High Energy Astrophysical Phenomena
Constraints on the central engine of merger-driven long gamma-ray bursts
Muskan Yadav, Roberto Ricci, Paz Beniamini et al. (+4 more)
Recent observations have identified a new class of long-duration gamma-ray bursts (GRBs) likely produced by compact binary mergers. Using
radio observations and lightcurve modelling, we investigate whether a magnetar remnant can power the long-lasting
prompt emission observed in this merger-driven GRB sample. We derive constraints on the magnetars' rotational energy and
magnetic-field strength, and assess whether the magnetar central-engine model is viable for the observed events. We conducted 2.1 GHz
radio observations of seven nearby merger-driven GRBs ($z<0.25$) using the Australia
Telescope Compact Array (ATCA), obtaining sensitive upper limits on late-time
radio emission 520-6900 days post-burst. We modelled the expected
radio light curves from magnetar-energized ejecta interacting with the circumburst medium and compared them to our observations. We separately tested the magnetar hypothesis against the extended gamma-ray emission using a fallback-accreting magnetar model. No
radio counterpart is detected in any of the observed GRBs, with 3$\sigma$ flux density upper limits of 33-72 $\mu$Jy at 2.1 GHz. Modelling the expected synchrotron emission from magnetar-energized ejecta interacting with the circumburst medium, we find that the
radio non-detections remain compatible with energetic
outflows in low-density environments. The analysis of the
prompt gamma-ray emission provides complementary constraints on the
spin period and
magnetic field of the magnetar engine. Once fallback
accretion and jet
baryon-loading are considered, the parameter space is narrowly confined.
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All authors Muskan Yadav, Roberto Ricci, Paz Beniamini, Hira Waseem, Tatsuya Matsumoto, Simone Dichiara, Eleonora Troja
Earth and Planetary Astrophysics
Stellar Ages of M Dwarf Hosts of Temperate Sub-Neptunes
Lalitha Sairam and Nikku Madhusudhan
Measuring M
dwarf ages is a central challenge in
stellar astrophysics. These
stars evolve so slowly that isochrone fitting gives little constraint, requiring alternative methods based on rotation, activity, and kinematics. Reliable ages help constrain the formation and
evolution of planetary systems around M
dwarfs, including the temperate sub-Neptunes now being characterised with the James Webb Space
Telescope (JWST). We present an age analysis of six nearby M
dwarf planet hosts (TOI-732, TOI-736, TOI-270, TOI-1468, TOI-1231, and K2-18) using lithium absorption at 6708 Å, rotation periods, and
Galactic kinematics. The Li I 6708 Åfeature is absent above 3$\sigma$ in all targets, implying substantial depletion and ages exceeding 200 Myr. Rotation periods of 39-145 days yield ages of 2.8-8.6 Gyr, calibrated against open cluster M
dwarfs and including the intrinsic dispersion of the rotation-age relation. Kinematic ages span 0.8-13 Gyr with uncertainties of 4-6 Gyr. These are less precise per
star but help identify outliers such as TOI-1231 (~13 Gyr) and K2-18 ( ~1-2 Gyr) and place the
stars in
Galactic context. Rotation yields age constraints 2-6 times tighter than kinematics where periods are measured, and comparable constraints where periods must be inferred from chromospheric activity. Combining multiple indicators enables more secure classification of these
stars' evolutionary states, providing reference points for future comparative studies.
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Materials Science
Enhanced thermal stability of SiGeSn by suppressing surface-mediated degradation
Anis Attiaoui, Sebastian Koelling, Lu Luo et al. (+2 more)
$\text{SiGeSn}$
alloys are promising silicon-compatible
semiconductors for monolithic infrared photonics. However, their metastable nature limits the thermal budgets available for post-growth device processing, and the mechanisms governing their thermal degradation remain unresolved. Here, we investigate the thermal stability of $\text{Si}_{0.08}\text{Ge}_{0.83}\text{Sn}_{0.04}$
alloys using in situ spectroscopic ellipsometry (SE) during isothermal annealing at 550 {\deg}C. We show that adding an ultrathin
oxide cap kinetically suppresses Sn exchange with the free surface while leaving bulk
diffusion pathways largely unaffected. Uncapped films undergo phase separation after 50 min, accompanied by void formation, a 60% thickness reduction, and a 400 meV blueshift of the $E_{2}$ critical point (CP) transition, consistent with substitutional Sn depletion from the probed volume through surface segregation. In contrast,
oxide-capped films exhibit a small compositional change (<1 at.% Sn) and optical shift (<20 meV) over the same period, with suppressed void formation, strain relaxation, and
alloy decomposition. This surface-kinetic control additionally yields a 25-fold reduction in contact resistivity relative to annealed uncapped
alloys. These results identify surface Sn transport as the dominant degradation pathway in SiGeSn and demonstrate that an ultrathin
oxide cap extends the thermal stability of metastable group-IV
alloys, providing a practical route toward their integration into advanced silicon photonic and electronic platforms.
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All authors Anis Attiaoui, Sebastian Koelling, Lu Luo, Simone Assali, Oussama Moutanabbir
Quantum Physics
A Case Study on Noise Resilient Operator Selection in Adaptive Variational Quantum Algorithms
Soorya Haravu, Mafalda Ramôa and Bharath Sambasivam
Hardware noise has been shown to significantly impact the accuracy of ADAPT-VQE, a ground state preparation
algorithm. While previous work has studied the impact of noise on its parameter optimization step, its impact on the critical operator selection step remains comparatively unexplored. In this work, we examine the impact of a variety of noise channels on this step, using a linear H$_3$ molecule as a test case. We show that, despite the selection criterion's natural resilience to some noise, both coherent and incoherent noise can prevent convergence for sufficiently high noise rates. We employ
quantum error mitigation techniques–dynamical decoupling, zero noise extrapolation, and Pauli twirling–and show that when combined appropriately, these techniques are capable of restoring a successful convergence profile. Our results highlight how error mitigation can improve the performance of ADAPT-VQE and enable convergence in the presence of hardware noise, offering valuable insights into the implementation of the
algorithm on near-term
quantum hardware.
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Mesoscale and Nanoscale Physics
Visualizing Berry curvature in a Floquet-Chern insulator
Younsik Kim, Rishi Acharya, Hannah E. Aguirre et al. (+3 more)
Circularly polarized light can open a topological gap in a gapless Dirac system, creating a Floquet-Chern
insulator. However, its Berry
curvature has not been directly resolved. Here we use circular-dichroism time- and angle-resolved photoemission spectroscopy (Tr-ARPES) to map the light-induced Berry
curvature of Floquet-Bloch states on the surface of Bi$_2$Se$_3$. By comparing spectra for opposite helicities of the mid-infrared pump, we isolate the induced
geometric response. We observe alternating-sign Berry-
curvature features at Floquet gaps that repeat at intervals set by the pump
photon energy and redistribute with pump field strength in agreement with calculations for a periodically driven Dirac
Hamiltonian. Both the induced Berry-
curvature and the Floquet Dirac gap decay faster than the replica intensity, showing that spectral replicas can persist even after coherent Floquet hybridization weakens. These results establish momentum-resolved Berry-
curvature mapping as a direct probe of light-induced
topology and coherent Floquet band formation.
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All authors Younsik Kim, Rishi Acharya, Hannah E. Aguirre, Lucca Figari, Daniel P. Shoemaker, Fahad Mahmood
Quantum Physics
Antidistinguishability of states in General Probabilistic Theories
Satyaki Manna and Anandamay Das Bhowmik
We investigate antidistinguishability of states within the framework of general probabilistic theories (GPTs). We formulate antidistinguishability, strong and equal antidistinguishability as refined notions that imposed additional constraint on the measurement effects. We establish general results relating these notions of antidistinguishability and derive an upper bound on the cardinality of equally antidistinguishable sets in terms of the affine dimension of the state space. We then study antidistinguishability in polygonal theories, obtaining conditions for antidistinguishability of a set of states. In consequence, we show that the set of all pure states in a polygon model is antidistinguishable. Additionally, we identify broad families of strongly and equally antidistinguishable states. Finally, using Random Exclusion Codes, whose success probability is governed by the antidistinguishability of different sets of encoding states, we probe the nonclassicality of polygon theories. We find that certain polygon models can outperform the optimal
quantum value, while their optimal performance converges to the
quantum limit in the large-polygon limit.
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Quantum Physics
Beyond Hardware: Adaptive Algorithmic Control by State-Proxy Equalization
Jianlong Lu, Hongrui Zhang, Thorsten Koch et al. (+1 more)
Recent advances in
quantum computing have been driven primarily by improvements in hardware. Here we show that substantial gains can instead arise from how finite computational resources are allocated throughout a
quantum computation. We introduce Adaptive Algorithmic Control (A2C), a software paradigm founded on a State-Proxy Equalization
theorem, which proves that the optimal allocation for a state-derived proxy-error functional equalizes cumulative computational hardness rather than physical time. The required computational hardness is inferred directly from the evolving
quantum state, avoiding explicit reconstruction of the exponentially large many-body spectrum. Across
quantum optimization problems containing up to 156
qubits, combining exact simulations, large-scale supercomputer computations and IBM
quantum hardware experiments, A2C improves the low-energy sampling probabilities by $22\%$ to over $100,000\%$ under matched
circuit depths and measurement budgets. These results demonstrate that
quantum computational performance depends not only on hardware capabilities, but also on how finite computational resources are organized, establishing adaptive algorithmic control as a complementary software pathway for advancing
quantum computation.
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All authors Jianlong Lu, Hongrui Zhang, Thorsten Koch, Ying Chen
Quantum Physics
Query-optimal quantum simulation of Lindblad evolution
Chunhao Wang and Christopher Ye
For the problem of simulating Lindblad
evolution for time $t$ to precision $\epsilon$,
Hamiltonian simulation provides an additive query lower bound, informally, $\Omega(t + \mathrm{polylog}(1/\epsilon))$. However, the best previously known
algorithms for general Lindblad simulation achieve a multiplicative upper bound, informally, $\mathcal{O}(t\,\mathrm{polylog}(1/\epsilon))$, in query complexity. It has remained open whether this multiplicative dependence is necessary. In this paper, we close the gap in query complexity by giving an
algorithm with optimal additive dependence on
evolution time and precision in the block-encoding model. Our approach uses the transducer framework to reduce the query cost of composing first-order approximations to the
evolution channel, together with linear combinations of reuse
circuits of different lengths to suppress catalyst-removal error. We further achieve nearly optimal gate complexity in
evolution time and precision through history compression and an efficient implementation of the query-free part of the transducer using operation reordering and linear combinations of
unitaries, while preserving the optimal query complexity.
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Optics
Hysteresis and trap emission in dc-biased integrated lithium niobate electro-optic modulators
Matthew Yeh, CJ Xin, Donald Witt et al. (+3 more)
The electro-optic effect is crucially important for low power and efficient tuning of integrated photonic
circuits. However, in electro-optic materials such as lithium niobate, dc biasing for an extended duration of time results in the emergence of numerous nonidealities, including hysteresis – a persistent degradation of the magnitude and linearity of the dc electro-optic response. We show that electro-optic hysteresis can be reversed under both zero-bias and reverse-bias conditions, given sufficient time or reverse voltage and consistent with a defect model of the underlying physics. Specifically, we find that drift phenomena at short time scales can be explained by charge trapping dynamics near the contact junction, and thereby devise an active reset protocol that restores the magnitude of the response and partially restores the drift time scales.
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All authors Matthew Yeh, CJ Xin, Donald Witt, David R. Barton, Evelyn L. Hu, Marko Lončar
High Energy Physics (Phenomenology)
Rotational Brownian Motion and $\mathrm{J/\psi}$ Spin Alignment in Heavy-Ion Collisions
Bhagyarathi Sahoo and Captain R. Singh
The heavy-
quark polarization in ultra-relativistic heavy-ion collisions (HICs) serves as a probe for unfolding the characteristics of deconfined QCD. The present study explores the
spin alignment of $\mathrm{J/\psi}$ in the HICs by employing the rotational Brownian motion of charm
quarks in the presence of a strong
magnetic field. We derive an analytical expression for the polarization of the $c$-$\bar{c}$ pair based on the Fokker-Planck equation under the consideration of
spin-vorticity coupling. These polarized $c$-$\bar{c}$ pairs lead to the formation of the $\mathrm{J}/\psi$ at the hadronization surface via the coalescence and fragmentation mechanisms. Correspondingly, we obtain the $m=0$ diagonal element $\rho_{00}$ of the $\mathrm{J}/\psi$
spin-density
matrix, which quantifies its
spin alignment along the chosen quantization axis. Our study provides a microscopic description of heavy-
quark spin transport and suggests rotational
diffusion as a possible mechanism underlying the observed $\mathrm{J}/\psi$
spin alignment.
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Quantum Physics
Predictive Structure Behind Rare Outcomes in Random Quantum Circuits
Myeongsu Kim, Travis Humble and Sabre Kais
Local random
quantum circuits selected for unusually large output peaks reveal intermediate-state structure that predicts new peak formation and guides
circuit construction. In one-dimensional Haar-random brickwall
circuits, the selected trajectories combine stronger pairwise correlations and probability redistribution with lower bipartite
entanglement and output
entropy. We test the predictive value of this structure by keeping each
circuit's initial segment fixed and independently regenerating the remaining gates. Across the tested size-depth grid at n=8-14, peak-selected states have higher new-peak probability than normal/nonpeak controls, with an overall probability ratio of 3.23 at the primary depths. Within a separate unconditioned ensemble, a fixed structural score computed from the initial segment predicts new-peak probability and gives a 1.86-fold yield gain in a replay with equal numbers of remaining-
circuit evaluations. Randomizing relative phases while preserving computational-basis probabilities strongly attenuates the selected-state advantage, demonstrating a functional contribution from relative-phase organization. Structural and phase-intervention tests extend to n=16. Structure-guided gate selection improves high-peak yield under common local refinement, while guidance using multiple intermediate observables improves new-peak probability over peak-only guidance in all 16 tested size-depth settings. Together, these results show how intermediate-state structure can predict and promote new peak formation under finite-depth local dynamics.
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Optics
Stitch-Free, Diamond-Scribed Silicon Nitride Photonic Integrated Circuits for the Visible Band
Kishor Kumar Mandal, Lekshmi Eswaramoorthy, Parul Sharma et al. (+5 more)
Silicon nitride photonic integrated
circuits for the visible band are conventionally built with a buried
oxide overcladding and singulated with wafer-scale tooling, constraints that preclude evanescent access to the guided mode for externally integrated emitters. We report a PECVD grown $Si_3N_4$ platform designed around an air-clad waveguide whose evanescent field remains accessible along the full device length. Two process elements make this geometry practical at chip scale. Fixed-beam moving-stage electron-beam lithography writes 500 nm single-mode waveguides as one continuous exposure across the 5 mm chip, removing write-field stitching which, given the $\sigma^{2}/d^{4}$ scaling of sidewall scattering in this high-confinement geometry at 635 nm, would otherwise dominate the loss budget. Chip singulation is performed by pen-type diamond scribing along lithographically patterned markers registered to in-plane direction, cleaving the Si(100) substrate to yield end-facets within $2^\circ$ of normal at $80 \%$ yield. Structural characterization by scanning electron microscopy confirms stitch-free waveguide geometry and undamaged, near-vertical scribed facets; light is coupled end-fire into fabricated devices and guided to a microring with evanescent bus-to-ring coupling confirmed by scattering imaging, and a sidewall-roughness-dependent scattering-loss model indicates that loss remains low in the roughness regime consistent with the observed facet and sidewall quality. Building on the intrinsic emitter-resonator coupling demonstrated in, this platform extends monolithic $Si_3N_4$ photonics toward scalable visible-to-near-infrared
quantum and classical
circuits.
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All authors Kishor Kumar Mandal, Lekshmi Eswaramoorthy, Parul Sharma, Anuj Kumar Singh, Brijesh Kumar, Tanmay Gupta, Venu Gopal Achanta, Anshuman Kumar
Disordered Systems and Neural Networks
Bias-Induced Crossover in Absolute Capacity of Dense Associative Memory
Yuto Sakurai, Takeaki Shimokawa, Kazunori Iwata et al. (+1 more)
The absolute capacity of dense associative
memory has mainly been analyzed for unbiased patterns. Here we examine the effect of bias in centered binary patterns under the Krotov-Hopfield single-site criterion $P_{\mathrm{error}}=1/N$, where $P_{\mathrm{error}}$ is the probability that a single-site flip lowers the energy of a stored pattern and $N$ is the number of
neurons. Each pattern component takes $1-q$ with probability $q$ and $-q$ otherwise, where $0<q\le1/2$. For
polynomial interactions of order $n$, a signal-to-noise analysis gives an absolute capacity of order $N^{n-1}/\ln N$ at $q=1/2$. For fixed $q<1/2$, however, the capacity is $O(N^{n/2})$ for even $n\ge4$ and $O(N^{(n+1)/2})$ for odd $n\ge5$. For $n=3$, both the unbiased and fixed-bias capacities remain $O(N^2/\ln N)$. For $n\ge4$, these different asymptotic forms imply a nonuniform large-$N$ limit near $q=1/2$. Asymptotic matching predicts a bias-induced crossover in the region $1-2q=O(\ln N/N^{\lfloor n/2\rfloor-1})$. The crossover originates from a bias-dependent crosstalk mean that reduces the stability of sites carrying the more frequent value $-q$. Computer simulations are compared with the finite-size conditioned-Gaussian predictions. An activity-dependent control potential that cancels the conditional crosstalk mean restores the $N^{n-1}/\ln N$ capacity for fixed $0<q<1/2$ within the conditioned-Gaussian approximation.
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All authors Yuto Sakurai, Takeaki Shimokawa, Kazunori Iwata, Kazushi Mimura
Materials Science
Designing Homogeneous Ti-Nb-Fe-Sn $\beta$ Titanium Alloys by PBF-LB: A Pre-Alloyed Powder Blend Strategy
João Felipe Queiroz Rodrigues, Kristína Bartha, Mariano Casas-Luna et al. (+10 more)
Metastable $\beta$ titanium
alloys are attractive for biomedical and structural applications owing to their low elastic modulus, high specific strength, and excellent corrosion resistance.
Laser powder bed fusion (PBF-LB) enables complex-shape production and controlled compositional variation through powder blending. However, processing elemental Ti-Nb blends often results in chemical heterogeneity from incomplete dissolution of Nb-rich particles and non-
equilibrium phase formation. To address this, low-modulus Ti-Nb-Fe-Sn
alloys were produced by PBF-LB using Ti-42Nb, Ti-20Nb-15Fe, and Ti-20Nb-20Sn master-
alloy powders blended with commercially pure Ti. Ti-23Nb-3Fe-4Sn, Ti-26Nb-2Fe-4Sn, Ti-29Nb-1Fe-4Sn, and Ti-32Nb-4Sn were fabricated using an uncommonly large 70 $\mu$m layer thickness with layer remelting, followed by heat treatment at 1000 $\deg$C for 2 h and water quenching. After heat treatment, all
alloys exhibited low porosity, homogeneous chemical distribution, and single $\beta$-phase microstructures with predominantly equiaxed grains and weak crystallographic texture. Thermodynamic calculations indicated that solidification descriptors alone could not explain the non-monotonic grain-size
evolution, which was attributed to inherited solidification structure, transient TiFe-like phase formation, Nb/Sn partitioning, and/or solute-drag-controlled $\beta$-grain growth. Hardness and yield strength decreased with decreasing Fe and increasing Nb contents, from 268 to 224 HV and 691 to 468 MPa, respectively. Young's modulus, determined by resonant ultrasound spectroscopy, ranged 63-81 GPa. These results demonstrate that pre-alloyed master-
alloy blends combined with remelting and heat treatment provide an effective route for producing chemically homogeneous Ti-Nb-Fe-Sn $\beta$
alloys while revealing how small compositional changes govern grain-growth behavior and mechanical response.
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All authors João Felipe Queiroz Rodrigues, Kristína Bartha, Mariano Casas-Luna, Gilberto Vicente Prandi, Márcio Sangali, Kateřina Ficková, Jiří Kozlík, Michaela Šlapáková, Martin Koller, Adam Strnad, Josef Stráský, Miloš Janeček, Rubens Caram
Nuclear Theory
An Extended Chiral Mean-Field Model with Medium-Modified Thermal Mesons for Hot and Dense Hadronic Matter
Micheal Kahangirwe, Rajesh Kumar, Joaquin Grefa et al. (+5 more)
In this conference proceeding we review an extension of the
Chiral Mean Field (CMF) model that consistently incorporates interacting thermal
mesons with self-consistent in-medium masses. In this approach, the in-medium masses of pseudoscalar and vector
mesons are evaluated through the explicit
chiral symmetry-breaking and vector-interaction terms in the Lagrangian respectively, before applying the mean-field approximation. These medium-modified
meson properties introduce additional feedback into the CMF equations of motion, leading to a revised equation of state. The impact of this refinement is analyzed by comparing the hadronic model predictions with recent
lattice QCD data and other hadronic descriptions, such as the
hadron resonance gas model. The modified CMF framework, featuring an improved
meson treatment (mCMF),demonstrates enhanced consistency with
lattice-QCD results for thermodynamic observables across a broad range of temperatures and
baryon chemical potentials.
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All authors Micheal Kahangirwe, Rajesh Kumar, Joaquin Grefa, Konstantin Maslov, Yuhan Wang, Arvind Kumar, Claudia Ratti, Veronica Dexheimer
General Relativity and Quantum Cosmology
Quasinormal modes of Kerr-Newman-de Sitter black holes from Heun connection formulae
Hideo Furugori, Naotaka Kubo, Hayato Motohashi et al. (+1 more)
We study quasinormal modes governed by the Teukolsky equation in Kerr-Newman-de Sitter spacetime, formally treating the
spin weight and field charge as arbitrary parameters. We use exact Heun connection formulae expressed through classical conformal blocks. We analytically derive the quasinormal mode spectra in the small cosmological constant, near-extremal, and near-Nariai limits. In the small cosmological constant limit, we obtain the leading charged de Sitter spectrum together with its subleading corrections. In both the small cosmological constant and near-extremal limits, solving the full connection condition beyond the leading pole approximation gives rise to generically noninteger-power corrections to the quasinormal mode frequencies, whereas no analogous correction appears in the near-Nariai limit. We also analyze the angular
eigenvalue problem as an illustration of the same connection-formula method.
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All authors Hideo Furugori, Naotaka Kubo, Hayato Motohashi, Daisuke Yoshida
Nuclear Theory
Including Thermal Mesons and Meson Resonances in the Chiral Mean-Field Equation of State
Micheal Kahangirwe, Joaquin Grefa, Mateus Reinke Pelicer et al. (+3 more)
The
Chiral Mean-Field (CMF) model describes dense matter in terms of
baryons and
quarks interacting through scalar and vector
meson mean fields. In the mean-field approximation, the
meson fields are replaced by their expectation values. Their role in generating interactions and in-medium properties is retained, but explicit thermal mesonic excitations are absent. This becomes increasingly problematic at high temperature, where
mesons contribute significantly to the thermodynamics of hadronic matter. Here, we keep the original CMF description of dense matter and add the thermal mesonic degrees of freedom using the mesonic sector of the
Hadron Resonance Gas (HRG) module in the MUSES framework. Ground-state pseudoscalar and vector
mesons account for the missing thermal excitations, while mesonic resonances provide, within the HRG picture, an effective description of mesonic interactions through resonance formation. We study how these contributions affect the pressure,
entropy density, energy density, and
baryon density, and compare the resulting equation of state with continuum-extrapolated
lattice-QCD calculations.
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All authors Micheal Kahangirwe, Joaquin Grefa, Mateus Reinke Pelicer, Rajesh Kumar, Claudia Ratti, Veronica Dexheimer
Quantum Physics
Quantum Compiler Design for Fault-Tolerant Quantum Computing
Chenghong Zhu, Jiahan Chen, Keming He et al. (+9 more)
Scalable
quantum computation is expected to rely on fault-tolerant
quantum computation (FTQC), in which
quantum error correction (QEC) suppresses physical errors sufficiently to support reliable logical operations. This requires
quantum compilation to move beyond general-purpose
circuit optimization toward encoding-aware and protocol-structured compilation across the full stack of fault-tolerant
quantum computers. Beyond
circuit synthesis and hardware mapping, an FTQC compiler must lower
algorithm-level operations into the logical gate set supported by the chosen code, coordinate encoded data and ancilla resources, realize logical operations together with repeated syndrome extraction under hardware constraints, and provide the resulting measurement stream to real-time decoding. This survey presents a full-stack view of compiler design for QEC-protected
quantum computation. We organize existing work into three interacting layers: logical-level QEC compilation, physical-level QEC realization, and decoder runtime integration. At the logical level, we review surface-code
lattice-surgery compilers, beyond-surface-code code-surgery frameworks including emerging qLDPC approaches, and compilation support for non-Clifford operations such as magic-state
distillation and code switching. At the physical level, we survey hardware-aware QEC realization on superconducting, trapped-ion, and neutral-atom platforms. We further examine decoder models, real-time decoding systems, and frame-management mechanisms that close the feedback loop during fault-tolerant execution. Finally, we identify open challenges in cross-layer optimization, qLDPC compilation, compiler-decoder co-design, runtime adaptivity, and the development of integrated and benchmarkable FTQC compilation stacks. An actively maintained paper list is available at: github.com/chenghongz/QEC-compiler-design.
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All authors Chenghong Zhu, Jiahan Chen, Keming He, Hongshun Yao, Zhaohui Yang, Jin-Guo Liu, Anbang Wu, Xiaotong Ni, Xingsheng Luan, Zhuo Fu, Shenggen Zheng, Xin Wang
General Relativity and Quantum Cosmology
Symmetry of the Klein-Gordon Equation under Disformal Transformations with Higher-Order Derivatives
Yurev Ivan Ross B. Carag and Allan L. Alinea
Scalar-Tensor theories extend General Relativity (GR) by including both a scalar field and a metric tensor in describing
gravity. Although the matter sector is minimally coupled to the metric in GR, the scalar field coupling to matter may be adjusted by means of Disformal Transformations. One of the most general of these transformations, formulated by Takahashi, Motohashi, and Minamitsuji, include arbitrarily high-order derivatives of the scalar field and are designed to map between two ghost-free Higher-order Scalar-Tensor theories. We used these transformations to determine the most general conditions for the disformal form-invariance of the Klein-Gordon equation for the scalar field. In the second-order case, we identified a family of disformally-related metrics that result in the same propagation solutions. Additionally, higher-order cases could comply with theoretical and phenomenological constraints alongside KG-invariance. Finally, we investigated the notion of disformal transformations as “deformations” of the spacetime
manifold.
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Mathematical Physics · Cross-listed from math.PR
Mass gap for the hierarchical sinh-Gordon model
Omar Abdelghani, Roland Bauerschmidt, Michael Hofstetter et al. (+1 more)
The (massless) sinh-Gordon model is defined in terms of a continuum massless Gaussian free field perturbed by a cosh interaction. For the hierarchical version of the model, we prove existence of the infinite volume limit, a uniform log-Sobolev inequality, and a mass gap. Our results hold for all $b^2 \in (0,1)$ and simplify for $b^2 \in (0,1/2)$ for which the Gaussian multiplicative chaos has two moments. In an appendix, our renormalization group analysis is compared with the
conjectures and controversies in physics which are mostly based on formal analytic continuation of
conjectures for the sine-Gordon model and we raise some questions.
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All authors Omar Abdelghani, Roland Bauerschmidt, Michael Hofstetter, Ofer Zeitouni
Atomic Physics
Angle-of-Arrival Determination of Radio-Frequency Fields Using Stark-Shifted Rydberg-EIT Spectra
Rajavardhan Talashila, Zoya Popovic, Nikunjkumar Prajapati et al. (+2 more)
We demonstrate a method for determining the magnitude of the angle of arrival (AoA) of a linearly polarized
radio-frequency (RF) field using the angle-dependent spectral amplitudes of AC Stark-shifted electromagnetically induced transparency (EIT) resonances. An off-resonant RF field produces distinct Stark shifts of the $|m_J|$ sublevels, while their relative excitation strengths depend strongly on the relative orientation of the RF and optical polarizations. Under the controlled polarization geometry considered here, this dependence enables determination of the AoA magnitude without requiring RF phase measurements or spatially separated sensing locations. We experimentally demonstrate the method at RF frequencies of 1.27 GHz, 2 GHz, 3 GHz, and 4 GHz using a subwavelength cesium vapor
cell. Within the $20^\circ-40^\circ$ region of highest angular sensitivity, the estimated repeatability-based $1\sigma$ AoA uncertainty ranges from approximately $0.6^\circ$ to $2^\circ$ across the investigated RF frequencies. A model combining Floquet-Shirley calculations of the RF-dressed Rydberg states with a coherent hyperfine-to-fine-structure optical excitation model qualitatively reproduces the experimental observations. These results establish a path toward compact, phase-independent AoA sensing using spatially localized Rydberg-atom spectroscopy.
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All authors Rajavardhan Talashila, Zoya Popovic, Nikunjkumar Prajapati, Noah Schlossberger, Christopher L. Holloway
Quantum Physics
One Gate at a Time: Complexity Growth in Random Quantum Circuits
Zhi Li
A random
unitary quantum circuit is expected to be incompressible for exponentially long times. We show that the constant-error
circuit complexity of a random
unitary circuit grows almost linearly with time as $\Omega(T/\log T)$. The bound holds for all $2\leq T\leq 4^n$ where $n$ is the system size, and involves no other $n$-dependence. This improves previous lower bounds derived from spectral gaps and
unitary designs by a factor of $\mathrm{poly}(n)$. Drawing on insights from
stochastic calculus,
geometric functional analysis, and randomized linear
algebra, our approach exploits the
circuit's response to variations of individual gates and requires no control over convergence to high-order
unitary designs.
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Atomic Physics
Improved calculation of the hyperfine structure of muonic helium
F. A. Martynenko, K. A. Seredina and A. P. Martynenko
Using perturbation theory for the fine-structure constant $\alpha$ and the electron-to-
muon mass ratio, we calculated new contributions to the hyperfine structure of the ground state of the
muon-electron helium atom. Compared to our previous results, we calculated new corrections in second-order perturbation theory. This calculation reduces the discrepancy between the theoretical value and the new experimental hyperfine structure measurement.
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Applied Physics
Fast, optimal readout of a tethered optomechanical pressure sensor
Stephen R. Chen, Yiliang Bao, John R. Lawall et al. (+2 more)
We demonstrate a fast readout method for tethered optomechanical pressure sensors. The fast readout method allows mechanical ring-down measurement rates that exceed the total mechanical damping rate $\Gamma_t$. We model the uncertainty of our ring-down measurements with the Cramér-Rao bound, including the effect of thermomechanical noise. Both our data and the Cramér-Rao bound indicate that measurement rates on the order of the mechanical damping rate produce the lowest uncertainty. At low pressures, using the optimal measurement rate allows 10$\times$ faster measurements or 3$\times$ lower uncertainty compared to allowing our sensor to ring down to the thermomechanical noise floor. Our results allow tethered optomechanical pressure sensors to operate at rates comparable to commercially available pressure gauges, removing an obstacle to adoption of optomechanical pressure sensors in industrial settings.
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All authors Stephen R. Chen, Yiliang Bao, John R. Lawall, Jason J. Gorman, Daniel S. Barker
Chaotic Dynamics
Dynamics, periodic orbits and $C^1$ non-integrability of the ABC flow
Wojciech Szumiński and Jaume Llibre
We study the Arnold-Beltrami-Childress (ABC) flow in perturbative regimes near its three elementary integrable coordinate axes. Starting from a degenerate family of periodic streamlines of the limiting integrable system, we use first-order averaging to prove the existence of two isolated periodic solutions of the perturbed flow. The three perturbative regimes are related by the cyclic
symmetry of the ABC vector field. In each case, the corresponding two-dimensional averaged system possesses two simple
equilibria, one
elliptic and the other
hyperbolic, depending on the sign of the relevant parameter ratio. Poincaré sections illustrate how the degenerate periodic structure of the integrable limit breaks under perturbation and how the isolated periodic orbits predicted by averaging emerge within the surrounding dynamics. These periodic orbits provide the natural link between the perturbative analysis and the integrability problem. The
eigenvalues of the linearized averaged system determine the leading-order behavior of the nontrivial characteristic multipliers of the bifurcating periodic solutions. Combining this relation with the Poincaré-Llibre-Valls criterion, we prove that, in a neighborhood of each of these periodic orbits, there exists no nonconstant first integral $H\in C^1$ that is regular along the orbit. The analytical results are further illustrated and confirmed by direct shooting, monodromy-
matrix computations, and continuation of the
elliptic and
hyperbolic branches, demonstrating that the first-order averaging approximation remains quantitatively accurate over a substantially wider parameter range than the strict asymptotic regime.
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High Energy Physics (Theory)
On the relaxation dynamics of non-equilibrium quantum systems
Matthias Carosi, Björn Garbrecht, Silvia Pla et al. (+2 more)
We investigate the relaxation of an approximately conserved charge in interacting
quantum systems close to local
equilibrium. To this end, we provide a pedagogical review of Zubarev's non-
equilibrium statistical operator approach in the minimal setting of a single non-conserved charge and apply it to the problem at hand. We explicitly highlight the physical assumptions that lead to a local relaxation law: weak charge violation, a separation between the short timescale of microscopic correlations and the much longer timescale of charge relaxation, and the resulting loss of microscopic
memory. Under these conditions, the leading relaxation rate is determined by an
equilibrium correlation function of the charge-violating operator. We show that the same result follows from a simpler local-
equilibrium construction based on the system's
evolution over an intermediate timescale, providing a direct alternative for practical calculations and making the common physical ingredients of the two approaches explicit. Beyond the decay law itself, we relate the relaxation rate to the
equilibrium diffusion of the same charge. We then allow the charge density to vary in space, which leads to a
diffusion-relaxation equation. Finally, we illustrate the formalism through electroweak $\mathrm{B+L}$ washout and a perturbative scalar model, where agreement with the linearized Boltzmann equation establishes a direct connection between
equilibrium-correlator and kinetic descriptions.
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All authors Matthias Carosi, Björn Garbrecht, Silvia Pla, Nils Wagner, Edward Wang
Optics
Bridging high-Q and Kerr-nonlinear photonics using modal phase matching
Jordan R. Stone, Saleha Fatema, Christopher V. Poulton et al. (+3 more)
Integrated Kerr microresonators provide on-chip optical nonlinearity for wavelength conversion, optical frequency combs, and
quantum light sources. Traditionally, their dispersion engineering has tied nonlinear functionality to resonator geometry, forcing trade-offs with other device objectives. In particular, Kerr microresonators usually feature narrow resonator waveguides, but wide waveguides support higher Q through reduced sidewall scattering. We propose that modal phase matching - invoking multiple spatial mode families to satisfy dispersion requirements - facilitates Kerr nonlinear optics beyond traditional geometries. Working with a commercial foundry, we design and fabricate high-$ (>10^7) microresonators on a 160-nm-thick silicon nitride platform and demonstrate Kerr optical parametric oscillation. We achieve 20% conversion efficiency and gap-free wavelength tuning over >1 nm for parametric oscillation at the cesium D1 transition. Modal phase matching further supports pumping in both 1060-nm and 795-nm bands, without custom device layers, for wavelength generation between 600 nm to 1400 nm. Our work expands the Kerr design space, effectively decoupling Q and dispersion to create new opportunities with high-Q nonlinear devices.
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All authors Jordan R. Stone, Saleha Fatema, Christopher V. Poulton, Michael G. Wood, Gordon A. Keeler, Kartik Srinivasan
Mathematical Physics
Diassociative conformal algebras and their deformation cohomology
Anupam Sahoo and Apurba Das
In this paper, we introduce diassociative conformal
algebras that unify both associative conformal
algebras and diassociative
algebras. We show that the category of diassociative conformal
algebras is equivalent to the category of equivalence classes of formal distribution diassociative
algebras. By employing its Maurer-Cartan characterization, we then define the
cohomology of a diassociative conformal
algebra and show that it carries a Gerstenhaber
algebra structure. Our
cohomology can be used to study deformations and extensions of the structure. Finally, we define averaging operators on associative conformal
algebras and find their close relations with diassociative conformal
algebras.
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Quantum Physics
Evaluating Verified Autonomy in Quantum Engineering
Naixu Guo, Changhao Li, Siyu Cheng et al. (+6 more)
Reliable
quantum engineering is essential for turning
quantum phenomena into practical technologies. As
quantum platforms grow in scale and complexity, their characterization and operation require increasing human effort and coordination. Scientific artificial intelligence
agents, which can plan experiments, operate instruments, and analyze observations, offer a promising route towards autonomous
quantum engineering. Yet whether current
agents can perform reliably in this setting has not been systematically established. To fill this gap, we developed
Quantum-Harbor, a virtual laboratory that provides a controlled execution environment for
agents to interact with
quantum systems. This design enables direct verification of both the actions taken and the conclusions drawn. Building on this framework, we introduce QIQCBench, a
benchmark of $49$ expert-authored tasks spanning multiple layers including calibration and control, error correction and compilation, sensing and networking. Across $17$ frontier agentic systems, QIQCBench reveals wide variation in verified performance. These results expose a substantial gap between demonstrating capability and achieving reliable operation, and establish
Quantum-Harbor as a foundation for measuring progress towards verified autonomy in
quantum engineering.
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All authors Naixu Guo, Changhao Li, Siyu Cheng, Qicheng Tang, Binzhao Luo, Bikun Li, Yuxuan Du, Shihao Ru, Jiaqi Cai
High Energy Astrophysical Phenomena
Spontaneous wandering of the magnetic axis in pulsars: 3D magneto-thermal simulations and the imprint on braking indices
Clara Dehman and Daniele Viganò
Braking index measurements of hundreds of
pulsars, despite observational caveats, show a clear trend: $n<3$ at early ages, $n>3$ at middle ages, and increasingly large, fluctuating values at larger characteristic ages. Crustal
magnetic fields in isolated
neutron stars evolve through Ohmic dissipation and non-linear
Hall redistribution across scales, with additional early-time contributions from the
chiral magnetic effect and post-burial re-emergence. Initial conditions are usually assumed dipole-dominated, whereas more complex and realistic fields, with energy spread more evenly over a broad range of scales, have not been explored in this context. We assess how the internal dynamics of initially non-trivial fields change the dipolar field strength and obliquity, and how their combined contribution to the braking index $n$, together with that of the
alignment, compares with the observed values. To this end we perform long-term 3D magneto-thermal simulations, for configurations ranging from the dipole-dominated case to tangled, small-scale-dominated fields. Small-scale dominated configurations with weak dipolar components show rich dynamics: the dipolar mode is continuously fed by the small scales and may grow or decay depending on the initial spectrum, driving $n<3$ or $n>3$, while the obliquity varies on timescales as short as ${\cal O}$(kyr). These spontaneous changes often dominate the
alignment torque and can account for the large values of $n-3$ of either sign observed at characteristic ages $\tau_c\gtrsim10^5$ yr, unlike the dipole-dominated models. However, short-term magnetospheric fluctuations or superfluid-driven variations of the torque may still be needed to explain the measurements and the structured timing residuals quantitatively. Future work comparing these models with the observed timing properties could fine-tune the most promising initial configurations.
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