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Physics

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Friday 17 July

Quantum Physics

Quantum-classical crossover in fault-tolerant quantum dynamics simulation

Jinzhao Sun, Bozhen Zhou, Jue Xu et al. (+28 more)

While quantum computers promise to solve classically intractable problems, identifying the point at which fault-tolerant quantum computation outperforms the best classical algorithms for practical applications remains an outstanding challenge. Here we establish a concrete quantum-classical crossover for quantum many-body dynamics under realistic hardware conditions. We introduce a scalable fault-tolerant framework that combines coherent observable estimation with a space-time-efficient implementation of non-Clifford rotations, suppressing the residual logical errors that limit existing partially fault-tolerant approaches. A benchmark against state-of-the-art tensor-network and variational Monte Carlo algorithms reveals a concrete crossover for mixed-field Ising dynamics at modest system sizes. For a physical error rate of $p=10^{-3}$, fault-tolerant simulation requires approximately 2 hours and $3.7 \times 10^5$ physical qubits for a 100-site 1D system, whereas tensor network approaches would require about 100 years. For 2D models, where rapid entanglement growth limits the classical evolution time, we project quantum runtimes within minutes. A physical error rate of $p=10^{-4}$ leads to at least an order of magnitude reduction in qubit count ($3.1 \times 10^4$ physical qubits) and runtime (minutes for 1D and seconds for 2D). The reduction in quantum runtime arises from our improved rotation-state injection and co-design of quantum error correction and observable-estimation protocols, which jointly suppress logical-error accumulation and reduce sampling overhead. Our results establish a scalable route towards practical quantum advantage and identify quantitative engineering targets for future fault-tolerant architectures.
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All authors Jinzhao Sun, Bozhen Zhou, Jue Xu, Yuan Yao, Zhenyu Du, Zixu Zhang, Yuntian Gu, Junxiang Huang, Shuo Zhou, Ziruo Wang, Alexander Yosifov, Wenzheng Dong, Yiming Huang, Daniel Serrano, Xinzhao Wang, Tianfeng Feng, Shreyas Sadugol, Wenjun Yu, Zhou You, Dayue Qin, Xiao-Ming Zhang, Yantao Wu, Aditya Iyer, You Zhou, Tongyang Li, Ying Li, Xiongfeng Ma, Qi Zhao, Pei Zeng, Pan Zhang, Xiao Yuan

Quantum Physics

Parameterized Quantum Circuit Semantics Through Enriched Categories

Neil J. Ross and Scott Wesley

It is well-known that combinatorial circuits are modeled mathematically by string diagrams in monoidal categories. Given a gate set $\Sigma$, the circuits over $\Sigma$ can be thought of as string diagrams in the free monoidal category generated by $\Sigma$. In this model, circuit semantics are then given by monoidal functors out of this free category. For quantum circuits, this functor is often valued in the category of unitary matrices. This model suffices for concrete quantum circuits, but fails to describe parameterized families of quantum circuits, such as those which arise in the analysis of ansatz circuits. In this paper, we introduce an approach to parameterized circuit semantics, which is based on enriched category theory. We first introduce an abstract categorical construction, and use this to gain new insights on controlled operations and quantum communication. We then study the special cases of Cartesian monoidal parameters and monoidal closed parameters, both endowing the parameterized semantics with useful constructions. We conclude by showing that the monoidal closed case can be used to unify two perspectives on quantum control.
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Instrumentation and Methods for Astrophysics

Commissioning and on-sky performance of FiberPol: a fiber-fed spectropolarimetric system for the SAAO 1.9 m telescope

Siddharth Maharana, K. C. J. Dennison-Farrar, Sabyasachi Chattopadhyay et al. (+8 more)

At the South African Astronomical Observatory (SAAO), we have developed FiberPol$-$ a spectropolarimetric front-end for the SpUpNIC spectrograph on the 1.9 m telescope fed by fibers. In conjunction with SpUpNIC, it combines two niche techniques: fiber-spectroscopy and polarimetry to enable a wide range of science cases, particularly for studies of the interstellar medium, and serves as a technology pathfinder for implementing polarimetry larger facilities such as the 10 m Southern African Large Telescope. Commissioned in early 2025, FiberPol has already demonstrated key performance benchmarks. Based on a preliminary data reduction pipeline, we find that the uncertainties in the measured Stokes parameters $q$ and $u$, and the degree of polarization $p$ are in the range of 0.2% to 0.3% in 5 nm spectral bins across the 400 to 700 nm wavelength range. With improved calibration and refined analysis, we expect to reach our design goal of 0.1% accuracy per bin. Several science programs are already underway following its successful commissioning. FiberPol employs a Wollaston prism and half wave plate system to analyze linear polarization and extract spectropolarimetric data comprising wavelength ($\lambda$) and the Stokes parameters ($I$, $q$ and $u$). Its compact and modular design uses primarily small, commercially available optical and optomechanical components, making it straightforward to adapt to other spectrographs, including those on larger telescopes. This paper presents the design, laboratory validation, and commissioning results of FiberPol, and outlines planned upgrades to further enhance its scientific impact.
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All authors Siddharth Maharana, K. C. J. Dennison-Farrar, Sabyasachi Chattopadhyay, Nikita Rawat, Nidhi Mehandiratta, J.C. Viljoen, Matthew Bershady, David Buckley, Lisa A. Crause, Hitesh Gajjar, Stephen Potter

High Energy Physics (Theory)

Combinatorial aspects of holographic quantum secret sharing

Ning Bao, Keiichiro Furuya and Jacob March

We introduce combinatorial holographic quantum secret sharing (CHQSS) for a bulk subregion in AdS$_3$/CFT$_2$ to study how logical information of the bulk subregion is encoded in the boundary and protected from erasures of boundary subregions. We introduce a distance, a reconstruction threshold, and a secret threshold to characterize CHQSS schemes. We present the phase transitions of multipartite entanglement wedges in a symmetric setup and observe multiple distinct phase transition points. The distance and thresholds depend on the holographic phase and the choice of bulk subregion. We derive the maximum distance. Moreover, we derive the relations between the distance and the thresholds. We construct a family of CHQSS schemes in the symmetric setting that includes perfect threshold CHQSS and perfect non-threshold CHQSS.
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Materials Science

Subgrain-resolved Analysis of Degradation in Cu Metallization via Scanning 3DXRD and Thermomechanical Modeling

Nikhil Prabhu, Laura Neumann, Michael Reisinger et al. (+7 more)

Metallization layers play a key role in the performance and reliability of modern power semiconductor devices. During short-circuit events, rapid heating of power metallization layers induces thermomechanical incompatibility stresses, which may contribute to material degradation and impact device performance. In this work, potential degradation hotspots associated with thermomechanical loading in Cu power metallization are investigated using a combined experimental–computational approach. Scanning three-dimensional X-ray diffraction measurements are coupled with thermomechanical crystal plasticity simulations to probe the evolution of grain-resolved plastic deformation during rapid cyclic loading. This integrated approach provides insight into the microstructural processes governing degradation hotspot formation, laying the groundwork for future microstructure-informed, physics-based reliability assessment of Cu metallization.
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All authors Nikhil Prabhu, Laura Neumann, Michael Reisinger, James A. D. Ball, Cedric Corley-Wiciak, Manuel Petersmann, Agnieszka Corley-Wiciak, Jonathan Wright, Carsten Detlefs, Martin Diehl

Astrophysics of Galaxies

Dynamics and geometry of the inner sub-parsec-scale jet in 3C 279 observed with the Event Horizon Telescope

Hendrik Mueller, Sebastiano D. von Fellenberg, Ai-Ling Zeng et al. (+275 more)

The 2021 Event Horizon Telescope observations resolve the innermost jet region of the blazar 3C279 with unprecedented detail. The reconstructed images consistently reveal a compact core elongated nearly orthogonal to the large-scale jet axis. This rarely observed morphology recurs across multiple epochs and from 22-230 GHz and is therefore intrinsic rather than an imaging artifact. Geometric model fitting identifies several components with apparent speeds up to 10c, requiring bulk Lorentz factors greater than 10.3 and constraining viewing angles to extremely small values (smaller than one degree). Rest-frame brightness temperatures are systematically low (between 10^9 and 10^10 K), consistent with optically thin emission at 230 GHz. These results suggest that the jet bends toward the observer on sub-parsec scales, producing strong relativistic beaming. Possible drivers of the observed jet bending and temporal evolution include the jet's interaction with the interstellar medium, kink or Kelvin–Helmholtz instabilities, magnetic reconnection near the horizon, or binary-induced precession. However, the current temporal coverage of VLBI data remains insufficient to distinguish between these mechanisms. Continued multifrequency VLBI monitoring will be essential to constraining the dynamics and geometry of the jet base in 3C279.
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All authors Hendrik Mueller, Sebastiano D. von Fellenberg, Ai-Ling Zeng, Paul Tiede, Thomas P. Krichbaum, Roman Gold, Tuomas Savolainen, Jae-Young Kim, Sijia Peng, Teresa Toscano, Michael Janssen, Boris Georgiev, Dhanya G. Nair, Iniyan Natarajan, Lindy Blackburn, Kazunori Akiyama, Ezequiel Albentosa-Ruiz, Antxon Alberdi, Walter Alef, Juan Carlos Algaba, Rohan Ganesh Amanaganti, Richard Anantua, Eleni Antonopoulou, Keiichi Asada, Rebecca Azulay, Anne-Kathrin Baczko, David Ball, Bidisha Bandyopadhyay, John Barrett, Michi Bauböck, Bradford A. Benson, Dan Bintley, Raymond Blundell, Katherine L. Bouman, Geoffrey C. Bower, Michael Bremer, Roger Brissenden, Silke Britzen, Avery E. Broderick, Dominique Broguiere, Thomas Bronzwaer, Sandra Bustamante, Douglas F. Carlos, John E. Carlstrom, Andrew Chael, Chi-kwan Chan, Chin-Shin Chang, Dominic O. Chang, Koushik Chatterjee, Erandi Chavez, Ming-Tang Chen, Yongjun Chen, Xiaopeng Cheng, Paul Chichura, Ilje Cho, Nicholas S. Conroy, John E. Conway, Thomas M. Crawford, Geoffrey B. Crew, Alejandro Cruz-Osorio, Yuzhu Cui, Brandon Curd, Rohan Dahale, Jordy Davelaar, Joost de Kleuver, Mariafelicia De Laurentis, Roger Deane, Jason Dexter, Vedant Dhruv, Indu K. Dihingia, Sheperd S. Doeleman, Sergio A. Dzib, Razieh Emami, Heino Falcke, Joseph Farah, Vincent L. Fish, Edward Fomalont, H. Alyson Ford, Marianna Foschi, Raquel Fraga-Encinas, William T. Freeman, Per Friberg, Christian M. Fromm, Antonio Fuentes, Peter Galison, Charles F. Gammie, Roberto Garcia, Olivier Gentaz, Ciriaco Goddi, Arturo I. Gomez-Ruiz, Brissa Gomez Miller, Jose L. Gomez, Minfeng Gu, Mark Gurwell, Kazuhiro Hada, Daryl Haggard, Ronald Hesper, Dirk Heumann, Luis C. Ho, Paul Ho, Mareki Honma, Chih-Wei L. Huang, Lei Huang, David H. Hughes, Shiro Ikeda, C. M. Violette Impellizzeri, Makoto Inoue, Sara Issaoun, Yuhei Iwata, David J. James, Buell T. Jannuzi, Britton Jeter, Wu Jiang, Alejandra Jiménez-Rosales, Michael D. Johnson, Svetlana Jorstad, Adam C. Jones, Abhishek V. Joshi, Taehyun Jung, Tomohisa Kawashima, Garrett K. Keating, Mark Kettenis, Dong-Jin Kim, Jongsoo Kim, Junhan Kim, Motoki Kino, Jakob Knollmüller, Jun Yi Koay, Prashant Kocherlakota, Yutaro Kofuji, Patrick M. Koch, Shoko Koyama, Carsten Kramer, Joana A. Kramer, Michael Kramer, Cheng-Yu Kuo, Noemi La Bella, Deokhyeong Lee, Sang-Sung Lee, Aviad Levis, Shaoliang Li, Zhiyuan Li, Rocco Lico, Greg Lindahl, Michael Lindqvist, Mikhail Lisakov, Jun Liu, Kuo Liu, Elisabetta Liuzzo, Wen-Ping Lo, Andrei P. Lobanov, Laurent Loinard, Colin J. Lonsdale, Amy E. Lowitz, Ru-Sen Lu, Nicholas R. MacDonald, Jirong Mao, Nicola Marchili, Sera Markoff, Daniel P. Marrone, Alan P. Marscher, Ivan Marti-Vidal, Satoki Matsushita, Lynn D. Matthews, Lia Medeiros, Karl M. Menten, Hugo Messias, Izumi Mizuno, Yosuke Mizuno, Joshua Montgomery, Kotaro Moriyama, Monika Moscibrodzka, Wanga Mulaudzi, Cornelia Müller, Alejandro Mus, Gibwa Musoke, Ioannis Myserlis, Hiroshi Nagai, Neil M. Nagar, Masanori Nakamura, Gopal Narayanan, Antonios Nathanail, Santiago Navarro Fuentes, Joey Neilsen, Chunchong Ni, Andy Nilipour, Michael A. Nowak, Hiroki Okino, Hector Raul Olivares Sanchez, Feryal Özel, Daniel C. M. Palumbo, Georgios Filippos Paraschos, Jongho Park, Harriet Parsons, Nimesh Patel, Ue-Li Pen, Dominic W. Pesce, Vincent Pietu, Alexander Plavin, Aleksandar PopStefanija, Oliver Porth, Cora Prather, Giacomo Principe, Dimitrios Psaltis, Hung-Yi Pu, Alexandra Rahlin, Venkatessh Ramakrishnan, Ramprasad Rao, Mark G. Rawlings, Luciano Rezzolla, Angelo Ricarte, Luca Ricci, Bart Ripperda, Jan Röder, Freek Roelofs, Cristina Romero-Cañizales, Eduardo Ros, Arash Roshanineshat, Helge Rottmann, Alan L. Roy, Ignacio Ruiz, Chet Ruszczyk, Kazi L. J. Rygl, Leon D. S. Salas, Salvador Sanchez, David Sanchez-Argüelles, Miguel Sanchez-Portal, Ali SaraerToosi, Mahito Sasada, Kaushik Satapathy, Saurabh, Karl-Friedrich Schuster, Zhiqiang Shen, Sasikumar Silpa, Randall Smith, Bong Won Sohn, Jason SooHoo, Kamal Souccar, Joshua S. Stanway, He Sun, Alexandra J. Tetarenko, Remo P. J. Tilanus, Michael Titus, Kenji Toma, Pablo Torne, Efthalia Traianou, Sascha Trippe, Matthew Turk, Akhil Uniyal, Ilse van Bemmel, Bram van den Berg, Huib Jan van Langevelde, Daniel R. van Rossum, Jesse Vos, Jan Wagner, Zhiren Wang, Derek Ward-Thompson, John Wardle, Jasmin E. Washington, Jonathan Weintroub, Maciek Wielgus, Kaj Wiik, Michael F. Wondrak, George N. Wong, Jompoj Wongphexhauxsorn, Qingwen Wu, Paul Yamaguchi, Aristomenis Yfantis, Doosoo Yoon, Andre Young, Ziri Younsi, Wei Yu, Feng Yuan, Ye-Fei Yuan, J. Anton Zensus, Shuo Zhang, Brandon Zhao, Guang-Yao Zhao

High Energy Physics (Theory)

Symmetry extension by condensation defects II: general dimensions and higher-groups

Matteo Bertolini, Lorenzo Di Pietro, Stefano C. Lanza et al. (+1 more)

We discuss a class of symmetry structures in general spacetime dimension that arise when gauging symmetries in theories with a cubic 't Hooft anomaly. The anomaly mixes two Abelian discrete symmetries $A$ and $B$ with a characteristic class for an additional symmetry $C$, and we gauge $A\times B$. The novelty of this construction is that the resulting symmetry structure involves certain condensation defects of the dual symmetry $\widehat{A}\times\widehat{B}$. Specifically, these defects generate an invertible symmetry that extends $C$, either as an ordinary group extension or as a higher-group, depending on the characteristic class. We describe the corresponding charged operators and states, and illustrate the mechanism in several examples.
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All authors Matteo Bertolini, Lorenzo Di Pietro, Stefano C. Lanza, Antonio Santaniello

Quantum Physics

Object-relative ultraviolet weighting of electromagnetic modes and one-loop ultraviolet finiteness of internal photon lines in quantum electrodynamics

Christian Rembe

This work explores whether localized electromagnetic interactions can be modeled by a physically concluded object-relative ultraviolet weighting of photon modes. The proposal is motivated heuristically by a weak-field self-backreaction estimate for localized energy-carrying modes and by a three-dimensional overlap argument. In the resulting ansatz, the infrared sector remains unchanged up to a characteristic angular wavenumber k_c, while ultraviolet contributions are suppressed asymptotically by a factor of order k_c^3/k^3. The mode structure is object-relative: a real photon is weighted by its frequency u k in the rest frame of the interaction object with four-velocity u. The occupation of the modes and the amplitudes of the vacuum fluctuations, in contrast, follow the rules of special relativity, so that virtual photons in loops are weighted by the invariant k k, i.e. by the Euclidean photon momentum. The weighting applies to photon lines only; applied in the same way to the electron line, it conflicts with gauge invariance or with the measured running of the fine-structure constant. One-loop diagrams with internal photon lines become ultraviolet finite, and the weighting can be represented by a gauge-invariant kinetic term of the photon field, so that the Ward-Takahashi identities are preserved. Four test cases are discussed. A Bethe-type estimate of the Lamb shift places the characteristic scale near the electron Compton wavenumber. The anomalous magnetic moment and the relativistic part of the Lamb shift show, however, that a photon weighting at this scale requires additional structure on the electron line to remain compatible with high-precision measurements. This structure, the vacuum polarization, and the spectral consistency of the weighting define the tasks for future work.
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Materials Science

Emergent Interfacial Magnetism in Epitaxial RuO$_2$

Yudi Yang, Zhuang Qian, Shi Liu et al. (+1 more)

The magnetic ground state of the altermagnet candidate RuO$_2$ remains controversial, with magnetic signatures observed mainly in epitaxial films. Here we show, using first-principles calculations, that magnetism in epitaxial RuO$_2$ can emerge as an interfacial boundary phase at TiO$_2$/RuO$_2$ interfaces. While TiO$_2$-induced epitaxial strain alone does not make (001)-oriented RuO$_2$ magnetic, explicit TiO$_2$/RuO$_2$ interfaces stabilize sizable Ru moments confined to the first few Ru layers. Charge-density and orbital-resolved analyses reveal interfacial electronic reconstruction, and substrate doping provides a route to tune the induced moments. In symmetric TiO$_2$/RuO$_2$/TiO$_2$ heterostructures, the two magnetic interfaces couple through the metallic RuO$_2$ spacer, producing a thickness-dependent alternation between weak-ferromagnetic and compensated altermagnetic states. Our results identify interface engineering as a practical route to stabilize and control fragile magnetism in RuO$_2$.
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All authors Yudi Yang, Zhuang Qian, Shi Liu, Congjun Wu

Soft Condensed Matter

Programmable transport of rotating particles in obstacle arrays

Marcos Puerto, Alfredo Alexander-Katz, Juan L. Aragones et al. (+1 more)

Rotating colloids, or spinners, in obstacle arrays exhibit frequency-set stationary orbits and currents set by the competition between an inertial, Magnus-like lift and short-range attraction. Fully resolved lattice-Boltzmann simulations reveal the hydrodynamic coupling and identify the lift mechanism, while a symmetry-based Langevin model captures the resulting balance. In periodic lattices, the superposition of scalar and vector potentials produces two robust orbital regimes: corner states, in which spinners orbit individual posts, and inner states, in which orbits couple across four neighboring obstacles. Slow frequency modulation toggles these states and produces directed, stepwise transport across the grid. This establishes a minimal hydrodynamic mechanism, controlled by a single driving parameter, for programmable guidance of active rotors in structured environments.
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All authors Marcos Puerto, Alfredo Alexander-Katz, Juan L. Aragones, J.V. Alvarez

Plasma Physics

Non-invasive monitoring of process-relevant plasma parameters by Fiber PROES in capacitively coupled Ar/CF$_4$ plasmas

Florian Beckfeld, Maximilian Ryppa, Constantin Neuroth et al. (+3 more)

Monitoring changes of process-relevant plasma parameters, such as the electron density and ion flux to the wafer, is essential for the development and control of plasma processes. However, invasive plasma diagnostics, such as probe measurements, typically cannot be applied to commercial reactors. At the example of a low pressure capacitive radio frequency discharge operated in different mixtures of CF$_4$ and Ar, we demonstrate that changes of such plasma parameters can be monitored non-invasively by phase resolved optical emission spectroscopy via optical fibers (Fiber PROES), for which the ports are usually available at industrial plasma sources. In this way, the spatio-temporally resolved dynamics of energetic electrons are tracked by observing a selected emission line. By measuring the electron density and ion flux directly via probe and retarding field energy analyzer diagnostics as a function of driving voltage and pressure, changes of these plasma parameters, including hysteresis effects, are found to be correlated with transitions of the electron power absorption mode revealed by Fiber PROES. Such mode transitions cause the electron energy distribution function (EEDF) to change and, thus, affect such plasma parameters. Based on these findings, Fiber PROES can be used as a non-invasive diagnostic for the monitoring and knowledge-based development of plasma processes.
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All authors Florian Beckfeld, Maximilian Ryppa, Constantin Neuroth, Li Wang, Ihor Korolov, Julian Schulze

Cosmology and Nongalactic Astrophysics

Constraints on the remote quadrupole field from the polarized Sunyaev Zel'dovich effect

Jordan Krywonos, Matthew C. Johnson, Elena Pierpaoli et al. (+1 more)

The polarized Sunyaev Zel'dovich (pSZ) effect is a cosmic microwave background (CMB) polarization anisotropy induced by Thomson scattering from free-electrons in non-linear structure. The pSZ signal is determined by the distribution of ionized gas tracing the cosmic web and the CMB quadrupole at the location of free-electrons - the remote quadrupole field. Measuring the pSZ effect provides a consistency check of the optical depth to reionization and sheds light on the anomalous nature of the large-scale CMB temperature anisotropies, such as the low observed CMB temperature quadrupole. In this paper, we demonstrate that a CMB-CMB-galaxy bispectrum summarizes several existing pSZ statistics, and that in our observable Universe the ideal galaxy sample to detect pSZ is at $z \sim 1-2$. We evaluate the bispectrum using CMB data from Planck and ACT with galaxy density from the unWISE galaxy redshift catalog as well as Planck cosmic infrared background (CIB) maps. We do not make a statistically significant detection of the pSZ effect, which is consistent with the expected O$(1)$ signal-to-noise from this data combination. The measured amplitude of the pSZ bispectrum provides constraints on the optical depth bias associated with large-scale structure (the amplitude of the pSZ signal) of $b_q=1.02 \pm 2.64$, the optical depth to reionization of $\tau_{\rm rei} = -0.01 \pm 0.14$, and the tensor-to-scalar ratio $r$ of $\sigma_r \sim 150$ ($n_t = 0$) or $\sigma_r \sim 3$ ($n_t = -1$). We forecast that future measurements could tighten the constraints on these quantities by roughly a factor of 3, which is sufficient to provide independent confirmation of the low CMB quadrupole and the optical depth to reionization.
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All authors Jordan Krywonos, Matthew C. Johnson, Elena Pierpaoli, Haoyu Wu

Quantum Physics

Operator Entanglement in Quantum Dynamics Simulations: Formalism and Analysis Tools

Tzu Yu Wang, Michael Schuurman and Simon Neville

We review the framework of operator Hilbert space and introduce the one- and two-particle super reduced density matrices (1-SRDMs and 2-SRDMs), as well as the super mutual information (SMI). The eigenvectors of the 1-SRDMs define what we term natural single particle operator bases, and provide a way to compress vibrational and vibronic Hamiltonians with controlled error. The SMI is defined from the operator entanglement entropy of the 1-SRDMs and 2-SRDMs, and captures the correlation between operators acting on different one-mode subspaces, which may be used to reveal and quantify both direct and indirect couplings that might otherwise be difficult to extract. Efficient numerical approaches for the calculation of SRDMs and the SMI are developed and applied to a set of prototypical vibrational and vibronic Hamiltonians, as well as approximations to the corresponding time-evolution operators. Through this, we demonstrate that: (i) commonly used vibronic Hamiltonians are amenable to extremely high levels of compression without compromising accuracy, and; (ii) SMI analysis can be used to systematically and quantitatively reveal both direct and indirect couplings that might otherwise be difficult to extract, including indirect couplings of vibrational modes via intermediary electronic-vibrational interactions.
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General Relativity and Quantum Cosmology

Massless scalar scattering by Kerr-Bertotti-Robinson black holes:transparent-end channels and superradiance

Hai Huang, Xudong Sun and Juhua Chen

We formulate and numerically solve the real-frequency scattering problem for a neutral, minimally coupled, massless scalar on the rotating Kerr–Bertotti–Robinson (Kerr–BR) black-hole geometry, using a specified transparent boundary condition at the coordinate end. Since the Maxwell stress tensor of the background is traceless, the minimally coupled wave equation reduces to the four-dimensional conformal wave equation, enabling exact Carter-like separation after scaling the scalar field by the conformal factor. Unlike the asymptotically flat case, the coordinate end $r\to\infty$ lies at a finite tortoise distance. We show that the resulting reflection data are conditional on this boundary prescription rather than defining a unique, observer-independent cross section. Within the transparent-end model,open-channel superradiance is governed by a double-gate mechanism requiring both the local horizon condition and the outer propagation condition $q_\infty^2>0$. At the benchmark spin $a/M=0.9$, the co-rotating dipole amplification decreases as the external magnetic field increases. Crucially, the field narrows and closes the open superradiant window at $BM\simeq0.243$. Near the propagation threshold, the amplification coefficient vanishes linearly with the outer wave number.
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Optics

Optical Control of Chirality by Ultrafast Symmetry Breaking in Membrane Metasurfaces

Nikita Glebov, Alena Mamonova, Olesia Pashina et al. (+7 more)

Chirality underpins a wide range of light-matter interactions, yet methods for its dynamic control in photonic systems remain limited. Here, we demonstrate ultrafast all-optical control of chirality in silicon metasurfaces through transient symmetry breaking. Our approach exploits photonic eigenstates of opposite spatial parity engineered to be highly susceptible to symmetry perturbations. Optical excitation generates free carriers that establish a transient refractive-index gradient across the membrane thickness, breaking out-of-plane mirror symmetry and facilitating hybridization of the parity-opposite modes into chiral photonic states. This enables the reversible creation and modulation of chirality on a 10-100 ps timescale, manifested by pronounced changes in the metasurface circular dichroism. By dynamically reconfiguring a fundamental symmetry property of the photonic structure rather than merely its optical response, our work establishes a route towards ultrafast control of chiral light-matter interactions and opens opportunities for active nanophotonic and information processing technologies.
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All authors Nikita Glebov, Alena Mamonova, Olesia Pashina, Felix Ulrich Brikh, Aleksei Ezerskii, Sergey V. Makarov, Mihail Petrov, Maxim Gorkunov, Ivan Sinev, Hatice Altug

Instrumentation and Methods for Astrophysics

OpenCosmo: Community Portal and Analysis Framework for Flagship Cosmological Simulations

Patrick R. Wells, Michael Buehlmann, Patricia Larsen et al. (+11 more)

Cosmology is a precision observational science, and large simulations are necessary components of many analyses. These simulations are computationally expensive and produce massive, complex datasets; sharing them widely – to enable further explorations, comparison with observations, and communication with general audiences – is crucial to realizing their scientific value. In this paper, we introduce the OpenCosmo project, which provides flexible access to, and analysis of, flagship cosmological simulations performed with HACC. A web-based portal (https://opencosmo.science) serves custom subsets – halo catalogs, profiles, particles, galaxy catalogs, and lightcone catalogs and maps – from simulations including the two-trillion-particle Frontier-E gravity-only run, Last Journey, Discovery, and a 64-member hydrodynamic suite. A companion Python toolkit analyzes the returned data and scales without modification from laptop-sized subsets to full simulations on supercomputers. OpenCosmo supports multiple levels of interaction, from browser-based search and download to programmatic and AI-agent-driven workflows, by integrating with existing high-performance computing and data infrastructure. Its architecture, built on Globus services, provides a scalable and adaptable framework that can be extended to other scientific domains seeking to couple data sharing with computational capability.
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All authors Patrick R. Wells, Michael Buehlmann, Patricia Larsen, William M. Hicks, Manpreet Dhillon, Idunnuoluwa A. Adeniji, Katrin Heitmann, Salman Habib, Benoit Côté, Thomas Uram, Gideon McFarland, Andrew Hearin, Ezar Shinabro, Michael E. Papka

Superconductivity

Coherent driving of displacive Higgs fluctuations in superconductors

Jacopo Fiore, Irene Zanotti, Kota Katsumi et al. (+4 more)

Intense phase-stable terahertz (THz) laser pulses can drive collective modes coherently via multi-photon excitation pathways in a manner different than the standard resonant mechanism operative in linear response. Here we show that in superconductors the nonlinear optical response can be enhanced when excited quasiparticles activate a (non-resonant) static displacement of the superconducting order parameter, in full analogy with the displacive excitation of coherent phonons in opaque materials. By combining numerical simulations with analytical results we demonstrate that the displacive mechanism to excite the Higgs mode is operative in both $s$-wave and $d$-wave superconductors. We validate this prediction experimentally by the temperature dependence of the phase of the nonlinear first harmonic in superconducting $s$-wave NbN. We also discuss how the order-parameter relaxation at large times, which can be experimentally accessed via pump-probe protocols is connected to energy-dissipative processes. Our results offer a novel perspective on the ability of intense THz fields to measure, and eventually control, the parametric dependence of the optical response on collective degrees of freedom.
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All authors Jacopo Fiore, Irene Zanotti, Kota Katsumi, N. P. Armitage, Claudio Castellani, Goetz Seibold, Lara Benfatto

Materials Science

Structural Relaxation Enables Millisecond Infrared Photodetection in Selenium Iodine Semiconductors

Biman Jana

The optoelectronic performance of amorphous and partially crystalline semiconductors is strongly governed by structural disorder, yet establishing direct correlations between structural evolution and carrier transport remains challenging. Here, we show that the solid state optoelectronic response of selenium iodine (SeI2) is dictated by its transformation from a metastable glassy phase into an ordered lamellar structure. Vertically resolved transport measurements reveal pronounced depth-dependent electrical conductivity within thick SeI2 films, arising from compositional and structural inhomogeneity developed during solidification. Immediately after solidification, the glassy SeI2 network exhibits sluggish carrier transport and persistent photoconductivity. Upon prolonged structural relaxation, however, the material undergoes significant transport enhancement, enabling millisecond-scale infrared photodetection with a response time of 4.3 ms, stable operation up to 8 kHz modulation frequency, and shot-noise-limited detectivities of 108 Jones at 1550 nm and 1011 Jones in the visible. Spatial photocurrent mapping demonstrates highly uniform carrier collection despite the self-assembled lamellar morphology, while infrared thermal imaging confirms practical imaging capability over a broad temperature range. These results establish structural relaxation as a powerful strategy for engineering carrier transport in selenium-based semiconductors and position SeI2 as a promising solution-processable platform for infrared photodetection and thermal imaging.
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High Energy Physics (Phenomenology)

Minimalist Seesaw-Scotogenic Mechanism as a Source for Neutrino Physics

Eduardo Peinado, Abdel Pérez-Lorenzana and Isangel Toledo

We identify the smallest discrete flavor symmetry and minimal field content that can simultaneously account for neutrino masses and the dark sector in the context of the discrete dark matter. Minimality is achieved with a $D_4$ symmetry by adding three right-handed neutrinos and three scalar doublets. Within this framework, tree-level and one-loop contributions yield the observed solar–atmospheric mass splitings as well as the observed neutrino mixings. Furthermore, by including CP-violating phases, the model successfully accommodates both normal and inverted ordering. Spontaneous $D_4$ breaking leaves a residual $\mathbb{Z}_2$ symmetry that stabilizes the dark matter candidate, with a predicted mass within the $50$–$200$ GeV range, consistent with LUX-ZEPLIN limits.
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Atomic Physics

Collinear Laser Spectroscopy on a Fast Atomic Beam of Boron Generated by Photodetachment of Accelerated B- Ions

L. Renth, P. Imgram, B. Maass et al. (+6 more)

Atomic beams for collinear laser spectroscopy are typically produced via charge exchange reactions in an in-beam vapor cell. This process is accompanied by the formation of a considerable amount of longer-lived excited state population, which is not accessible for spectroscopy and also induces fluorescence background to photon detectors. We present an alternative method to produce an atomic beam, consisting exclusively of ground-state atoms. Negative ions are neutralized in-flight by photodetachment and are subsequently used for fluorescence spectroscopy. As a test candidate, a negative boron ion beam was produced in a cesium sputtering source and superimposed with a co-propagating high-power pulsed infrared laser. The neutral atoms were subsequently excited along the $2s^2 2p\,{}^{2\!}P_{1/2,3/2} \rightarrow 2s^2 3s\,{}^{2\!}S_{1/2}$ transitions by a continuous-wave laser at about 250 nm. The statistics and efficiency were limited by the combination of a continuous ion beam with a low-repetition-rate laser, but a clear route for the improvement combining existing techniques is presented, which can then be applied to other elements as well as negative molecular ions.
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All authors L. Renth, P. Imgram, B. Maass, D. Hanstorp, J. Krämer, D. Koestel, D. Lu, W. Nörtershäuser, T. Walther

Quantum Physics

Rigorous Time-dependent Hamiltonian Learning via Continuous Weak Measurements

Jesús Jiménez-Rodríguez, Giacomo Franceschetto, Antonio Acín et al. (+1 more)

Characterizing the Hamiltonian that a quantum processor actually implements is central to calibrating and validating current quantum hardware. Many devices, however, operate with generators that are time-dependent by design. Here we develop a rigorous and experimentally friendly protocol for learning time-dependent many-body Hamiltonians from continuous weak-measurement signals. The key observation is that interaction sparsity reduces the global reconstruction to a set of local inverse problems, whose size is controlled by the interaction connectivity rather than by the system size. Pure separable probe states suffice to drive these inversions, and a graph-coloring construction embeds them into a small number of global product-state preparations. We derive explicit reconstruction-error bounds and a sample-complexity theorem that cleanly separates the finite-sampling statistical noise from the deterministic bias, which arises from the derivative approximation and the state propagation, and we validate the protocol on time-dependent spin chains with up to \(n=8\) qubits. Beyond these results, our analysis provides a rigorous foundation for time-dependent Hamiltonian learning from continuous monitoring in many-body systems, establishing a framework that extends naturally to many platforms and probe ensembles.
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All authors Jesús Jiménez-Rodríguez, Giacomo Franceschetto, Antonio Acín, Luciano Pereira

Adaptation and Self-Organizing Systems · Cross-listed from cs.SI

Growing Hypergraphs with Homophily

Violet Ross, Francis Cataldo and Philip S. Chodrow

There are many extant models of hypergraphs with interactions governed by attribute-based homophily between nodes, but most assume independence between edges conditional on node parameters. Relaxing this assumption, we study a mechanistic model of growing hypergraphs in which edge formation is influenced by both previous edges and binary node labels. Edges form in this model as noisy copies of previous edges, where the transmission of nodes from one edge to the next depends on multiple homophilic mechanisms between labels. These homophilic mechanisms give rise to tunable assortative structure in the hypergraph. We derive a power law for the degree distribution in this model and describe the long-term dynamics of the joint distribution of labels contained in edges. Our model defines a likelihood over a labeled hypergraph, allowing us to use standard maximum-likelihood techniques to structure algorithms. We estimate the model parameters on synthetic and real data via (stochastic) expectation maximization. These estimates give statistically-principled descriptions of the operation of homophily in empirical polyadic systems. We also demonstrate an approach to community detection via simulated annealing which, though computationally expensive, achieves competitive results on both synthetic data and certain empirical data sets known to be challenging to community detection techniques based on the edge-independence assumption. Our findings highlight the benefits of incorporating edge- and label-dependence in higher-order modeling and data analysis, and point to several directions for future work.
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Mathematical Physics

Inertial motion of incompressible continua

Francesca Berlinghieri and Giulio G. Giusteri

We study the inertial motion of incompressible continua within a geometric and variational framework, extending the classical Arnold-Ebin-Marsden theory from the group of volume-preserving diffeomorphisms of a fixed domain to configuration spaces of deformations with variable image. In the latter case, the lack of a group structure requires proving some results that are instead immediate in the classical setting. We show that the orientation-preserving deformations with suitable regularity constitute a Hilbert manifold and that volume-preserving deformations form a submanifold with tangent vectors that are mapped onto divergence-free vector fields by the Lagrangian-to-Eulerian-picture correspondence. In so doing, we also present the geometric structure corresponding to compressible continua. The kinetic energy of the continuum gives rise to both a Lagrangian action, from which the equations of inertial motion are deduced, and a metric, with geodesics that are identified precisely by inertial motions. While the inertial motion can coincide with a physical one only for incompressible perfect fluids, it can be used to provide a natural parametrization of the configuration manifold for generic continua. We obtain a general result of local-in-time existence of solutions for the geodesic flow equation and we present explicit examples showing that, for the same initial data, the geodesic followed by the continuum in the compressible case can leave the manifold of admissible deformations in finite time, while the corresponding incompressible geodesic exists for all times.
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High Energy Physics (Phenomenology)

$P_{c}(4312)$, $P_{c}(4440)$, and $P_{c}(4457)$ productions in $e^{+} e^{-}$ collisions

Quan-Yun Guo and Dian-Yong Chen

In the present work, we propose to investigate the productions of $P_{c}(4312)$, $P_{c}(4440)$, and $P_{c}(4457)$ in the $e^{+} e^{-} \rightarrow p \bar{p} J/\psi$ process by utilizing an effective Lagrangian approach, where $P_{c}(4312)$ is considered as $\Sigma_{c} \bar{D}$ molecular state with $J^{P}=1/2^{-}$, while $P_{c}(4440)$ and $P_{c}(4457)$ are considered as $\Sigma_{c} \bar{D}^{\ast}$ molecular states with $J^{P}=1/2^{-}$ and $J^{P}=3/2^{-}$, respectively. For the $e^{+} e^{-} \rightarrow \bar{p} P_{c}(4312)$, $e^{+} e^{-} \rightarrow \bar{p} P_{c}(4440)$, and $e^{+} e^{-} \rightarrow \bar{p} P_{c}(4457)$ processes, the cross sections are evaluated to be ($27.8^{+42.2}_{-17.9}$) fb, ($38.7^{+58.6}_{-25.1}$) fb, and ($1.44^{+2.18}_{-0.93}$) fb at $\sqrt{s}=6$ GeV, respectively, where the central values are estimated with $\Lambda_{r}=2.5$ GeV, and the uncertainties are resulted from the variations of $\Lambda_{r}$ from 2.0 to 3.0 GeV. Considering that the $P_{c}$ states can decay into $J/\psi p$, we estimate the cross sections for $e^{+} e^{-} \rightarrow p \bar{p} J/\psi$ and the differential cross sections depending on the $J/\psi p$ invariant mass. At $\sqrt{s}=6$ GeV, the cross sections for $e^{+} e^{-} \rightarrow p \bar{p} J/\psi$ are estimated to be ($14.7^{+22.2}_{-9.50}$) fb. Moreover, our estimations indicate that the cross section resulted from the $P_{c}(4440)$ and $\bar{P}_{c}(4440)$ intermediate states is dominant. In the $J/\psi p$ invariant mass spectrum, our estimations reveal that the peak structure between 4.42 and 4.46 GeV primarily originates from $P_{c}(4440)$.
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Strongly Correlated Electrons

Deconfined quantum critical point in a dissipative spin-1/2 chain

Longye Lu, Shifeng Cui and Wenan Guo

Open quantum spin systems offer a previously unexplored route to realizing deconfined quantum criticality. We consider a spin-1/2 $J$-$Q_3$ chain, consisting of an antiferromagnetic (AFM) Heisenberg exchange and a competing multi-spin interaction favoring a valence-bond solid (VBS) state, with each spin component coupled to a bosonic bath. Using non-Abelian bosonization and renormalization-group (RG) analysis, combined with large-scale quantum Monte Carlo (QMC) simulations, we determine the phase diagram and the associated phase transitions of the model. We show that strong dissipation stabilizes an AFM phase for sub-Ohmic, Ohmic, and super-Ohmic baths. Continuous AFM-VBS transitions at finite dissipation are found upon increasing the multi-spin interaction in both the sub-Ohmic and Ohmic regimes. Critical properties are obtained through perturbative RG analysis and QMC simulations. In the Ohmic case, the critical point features spinon deconfinement and emergent O(4) symmetry. In the sub-Ohmic regime, the transition may also involve spinon deconfinement, provided that spinons remain deconfined in the dissipative VBS phase. In addition, in the super-Ohmic regime, we propose a transition from AFM phase to a quasi-long-range ordered phase.
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Chaotic Dynamics · Cross-listed from stat.ME

Dynamic models with $p$ parameters are identified by $2p+1$ random features

Michael Wieck-Sosa and Cosma Rohilla Shalizi

A foundational principle in nonlinear dynamics is that the structure of a dynamical system can be recovered from a small number of generic measurements or coordinates. We develop an analogous principle for the identification of dynamic models for time series with noise, which builds on previous identification results for noiseless dynamical systems. The noise is allowed to be non-iid, non-Gaussian, and dependent on the state. Our results cover noisily observed differential equations and discrete-time dynamical systems, as well as stochastic models with process noise. We illustrate the utility of this identification principle using a Lorenz-63 model and a Hénon map model, both with observational noise.
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High Energy Physics (Theory)

New Tools in the Landau Bootstrap

Piotr Bargieła, Giulio Crisanti, Craig Larkin et al. (+4 more)

We describe recent advances in our understanding of the analytic structure of Feynman integrals. In particular, we describe two new classes of constraints on such integrals, that identify discontinuities that either cannot be repeated, or that always give rise to the same result (no matter which other discontinuities are computed first). These new constraints hold at all orders in dimensional regularization, and provide us with new input for the Landau bootstrap, where information about the singularities and discontinuities of individual Feynman integrals is used to construct their functional form.
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All authors Piotr Bargieła, Giulio Crisanti, Craig Larkin, Luke Lippstreu, Andrew J. McLeod, Maria Polackova, Laura Walsh

Medical Physics

Fast ungated five-dimensional cardiac MRI on a 1.5 T MR-linac for MRI-guided radiotherapy

M.L. Terpstra, T.E. Olausson, M.M.N. Aubert et al. (+4 more)

Background: Stereotactic arrhythmia radio-ablation (STAR) for patients with ventricular tachycardia is currently limited by complex cardiorespiratory motion. Current 5D-MRI motion models require long acquisition and reconstruction times, limiting clinical viability. Objective: To develop a fast, ungated 5D-MRI reconstruction method for personalized motion characterization to support MRI-guided STAR treatments. Methods: We propose a fast, ungated 5D-MRI reconstruction method based on the CMR-MOTUS framework. The method uses a 3D Cartesian acquisition with a joint optimization framework to reconstruct a motion-corrected reference image and low-rank deformation vector fields (DVFs). By exploiting the low rank structure, we explicitly disentangle respiratory and cardiac motion during optimization. Then, the DVFs are used for 5D-MRI reconstruction with a retrospectively adjustable number of motion states. Validation was performed using digital and physical cardiorespiratory phantoms. Furthermore, the approach was evaluated using 10 healthy volunteers, comparing motion consistency with 2D cine MRI. Results: Validation of 5D CMR-MOTUS using digital and physical phantoms demonstrated accurate 5D-MRI reconstruction. In the physical phantom, 5D CMR-MOTUS achieved a left-ventricle DICE of 0.96 +/- 0.01. In the volunteer cohort, the 5D-MRI scans showed strong motion to 2D cine MRI, with a cardiac motion error of 0.1 +/- 0.9 mm and a respiratory motion error of 0.2 +/- 2.9 mm. Crucially, 5D-MRI data were acquired in 1 minute and reconstructed in 6 minutes. Conclusions: The proposed 5D-MRI method enables rapid, high-quality, and personalized motion characterization, demonstrating potential for integration into MRI-guided STAR treatments. Data Availability: The 3D k-space data and 5D reconstructions for the ten volunteers are publicly available at https://doi.org/10.5281/zenodo.21278894
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All authors M.L. Terpstra, T.E. Olausson, M.M.N. Aubert, C. Beijst, A. Sbrizzi, C.A.T. van den Berg, M.F. Fast

Quantum Physics

Rethinking Quantum Continual Learning with Quantum Fisher Information

Yu-Chao Hsu, Yu-Cheng Lin, Tai-Yue Li et al. (+2 more)

Quantum continual learning aims to train quantum models on sequential tasks without losing previously learned knowledge. However, variational quantum classifiers (VQCs) are prone to catastrophic forgetting under nonstationary task distributions. We propose quantum elastic weight consolidation (QEWC), a quantum Fisher information (QFI)-informed regularization method for mitigating forgetting. Unlike conventional elastic weight consolidation based on classical Fisher information (CFI), which measures parameter importance through measurement-dependent output statistics, QEWC uses QFI to quantify the intrinsic sensitivity of the parameterized quantum state. This gives an information-geometric view in which important parameters are identified by the local response of the quantum state manifold. We evaluate QEWC on VQCs trained on sequential binary classification tasks, including classical image-classification and quantum phase-classification tasks. Simulations show that sequential training without regularization causes severe forgetting, while both CFI-based EWC and QFI-based QEWC improve retention of previous tasks. Mechanistic analyses further show that the two methods impose different regularization geometries: CFI acts selectively on measurement-sensitive directions, whereas QFI imposes a denser state-geometric constraint over parameter space. Under depolarizing noise, CFI values are strongly suppressed by degraded measurement statistics, while QFI preserves a more stable sensitivity structure of the noisy parameterized quantum state. These results establish QEWC as a physically motivated approach for studying and mitigating forgetting in quantum continual learning through quantum-state geometry.
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All authors Yu-Chao Hsu, Yu-Cheng Lin, Tai-Yue Li, Nan-Yow Chen, En-Jui Kuo

Quantum Physics

Quantum Mechanics on Lie Groups: II. Path Integrals

Mathieu Beauvillain, Blagoje Oblak and Marios Petropoulos

We continue our study of quantum dynamics on a Lie group $G$, initiated in arXiv:2512.19840, by building the path integral that governs transition amplitudes in the Hilbert space $L^2(G)$. This relies on the proper handling of both a noncommutative momentum space and the presence of compact directions in $G$. We show that compactness can be handled through a sum over winding numbers in maximal tori of $G$, generalizing the similar sum commonly encountered for path integrals on a circle. As applications, we compute semiclassical approximations of propagators and partition functions of Euler-Arnold systems, up to (and including) two-loop order.
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