General Physics
Examining the Linear and Quadratic Dark Energy Parameterizations with DESI DR2 via AIC and BIC Selection
Laiphangbam Khumaba Mangang, Yumnam Prakash Singh and N. Chandrachani Devi
We examine whether or not the current observational preference for a dynamical dark energy(DE), as reported by DESI, is an artifact of the chosen functional form of dark energy equation of state (EoS) parameter $w(z)$ by considering a higher-order quadratic extension in EoS. We explore three distinct parameterizations of the DE models: the two-parameter (linear) Chevallier-Polarski-Linder (CPL) and Wang models, alongside a three-parameter
parabolic (quadratic) formulation. Using a joint
dataset of CMB measurements from Planck and ACT DR6,
baryon acoustic oscillations of DESI DR2, and Type Ia
supernovae from Pantheon+ and DES-SN5YR, we constrain the model parameters and observe a maximum frequentist preference of up to $\sim 4\sigma$ for these dynamical models. Specifically, the joint CMB + DESI + DES-SN5YR combination yields a substantial improvement in fit over $\Lambda\text{CDM}$, with $\Delta\chi^2_{\text{min}}$ values of $-20.5$, $-19.4$, and $-21.7$ for CPL, Wang, and
Parabolic models, respectively. In addition, the Akaike Information Criterion (AIC) provides weak to no evidence for $\Lambda$CDM, consistently favoring the dynamical DE models instead. On the other hand, the
Bayesian Information Criterion (BIC) imposes a heavy penalty on all the three models, reflecting its high sensitivity to
dataset size and model complexity. We find at best a mild support for CPL and Wang models but the
Parabolic model is strongly disfavored ($\Delta \text{BIC} \sim +6.4$ to $+15.6$). Furthermore, due to its expanded parameter space, the
Parabolic model exhibits a significant reduction in the Figure of Merit (FoM) compared to the two-parameter counterparts, demonstrating that the current cosmological
datasets do not yet justify an introduction of the higher-order DE models. So, as a result, the two-parameter descriptions of $w(z)$ remain the optimal choice for testing the dynamical DE signatures.
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General Physics
Vacuum Spin-Torsion Energy Density and Two-Modulus Stability on $S^2\times\mathbb{C}P^2$
Edward J. Shaya
In Einstein–Cartan–Kaluza–Klein compactification on $S^2\times\mathbb{C}P^2$, elimination of the non-propagating torsion generates a quartic
spin-current contact interaction whose
vacuum expectation value is nonzero even at zero
fermion occupation. We reduce the ten-dimensional $\Gamma_{ABC}$ structure to the zero-mode sector and find that the reduction is channel-resolved: each of the three internal Cartan-plane bilinears contribute with the opposite sign to the external (axial) channel, so that the full trace is $R_{ch} = T_{\rm vac}/T_{\rm axial} = 1 + 3\,(-1) = -2$. The
vacuum term is therefore twice the axial estimate and opposite in sign, and, combined with the elimination constant $c_{10} = -\kappa_{10}/32$, verified by explicit Clifford computation, it is attractive and proportional to $N_{\rm fam}^2$. We obtain the separated-point correlator, which in the continuum scales as $N_{\rm fam}^2 d_R/(V_6\,r^6)$, and, conditional on the physical
quantum-boundary prescription, evaluate it at the minimum supported separation. The finite-density piece of the same correlator has the same sign and grows with chemical potential. Binding deepens after nucleation; the single-particle Hartree self-contraction vanishes for
chiral zero modes. Using the derived $1/(a_1^2a_2^4)$
vacuum term with the Einstein-frame
curvature and quantized-flux contributions, we analyze a coupled two-modulus toy potential. At fiducial couplings, the $(m,n)=(3,3)$ sector has a finite-radius stationary point with positive Hessian in both radion directions, while the four-family $(4,3)$ minimum lies beyond the adopted
quantum-
curvature boundary. The three-family sector $(1,5)$ is also locally stable but is less bound. 3-family dominance of the thermal nucleation weight further imposes the condition $\kappa_4 \lesssim 7.5\,(16/B)\,\ell_P^2$. These results serve as inputs to our higher-level synthesis.
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Mathematical Physics
Exact topology of conservative multiplicative cascades: An ultrametric transfer-operator genus
Cristiano G. Sabiu
The multiplicative cascade is a well-known method for generating random fields that are both genuinely non-Gaussian and scale invariant. Its one-point and scaling statistics, namely the multifractal spectra $\tau(q)$, $D_q$, and $f(\alpha)$, are known exactly; however, its
geometric and topological measures are not. In this work, we show that the topological structures of a conservative (microcanonical) random permutation cascade can be precisely predicted. We compute the digital (cubical) Euler characteristic, or genus, of the level-$j$ excursion set of the two-dimensional cascade in closed form, using a transfer operator on the cascade's $b$-ary tree closed by its ultrametric structure and a conservative without-replacement sibling split. The result requires no Monte Carlo and matches simulated realizations with a maximum residual of $\sim\!10^{-4}$ in the Euler density, a controlled discretization artifact of the atomic measure. We tie the genus scaling analytically to the multifractal spectrum, and show that for a
geometric ladder of weights the genus is exactly self-similar under the multifractal-width dial. The construction uses the tree-sum cumulant machinery of Greiner et al. (Phys. Rev. E 58, 554, 1998), specialized to topological functionals; the conservative split carries the microcanonical fingerprint $\mathrm{Cov}(\ln w_a,\ln w_b)/\mathrm{Var}(\ln w)=-1/(n-1)$ that distinguishes it from canonical and lognormal cascades. The cascade is the multiplicative counterpart of the Rayleigh–Lévy flight and a controlled
benchmark for the morphology of strongly non-Gaussian fields.
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Instrumentation and Detectors
Demonstration of 255-kV high-voltage generation with a Cavallo multiplier system
S. M. Clayton, T. M. Ito, A. Jacobs et al. (+11 more)
Many cryogenic precision measurements require large electric fields in environments where conventional high-voltage feedthroughs are impractical. To address this, we developed a Cavallo electrostatic multiplier designed for in situ high-voltage generation under such conditions. Here, we report a room-temperature demonstration of this device. Using a mechanically translated transfer electrode and a custom rotary field mill for noncontact voltage measurement, the system reached output voltages up to approximately $255~\mathrm{kV}$ from a $25~\mathrm{kV}$ DC-biased input voltage in approximately $600~\mathrm{Torr}$ of SF$_6$. The charging curves are quantitatively described by a capacitance-based model once realistic electrode misalignment is included. Voltage-hold measurements show picoampere-scale leakage currents on long time scales, whereas operation near the maximum voltage is limited by transient discharge processes associated with electrode surface condition and local field enhancement, rather than by the intrinsic dielectric strength of the gas. These results demonstrate the Cavallo multiplier as a viable low-current, in situ high-voltage source and indicate that electrode surface preparation,
alignment tolerances, and insulation performance are the principal requirements for reliable operation in future cryogenic implementations.
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All authors S. M. Clayton, T. M. Ito, A. Jacobs, A-T. Le, M. F. Makela, C. M. O'Shaughnessy, N. S. Phan, E. Renner, T. A. Sandborn, T. J. Schaub, I. L. Smythe, J. Surbrook, M. A. Blatnik, B. W. Filippone
Instrumentation and Detectors
Operando Measurements of Pressure-Based PDMS Deformations in Electrochemical Microfluidic Devices
F. Lavanchy, Y. Sasaki, T. Minami et al. (+1 more)
Polymer based microfluidics, using polydimethylsiloxane (PDMS), are highly adaptable platforms for electrochemical studies commonly used for numerous applications. Deformations of these PDMS devices due to the flow pressure drop in microchannels have been widely documented in literature but cannot be prevented in all applications even though it is critical to measure quantitative data. In this work, we show that in electrochemical microfluidic devices used in energy conversion systems, the velocity profiles and channel deformations can be quantitatively measured based on spectro-electrochemistry and numerical simulations of Hagen-Poiseuille flows. PDMS deformations are found amplified in the case of large channel aspect ratios (i.e. close to 100), with deformation $\Delta$ h / h 0 > 100 % at 50 kPa, and start to be non-negligible > 10 % for channel internal pressure above 5 kPa. Finally, by considering these channel deformations in the Beer-Lambert law, we show that accurate absorbance and concentration measurements can be obtained using visible spectroscopy regardless the channel internal pressure.
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All authors F. Lavanchy, Y. Sasaki, T. Minami, S. Chevalier
Biological Physics
Influence of Oscillating Magnetic Fields on the Electric Dipole Moment of Radical Pairs in Cryptochrome Based Magnetoreception
Ali Soltanmanesh, Mahboobe Sehati, Sareh Rostami et al. (+2 more)
Radical pairs induced by light-driven reduction of cryptochrome
protein constitute a
spin dependent mechanism that is accompanied by an electric dipole moment and is found to be sensitive to external
magnetic fields. In this research, to investigate for the further proof of such model, the simultaneous effect of the Earth's static
magnetic field and the time-dependent
magnetic field noise on the electric dipole moment of the radical pair has been studied within the
quantum mechanical framework. The effect of the external
magnetic field discussed in different angles regarding the Earth
magnetic field within various frequencies and magnitudes. The sensitivity of the system behavior to the external
magnetic field frequencies and magnitudes, vastly differs among the changes in the
magnetic field angle to the Earth's static field. Furthermore, the sensitivity studied under the effect of the environmental noise. The relative spatial orientation of the two
magnetic field components plays an important role in the time
evolution of the electric dipole moment. Also, deeper discussions on specific relative orientations of the external
magnetic fields, such as 24 degree, shows that the
quantum model of radical pairs which is based on dipole moment, is in agreement with the results of the birds behavorial studies. These findings provide new insights into the sensitivity of the radical pair model to the combination of
magnetic fields and may contribute to a comprehensive understanding of the phenomenon of magnetoreception and the advancement of bioinspired
magnetic sensors.
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All authors Ali Soltanmanesh, Mahboobe Sehati, Sareh Rostami, Abolfazl Bahrampour, Alireza Bahrampour
Medical Physics
AQP4 Regulates Gap-Dominated Glymphatic Clearance through Dynamic Gliovascular Coupling
Tanran Zhang, Huaxiong Huang, Robert Eisenberg et al. (+1 more)
Aquaporin-4 (AQP4) is enriched at perivascular astrocytic endfeet, and impaired AQP4 function or localization is associated with reduced glymphatic transport. However, mechanical models suggest that pressure-driven exchange across the gliovascular interface occurs predominantly through inter-endfoot gaps rather than directly through the AQP4-rich membrane. How AQP4 regulates clearance in such a gap-dominated system remains unclear. We develop a reduced arterial PVS-ECS-venous PVS model coupling vascular deformation, AQP4-mediated endfoot water exchange, dynamic inter-endfoot gap regulation, and tracer transport. Cardiac-like oscillations generate strong bidirectional exchange but weak net clearance, whereas asymmetric vasodilation enhances directional transport by suppressing recovery-phase backflow. Dynamic gap regulation provides additional hydraulic rectification. Although gap-mediated flux is much larger than direct AQP4-mediated flux, PVS-facing AQP4 substantially affects clearance by altering the pressure–volume balance and hence the driving force for the dominant gap pathway. Reducing PVS-facing AQP4 permeability, or redistributing AQP4 away from the PVS-facing membrane at fixed total conductance, reduces cumulative venous output by about 40%. Aging-like changes in vascular motion, PVS mechanical coupling, and perivascular AQP4 enrichment further compound this impairment. These results suggest that AQP4 regulates gap-dominated glymphatic clearance through dynamic hydraulic coupling at the gliovascular interface.
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All authors Tanran Zhang, Huaxiong Huang, Robert Eisenberg, Shixin Xu
Atmospheric and Oceanic Physics · Cross-listed from stat.ML
Disentangling Forced and Internal Climate Variability in Single Realizations using Dynamic Mode Decomposition with Control
Nathan Mankovich, Andrei Gavrilov and Gustau Camps-Valls
Separating externally forced trends from internal
climate variability is a fundamental challenge in
climate science, particularly when analyzing observational records that exist only as a single realization. We show that a single
climate realization can be decomposed into forced and internal components by treating external forcing as a dynamical driver within a linear
stochastic system, an idea grounded in pullback attractor theory. This addresses a central challenge for
climate projection and for detecting and attributing the forced response. Existing single-realization methods rely on linear inverse models (LIMs), which ignore forcing, or linear regression, which omits dynamics. Here we introduce PullbackDMDc, a method grounded in non-autonomous dynamical systems theory and dynamic mode decomposition with control (DMDc), incorporating pullback attractor estimation to decompose a single
climate realization into spatial modes and their associated forced and internal components, yielding a physically interpretable picture of the underlying dynamics. After testing on a synthetic system with a known forced response, we illustrate the utility of PullbackDMDc for Earth System Model (ESM) evaluation by applying it to near-surface air temperature and sea-level pressure from reanalysis and four ESM large ensembles. PullbackDMDc estimates the forced response with skill matching or exceeding established baselines and helps select forcing predictors against model-based ground truth. Its internal-variability components reveal that ESMs qualitatively capture interannual and decadal modes while exhibiting systematic differences relative to each other and to observations. Skillful forced-response estimation and a novel decomposition position PullbackDMDc as a practical tool for single-realization
climate analysis and ESM evaluation.
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Plasma Physics
Automated Outlier-Robust Bayesian Profile Fitting for Magnetically Confined Plasmas with Modified Tanh Profiles and Good-and-Bad Gaussian Mixture Likelihoods
Jaewook Kim, Jekil Lee, Laurent Jung et al. (+2 more)
We present an outlier-robust
Bayesian approach for automated kinetic profile fitting in magnetically confined
plasmas with the modified tanh (mtanh) parametrisation and demonstrate its implementation on KSTAR. The method addresses two systematic obstacles: anomalous diagnostic channels can bias least-squares fits, and multimodality of the mtanh cost surface can trap deterministic optimisers in secondary minima. The deployed workflow uses a good-and-bad Gaussian mixture likelihood based on the Box–Tiao formulation as the default outlier-robust likelihood for fitted diagnostic channels, with posterior outlier probabilities retained as channel-level quality indicators. The posterior is sampled with an affine-invariant ensemble MCMC sampler initialised near the result of deterministic maximum a posteriori (MAP)-seeking optimisation, reducing sensitivity to secondary minima on the
multimodal mtanh surface. A batch automation layer retrieves diagnostic data from MDSplus and fits arbitrary time slices in parallel for the quantities \(n_e\), \(T_e\), \(T_i\), and \(v_T\) for which the relevant diagnostics are available. Results are written in formats suitable for MDSplus upload and downstream analysis. Representative KSTAR H-mode cases show that the mixture likelihood downweights contaminated measurements while preserving plausible pedestal profiles. The workflow provides a practical basis for future large-scale kinetic profile production for kinetic-EFIT, TRANSP, FASTRAN, and data-driven analysis workflows.
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All authors Jaewook Kim, Jekil Lee, Laurent Jung, Sang-hee Hahn, Sehyun Kwak
Quantum Physics
Loophole-Robust Certification of Quantum Advantage
Prosanta Pal, Gargee Sharma and Ramakrishna Podila
Claims of
quantum advantage should remain robust even when classical strategies have access to side information correlated with the
benchmark under evaluation, just as Bell certification must account for measurement dependence. We formalize such correlations as
benchmark dependence, a task-level generalization of measurement dependence. For every bounded-reward task, we show that the optimal
benchmark-dependent classical score obeys $S_\eta\leq\min\{1,S_{\mathrm{cl}}+\eta\}$, and construct a family of tasks that saturates this bound, showing that the linear dependence on $\eta$ is tight without further assumptions. For repeated product tasks with roundwise dependence, we obtain the stronger multiplicative bound $S_\eta^{(n)}\leq(\omega_{\mathrm c}+\eta)^n$, and extend the framework to finite-sample data, mutual-information constraints, multipartite tasks, and correlations distributed along a causal path. Applying these results to aggregated IBM hardware data, we obtain positive raw-count cycle-product certificates of 0.0812 for CHSH and 0.2178 for Mermin–GHZ, while the nine-context magic-square construction remains uncertified; readout-mitigated values are reported separately as sensitivity estimates. We also analyze a non-Bell
quantum-kernel
benchmark, where a label-construction variable has measured conditional dependence $\widehat{\eta}_{\lambda}^{(Y)}=0.5$, above the threshold $\eta_{\mathrm{req}}=0.375$, required to close the reported score gap, and yields perfect classical classification. The framework therefore converts a
quantum–classical score separation into a quantitative lower bound on the
benchmark-correlated classical information required to explain the score separation.
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History and Philosophy of Physics · Cross-listed from cs.GL
The Reconstructions of Konrad Zuse's Z3 Computer
Raul Rojas
This paper reviews the various reconstructions of Konrad Zuse's Z3 computer, built in 1941. The first is the reconstruction made by Zuse himself in the 1960s, which is now housed at the Deutsches Museum in Munich. Second is the 2001 reconstruction, made in Berlin, and which has a didactic purpose. Third is the Z3r, a Z3 reconstruction built by Horst Zuse in honor of his father's 100th birthday. Fourth is the reconstruction by Christoph Traber in Switzerland. All of these machines strive to preserve the cultural heritage that the Z3 represents.
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Superconductivity
Cooper Pairing Mediated by Onsite Exchange: A Possible Mechanism For High-Temperature Superconductivity
Jacques R. Eone
Among the various mechanisms proposed for unconventional superconductivity, this paper focuses on the Coulomb interaction responsible for $d$-wave and $s_\pm$-wave pairing
symmetries in cuprates and iron pnictides. Although the effective multi-orbital interaction $U_\text{eff}=U-J$ is predominantly repulsive, an attractive component driven by the Hund's coupling parameter $J$ is sufficient to bind fractional charges. This attractive multi-orbital contribution and a repulsive term of the single-band Hubbard model yield the superconducting pairing gap $\Delta_0$ and an estimate of the transition temperature $T_c$. Given the complex electronic structure and vast compositional space of these materials, the model focuses exclusively on the doped superconducting plane hosting these fractional charges. Through this approach, an analytical expression mainly dependent on the Hubbard $U$ and Hund $J$ parameters that reproduces the empirical superconducting dome is derived. Furthermore, the model addresses the characteristic electron and hole doping asymmetry observed in cuprates by accounting for Hund's coupling parameters. Finally, while the model describes strange metal behavior, it currently provides only a qualitative explanation for the pseudogap phase and the underdoped isotope effect.
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Popular Physics
Retaining Earth's Habitability Beyond the Life of the Sun
Gabriel Harry
The Earth is rare and large-scale interstellar travel may be unfeasible - instead of migrating to other
solar systems, future civilisations on Earth may have to remain. However, left unchecked, the Earth's current habitability will end in one billion years. This paper investigates and conceptualises a set of megaengineering concepts required to safeguard against seven long-term threats to Earth's habitability:
solar luminosity,
solar engulfment, the end of tectonics, water loss, obliquity and rotation, object collision, and extra-system threats. Implementing and maintaining the set of safeguards would allow the Earth to remain habitable for 9.1 quadrillion years. This could be raised to nonillions of years via capturing interloping interstellar medium onto Jupiter. Compared with alternatives, advantages of the safeguards such as greater feasibility, lower requisite rate of energy production, and utilisation of economically viable space mining infrastructure may present remaining on Earth as a more attractive long-term survival strategy.
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High Energy Physics (Phenomenology)
Probing the X(3700) through two-photon $D \bar{D}$ production in ultraperipheral collisions and at the EIC
F.C. Sobrinho, F.S. Navarra, K.P. Khemchandani et al. (+1 more)
We investigate whether
photon-induced production in ultraperipheral heavy-ion collisions and at the EIC can provide a new environment to search for the scalar $D \bar{D}$ molecular candidate usually denoted as $X(3700)$. We calculate the tree-level amplitudes for $\gamma\gamma\to D^+ D^-$ and $\gamma\gamma\to D^0 \bar{D^0}$, dress the outgoing pair with a coupled-channel Bethe-Salpeter interaction in the $(D^+ D^- , D^0 \bar{D^0})$ basis, and convolute the resulting subprocess cross sections with equivalent-
photon spectra. In the adopted two-channel scenario the analytic continuation of the $T$-
matrix gives a bound state at $M_X=3.7162$~GeV, which is below the $D^0 \bar{D^0}$ threshold. As a consequence of this, the observed signal in the continuum is not simply an isolated narrow peak, and a characteristic near-threshold line-shape distortion is produced: around $3.70 \leq W \leq 3.85$~GeV the integrated dressed-to-bare ratios are $(13.71,0.35)$ in Pb-Pb UPCs and $(13.74,0.35)$ in $e$-Au collisions for $(D^+D^-,D^0 \bar{D^0})$. Using the BABAR-fitted central normalization $K_{\rm dressed}=0.382$, the corresponding dressed cross sections are $(24.6,14.6)~\mu{\rm b}$ in Pb-Pb UPCs and $(2.41,1.43)~\rm nb$ at the EIC. The charged-to-neutral ratios are directly accessible observables, whereas the dressed-to-bare ratios provide theoretical diagnostics of the final-state interaction. The near-threshold features are controlled by the common $\gamma\gamma\to D\bar{D}$ dynamics and are rather independent of the external
photon source.
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All authors F.C. Sobrinho, F.S. Navarra, K.P. Khemchandani, A. Martínez Torres
Fluid Dynamics · Cross-listed from math.NA
A Log-Gaussian Scale-Space Limiter for Hybrid Continuum–Ballistic Gas Dynamics
Bjørn Wu
We propose a log-Gaussian scale-space limiter for hybrid continuum–ballistic gas dynamics. The method defines complementary continuum and ballistic weights as Gaussian cumulative probabilities in logarithmic Knudsen-number space and blends Navier–Stokes–
Fourier and half-range Maxwellian kinetic fluxes. The method is formulated as a lightweight hybrid closure intended for future implementation in finite-volume, discrete Boltzmann, or gas-kinetic solvers. Reduced one-dimensional closure/profile comparisons against DVM/BGK
Fourier and Couette data show that log-Gaussian weighting of NSF and jump/slip-corrected branches improves the tested macroscopic profiles relative to NSF. The same six DVM/BGK profiles are used both as reference profiles and to calibrate K0 and sigma; therefore, the approximately 40 percent reduction in combined mean profile error is an in-sample calibration result for the reduced profile model rather than independent validation or numerical validation of the proposed finite-volume face flux. Additional diagnostics assess non-
equilibrium moments, internal parameter robustness, and shock-layer activation.
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Superconductivity
Analytical solution of the Eliashberg equations for strong-coupling superconductivity in hydrides
Tomas J. Escamilla and Chumin Wang
The recent discovery of room-temperature superconductivity in hydrogen-rich materials under extreme pressures has renewed interest in
phonon-mediated pairing mechanisms described by the Eliashberg theory, which generalizes the BCS framework by incorporating
phonon retardation effects. In this article, we present an analytical solution to the isotropic Eliashberg equations for the superconducting critical temperature, formulated within the Debye model. This solution exhibits good agreement with fully selfconsistent numerical calculations across both weak- and strong-coupling regimes, correctly reproducing the exponential and square-root dependences on the electron-
phonon coupling parameter. We further apply the solution to YH6, benchmarking against experiment and the McMillan-Allen-Dynes formula. More broadly, across a diverse set of hydride
superconductors, the predicted critical temperature shows scaling consistency with ab initio calculations and experimental data.
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Adaptation and Self-Organizing Systems · Cross-listed from math.DS
Lie Meets Network Dynamics: Exact Macroscopic Reductions (Finite Systems)
Erik Andreas Martens and Sanjay Dharmavaram
We establish a unified framework for exact dimensional reductions in network dynamical systems using Lie-Scheffers theory. For network dynamical systems with mean-field Lie-Scheffers structure, we prove that networks of $n$ nodes with local dimension $d$ can be exactly reduced from $ n d $ dimensions to a fixed macroscopic system of dimension $ m d $, where $m$ is the number of fundamental solutions required by the nodal dynamics. Crucially, the superposition principle resulting from the Lie-algebraic structure allows the mean-field coupling to be expressed explicitly in terms of the macroscopic variables, yielding a closed self-consistent system independent of network size. This reduction collapses the high-dimensional network flow onto invariant
manifolds parameterized by $ \gamma = d(n-m) $ independent constants of motion. Our framework rigorously explains known reductions and provides a systematic method to discover new ones. We illustrate the theory with ensembles of Riccati equations (encompassing the Kuramoto model and Theta
neuron model), quasi-linear ODEs, and generalized Bernoulli equations, explicitly deriving the macroscopic flows and conserved quantities for each case.
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Astrophysics of Galaxies
Testing the recovery of the NGC 6505 Einstein ring in deep OSN 1.5-m imaging
Homer Dávila Gutiérrez, Julio Carlos Bertua Marasca, Alejandro Heredia Teva et al. (+4 more)
The discovery of a complete Einstein ring around the nearby elliptical
galaxy NGC 6505 (z = 0.042) by the Euclid mission provides a rare, precisely characterised low-
redshift strong lens. Its Einstein radius of 2.500 arcsec is comparable to the angular resolution attainable from typical mid-aperture ground-based facilities, which makes the recoverability of the ring from the ground an open practical question. We test whether the ring can be recovered in deep Cousins-R imaging of NGC 6505 obtained with the 1.5-m T150
telescope at the Sierra Nevada Observatory (OSN), totalling 8.03 h of integration at a final effective seeing of FWHM = 2.47 arcsec, corresponding to an Einstein-radius-to-FWHM ratio of 1.01. After subtracting a non-parametric isophotal model of the
galaxy, we search the residual for coherent arc- or ring-like structure and find none at the Euclid-measured Einstein radius, with a maximum value of 1.5 sigma for the adopted radial recovery metric. An injection-recovery experiment using a simplified, Euclid-informed synthetic ring, processed through the same isophotal-modelling and residual-analysis pipeline, yields a maximum recovered significance between 0.42 sigma and 1.86 sigma across three PSF descriptions, below our operational 3 sigma recovery threshold in every case. We interpret this as a
dataset-specific non-recovery driven by the regime in which the Einstein radius is approximately equal to the FWHM of these observations, rather than as a general detectability law.
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All authors Homer Dávila Gutiérrez, Julio Carlos Bertua Marasca, Alejandro Heredia Teva, Irene Naranjo Arroyo, Fernando Núñez Martínez, Miguel Ruiz Travesí, Eugenio Grande Sáez
Atomic Physics
Defect assignment of the clock site in $^{229}\text{Th:CaF}_2$
Daniel A. Rehn, Harry W. T. Morgan, Harris E. Mason et al. (+6 more)
The performance of solid-state $^{229}\text{Th}$
nuclear clocks depends sensitively on the microscopic environment of the thorium
nucleus in the host
crystal. Here we reassess the dominant quadrupole-split thorium site in $^{229}\text{Th:CaF}_2$, which has been assigned to a thorium dimer in recent spectroscopic work. Thermodynamic estimates, density functional theory calculations, and electric-field-gradient comparisons instead favor an isolated $\text{Th}^{4+}$ substitution on a $\text{Ca}^{2+}$ site charge-compensated by two nearby fluorine interstitials in a relaxed $90^\circ$ motif. The same calculation identifies a higher-energy mixed-shell interstitial motif as a plausible minor site. The clock-active quadrupole-split site is therefore controlled by local fluoride compensation rather than unavoidable thorium aggregation. This defect assignment also has implications for achievable linewidths and provides a microscopic basis for reducing broadening in solid-state
nuclear clocks.
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All authors Daniel A. Rehn, Harry W. T. Morgan, Harris E. Mason, H. B. Tran Tan, Ricky Elwell, Igor M. Savukov, Michael J. Martin, Andrei Derevianko, Eric R. Hudson
Plasma Physics
Exact Solution of the Direct and Inverse Quasi-stationary Dynamo Problem in the Expanding Plasma Ball
Yurii V. Dumin
It is shown that differential equation of the quasi-stationary dynamo effect (i.e., generation of the electric fields and currents) in a uniformly-expanding
plasma ball with strongly anisotropic conductivity possesses the unique mathematical property: namely, the spectrum of its
eigenvalues is universal and independent of physical parameters of the medium. As a result, it becomes possible to introduce a special set of eigenfunctions - which we called the generalized spherical functions - that can be used to solve the dynamo problem in exactly the same way as ordinary spherical functions are used to solve the Laplace equation. The corresponding exact solutions should be especially valuable for treating the inverse dynamo problem, i.e., determination of the
plasma parameters from the experimentally measured electric fields and currents.
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Materials Science
Phase-Controlled Epitaxy and Anisotropic Antiferromagnetism of Polar Wurtzite MnTe
Janusz Sadowski, Jaroslaw Z. Domagala, Piotr Dziawa et al. (+8 more)
Altermagnetic spintronics requires materials in which compensated
magnetic order,
symmetry-controlled electronic responses, and epitaxial tunability can be combined in experimentally accessible thin films. MnTe is a key material in this context, but experimental studies have focused mainly on the stable NiAs-type polymorph, whereas the polar wurtzite phase remains largely unexplored. Here we demonstrate molecular-beam epitaxy growth and investigate properties of nearly phase-pure wurtzite MnTe deposited directly on GaAs(111)B, and show that small changes in the growth conditions strongly modify the phase composition, from a multiphase state with endotaxial NiAs-type inclusions embedded in wurtzite MnTe
matrix to an almost single-phase polar wurtzite layer.
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All authors Janusz Sadowski, Jaroslaw Z. Domagala, Piotr Dziawa, Anna Kaleta, Sania Dad, Maciej Wójcik, Dorota Janaszko, Sławomir Kret, Oleksii Liubchenko, Maciej Sawicki, Katarzyna Gas
Quantum Physics
Nearly optimal polynomial approximations for the quantum singular value transform
Evan Rule
We introduce
polynomial approximations of the even and odd step functions on the interval $[-1,1]$ with simple Chebyshev coefficients, making their numerical implementation straightforward. We derive rigorous error bounds and demonstrate that these
polynomials are nearly optimal in the sense that their error deviates from the theoretically optimal error by a multiplicative factor that grows logarithmically with the
polynomial order. From these
polynomials, we derive related nearly optimal
polynomial approximations that can be used to perform
quantum phase estimation, linear amplitude amplification,
eigenvalue thresholding, and other
quantum algorithms using the
quantum singular value transform.
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Medical Physics
Paweł Moskal, Shiva Abbaszadeh, Harmanjeet Singh Bilkhu et al. (+19 more)
Annihilation
photons are
quantum entangled in their polarization, a property that is not accessible in state-of-the-art clinical Positron Emission
Tomography (PET). This roadmap describes the current status of research in the emerging field of
quantum entanglement applications involving these
photons for medical diagnosis. It outlines the underlying physics phenomena and the development of detector systems that can serve as a foundation for future
Quantum Entanglement PET (QE-PET) scanners. These scanners will be capable of utilizing the
entanglement between annihilation
photons by measuring their Compton scattering on electrons. This roadmap comprises up-to-date experimental results on the study of
quantum entanglement and the decoherence of annihilation
photons, alongside the current theoretical understanding of these phenomena. The methods and detector technologies described herein are being developed (i) in order to enhance standard PET imaging by suppressing random coincidences in the reconstruction of annihilation site density distributions, (ii) in order to establish the degree of
quantum entanglement as a diagnostic biomarker for tissue pathology and oxygenation, and (iii) in order to elaborate a method for pH imaging. Whether
entanglement-based imaging and pH mapping can be successfully translated into clinical practice remains an open question and a subject of exciting ongoing research. This roadmap serves as an invitation to the scientific community to join this burgeoning field.
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All authors Paweł Moskal, Shiva Abbaszadeh, Harmanjeet Singh Bilkhu, Peter Caradonna, Pragya Das, Praveen Gurunath Bharathi, Ana Marija Kožuljević, Zdenka Kuncic, Deepak Kumar, Mihael Makek, Marek Nowakowski, Siddharth Parashari, Kaustav Prasad, Gregory R. Romanchek, Sushil Sharma, Kenji Shimazoe, Ewa Stępień, Sodai Takyu, Miwako Takahashi, Mizuki Uenomachi, Ritesh Verma, Taiga Yamaya
Atmospheric and Oceanic Physics
Modeling the response of the marine carbon cycle to extreme CO$_2$ injection events
Punit Gandhi, Rowan Lockwood, Corinne Myers et al. (+4 more)
We explore how the response of a conceptual model of the marine carbon cycle depends on the way in which carbon is injected from the atmosphere. We find that, for single-injection pulses, the threshold amount required for a large response of the excitable system depends on pulse duration but not on its specific form. We do, however, see differences in the number of large transient responses in carbon and, correspondingly, the duration of the response for different pulse shapes. These differences are magnified as the system is pushed towards increased excitability and can be understood in terms of the geometry of an increasingly winding heteroclinic orbit. Inspired by Large Igneous Provinces (LIPs), we also consider random sequences of injection pulses. We find a wide range of possible responses for a given overall amount injected and duration, depending on the mean characteristics of the individual pulses. We also identify a resonance-like "Goldilocks" zone, in which intermediate pulse durations or arrival frequencies produce the largest number of repeated transients, and we test the framework with illustrative scenarios motivated by the Siberian Traps and Columbia River Basalt Group.
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All authors Punit Gandhi, Rowan Lockwood, Corinne Myers, Parimita Roy, Ivan Sudakow, James Witts, Hao Helen Zhang
Quantum Physics
Anticipating Decoder Side-channel Attacks in Fault-tolerant Quantum Computers
Shashvat Shukla, Dan E. Browne and Shin Nishio
As
quantum computing emerges as an applied technology, there is a growing need to protect
quantum computers against information security attacks. This work identifies a new class of side-channel attacks against fault-tolerant
quantum computers, in which the syndrome data that is sent to the decoder system is used to infer which computation (logical
circuit) is taking place on the
quantum computer. Our work introduces the concept of gate fingerprints, which describes those patterns present in syndrome data that indicate which logical operation took place on the
quantum computer. We show different effects by which logical operations produce gate fingerprints by focusing on Clifford+T computation in the surface code. We then explore how gate fingerprint information can be used to make inferences about the
circuits or
algorithms run on a
quantum computer. Our findings indicate that decoder systems can be a vector for side-channel attacks and thus to prevent this, decoder systems should either be secured or built by a trusted party.
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Atomic Physics
Wichmann-Kroll Correction to the Interelectronic Interaction in He- and Li-Like Ions
J. Sommerfeldt, V. A. Yerokhin, Z. Harman et al. (+1 more)
We present a theoretical study of the higher-order QED contribution to the interelectronic interaction in He- and Li-like ions, where a virtual electron-positron loop is inserted into the
photon line of the one-
photon exchange diagram. Our approach is based on the Dirac-Coulomb Green's function and accounts for the interaction of the virtual $e^+e^-$ pair with the electric field of the
nucleus to all orders in $\alpha Z$, with $\alpha$ being the fine-structure constant and $Z$ the atomic charge number. We show that the numerical convergence of the involved integrals can be significantly improved by explicitly subtracting the non-gauge-invariant spurious contributions from the integrands. We present improved numerical values for this contribution to the Lamb shift over a wide range of
nuclear charge numbers $Z$. Our calculations agree well with previous results by Artemyev and co-workers [Phys. Rev. A 56, 3529 (1997); Phys. Rev. A 60, 45 (1999)] for He-like ions, but we find a discrepancy in the Li-like case. Moreover, we calculate the finite
nuclear size correction to this diagram, which can reduce its size by more than 5% for heavy ions. The improved QED calculations not only decrease the uncertainty of theoretical predictions for the interelectronic interaction in few-electron ions but the methods could also be used in the future to improve calculations of closely related one-electron two-loop QED diagrams.
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All authors J. Sommerfeldt, V. A. Yerokhin, Z. Harman, C. H. Keitel
Optics
Long baseline optical interferometric imaging with active phase stabilization
Joshua J. Collier, Leuca Patmore, John S. Wallis et al. (+3 more)
Astronomical observations allow us to better our understanding of the universe. As we observe smaller and more distance features, we run into the diffraction limit of our observation system. This limit is a function of the wavelength observed and the size of the primary aperture used. We can synthesize a larger primary aperture by implementing interferometry. Long baseline optical interferometry would lead to significant improvements in astronomical imaging resolution. Building optical interferometers with free space baselines becomes significantly more difficult as the baseline increases. A promising alternative is to use optical fiber to connect
telescopes. Fiber-based interferometers are much more susceptible to phase noise than their free-space counterparts due to inhomogeneities in the fiber medium. This leads to significant degradation of interferometric signals used for astronomical measurements. We implement phase stabilization techniques used in
quantum communications to stabilize an optical interferometer with a 170km pseudo-baseline. We use a
quantum optimal measurement technique with this interferometer to resolve the extent of a source four times smaller than the diffraction limit of the system within 1.5% error. These results bring the potential for a full-scale on-sky long baseline interferometer significantly closer. A 350km baseline optical interferometer at 1550nm would allow us to resolve sub microarcsecond features in the universe.
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All authors Joshua J. Collier, Leuca Patmore, John S. Wallis, Elrina Hartman, Benjamin P. Dix-Matthews, David R. Gozzard
Quantum Physics
Axion like particles multi-parameter sensing
Hassan Manshouri, Moslem Zarei and Mehdi Abdi
The search for the
axion like particles (APLs)-one of the deepest puzzles in modern cosmology-may hold the key to understanding dark matter and dark energy. In this work, we introduce a setup taking advantage of the
quantum metrology techniques to constrain the hypothetical mass and coupling constants of APLs by employing exotic pseudoscalar
spin-
spin interactions between
fermions mediated by ALPs. A key advantage of our approach is the exploitation of position-dependent
spin sensor results to the high sensitivity of the probe. To simultaneously investigate the
axion mass and coupling constants, we invoke a multi-probe detection strategy. Through this strategy, we circumvent the singularity of the
quantum Fisher information
matrix as an ultimate upper bound on the sensitivity of any probe. For the
axion masses in the range of $m_a {\le} 10^{-3} \text{eV}$, this setup can exclude values of
axion coupling constants $g^e_pg^n_p$ down to $10^{-7}$.
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Quantum Physics
Witnessing the Quantum Mpemba Effect with a Single Observable
J. M. Z. Choquehuanca, P. A. C. Obando, M. S. Sarandy et al. (+1 more)
The Mpemba effect, in which a system farther from
equilibrium relaxes faster than one closer to it, defies the intuition of nonequilibrium statistical mechanics. Here, we introduce a general framework to unambiguously witness this phenomenon based on a single observable defined for Markovian open
quantum systems. The Mpemba observable bypasses full state
tomography, offering utility for state preparation and thermal task optimization. We illustrate our method using local magnetization as a Mpemba signature, applying it to a
qubit under generalized amplitude damping.
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All authors J. M. Z. Choquehuanca, P. A. C. Obando, M. S. Sarandy, F. M. de Paula
Fluid Dynamics · Cross-listed from math.AP
Homothetic Self-Similar Solutions to the Incompressible Navier-Stokes Equations
Tim Binz and Matei P. Coiculescu
We investigate homothetic forward self-similar solutions of the incompressible Navier-Stokes equations: the solutions $\overline{U}$ for which both $\overline{U}$ and $\beta \overline{U}$ are self-similar profiles for some nontrivial $\beta$. Homothetic solutions are, in addition, the only solutions for which a singular limit argument can be used to prove non-uniqueness of Leray-
Hopf solutions along the lines of the Jia-Šverák program. In three dimensions, and for sufficiently regular initial data, we prove a Liouville
theorem that rules out the existence of non-trivial homothetic solutions. In two dimensions, our Liouville
theorem reproves a result of Luo and Shvydkoy that the only decaying homothetic solution with continuous angular data is the Oseen
vortex. In addition, we prove that the Euler equations linearized around the Oseen
vortex are stable in some subspaces of $L^2(\mathbb{R}^2)$, for example in the space of $2$-fold rotationally symmetric functions. On the other hand, we also discover a homothetic solution for which an unstable approximate
eigenvalue of the linearized Euler equations exists.
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