General Physics
Three-Dimensional Modified Dirac Oscillator in Standard and Generalized Doubly Special Relativity
Abdelmalek Boumali and Nosratollah Jafari
% Doubly Special Relativity (DSR) introduces, besides the invariant speed of light $c$, an observer-independent high-energy % scale that deforms relativistic kinematics and can be implemented through modified dispersion relations or effective % wave equations with energy-dependent spatial operators. In this work we develop a three-dimensional, exactly solvable %
benchmark for such deformations in the
spin-$\tfrac12$ sector: the Dirac oscillator. Following the original % construction of Moshinsky and Szczepaniak, the oscillator is introduced through a linear non-minimal momentum coupling, % which preserves Hermiticity and yields, after decoupling the Dirac equation into large and small components, a % three-dimensional isotropic harmonic-oscillator operator supplemented by a strong
spin–orbit term. % We then incorporate Planck-scale deformations in two standard DSR realizations (Amelino–Camelia and % Magueijo–Smolin, characterized by an invariant energy scale $k$) and in a generalized DSR framework based on a % first-order expansion in the Planck length $l_p$. In all cases the bound-state eigenfunctions retain the % oscillator-spinor structure dictated by spherical
symmetry, while DSR deforms the algebraic relation between
quantum % numbers $(N,j,\ell)$ and the relativistic energy, producing branch-dependent shifts for both particle and antiparticle % solutions. The undeformed limit ($k\to\infty$ or $l_p\to0$) is recovered smoothly and the deformation signal increases % with excitation through the oscillator scale and
spin–orbit splitting.
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Physics and Society
From description to design: Automated engineering of complex systems with desirable emergent properties
Thomas F. Varley and Josh Bongard
The study of complex systems has produced a huge library of different descriptive statistics that scientists can use to describe the various emergent patterns that characterize complex systems. The problem of engineering systems to display those patterns from first principles is a much harder one, however, as a hallmark of complexity is that macro-scale emergent properties are often difficult to predict from micro-scale features. Here, we propose a general optimization-based pipeline to automate the difficult problem of engineering emergent features by re-purposing descriptive statistics as loss functions, and letting a gradient descent optimizer do the hard work of designing the relevant micro-scale features and interactions. Using Kuramoto systems of coupled oscillators as a test bed, we show that our approach can reliably produce systems with non-trivial global properties, including higher-order synergistic information, multi-attractor metastability, and meso-scale structures such as modules and integrated information. We further show that this pipeline can also account for and accommodate constraints on the system properties, such as the costs of connections, or topological restrictions. This work is a step forward on the path moving complex systems science from a field predicated largely on description and post-hoc storytelling towards one capable of engineering real-world systems with desirable emergent meso-scale and macro-scale properties.
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Optics
Correlated inhomogeneous absorption profiles across distinct optical transitions in a rare-earth doped crystal
Flora Segur, Sacha Welinski, Alban Ferrier et al. (+2 more)
In rare-earth ion-doped
crystals, inhomogeneous absorption profiles reflect the distribution of local environments experienced by individual ions. While each optical transition probes this distribution differently, their fine spectral structures may retain correlations arising from shared local perturbations. In this paper, we present a low-temperature, high-resolution spectroscopic study in Er$^{3+}$:YSO of the transition $^{4}I_{15/2}$ - $^{4}I_{11/2}$ at 980 nm and compare it to the well-known transition $^{4}I_{15/2}$ - $^{4}I_{13/2}$ at 1.5 $\mu$m. Using spectral hole burning on one transition while monitoring the other, we uncover for the first time spectral correlations between two optical transitions, providing new insight into the microscopic origin of inhomogeneous distributions in rare-earth-doped
crystals.
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All authors Flora Segur, Sacha Welinski, Alban Ferrier, Perrine Berger, Anne Louchet-Chauvet
Fluid Dynamics
Spatial symmetry invariance of solution of Kolmogorov flow
Shijun Liao
We prove a mathematical
theorem that solution for all $t > 0$ of the two-dimensional (2D) Kolmogorov flow governed by Navier-Stokes (NS) equations with periodic boundary condition keeps the same spatial
symmetry as its smooth initial condition. The proof of a similar
theorem for the three-dimensional NS equations is given in the appendix. These mathematical
theorems can be used to check the correctness and reliability of numerical simulations of NS
turbulence. For example, they support the corresponding CNS (clean numerical simulation) results of the 2D and 3D turbulent Kolmogorov flows [1-3] that remain the same spatial
symmetry in the whole time interval of simulation, but do not support the corresponding DNS (direct numerical simulation) results that lose the spatial
symmetry quickly. In other words, these DNS results violate these mathematical
theorems. Thus, these mathematical
theorems rigorously confirm that the spatiotemporal trajectories of NS
turbulence given by DNS are indeed quickly polluted by numerical noises badly. All of these indicate that CNS can indeed provide helpful enlightenments to deepen our understanding about
turbulence and besides approach some mathematical truths about NS equations.
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Instrumentation and Detectors
Fused-Silica Activation Cherenkov Detector for Pulsed D–T Fusion Yields
N. Kaneshige, S. Alawabdeh, W. Hennig et al. (+3 more)
We demonstrate a compact, non-toxic, low-cost
neutron-yield diagnostic for pulsed D–T fusion systems using an undoped fused-silica (SiO$2$) rod as both activation target and Cherenkov radiator. D–T
neutrons (14.1 MeV) activate $^{28}$Si and $^{16}$O to produce short-lived $^{28}$Al ($T{1/2}=134,\mathrm{s}$) and $^{16}$N ($T_{1/2}=7.13,\mathrm{s}$). The resulting $\beta^-$ particles exceed the Cherenkov threshold and generate UV–visible light detected by a fast photomultiplier tube. A SiO$_2$ rod of dimensions $6,\mathrm{in}\times1,\mathrm{in}$ (length $\times$ diameter) is optically coupled and read out with a CAEN DT5730 digitizer operating in list mode with digital pulse processing. The post-pulse count rate is fit using fixed $^{16}$N and $^{28}$Al half-lives together with background terms to infer
neutron fluence. Testing at the ZEUS D–T Dense
Plasma Focus established a reference calibration and agreement with a praseodymium-calibrated silver activation detector. Measurements near a D–D Dense
Plasma Focus show no activation signal, confirming D–T selectivity. The diagnostic enables pulse-to-pulse yield measurements within minutes following a pulse and is being deployed on Helion Energy's seventh fusion prototype, Polaris.
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All authors N. Kaneshige, S. Alawabdeh, W. Hennig, D. Cech, M. Hua, R. Grazioso
Atomic Physics · Cross-listed from hep-ph
Effects of dispersion parity-violating interaction in electron scattering and atoms
V. V. Flambaum and I. B. Samsonov
Exchange of two
neutrinos (as well as other
fermions) generates a long-range parity-violating potential of the form $\sim G^2/r^5$, with characteristic range $\hbar/(2m_\nu c)$. In atomic systems the corresponding
matrix elements converge at distances $r < 10/M_Z$, so that the interaction between electron and
quarks effectively reduces to a contact term $\sim G^2 M_Z^2 \delta^{3}(\vec{r}) \sim G\,\alpha\,\delta^{3}(\vec{r})$. This interaction produces a $-0.8\%$ correction to the effective weak charge of cesium, resolving the $2\sigma$ discrepancy between the Standard Model prediction and the measured Cs parity-violation amplitude. The corresponding value of the weak mixing angle is $\sin^2\theta_W = 0.2375(19)$ at $q^2 \approx 0$, in agreement with the Standard Model prediction $\sin^2\theta_W = 0.23873$. The relative correction to the
proton weak charge is about $3\%$. Using these results, we revisit the limits on an additional $Z'$
boson and obtain a constraint on isospin-conserving oblique radiative corrections characterized by the Peskin–Takeuchi parameter $S = -0.32(53)$ at $q^2 \approx 0$.
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Instrumentation and Detectors · Cross-listed from nucl-ex
The 2027-2034 Vision for Nuclear Physics in Canada, with an outlook to 2041
Corina Andreoiu, Svetlana Barkanova, Gregory Christian et al. (+4 more)
The Canadian subatomic physics community establishes its scientific, and thus funding, priorities through periodic Long-Range Plans (LRP). The community is now putting together a new LRP, which will be in effect from 2027 through 2034, with its scope extending through 2041. As part of this process, the Canadian Institute of
Nuclear Physics (CINP) has put together a strategic report, following an extensive consultation process. The report describes the broad and ambitious research program undertaken by the Canadian
nuclear physics research community, both onshore and abroad, touching on key questions regarding the origin,
evolution, and structure of visible matter in the universe. This document provides a grid of different Canadian
nuclear physics projects undertaken now and in the future, and their associated timelines. It concludes with specific recommendations for maximizing Canadian scientific output in
nuclear physics.
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All authors Corina Andreoiu, Svetlana Barkanova, Gregory Christian, Alexandros Gezerlis, Garth Huber, Jeffery W. Martin, Ruben Sandapen
Geophysics · Cross-listed from cond-mat.mtrl-sci
Mimicking the earth core conditions with ultrafast laser materials interaction
Mohamed Yaseen Noor, Aram Yedigaryan, Gabriel Calderon et al. (+6 more)
Ultrafast
lasers create extreme, non-
equilibrium thermodynamic conditions that can transiently reach pressures and temperatures comparable to interior core of the earth. Here we show that femtosecond excitation of amorphous silica-hafnia multilayer dielectrics drives the formation of high-pressure crystalline phases of silica including stishovite, seifertite, and the pyrite-type high density structure, within confined subsurface regions.Using TEM, SAED, and 4D-STEM, we directly map nanoscale phase
evolution and identify crystalline motifs embedded inside
laser generated blisters.Complementary molecular dynamics simualtions reveal the thermodynamic pathway underlying these transformations, where rapid electronic pressure initiates densification and octahedral coordination, followed by temperature driven crystallization and displacive transitions during ultrafast quenching. The resulting polymorphs reflects a dual-stage pathway inaccessible under
equilibrium processing. Our results establish femtosecond
laser excitation as a viable route to synthesize and stabilize ultrahigh-density high pressure silica phases under ambient conditions, without a diamond anvil
cell, with implications for
laser-damage mechanisms, high-energy-density materials, and planetary physics.
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All authors Mohamed Yaseen Noor, Aram Yedigaryan, Gabriel Calderon, Arshak Tsaturyan, Elena Kanchan, Jinwoo Hwang, Carmen S. Menoni, Jean-Philippe Colombier, Enam Chowdhury
Atomic Physics · Cross-listed from cond-mat.quant-gas
Controlled symmetry breaking of the Fermi surface in ultracold polar molecules
Shrestha Biswas, Sebastian Eppelt, Weikun Tian et al. (+6 more)
Long-range anisotropic dipole-dipole interactions between ultracold polar molecules are predicted to drive exotic
quantum phases, yet direct many-body signatures of these interactions in degenerate
Fermi gases have remained elusive. Here, we report the observation of an interaction-induced controlled deformation of the
Fermi surface, providing a clear many-body signature in a deeply degenerate
Fermi gas of $^{23}\text{Na}^{40}\text{K}$ molecules. Using double microwave (MW) shielding, we prepare $8 \times 10^3$ molecules at $0.23(1)$ times the
Fermi temperature, achieving a three-fold suppression of inelastic losses compared to single MW shielding while preserving strong elastic dipolar scattering. We observe
Fermi surface deformations of up to $7\,\%$, more than two times larger than those observed in
magnetic atoms, despite operating at two orders of magnitude lower densities. Crucially, we demonstrate continuous tuning of the interaction potential from axial U(1) to biaxial C$_{2}$
symmetry, directly imprinting this geometry onto the
Fermi surface. We find excellent agreement between our experimental results and parameter-free Hartree-Fock theory. These results establish MW-shielded polar molecules as a highly tunable platform for exploring strongly correlated dipolar
Fermi matter and offer a promising path towards topological superfluidity.
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All authors Shrestha Biswas, Sebastian Eppelt, Weikun Tian, Wei Zhang, Fulin Deng, Christine Frank, Tao Shi, Immanuel Bloch, Xin-Yu Luo
Chemical Physics · Cross-listed from cond-mat.stat-mech
An Information-theoretic Collective Variable for Configurational Entropy
Ashley Z. Guo, Kaelyn Chang and Nicholas J. Corrente
Entropy governs molecular self-assembly, phase transitions, and material stability, yet remains challenging to quantify and directly control in molecular systems. Here, we demonstrate that the computable information density (CID), a data compression-based information theoretic metric, provides a general per-configuration structural descriptor that tracks configurational
entropy changes in molecular dynamics simulations, reflecting both local and long-range structural organization. We validate the CID across systems of increasing complexity, beginning with single-component Lennard-Jones melting before examining binary phase separation,
polymer condensation and dispersion, and assembly of amorphous carbon networks at multiple densities. Unlike conventional order parameters, CID requires no a priori knowledge of relevant structural features and captures organizational signatures across a variety of molecular systems and discretization resolutions. By establishing a data compression-based structural complexity metric as a practical proxy for configurational
entropy, this framework lays a foundation for future
entropy-driven materials design and optimization strategies.
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Fluid Dynamics
Kelvin wave and soliton propagation in classical viscous vortex filaments
Elio Sterkers and Giorgio Krstulovic
Vortex filaments are highly rotating localized structures of fluids that admits several types of excitation. Here, we study them by using numerical simulations of the three-dimensional incompressible Navier-Stokes equations. We first address the propagation of Kelvin waves, helicoidal excitations propagating along the filament, and measure their dispersion relation which turns out to be in good agreement with the original Lord Kelvin predictions. Then, inspired by the connection between
vortex line dynamics and an integrable system, we show numerically the existence of
solitons propagating along
vortex filaments and study the collision of two of such structures. Finally, we show numerically the experimental feasibility of studying
vortex solitons in the lab, by proposing an experiment for their generation.
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Optics · Cross-listed from quant-ph
Macroscopic Quantum Electrodynamics with Gain: Modified Fluctuations and Their Consequences
Daigo Oue
Macroscopic
quantum electrodynamics (MQED) provides a unified framework for describing
quantum electromagnetic fields in arbitrary macroscopic environments. Central to this theory is the field correlation, which governs both radiative (e.g., Lamb shifts and the Purcell effect) and mechanical phenomena, such as van der Waals and Casimir forces. In this tutorial, we provide an overview of MQED and its extension to active media, highlighting fluctuation-induced forces as manifestations of gain-modified field correlations.
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Space Physics
Anomalous cosmic rays within the inner heliosphere: Observations of helium by the High Energy Telescope onboard Solar Orbiter
Zigong Xu, Robert F. Wimmer-Schweingruber, Lars Berger et al. (+11 more)
Radial gradients of
cosmic rays are key parameters for understanding the transport of particles in space.
Solar Orbiter, launched on 2020 February 10, approaches the Sun approximately every half year, with a closest perihelion distance of 0.29 au after the end of 2022 during the nominal mission phase. The two double-ended high energy
telescopes(HET)onboard the
Solar Orbiter measure energetic particles in the energy range between a few MeV/nuc and a few hundred MeV/nuc, which are dominated by anomalous
cosmic rays (ACRs) and
galactic cosmic rays (GCRs) during
solar quiet times. By obtaining the radial gradient of the ACR helium in the inner heliosphere, we advance our understanding of how the transport of the
cosmic rays is affected by the particle drift effect and the large-scale
magnetic field. The helium observations at
Solar Orbiter/HET between 11.1 and 49 MeV/nuc are analyzed. Since we focus on quiet time measurements, we remove the periods of
solar energetic particle (SEP) events. The intensities are averaged over the Carrington rotation period. The helium observations from the
Proton and Helium Instrument(EPHIN)onboard SOHO were utilized as the baseline to correct the long-term variation caused by the
solar modulations. We present the first observation of ACR helium at
Solar Orbiter/HET between 2020 February and 2022 July in the inner heliosphere before the sun became fully active. We derive the radial gradient of the ACR helium between 0.3 and 1 au. The averaged radial gradient between 11.1 and 49MeV/nuc is about 22$\pm$4%/au and the averaged value between 11.1 and 41.2MeV/nuc is raised to 32$\pm$8%/au after removing the GCR contribution, which is estimated by a GCR model. In addition, the temporal variation of radial gradients indicates that the gradients are increasing with the enhancement of the
solar modulation and the increased tilt angle of the heliospheric current sheet.
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All authors Zigong Xu, Robert F. Wimmer-Schweingruber, Lars Berger, Patrick Kühl, Alexander Kollhoff, Bernd Heber, Stephan I. Böttcher, Liu Yang, Verena Heidrich-Meisner, Roelf Du Toit Strauss, Raúl Gomez-Herrero, Javier Rodriguez-Pacheco, Daniel Pacheco, Richard A. Leske
Physics and Society · Cross-listed from cs.SI
False memories to fake news: The evolution of the term "misinformation" in academic literature
Alejandro Javier Ruiz Iglesias, Danny Benett, Julia Witte Zimmerman et al. (+2 more)
Since 2016, the term "misinformation" has become associated with a scientific paradigm that studies, at its core, people making, reading, and sharing false statements, usually on social media, and often warning of the harm to society resulting from the sum of many such events. By tracking the term through the academic literature, with special focus on the years 2011–2023, we connect the post-2016 paradigm with a strand of research dating to the Satanic panic of the 1980s. We argue that post-2016 misinformation research owes more to this intellectual lineage than is generally acknowledged, and we discuss the theoretical and practical implications of this connection. We conclude by drawing parallels between the Satanic panic and 2026, and, similarly, between misinformation research then and now.
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All authors Alejandro Javier Ruiz Iglesias, Danny Benett, Julia Witte Zimmerman, Christopher M. Danforth, Peter Sheridan Dodds
Computational Physics · Cross-listed from math.NA
A Reduced Order Model approach for First-Principles Molecular Dynamics Computations
Siu Wun Cheung, Youngsoo Choi, Jean-Luc Fattebert et al. (+2 more)
To leverage the redundancy between the electronic structure computed at each step of first-principles molecular dynamics, we present a data-driven modeling framework for Kohn-Sham Density Functional Theory that bypasses the explicit optimization of electronic wavefunctions. We sample a priori representative atomic configurations and construct a low-dimensional basis that efficiently approximates the electronic structure subspace. Subsequently, we employ this reduced basis in a direct solver for the electronic single particle density
matrix, thereby enabling the efficient determination of ground state without iterative wavefunction optimization. We demonstrate the efficacy of our approach in a Born-Oppenheimer molecular dynamics of a water molecule, showing that the resulting simulations accurately reproduce key structural properties, such as bond lengths and bond angle, obtained from full first-principles molecular dynamics. This work highlights the potential of data-driven approaches to develop efficient electronic structure solvers for first-principles simulations.
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All authors Siu Wun Cheung, Youngsoo Choi, Jean-Luc Fattebert, Jonas Kaufman, Daniel Osei-Kuffuor
Physics Education
Assessing student learning in quantum computing: Lessons from developing a test item on phase kickback
Josephine C. Meyer, Steven J. Pollock, Bethany R. Wilcox et al. (+1 more)
A major challenge for
quantum workforce development is the need to both understand and reliably assess student learning of
quantum information science (QIS) fundamentals. Yet student thinking is notoriously difficult to probe, even for seasoned education researchers. This article presents the story of Item 15 on the
Quantum Computing Conceptual Survey (QCCS). This assessment item underwent more revision and discussion within the team than the remaining 19 assessment questions combined. This paper provides a behind-the-scenes look at the development of this assessment question: a story that both reveals interesting findings about student
reasoning in
quantum computing and illustrates why
quantum education researchers insist on triangulating diverse quantitative and qualitative data sources when developing and refining assessment items, with implications for any researcher looking to understand and measure student conceptual
reasoning in
quantum computing, as well as for QIS curriculum and workforce development more broadly.
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All authors Josephine C. Meyer, Steven J. Pollock, Bethany R. Wilcox, Gina Passante
Computational Physics
Adaptive Patching for Tensor Train Computations
Gianluca Grosso, Marc K. Ritter, Stefan Rohshap et al. (+5 more)
Quantics Tensor Train (QTT) operations such as
matrix product operator contractions are prohibitively expensive for large bond dimensions. We propose an adaptive patching scheme that exploits block-sparse QTT structures to reduce costs through divide-and-conquer, adaptively partitioning tensors into smaller patches with reduced bond dimensions. We demonstrate substantial improvements for sharply localized functions and show efficient computation of bubble diagrams and Bethe-Salpeter equations, opening the door to practical large-scale QTT-based computations previously beyond reach.
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All authors Gianluca Grosso, Marc K. Ritter, Stefan Rohshap, Samuel Badr, Anna Kauch, Markus Wallerberger, Jan von Delft, Hiroshi Shinaoka
Plasma Physics
The Effect of Magnetization on Electron Heating in Low-Density Ultracold Neutral Plasmas
Ryan C. Baker, Bridget O'Mara and Jacob L. Roberts
Ultracold neutral
plasmas provide a useful system for studying extreme parameter regimes
plasma physics in an accessible laboratory setting. The parameter space of
plasma physics can be characterized in part by coupling strength and degree of magnetization. The range of achievable strong coupling is determined in part by the lowest possible temperatures that can be achieved. This work examines the early-lifetime electron heating of moderately coupled, strongly magnetized
plasmas. This heating is dominated by disorder-induced heating and heating due to Rydberg atom formation. By using experimentally informed simulations, it is found that disorder-induced heating has a large influence in electron temperature well into the
plasma lifetime. Additionally, the dependence of the minimum achievable electron temperature on magnetization and initial electron energy is examined. In this work, we find electron temperatures as low as $0.52^{+.10}_{-.05}\ \mathrm{K}$ (for electron density, $n_{e}$, of $6.1 \times 10^{12}\ \mathrm{m^{-3}}$), which determines the maximum coupling strength for the measured experimental conditions.
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Physics and Society · Cross-listed from cs.DC
Engineered Simultaneity: The Physical Impossibility of Consolidated Price Discovery Across Spacelike-Separated Exchanges
Paul Borrill
We define engineered simultaneity: the construction of a system that requires temporal comparison of events at spacelike-separated locations, implements this comparison via an implicit simultaneity convention, and represents the result as an objective measurement rather than a conventional choice. We show that the National Best Bid and Offer (NBBO) – the regulatory cornerstone of U.S. equity
markets – is an instance of engineered simultaneity. The NBBO requires determining “current” prices across exchanges whose spatial separation places their price events outside each other's light cones. Special relativity proves that the temporal ordering of such events is frame-dependent: there exist inertial reference frames in which the NBBO differs from the value reported by the Securities Information Processor. The impossibility is not approximate; it is exact and unavoidable within the causal structure of Minkowski spacetime. General relativity compounds the impossibility: gravitational time dilation introduces frame-rate discrepancies between exchanges at different altitudes, and recent work on indefinite causal order in
quantum information theory undermines the premise of a fixed causal structure altogether. We formalize the special-relativistic argument using the causal precedence relation, connect it to Lamport's
theorem on distributed ordering, and note that approximately \$5~billion per year in latency arbitrage profits are extracted from the gap between the NBBO's implicit simultaneity convention and physical reality.
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Applied Physics
Spatiotemporal modulation of surface texture for information encoding and object manipulation
Xiao Yang, Jay Sim and Ruike Renee Zhao
Dynamically tunable surface textures offer a powerful route to spatiotemporally regulate surface and interfacial properties, enabling emerging applications ranging from adaptive optics to soft robotic manipulation. However, achieving programmable, reversible, and spatiotemporal modulation of surface texture remains a fundamental challenge. Here, we present a photothermal-actuated
liquid crystal elastomer
bilayer that enables reversible, on-demand spatiotemporal modulation of surface textures through dynamically emerging and propagating wrinkles. Using direct
laser writing or projected light fields, programmable and self-erasable wrinkle patterns are generated for dynamic information encoding. This spatiotemporal wrinkling enables object manipulation across diverse geometries, including uphill transport and
navigation along predesigned paths. By coupling wrinkle-driven motion with thermally reversible dynamic bonding, the
bilayer further enables assembly and disassembly of dynamic
polymers, as well as cargo transportation. This work demonstrates spatiotemporally programmable wrinkling as a powerful mechanism for dynamic modulation of surface textures, establishing a versatile platform for multifunctional and reconfigurable smart surfaces.
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Applied Physics · Cross-listed from quant-ph
Fundamental Limits on QBER and Distance in Quantum Key Distribution
Stefano Pirandola
Quantum key distribution (QKD) enables information-theoretic secure communication, yet its ultimate tolerance to noise and achievable transmission distance remain fundamentally constrained. We establish the maximum
quantum bit error rate (QBER) compatible with secure QKD and derive corresponding upper bounds on communication distance. Our results follow from a fundamental capacity threshold for
qubit Pauli channels and apply to protocols based on two or more mutually unbiased bases, using either single-
photon or weak coherent sources. By connecting information-theoretic limits to realistic physical noise models, we obtain universal bounds on achievable distances in fiber and free-space links, including diffraction-limited constraints relevant to deep-space
quantum communications. These findings clarify the ultimate noise robustness of QKD and delineate the fundamental boundaries of secure
quantum communication.
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Atomic Physics · Cross-listed from quant-ph
Robustness-Runtime Tradeoff for Quantum State Transfer
Twesh Upadhyaya, Yifan Hong, T. C. Mooney et al. (+1 more)
Quantum state transfer is the primitive of transporting an unknown state on one site of a
lattice to another. Using power-law interactions, recent state transfer protocols achieve speedup by utilizing the intermediate ancilla sites. However, these protocols require the ancillas to be in a perfectly initialized state, which, due to noise or imperfect control, may not be the case. In this work we introduce the $\textit{robustness}$ of a state transfer protocol, which quantifies the protocol's tolerance to error in the initial ancilla state. In the Heisenberg picture, state transfer grows operators supported on the final site such that they no longer commute with all operators on the starting site. We prove that this robustness tightly bounds the Schatten $p$-norms of these commutators between initial and final-site operators. This generalizes the known cases of $p=\infty$ and $p=2$, which govern completely state-dependent and state-independent state transfer respectively, demonstrating that intermediate values of $p$ govern partially state-dependent state transfer. In conjunction with existing power-law light cones, our result gives new minimum runtimes for partially state-dependent protocols which, in certain regimes, are parametrically better than existing bounds. We introduce new robust state transfer protocols, charting the landscape between complete state-dependence and state-independence.
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All authors Twesh Upadhyaya, Yifan Hong, T. C. Mooney, Alexey V. Gorshkov
Geophysics · Cross-listed from cs.LG
Learning global river system hydrodynamics with a topology-informed foundation model
Hancheng Ren, Gang Zhao, Shuo Wang et al. (+12 more)
Accurate river prediction is essential for water, food, and energy security, yet extending it reliably from sparse in-situ gauges to the full river network remains an open challenge. Although machine learning has transformed Earth-system modelling, the same sparse and uneven observations have largely confined its advances for rivers to discrete basins rather than connected river systems. Here we introduce GraphRiverCast (GRC), a
topology-informed river foundation model for reach-level prediction across the global river network. Exploiting the connectivity and energetics of rivers, it is trained on sparse gauges and predicts daily multivariate hydrodynamics with no prior river conditions. GRC outperforms strong physics-based and machine-learning models. Attribution experiments show that, compared with standard autoregressive models that rely more on temporal recurrence, GRC reconstructs river states from
topology and forcing, learning the dynamics themselves and inheriting the self-correcting character of river systems. Its skill therefore barely decays with lead time, even far beyond its training horizon. It also generalises to ungauged reaches and finer-resolution networks, bringing reliable hydrodynamic prediction to poorly monitored regions. More broadly, harnessing the structure and energetics of a system offers a strategy for machine learning in other observation-limited Earth systems.
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All authors Hancheng Ren, Gang Zhao, Shuo Wang, Louise Slater, Dai Yamazaki, Shu Liu, Jingfang Fan, Xueying Li, Shibo Cui, Ziming Yu, Shengyu Kang, Depeng Zuo, Dingzhi Peng, Zongxue Xu, Bo Pang
Space Physics
Fluctuating polytropic processes, turbulence, and heating
G. Livadiotis and D.J. McComas
This paper explores the thermodynamics of fluctuating polytropic processes and their connection to
turbulence. It is shown that random fluctuations of polytropic processes produce a nonzero overall heating of a particle system, e.g.,
solar wind
plasma flowing out through the heliosphere; while any nonturbulent heating can be thermodynamically described by typical nonfluctuating polytropic processes, turbulent heating can be thermodynamically described through fluctuating polytropic processes. First, we derive the expression of the overall process and find that polytropic fluctuations lead to heat entering the system even if the respective nonfluctuating process is adiabatic. The temperature of the
solar wind
plasma protons decreases with heliospheric distance less than the adiabatic cooling, again, similar to when heating enters the system; this subadiabatic cooling is proportional to the variance of the fluctuations. We derive the heliospheric radial profiles of the thermodynamic expressions of the polytropic index, temperature, and heating rates. Then, we show that the analytical profiles of heating of fluctuating polytropic processes and of turbulent heating are identical, suggesting that
turbulence heats
plasma particle populations by fluctuating their polytropic processes. We apply the thermodynamics of fluctuating polytropic processes to the energy transfer from pickup ions (PUIs) to
solar wind
plasma protons, and derive the analytical expressions of PUI turbulent and nonturbulent heating rates, which are well fitted to the respective observations. Finally, we apply the thermodynamic model to the radial profile of PUI energy transfer to the
solar wind
plasma protons, where we derive the portion of PUI turbulent vs. nonturbulent heating rates.
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Data Analysis and Statistics
Maximum Likelihood Particle Tracking in Turbulent Flows via Sparse Optimization
Griffin M Kearney, Kasey M Laurent and Makan Fardad
Lagrangian particle tracking is essential for characterizing turbulent flows, but inferring particle acceleration from inherently noisy position data remains a significant challenge. Fluid particles in
turbulence experience extreme, intermittent accelerations, resulting in heavy-tailed probability density functions (PDFs) that deviate strongly from Gaussian predictions. Existing filtering techniques, such as Gaussian kernels and penalized B-splines, implicitly assume Gaussian-distributed jerk, thereby penalizing sparse, high-magnitude acceleration changes and artificially suppressing the intermittent tails. In this work, we develop a novel maximum likelihood estimation (MLE) framework that explicitly accounts for this non-Gaussian intermittency. By formulating a modified Gaussian process to model the random incremental forcing, we introduce a sparse optimization scheme utilizing a convex 1-norm relaxation. To overcome the numerical stiffness associated with high-order difference operators, the problem is efficiently solved using an iteratively reweighted least squares (IRLS)
algorithm. The proposed filter is evaluated against direct numerical simulation (DNS) data of homogeneous, isotropic
turbulence (Re approx. 310). Results demonstrate that the IRLS approach consistently outperforms state-of-the-art discrete MLE, continuous MLE, and B-spline methods, yielding systematic reductions in root-mean-squared error (RMSE) across position, velocity, and acceleration. Most importantly, the proposed framework succeeds in better recovering the heavy-tailed statistical structure of both acceleration and acceleration differences (jerk) across temporal scales, preserving the physical intermittency characteristic of high-Reynoldsnumber turbulent flows that baseline methods severely attenuate.
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Optics · Cross-listed from quant-ph
Quantum jumps in open cavity optomechanics and Liouvillian versus Hamiltonian exceptional points
Aritra Ghosh and M. Bhattacharya
Exceptional points, where two or more eigenstates of a non-Hermitian system coalesce, are now of interest across many fields of physics, from the perspective of open-system dynamics, sensing, nonreciprocal transport, and topological phase transitions. In this work, we investigate exceptional points in cavity optomechanics, a platform of interest to diverse communities working on gravitational-wave detection, macroscopic
quantum mechanics,
quantum transduction, etc. Specifically, we clarify the role of
quantum jumps in making a clear distinction between Liouvillian and
Hamiltonian exceptional points in optomechanical systems. While the Liouvillian exceptional point arises from the unconditional Lindblad dynamics and is independent of the
phonon-bath temperature, the
Hamiltonian exceptional point emerges from the conditional no-jump
evolution and acquires a thermal shift due to an enhanced conditional damping. Employing the thermofield formalism, we derive a unified spectral framework that interpolates between these regimes via an analytical hybrid-Liouvillian description. Remarkably, in the weak-
quantum-jump regime, the exceptional point is perturbed only at the second order, highlighting the robustness of the
Hamiltonian exceptional point under small hybrid perturbations. Our work reveals a continuous family of hybrid exceptional points, clarifies the operational and physical differences between the conditional and unconditional dissipative dynamics in optomechanical systems, and provides a probe for thermal baths.
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Fluid Dynamics · Cross-listed from cs.LG
Surrogate models for Rock-Fluid Interaction: A Grid-Size-Invariant Approach
Nathalie C. Pinheiro, Donghu Guo, Hannah P. Menke et al. (+4 more)
Modelling rock-fluid interaction requires solving a set of partial differential equations (PDEs) to predict the flow behaviour and the reactions of the fluid with the rock on the interfaces. Conventional high-fidelity numerical models require a high resolution to obtain reliable results, resulting in huge computational expense. This restricts the applicability of these models for multi-query problems, such as uncertainty quantification and optimisation, which require running numerous scenarios. As a cheaper alternative to high-fidelity models, this work develops eight surrogate models for predicting the fluid flow in porous media. Four of these are reduced-order models (ROM) based on one neural network for compression and another for prediction. The other four are single neural networks with the property of grid-size invariance; a term which we use to refer to image-to-image models that are capable of inferring on computational domains that are larger than those used during training. In addition to the novel grid-size-invariant framework for surrogate models, we compare the predictive performance of UNet and UNet++ architectures, and demonstrate that UNet++ outperforms UNet for surrogate models. Furthermore, we show that the grid-size-invariant approach is a reliable way to reduce
memory consumption during training, resulting in good correlation between predicted and ground-truth values and outperforming the ROMs analysed. The application analysed is particularly challenging because fluid-induced rock dissolution results in a non-static solid field and, consequently, it cannot be used to help in adjustments of the future prediction.
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All authors Nathalie C. Pinheiro, Donghu Guo, Hannah P. Menke, Aniket C. Joshi, Claire E. Heaney, Ahmed H. ElSheikh, Christopher C. Pain
Plasma Physics
Runaway electron generation in ITER mitigated disruptions with improved physics models
L. Votta, F. J. Artola, E. Nardon et al. (+2 more)
We assess runaway-electron (RE) generation in ITER disruptions mitigated by shattered pellet injection (SPI) using improved physics modelling in the 1D disruption simulation framework Dream. To this end, we extend Dream with four ITER-relevant physics models: (i) a reduced model for RE scrape- off associated with the vertical
plasma motion, (ii) a semi-analytical plasmoid- drift model for material deposition, (iii) an adaptive hyper-resistive transport model to suppress unphysical thin-current channels during the current quench (CQ), and (iv) an updated Compton RE generation seed calculated for the new ITER tungsten first-wall design. We simulate full-current 15 MA L-mode (H26, non-
nuclear) and H-mode (DTHmode24,
nuclear) scenarios, and an intermediate- current 7.5 MA H-mode non-
nuclear case, from realistic ITER inputs. Complete avoidance of a multi-MA RE beam is found to require a long pre-thermal quench (TQ) duration to thermalize the hot-tail electrons, high deuterium assimilation with limited neon, and a representative seed current comparable to a single RE in ITER. As previously found with lower fidelity setups [Vallhagen et al, Nucl. Fusion 64 (2024)], these conditions are met by staggered or low-Ne injections in H26, but are typically violated in DT H-mode when
nuclear seeds are present. In addition to analyzing the effect of the new models, we investigate the role of the current spike associated with the TQ and importance of radial transport of runaways in the CQ. After incorporating these additional physical effects into a comprehensive disruption model and analyzing their impact, we present a representative ITER DT H-mode SPI scenario which provides a theoretically viable route to tolerable RE currents in ITER fusion power operation.
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All authors L. Votta, F. J. Artola, E. Nardon, O. Vallhagen, M. Hoppe
Plasma Physics
Effects of realistic laser intensity and phase distribution on high-charge laser wakefield acceleration
Yuhui Xia, Zhenan Wang, Ziyao Tang et al. (+14 more)
Laser wakefield acceleration (LWFA) can produce relativistic electron beams and various secondary particles in centimeter-long
plasmas, making it a valuable particle source with important applications in many disciplines. In this work, we examine the effects of non-ideal transverse intensity and phase distribution of
laser pulses on LWFA through both experimental measurements and particle-in-
cell simulations. The complex transverse profile of the 75 TW
laser pulses reduces the self-focused intensity in
plasma compared with a transversely Gaussian
laser. Furthermore, the sheath structure of the nonlinear
plasma wake excited by realistic
laser pulses is wider and more complicated than that of a Gaussian
laser. These hinder the injection of the
plasma electrons. As the
laser pulse propagates through the
plasma, its intensity profile gradually becomes elliptical and drives a
plasma wake with a sharp sheath near the azimuths of the major axis, leading to an injection. When using a realistic
laser profile in simulations, both the charge and energy of injected electrons closely match experimental results ($\sim200$ pC of charge and $\sim 200$ MeV peak energy), whereas the Gaussian
laser simulations produce much higher charge ($\sim500$ pC). Our findings reveal the difference in injection dynamics between LWFA driven by non-ideal
laser pulses and those driven by Gaussian pulses, and are useful for applications of LWFA which demand high-charge electron beams.
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All authors Yuhui Xia, Zhenan Wang, Ziyao Tang, Jianghao Hu, Qianyi Ma, Yuekai Chen, Letian Liu, Zhiyan Yang, Hui Zhang, Chenxu Wang, Haoyang Lan, Di Wu, Xiuhong Yang, Yixing Geng, Yanying Zhao, Xueqin Yan, Xinlu Xu