,6,7,11,12-hexaol (BTH), for metal-selective topological assembly. By integrating multi-site coordination fields with sterically differentiated environments, BTH exhibits distinct topological programmability: different divalent metal ions direct divergent framework architectures. Specifically, coordination of BTH with divalent Cu(II) and Zn(II) ions assembles Cu-BTH-MOF with a dual-mode hexagonal pore
topology and Zn-BTH-MOF with uniform hexagonal channels, respectively, as supported by PXRD Pawley refinement, structural simulations, and pore-size distribution analysis. Furthermore, this topological divergence is accompanied by a significant divergence in charge-transport properties, with Cu-BTH-MOF reaching an electrical conductivity of 1.186 x 10-3 S cm-1, more than six orders of magnitude higher than that of Zn-BTH-MOF (3.38 x 10-10 S cm-1). This work establishes ligand desymmetrization as a programmable strategy for metal-selective topological diversification in 2D MOFs.
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All authors Huimin Qi, Jinkun Guo, Xinyan Wu, Weishan Li, Tongyang Zhao, Ze-Fan Yao, Hao Chen, Ling Zhang, Bin Jiang, Yi Liu, Haoyang Zhang, Yunlong Fan, Tianyang Chen, Qingqing Ji, Jin-Hu Dou
Soft Condensed Matter
Coarse-graining to create minimalist models for dynamic, end-linked star-polymer networks
Tyla R. Holoman, C. Levi Petix, Michael P. Howard et al. (+1 more)
Although minimalist models for patchy attractive particles have revealed powerful design rules for how particle valence directs colloidal assembly, less work has focused on comparably simple models of reversible, network-forming
star polymers. Here, we use relative-
entropy coarse-graining and simulation results from finer-resolution bead–spring
star polymers to generate 5-bead models of dynamic, end-associating four-armed poly(ethylene glycol) macromers. Our results comparing structural correlations, network connectivity, and phase behavior of the coarse- and fine-grained models provide insight into how the accuracy and transferability of the coarse-grained models depend on the state point chosen for coarse-graining. The results also reveal intrinsic trade-offs between reducing degrees of freedom and expanding the range of effective interactions in coarse-graining that impact the total number of pairwise interactions in the resulting model, with implications for its computational efficiency.
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All authors Tyla R. Holoman, C. Levi Petix, Michael P. Howard, Thomas M. Truskett
Statistical Mechanics
Energy Transport Structure and Fluctuation Theorem in Nonreciprocal Harmonic Chains
Ziwei Cheng, Geng Li and Zhanchun Tu
Nonreciprocal interactions fundamentally alter energy transport by breaking the
symmetry between forward and backward responses. Here, we uncover an exact transport structure for a one-dimensional harmonic chain with asymmetric nearest-neighbor couplings. Using a Green-function approach, we demonstrate that the direction of heat transport is determined not solely by the temperature bias, but by its competition with an effective directional asymmetry. This competition can reverse the direction of heat flow, enabling cold-to-hot transport. We further show that nonreciprocity introduces an additional power channel associated with the antisymmetric sector of the interaction, leading to a generalized steady-state energy balance involving two reservoir heat currents and a nonreciprocal power current. At the fluctuation level, the heat exchanges with the two reservoirs constitute correlated yet distinct
stochastic currents, whose joint scaled cumulant generating function obeys an exact Gallavotti-Cohen
symmetry. Together, these results establish a unified energetic and fluctuation framework for nonreciprocal heat transport and demonstrate that directional interactions can serve as an active resource for controlling nonequilibrium energy flows.
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High Energy Physics (Phenomenology)
Inclusive productions of $J/\psi+\eta_c$ in $e^{+}e^{-}$ annihilation at Belle
Zhan Sun, Shu-Jian Qi and Ying-Zhao Jiang
We study $e^{+}e^{-} \to J/\psi+\eta_c+X$ at next-to-leading order (NLO) in $\alpha_s$ within the nonrelativistic QCD (NRQCD) framework to assess the color-octet (CO) mechanism at low energies. QCD corrections significantly enhance both color-singlet (CS) and CO leading-order results, with non-negligible QED-diagram contributions to the CS channel. At $\Upsilon(4S)$, CO terms increase the inclusive cross section by $20\%$–$30\%$, and the enhancement grows rapidly with $\sqrt{s}$, yielding an energy dependence distinct from CS predictions and providing a sensitive test of NRQCD. For the central LDME choice, including $\psi(2S)$ feed-down further amplifies the NRQCD prediction by about $40\%$ at $\Upsilon(4S)$. With Belle's reconstruction of $J/\psi \to \mu^+\mu^-$ and six $\eta_c$ decay channels, the process shows promising potential for observation.
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Physics Education
Mechanics Cognitive Diagnostic: Testing Fine-Grained Learning Objectives in Introductory Physics
Vy Le, Jayson M. Nissen, Jason W. Morphew et al. (+2 more)
Physics courses use research-based assessments (RBAs) such as the Force Concept Inventory (FCI), Force and Motion Conceptual Evaluation (FMCE), and Energy and Momentum Conceptual Survey (EMCS) to measure learning in introductory mechanics, but their fixed-length, pretest-posttest design makes them retrospective: posttest scores summarize completed instruction and arrive after a course ends. We are developing the Mechanics Cognitive Diagnostic (MCD), a cognitive diagnostic computerized adaptive test that reports students' mastery of fine-grained learning objectives (LOs) throughout instruction. Using evidence-centered design, we defined 14 LOs from introductory mechanics textbooks and AP Physics standards, mapped FCI, FMCE, and EMCS items onto them with a Q-
matrix, and refined the mapping with the deterministic inputs, noisy "and" gate (DINA) model, using posttest responses from 24,394 students in 807 courses across 79 institutions through LASSO. The FCI and EMCS achieved good DINA model fit; the FMCE showed marginal fit. Classification accuracy for most LOs met or exceeded
benchmarks for low-stakes formative assessment. RBA items, though not developed for LO-level diagnosis, support it reliably, giving the MCD a working 14-LO item bank built from RBAs that physics courses already use. As data accumulate, we can revise or retire weak LOs and items and add new items through online calibration without interrupting testing. We plan to expand the MCD to 35 LOs, two per week, to cover a typical introductory mechanics course.
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All authors Vy Le, Jayson M. Nissen, Jason W. Morphew, Hua Hua Chang, Ben Van Dusen
Quantum Physics
Thermal Quantum Sensing: Fisher Information and Work Beyond Gaussian Signals
Yash Chitgopekar, Nikolaos Koukoulekidis and Iman Marvian
Understanding how thermal fluctuations modify or suppress
quantum-enhanced sensing is a central problem in
quantum metrology. Closely related questions arise in
quantum thermodynamics, particularly regarding the relation between the work induced by a signal and the information acquired by a sensor. Here, we establish general relations among the sensitivity of thermal
quantum states, as quantified by different
quantum Fisher information metrics, their temperature dependence, and the work induced by a
unitary signal. We further show that, at high temperature, all monotone QFI metrics coincide to leading order with a universal quantity that can be expressed as the variance of a simple observable and itself defines a lesser-known QFI metric. This emergent uniqueness is reminiscent of the uniqueness of classical Fisher information in information geometry. In continuous-variable systems, the infinite-temperature limit is finite and generically non-zero for quadratic Gaussian signals, while it diverges for higher-degree signals. Remarkably, for any purely quadratic signal generator, the infinite-temperature QFI is at least twice the zero-temperature SLD QFI or, equivalently, at least eight times the ground-state variance of the generator. Consequently, the Cramér–Rao lower bound on the
estimator variance is reduced by at least a factor of two. We illustrate these results using harmonic chains of bosonic modes relevant to trapped-ion platforms and
quantum field-theoretic models.
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Quantum Physics
ECDSA.Fail: Open Autoresearch for Optimizing Elliptic-Curve Point Addition in Shor's Algorithm
Jieyi Long, Theodore Pender, Zhao Huang et al. (+32 more)
We propose Open Autoresearch, a paradigm in which humans and AI
agents publish evaluator-verified improvements to a public leaderboard. We instantiate it in ECDSA.Fail, optimizing reversible secp256k1 point-addition
circuits, a bottleneck in Shor's
algorithm for
elliptic-curve cryptography. The
benchmark minimizes the spacetime-inspired score $S=Q\times T$, where $Q$ is peak logical
qubit width and $T$ is average executed Toffoli count. Participants reduced $S$ by 86.1%. At the data cutoff (26 July 2026), the best-scoring
circuit uses 1,151
qubits and 1,299,453 average executed Toffoli gates, giving $Q\times T\approx1.496$ billion. This is more than 50% below Google's published point-addition score thresholds (arXiv:2603.28846), under different accounting conventions. Because the
benchmark supplies one addend classically, we construct a coherent windowed-addition-compatible variant implementing the single-call interface required by windowed Shor. It uses 1,162
qubits and 1,684,161 average executed Toffoli gates. On 100,000 random inputs, its empirical success probability is $\hat{p}=0.99809$, giving $Q\times T/\hat{p}\approx1.961$ billion under an independently rerunnable per-call sensitivity model, not a full-Shor success estimate. Its
qubit and Toffoli counts lie below Google's published thresholds and Schrottenloher's reported operating points (arXiv:2606.02235), although differing interfaces, accounting conventions, and validation scope preclude formal dominance. After the cutoff, the score was further reduced to 1.259 billion, while a separate low-width
circuit reached 813
qubits. The public record shows AI
agents complementing human judgment, providing evidence for open autoresearch on efficiently evaluable, machine-checkable objectives.
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All authors Jieyi Long, Theodore Pender, Zhao Huang, Manuel B. Santos, Samrendra Kumar Singh, Bartosz Naskręcki, Bit Wonka, Pierre-Luc Dallaire-Demers, Francesco Giannicola, Ruben M. L. Paschoarelli, Oli Freuler, Jackie Chia-Hsun Lee, Vasily Gnuchev, Gopi Kannappan, John Boyer, Xavier Butler, Akash Balasubramani, Jordan Newman, Bereket Dereje, Alexander Hertlein, Robert Kodra, Lucas Levy, Shaan Patel, JT Rose, Matt Zweil, Okechukwu Wisdom, Tarek El-Eter, Edison Lee, Michael Dong, Alan Li, Anto Joseph, Gajesh Naik, Gautham Anant, Soubhik Deb, Justin Drake
Mesoscale and Nanoscale Physics
The effect of Coulomb interactions of thermoelectric characteristics of Marcus molecular junctions
Natalya A. Zimbovskaya
We present a theoretical study focused on the influence of Coulomb interactions on thermoelectric properties of molecular junctions assuming that electron transport is strongly affected by thermalized
phonon modes in the molecular ambient. It is shown that the combined effect of Coulomb interactions between electrons on the molecular states and the reorganization processes in the ambient may significantly affect both Seebeck coefficient and the power factor. Specifically, we show that electron-electron interactions may counter-balance the effect of the ambient molecules reorganizations resulting in qualitative changes in the behavior of both zero-bias conductance and thermopower.
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Soft Condensed Matter
The validity of the Stokes-Einstein relation in ionic liquids
Gan Ren and Tao Duan
Ionic
liquids (ILs) exhibit supercooled
liquids behavior even above room temperature and the Stokes-Einstein (SE) relation is often considered to be invalid in ILs as that in supercooled
liquids. However, the conclusion is usually drawn based on some variants of SE relation. In this work, we have systematically investigated the validity of the Stokes-Einstein relation in ILs by performing molecular dynamics simulations of coarse-grained IL within the temperature range of 400-800 K. Both the original SE formulation, and two commonly employed variants, were examined to assess their applicability and consistency. These three formulas yield distinctly different results, indicating that the two variants are not reliable substitutes for the original SE relation. The inconsistency suggests the fact that the r in Stokes law varies with conditions. The breakdown arises from the ion correlations introduced by the strong electrostatic interactions. This proposition is further confirmed by simulations.
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Quantum Physics
Momentum-resolved magnetic noise spectroscopy using ensembles of diamond quantum sensors
Zeeshawn Kazi, Kai-Hung Cheng, Jared Rovny et al. (+1 more)
Spatiotemporal fluctuations across multiple scales govern and characterize the emergent properties, phase boundaries, and low-energy excitations of strongly correlated matter. However, capturing these dynamics has remained a major experimental challenge, as conventional probes typically offer either high spatial or temporal resolution, but not both simultaneously. Here, we leverage high-fidelity wide-field imaging of dense diamond nitrogen vacancy center ensembles to measure the momentum and frequency power spectral density of
magnetic fluctuations. To access spatial wavevectors below the diffraction limit, we tune the sensing volume continuously through optical depletion. This approach enables study of
equilibrium and driven fluctuations across three orders of magnitude in spatial scale and tunable frequency bands, providing a direct means to map low-energy, long-wavelength fluctuations in correlated systems.
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All authors Zeeshawn Kazi, Kai-Hung Cheng, Jared Rovny, Nathalie P. de Leon
Materials Science
Composition and Surface Termination Control Band Alignments in P3HT/Perovskite Heterostructures
Somayyeh Alidoust and V. Ongun Özçelik
Hybrid organic-inorganic perovskite
heterostructures are emerging platforms for energy conversion and optoelectronic devices, yet the effects of composition and surface terminations on band
alignment remain poorly understood. Here, using high-throughput first-principles calculations, we systematically reveal the effect of composition and surface termination on the band
alignment of 820
heterostructures formed between poly(3-hexylthiophene) (P3HT) variants and conventional and mixed-cation metal halide perovskites. Band edge analysis predicts concentration dependent band
alignments, with most Pb and Sn based perovskites exhibiting Type II and III behavior while mixed-cation CsMASnBr3 uniquely forms Type-I junctions with all P3HT variants. Explicit interface calculations reveal that surface termination can reverse the predicted
alignment in conventional tin perovskites, while the mixed cation perovskite preserves Type-I
alignment with P3HT regardless of termination. Despite negligible charge transfer, termination dependent band offsets produce markedly different carrier confinement, establishing design principles for engineering P3HT/perovskite interfaces.
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Disordered Systems and Neural Networks
Curvature-Induced Geometric Universality in Non-Hermitian Anderson Transitions
Chen Wang, Run-Qiu Yang, X. R. Wang et al. (+1 more)
In Euclidean space, universality classes of Anderson transitions are primarily determined by
symmetry and spatial dimensionality. Here, we present evidence for a geometry-controlled universality class of non-Hermitian Anderson transitions on
hyperbolic-like
lattices. In this setting, critical behavior is influenced by the large-scale
hyperbolic geometry, characterized by negative
curvature, exponential volume growth, and a non-Euclidean notion of spatial scaling. Finite-size scaling of participation ratios across several distinct \( \{p,q\} \) tilings reveals one-parameter scaling collapses with a common critical exponent \( \nu\simeq1 \) within numerical accuracy. A complementary phenomenological coarse-grained Landau-Ginzburg analysis shows how exponential correlation-volume growth suppresses critical fluctuations, offering a rationale for the observed mean-field-like scaling. Our results suggest that spatial
curvature can act as an additional organizing principle for Anderson-transition universality beyond the conventional dimensionality- and
symmetry-based classification.
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All authors Chen Wang, Run-Qiu Yang, X. R. Wang, Hechen Ren
Quantum Physics
From Certifying Rank $k$ Projectors To Non-Positivity, Entanglement, And Non-Hermitian Witnesses Through Traces Of Matrix Powers
H. F. Chau
We all know that a density
matrix $\rho$ is pure if and only if $\mathrm{Tr} \,\rho^2 = 1$. But is this the only way to prove the purity of $\rho$ using the trace of its powers? Here I systematically study the necessary and sufficient conditions of the more general question of guaranteeing that all
eigenvalues of a Hermitian
matrix belong to a specified set through its trace of powers. More importantly, these characterization results are automatically witnesses certifying a
quantum state as entangled, a Hermitian operator has least one negative
eigenvalue and a linear operator as non-Hermitian. I demonstrate the effectiveness of these witnesses, analyze their performance, and study their strength, weakness together with resource requirement through numerical simulation as well as analytical work. I also discuss briefly the effects of numerical stability, uncertainty in measurement and rounding errors on these problems.
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Astrophysics of Galaxies
Time-Domain Dust Astrophysics. II. TransRAT: Time-Dependent Grain Alignment and Disruption by Cosmic Transients and Their Observational Signatures
Thiem Hoang
We introduce TransRAT, a self-consistent time-domain framework that follows the coupled dynamical response of
dust to transient irradiation and predicts its observable signatures. We apply TransRAT to a Type~IIP
supernova illuminating a one-zone molecular cloud. Radiative heating raises the grain temperature, modifying the
magnetic susceptibility and Larmor precession, while the enhanced radiation field accelerates radiative precession and can switch the
alignment axis from the
magnetic field (B-RAT) to the radiation direction (k-RAT). Simultaneously, strong RATs align grains faster than gas randomization, extending fast
alignment to smaller grain sizes, and disrupt large grains through RAT disruption (RAT-D), irreversibly modifying the grain size distribution. As the transient fades, the
alignment axis returns to ${\bf B}$ at a rate controlled by the
magnetic susceptibility, whereas the enhanced aligned-grain population and RAT-D-modified grain size distribution can persist long after the radiation has faded- referred to as physical
memory effects. The time-dependent
evolution of grain
alignment and disruption produces distinctive observational signatures: a
flare in extinction and thermal
dust polarization followed by a RAT-D-induced dip; a blueward shift of the polarization peak $\lambda_{\max}$; a polarization-angle rotation equal to the projected ${\bf B}$–${\bf k}$ separation ($45^{\circ}$ for our adopted geometry) when RAT-D removes large high-$J$ aligned grains and leaves low-$J$ grains aligned with kRAT followed by angle reverberation as
alignment returns to ${\bf B}$; and a non-monotonic
evolution of $R_V$. The persistent observational manifestations of the transient irradiation, including enhanced polarization, blueshifted $\lambda_{\max}$, modified $R_V$, and polarization-angle
evolution, constitute fossil imprints of past
cosmic transients.
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High Energy Physics (Theory)
On general background of quantum non-invertible symmetry in 2D
Jin Chen and Qiang Jia
We study the dual
quantum symmetry $\mathrm{Rep}(G)$ in the two-dimensional theory $\widetilde{\mathfrak{T}}_{\mathrm{Rep}(G)}$ obtained by gauging a non-abelian
symmetry $G$ of $\mathfrak{T}_G$, where for Lie groups $G$ the gauging is understood as flat gauging. We develop a general framework for computing partition functions of $\widetilde{\mathfrak{T}}_{\mathrm{Rep}(G)}$ in arbitrary non-invertible
symmetry backgrounds, represented by topological defect networks of $\mathrm{Rep}(G)$, in terms of the partition functions of the original theory $\mathfrak{T}_G$. We also derive the inverse transformation, expressing partition functions of $\mathfrak{T}_G$ in $G$ backgrounds in terms of those of $\widetilde{\mathfrak{T}}_{\mathrm{Rep}(G)}$. We test the framework in several examples, including finite groups with multiplicity-free and higher-multiplicity fusion rules, and discuss a formal extension to compact Lie groups, focusing on $\mathrm{Rep}(SU(2))$.
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Mathematical Physics
Bargmann-Fock Representation and Global Estimates for the Linearized Hard-Sphere Boltzmann Operator
Ilya Karlin
We study the linearized Boltzmann collision operator for three-dimensional hard spheres and reorganize the complete operator so that its angular and radial structures are explicit before any Sonine truncation. From the Carleman representation, the collision integral becomes a superposition of orthogonal translations; in Hermite/Fock and Bargmann form these generate a single analytic coherent-state kernel for all Hermite collision brackets. Rotational covariance separates fixed angular-momentum sectors, each reducing exactly to a one-variable radial Bargmann space with an $\mathfrak{su}(1,1)$ structure. The radial operator is $\mathfrak A_\ell=\kappa\pi G(\mathcal J_\ell)-\mathfrak C_\ell$, where $\mathcal J_\ell$ is an explicit Laguerre–Jacobi operator and $\mathfrak C_\ell$ is compact. A
unitary intertwiner identifies this realization with the classical Burnett/Sonine coordinate, recovering the Burnett
matrix and standard stress and heat-flux corrections. For the untruncated operator, the compact gain gives only compact corrections, while the loss sets the common essential spectrum $[\nu_{\min},\infty)$. Radially squeezed $\mathfrak{su}(1,1)$ coherent packets yield threshold Weyl sequences in every fixed angular sector. With $\ell\to\infty$ and squeezing scaled as $\ell^{-1}$, they furnish full-space Weyl sequences throughout the essential band interior, with $\langle j\rangle\sim\ell^2$, revealing quadratic continuum corridors in the $(\ell,j)$ plane. At fixed $\ell$ and $j\to\infty$, the
matrix tail approaches a universal Toeplitz operator whose zero at $\theta=\pi$ is the local signature of the same threshold escape. Thus the Fock reformulation provides exact radialization and constructive control of the global spectral geometry.
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Quantum Physics
Sub-extensive non-stabilizerness in the Dyck-Fredkin spin chain
Yasunori Lee
The stabilizer Rényi
entropy is a quantitative measure of non-stabilizerness, or magic, and has typically been found to scale extensively with system size $N$ (i.e., $\Theta(N)$) for a variety of many-body
quantum states. In this note, we study the stabilizer Rényi
entropy of the ground state of the
spin-$\frac{1}{2}$ Dyck-Fredkin chain and its $t$-deformation, a local frustration-free model with unusual spectral-gap scaling. Exploiting the combinatorial structure, we carry out numerically exact finite-size calculations, which indicate asymptotic behavior depending on $t$: $\Theta(N)$ for $t<1$, $\Theta(\log N)$ at $t=1$, and $\Theta(1)$ for $t>1$. The scaling at $t=1$ could be another manifestation of the unconventional criticality of the model, while the contrast with the behavior of the
entanglement entropy suggests that non-stabilizerness might provide a new window into
quantum many-body systems.
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