Nuclear Theory
Analyzing momentum distributions in light nuclei with the operator product expansion
Jiexin Yu and Bingwei Long
We analyze the high-momentum tails of nucleon distributions in
nuclei using the operator product expansion (OPE) and Pionless effective field theory. The OPE factorizes the distributions into Wilson coefficients, determined from two-nucleon scattering, and local-operator
matrix elements (LOMEs). Because the leading ${{}^1S_0}$ and ${{}^3S_1}$ Wilson coefficients are nearly degenerate in the single-nucleon distribution, we construct the OPE of the two-nucleon momentum distribution, which separates the two contributions into distinct
spin-isospin channels. From variational Monte Carlo two-nucleon distributions of \isotope[3]{He}, \isotope[4]{He}, \isotope[6]{Li}, and \isotope[12]{C}, we extract the LOMEs and accurately reconstruct the single-nucleon distributions at large momenta. In potentials without explicit non-nucleon degrees of freedom such as AV18, the Wilson coefficients of the single- and two-nucleon OPEs are proportional, yielding approximate relations between the two distributions.
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Quantum Physics
Explicit block encodings of rate matrices for simulating polymerization kinetics on quantum computers
Yuhei Ikeda, Hokuto Iwakiri, Soichiro Nishio et al. (+1 more)
Predicting how molecular weight distribution and monomer sequence evolve during polymerization is central to
polymer science, yet classical approaches face a trade-off between molecular resolution and computational cost: for copolymers, the number of distinguishable species grows exponentially with chain length.
Quantum computing offers a potential alternative, provided the non-
unitary rate
matrices governing the kinetics can be embedded into
unitary quantum circuits, a task known as block encoding. Here we construct explicit block-encoding
circuits for two kinetic models of living polymerization: Model A, single-monomer polymerization, whose lower-bidiagonal rate
matrix is encoded via a sparse-oracle construction and a two-term linear combination of
unitaries (LCU) decomposition; and Model B, two-monomer copolymerization, where a bijective labeling of
polymer species by an integer index (the m-index) yields a structured sparse
matrix encoded via either a five-term LCU or a sparse-oracle construction. Numerical simulations with the sparse-oracle encodings reproduce the classical time
evolution for reactivity ratios drawn from reported olefin copolymerization systems spanning near-random ($r_1 r_2 \simeq 1$) and blocky ($r_1 r_2 > 1$) microstructures, and the LCU encodings are verified by explicit reconstruction of the encoded
matrix block. Resource estimation shows that both implementations require only $O(\log N)$
qubits in the
matrix dimension $N$ (an exponential
memory saving over the classical state space), with gate counts growing gradually, reaching $10^4$ to $10^5$ gates at $10^3$ system
qubits. These results establish a concrete
quantum circuit foundation for simulating polymerization kinetics on fault-tolerant
quantum hardware, and a first step toward exploiting exponential state-space compression for high-dimensional
polymer reaction networks.
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All authors Yuhei Ikeda, Hokuto Iwakiri, Soichiro Nishio, Kentaro Matsumoto
High Energy Astrophysical Phenomena
Near-Horizon Tidal Disruption Events
Yang Yang and Xian Chen
Tidal disruption events (TDEs) offer a unique dynamical probe of the spacetime geometry around supermassive black holes (SMBHs). While conventional TDEs occur around SMBHs of $M_\bullet \sim 10^6 - 10^7 M_\odot$, where
stars are disrupted far from the event horizon, here we identify a special class of TDEs around rapidly spinning SMBHs with masses $M_\bullet \gtrsim 10^8 M_\odot$, where the
tidal-disruption radius approaches the gravitational radius. We term these events "near-horizon TDEs" and, by calculating geodesics in Kerr spacetime, investigate how the proximity of the horizon modifies the debris
evolution and subsequent fallback. We find that for
stars encountering the SMBH on
parabolic orbits, up to $\sim (90 \%-95 \%)$ of the
stellar debris either plunges directly into the SMBH or escapes the system. Bound orbits, by contrast, retain a substantially larger fraction of the debris. Using the resulting debris distribution, we calculate the fallback rates and find that bound orbits produce intrinsically higher peak fallback rates and shorter decay timescales, by factors of $\sim 10^3$ relative to
parabolic orbits. However, when the
stellar orbital angular momentum is particularly low, the peak fallback rate can be substantially suppressed by debris lost to plunge orbits. This combination of rapid fallback and a mass deficit naturally explains overluminous TDEs such as ASASSN-15lh, which standard TDE models have struggled to reproduce. Our work establishes near-horizon TDEs as a new probe of strong-field
gravity and a promising tool for identifying massive, rapidly spinning SMBHs.
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High Energy Physics (Experiment)
Readout electronics for SUBMET
Claudio Campagnari, Sungwoong Cho, Suyong Choi et al. (+20 more)
A dedicated data acquisition (DAQ) system has been developed for the SUB-Millicharge ExperimenT (SUBMET) at the Japan
Proton Accelerator Research Complex (J-PARC), a search for particles carrying a fractional electric charge $Q = \epsilon e$ with $\epsilon$ below $\mathcal{O}(10^{-3})$, hereafter referred to as millicharged particles (mCPs). Because such particles are expected to produce at most a few scintillation
photons, the system is optimized for single-photoelectron detection from the photomultiplier tubes (PMTs), combining high-speed waveform digitization with precise timing. To capture eight consecutive
proton bunches of the 30 GeV J-PARC beam within a single trigger, the eight channels of the Domino Ring Sampler 4 (DRS4) chip are cascaded in groups of four to form two readout inputs, each sampling 4096 points continuously at 820.5 MHz over an effective time window of 5 us. After calibration, timing differences between channels are within 1 ns on the same DRS4 chip, 2 ns on the same board, and 8 ns across different boards, well within the 30 ns coincidence window of the experiment. The front-end electronics achieve an RMS noise below 0.4 mV. The baseline is deliberately offset upward such that the negative-going pulses span a larger fraction of the digitizer range, improving voltage resolution and dynamic range. A trigger control board aggregates data from multiple readout boards and sustains the data-transfer rate required for beam operation. The measured performance confirms that the DAQ system meets the timing, noise, and throughput requirements of the experiment.
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All authors Claudio Campagnari, Sungwoong Cho, Suyong Choi, Seokju Chung, Matthew Citron, Albert De Roeck, Martin Gastal, Seungkyu Ha, Andy Haas, Christopher Scott Hill, Insung Hwang, Hoyong Jeong, Jaebak Kim, Jeonghwa Kim, Hyunki Moon, Ryan Schmitz, David Stuart, Eunil Won, Jae Hyeok Yoo, Jinseok Yoo, Ayman Youssef, Ahmad Zaraket, Haitham Zaraket
Mesoscale and Nanoscale Physics
From London to Morse via Binnig, Quate, and Gerber
Sofia Alonso Perez, Matthew O. Blunt, Frederick Carlisle et al. (+30 more)
In their landmark paper introducing the atomic force microscope [Phys. Rev. Lett. 56, 930 (1986)], Binnig, Quate, and Gerber presciently anticipated that the technique would ultimately be capable of probing interactions running the gamut from weak van der Waals interactions to strong covalent bonding. They also highlighted that the tip-sample forces central to AFM are present, and often highly influential, in scanning tunnelling microscopy; indeed, this realisation directly inspired the invention of the force microscope. In this perspective for the Forty Years of AFM special issue, we review selected aspects of two decades of work from our group at the University of Nottingham that span the force range highlighted by BQG and are united by a common, central theme: the probe as active participant rather than passive observer. Our selection of results also covers length- and correlation-scales from the microscopic right down to the single chemical bond limit, tracking a spectrum of interactions from van der Waals/Hamaker forces, through hydrogen bonding, to covalent bonds and, finally, atom-by-atom assembly of metal clusters via vertical tip-sample transfer. Echoing BQG's own observations on the prevalence of probe-sample forces in STM, we also discuss recent evidence that tip-induced heterogeneity underpins first-passage dynamics in molecular
diffusion and highlight the challenges in acquiring non-invasive measurements of
diffusion barriers for adsorbed molecules that are readily perturbed by the probe. We close with a perspective on machine learning's growing role in automating tip-driven atomic and molecular manipulation.
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All authors Sofia Alonso Perez, Matthew O. Blunt, Frederick Carlisle, Neil R. Champness, Janette L. Dunn, Matthew Edmondson, Rowan Evers, Connor Fields, Subhashis Gangopadhyay, James Hayton, Samuel P. Jarvis, Filipe Junqueira, Lev Kantorovich, Brian Kiraly, Natalio Krasnogor, Ioannis Lekkas, Morten Møller, Philip Moriarty, Chris Pakes, Emmanuelle Pauliac-Vaujour, Oliver Phillips, Adrian Radocea, Philipp Rahe, Mohammad Abdur Rashid, Hongqian Sang, Alex Saywell, Nikhil Seeja Sivakumar, Peter Sharp, Andrew Stannard, Julian Stirling, Adam Sweetman, Simon Taylor, Richard A.J. Woolley
Quantum Physics
Trapdoor Functions with Secure Key Leasing and Copy Protection
Fuyuki Kitagawa, Ryo Nishimaki, Yuki Shirakawa et al. (+1 more)
Inspired by the no-cloning
theorem in
quantum theory, a variety of
quantum cryptographic primitives with unclonable functionalities, such as secure key leasing and copy protection, have been proposed and attracted significant
attention. However, trapdoor functions (TDFs), fundamental primitives in public-key cryptography, have not been extensively studied in these areas. In this work, we initiate a study of TDFs in both secure key leasing and copy protection settings. We first introduce the definition of TDFs with secure key leasing (TDF-SKL), which enables leasing and deleting of
quantum trapdoors. We formalize TDF-SKL both with and without domain sampler, and give a construction of TDF-SKL without domain sampler based on the LWE assumption and a construction of TDF-SKL with domain sampler based on any standard PKE schemes combined with hinting pseudorandom generators [Koppula and Waters, CRYPTO 2019]. Next, we define TDFs with copy protection (TDF-CP), where the inversion functionality is copy protected by a
quantum trapdoor. We establish a construction of TDF-CP assuming indistinguishability obfuscation and the LWE assumption, following a modular framework of copy protection proposed by Ananth and Behera [CRYPTO 2024]. We also present applications of TDF-SKL and TDF-CP. Existing constructions of public-key encryption with secure key leasing (PKE-SKL) and single-decryptor encryption (SDE) suffer from a critical vulnerability:
quantum decryption keys may be destroyed after decrypting maliciously chosen ciphertexts. We construct PKE-SKL schemes and SDE schemes with robust
quantum decryption keys that remain reusable after decrypting arbitrary ciphertexts from TDF-SKL and TDF-CP, respectively.
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All authors Fuyuki Kitagawa, Ryo Nishimaki, Yuki Shirakawa, Takashi Yamakawa
General Relativity and Quantum Cosmology
Picard Iteration for the Characteristic Initial Value Problem in Einstein Equations
Shengrong Wu
We present an iteration
algorithm for
vacuum and Einstein scalar-field equations in double-null gauge, which transform the non-linear PDE into systems of ODE. The numerical realization combines characteristic constraint solves, LGL spectral elements, pole-free spherical operators, Galerkin projection, and independent first-order residual and consistency checks.
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High Energy Physics (Phenomenology)
Time evolution of scalar condensate decay
Ayuki Kamada and Kodai Sakurai
A scalar field, which oscillates coherently over the space and decays through production of daughter particles, plays an important role in cosmology. It was recently shown that the parametric-resonance and Feynman-diagrammatic approaches give the same decay rate for a Bosonic daughter particle at a large time duration. We study how the parametric-resonance result approaches to this asymptotic value, by numerically following the time
evolution of the phase density of the daughter particle. We see a difference among different instability bands in the narrow-resonance regime. The lowest-order instability band approaches to the Feynman-diagrammatic result in tens of scalar oscillation periods, while the high-order instability bands approach dependently also on a coupling between the scalar and daughter particles. This would infer that the total decay width, to which the lowest-order instability band contributes most dominantly in the perturbation theory, approaches to the Feynman-diagrammatic result also independently of the coupling. To confirm it, we consider a simpler and analytically solvable
quantum mechanical model: Rabi models. In the Bosonic Rabi model, the parametric-resonance and Feynman-diagrammatic results agree with each other for all the time. On the other hand, in the Fermionic Rabi model, they disagree at a large time duration. This difference would be attributed to Bose enhancement vs Pauli blocking.
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Optics
Fiber-based electro-optic dual-comb light source for fast linear and nonlinear spectroscopy
Debanuj Chatterjee, Fabio Motetta, Simon Boivinet et al. (+2 more)
Dual-comb spectroscopy (DCS) enables rapid, broadband and high-resolution optical measurements by mapping optical spectra into the
radio frequency (RF) domain. However, conventional DCS systems are fundamentally constrained by a tradeoff between optical bandwidth and interferogram acquisition speed, limiting their overall performance. Here, we demonstrate an all-fiber, polarization-maintaining (PM) frequency-agile electro-optic modulation (EOM) dual-comb source that simultaneously achieves a broad optical bandwidth of 10 THz and a high interferogram acquisition speed of up to 2.5 MHz. The high acquisition rate is enabled through an in-phase/quadrature (IQ) modulator-based architecture to shift the carrier frequency of one of the combs. We illustrate the performance of the source through proof-of-concept linear spectroscopy and nonlinear dual-comb coherent anti-Stokes Raman scattering (CARS) spectroscopy measurements. The combination of large spectral coverage, high refresh rate and an all-PM fiber configuration makes this dual-comb platform attractive for applications such as rapid molecular spectroscopy and high-speed nonlinear spectroscopic imaging.
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All authors Debanuj Chatterjee, Fabio Motetta, Simon Boivinet, Hervé Rigneault, Arnaud Mussot
Quantum Physics
Time-Dependent Quantum Monte Carlo for fermions: from Bayesian conditioning to spinor dynamics
Ivan P. Christov
The time-dependent
quantum Monte Carlo method represents a many-electron state by an ensemble of replicas, in which each electron is described by a cloud of walkers which samples its density in physical space, one walker and one guide wave per replica, and it replaces the Hartree potential by a conditional interaction built from the walker positions. The sampling is in physical space rather than in configuration space, which keeps the cost
polynomial. Here we derive that conditional interaction. Treating the walker as a localization of its electron to a finite resolution, we show that Bayes'
theorem and a single empirical substitution yield the Nadaraya-Watson form which the method has used heuristically. The nonlocality length then becomes the width of the conditioning, and the pair and mean-field limits follow from one construction. Because the conditioning removes the gauge freedom which eliminates the orthonormality multipliers in Hartree-Fock, we enforce orthonormality by a term derived from the constraint. We generalize the formulation to spinors, where the Pauli suppression at coincidence becomes graded by the local
spin alignment, and it reduces through the collinear and mean-field limits to the known two-particle
spin equations. For two electrons in a double
quantum dot in an inhomogeneous
magnetic field, compared with the exact solution, the spinor equations reproduce the non-collinear
spin geometry which collinear calculations cannot represent and recover the larger part of the
entanglement missing from a single determinant. In the crossover between the exchange and the Zeeman regimes, where the singlet-triplet coherence sets the
spin geometry, the replicas must carry that coherence themselves, as in the
spin-coupled pair of valence-bond theory.
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Quantum Physics
Efficient quantum state preparation on Quantinuum hardware
Archie Butterworth, Josh Green, Yusen Wu et al. (+2 more)
Preparation and verification of specific
quantum states is an important capability for
quantum devices to realise advantages over classical computations and
algorithms. In this work, we have demonstrated an end-to-end framework that combines resource-efficient
quantum state preparation with rapid, robust fidelity verification on near-term
quantum hardware. By experimentally preparing and validating a structured complex
quantum state encoding a digitized acoustic signal on the Quantinuum H2-1 trapped-ion platform, we achieved a high hardware fidelity of $F_{\mathrm{hw}} = 0.929$. Crucially, this milestone was realized without relying on idealized assumptions or deep fault-tolerant overhead, but rather through resource-minimal
circuits optimized for NISQ-era and early fault-tolerant devices. Furthermore, we addressed a key limitation in current
quantum state certification. While validation methods like shadow overlap work well for random states, their sample complexity can become prohibitively high for the structured states used in practical
algorithms. We mitigate this by introducing a pre-measurement basis-change technique that reduces the verification parameter, $\tau$, by over 10 orders of magnitude for structured targets. This approach tightens the theoretical certification guarantees of the shadow overlap method and integrates tensor-network preparation and shadow validation into a unified workflow. These results shift the paradigm of how structured classical data can be mapped to and verified on
quantum hardware under realistic noise and measurement budgets. By compressing a robust verification procedure to just 1,000 measurement shots, this framework offers an immediate, scalable benchmarking standard.
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All authors Archie Butterworth, Josh Green, Yusen Wu, Jie Pan, Jingbo Wang
Plasma Physics
Generalized Similarity Theory for Plasmas
Yangyang Fu
A generalized theory of
plasma similarity is established based on the scaling of the Boltzmann equation coupled with the full set of Maxwell's equations. The predicted similarity scalings are demonstrated through first-principles particle-in-
cell and fluid simulations across diverse operational regimes, including collisionless
plasmas with two-stream instabilities, pure electron diodes spanning the classical to relativistic regimes, electromagnetic-wave-driven
plasmas, and discharge
plasmas ranging from low to high ionization regimes. The generalized theory reveals the intrinsic scale-invariant nature of
plasmas under specified conditions, rooted in the
symmetry and scaling transformations of the governing equations.
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Atmospheric and Oceanic Physics · Cross-listed from cs.LG
Stochastically Perturbed Weights: Ensembles from Deterministic Machine-Learning Weather Models
Simon Adamov, Oliver Fuhrer, Reto Knutti et al. (+1 more)
Machine-learning weather models (MLWMs) now match or outperform operational numerical weather prediction (NWP) at global medium-range
forecasting, at far lower inference cost. Many deployed MLWMs are deterministic, producing a single forecast with no estimate of its own uncertainty, whereas a growing family of trained-probabilistic models generate calibrated ensembles directly, at the price of a dedicated training run. We ask instead how much uncertainty can be extracted from a deterministic checkpoint that already exists, without retraining it. Where physical ensembles represent model uncertainty by stochastically perturbing parametrisation tendencies, we perturb the network's raw weight tensors at inference time, a scheme we call stochastically perturbed weights (SPW). We also ask whether it works, where and on which scales to inject the noise, and where it fails. A three-phase ablation across four deterministic backbones, Aurora, GraphCast, SFNO, and AIFS, selects one production baseline per model, benchmarked against the trained-probabilistic AIFS-ENS, FourCastNet 3 and Atlas as well as the operational ECMWF ensemble (IFS-ENS) over 112 initialisation times. At a 240 h (10-day) lead time the SPW ensembles reach continuous ranked probability skill scores (CRPSS) between 0.04 and 0.13 below the best trained-probabilistic baseline, at zero marginal training cost. No injection site works across models: the productive tensor group is architecture-specific, so SPW is at present a tuning procedure rather than a plug-and-play recipe. Its main failure mode is a coherent whole-field offset that overdisperses the domain mean, and restricting the noise to coarse scales or perturbing the initial conditions each repair part of it.
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All authors Simon Adamov, Oliver Fuhrer, Reto Knutti, Sebastian Schemm
Quantum Physics
Performance of the subcarrier-wave quantum key distribution in the presence of spontaneous Raman scattering noise generated by classical DWDM channels
Fedor Kiselev, Roman Goncharov, Natalia Veselkova et al. (+3 more)
In this paper we study performance of the subcarrier-wave
quantum key distribution system (SCW QKD) in the presence of spontaneous Raman scattering (SpRS) noise generated by classical channels of dense wavelength division multiplexing (DWDM) network within a single-mode optical fiber. We present the mathematical model for evaluation of the
quantum bit error rate (QBER) and the secure key generation rate with the SpRS noise taken into account. We consider two regimes of the SCW QKD system: the continuous wave regime that uses continuous wave
laser and the pulsed regime. For these regimes, performance of the system is analyzed depending on receiver sensitivity of classical DWDM. It is found that the pulsed regime outperforms the continuous wave regime in both the secure key generation rate and the maximum achievable distance.
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All authors Fedor Kiselev, Roman Goncharov, Natalia Veselkova, Eduard Samsonov, Alexei D. Kiselev, Vladimir Egorov
Materials Science · Cross-listed from cs.LG
MLIP Detective: Active Failure Mode Discovery Beyond Benchmark Scores for Machine-Learning Interatomic Potentials
Ryuhei Okuno, Nontawat Charoenphakdee, Kaoru Hisama et al. (+1 more)
Universal machine-learning interatomic potentials (u-MLIPs) aim to generalize across diverse configurations.
Benchmarks enable reproducible evaluation but may not expose failures outside their predefined scope. Here, we show that physics-informed search can complement
benchmark-based evaluation by uncovering hidden failure modes. We introduce MLIP Detective, an agentic framework for active failure mode discovery. Starting from
benchmark evidence, MLIP Detective generates falsifiable, physics-informed failure hypotheses, screens them with inexpensive simulations, and escalates only the most suspicious cases to human experts together with proposed verification protocols. Without issue-specific prompting, MLIP Detective identified and characterized a systematic anomaly in MACE-MPA-0: the model predicted some relaxed adsorbate-surface systems involving O- or F-containing adsorbates to be higher in energy than their corresponding separated fragments. Using cross-model comparisons, MLIP Detective further inferred a likely training-data origin for the anomaly, consistent with recent reports.
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All authors Ryuhei Okuno, Nontawat Charoenphakdee, Kaoru Hisama, Yuta Tsuboi
Astrophysics of Galaxies
The Impact of Circumgalactic Rotation on Ly$\alpha$ Radiative Transfer
Hee-Gyeong Kym, Seok-Jun Chang, Max Gronke et al. (+1 more)
Hydrogen Lyman-alpha (Ly$\alpha$) is a prominent emission line from the circumgalactic medium (CGM). Due to its resonant nature, Ly$\alpha$ carries imprints of the physical properties and kinematics of the cold CGM. In particular, CGM rotation can modify the Ly$\alpha$ peak separation, which is often interpreted as a tracer of H I column density. We present 3D Monte Carlo Ly$\alpha$ radiative-transfer simulations in a CGM-like rotating medium and examine how the emergent spectra depend on rotational velocity ($V_{\rm rot}$), H I column density ($N_{\rm HI}$), viewing angle, clumpiness, and intrinsic source width. We find that rotation broadens the integrated spectra and increases the peak separation, with the strongest viewing-angle dependence when rotational Doppler shifts dominate over frequency
diffusion. At high $N_{\rm HI}$, numerous scatterings reduce the sensitivity of integrated spectra to rotation, producing a degeneracy between $V_{\rm rot}$ and $N_{\rm HI}$. Consequently, Ly$\alpha$ peak separation alone can overestimate $N_{\rm HI}$ in a rotating medium. Spatially resolved
halo spectra provide a clearer diagnostic: opposite sides of the rotating medium show systematic redshifted and blueshifted asymmetries associated with the line-of-sight velocity of the last-scattering gas. Such rotation-driven signatures can also contribute to velocity-map patterns often interpreted in terms of inflow or
outflow, highlighting the need to consider rotation in spatially resolved Ly$\alpha$ observations. We further show that the main signatures persist in simple clumpy media, while the
halo signatures are largely insensitive to the intrinsic source width. Our results demonstrate that spatially resolved Ly$\alpha$ observation is essential for disentangling CGM rotation from radiative-transfer effects.
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All authors Hee-Gyeong Kym, Seok-Jun Chang, Max Gronke, Kwang-Il Seon
High Energy Physics (Phenomenology)
Light cone distributions of $P$-wave quarkonia
Yang Li, Tianyang Hu, Xianghui Cao et al. (+1 more)
Motivated by renewed interest in the light-cone distributions of $P$-wave quarkonia, we investigate the leading-twist distribution amplitudes of these states within the basis light-front quantization (BLFQ) formalism. While our extracted distributions exhibit macroscopic shapes consistent with expectations from the non-relativistic limit, we find that relativistic effects introduce critical structural features. Most notably, we observe novel “W"-shaped structures in the distribution amplitudes of the axial vector
mesons, which arise from relativistically induced $S/D$ partial waves and cannot be explained by non-relativistic dynamics. These findings provide essential non-perturbative inputs for analyzing hard exclusive processes and highlight the importance of relativistic frameworks for understanding heavy quarkonium production and structure at modern high-energy
colliders.
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All authors Yang Li, Tianyang Hu, Xianghui Cao, Meijian Li
High Energy Physics (Experiment)
Prospects for precision Higgs boson measurements at a 10 TeV muon collider
Paolo Andreetto, Massimo Casarsa, Luca Castelli et al. (+6 more)
A 10 TeV
muon collider offers a powerful environment for precision studies of the
Higgs sector through its large vector-
boson-fusion production rates. This review presents projected sensitivities to single- and double-
Higgs production cross sections, the
Higgs boson mass, and the trilinear
Higgs self-coupling. The projections are obtained from detailed simulations of the MUSIC detector, including machine-induced background, for a baseline configuration of two experiments, each collecting an integrated luminosity of 10 $\mathrm{ab}^{-1}$. The $H\to b\bar{b}$ and $H\to WW^\ast$ production cross sections can be measured with statistical precisions of 0.18% and 0.35%, respectively, while precisions of 2.6%, 4.2%, and 6.9% are expected for $H\to\gamma\gamma$, $H\to ZZ^\ast$, and $H\to\mu^+\mu^-$. Combining the $H\to b\bar{b}$, $H\to\gamma\gamma$, and $H\to\mu^+\mu^-$ channels yields an expected
Higgs boson mass precision of about 19 MeV. Double-
Higgs production can be measured with statistical precisions of 4.2% in the $HH\to b\bar{b}b\bar{b}$ channel and 14% in the $HH\to b\bar{b}WW^\ast$ channel. Using the $HH\to b\bar{b}b\bar{b}$ channel, the trilinear
Higgs self-coupling can be determined with an expected precision of about 5%. These results demonstrate the potential of a high-energy
muon collider for precision
Higgs physics.
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All authors Paolo Andreetto, Massimo Casarsa, Luca Castelli, Alessio Gianelle, Donatella Lucchesi, Leonardo Palombini, Imran Raghib, Lorenzo Sestini, Davide Zuliani
Quantum Physics
A theoretical study of subcarrier-wave quantum key distribution system integration with an optical transport network utilizing dense wavelength division multiplexing
Fedor Kiselev, Natalia Veselkova, Roman Goncharov et al. (+1 more)
In this paper we study the performance of subcarrier-wave
quantum key distribution (SCW QKD) in the presence of classical channels of optical transport network utilizing dense wavelength division multiplexing (DWDM). We consider the impact of spontaneous Raman scattering noise as well as the four-wave mixing and channel isolation efficiency. We calculate
quantum bit error rate as well as the secure key generation rate of SCW-QKD protocol for different parameters of DWDM system and
quantum channel allocations. Our calculations show, that
quantum channel allocation at the wavelength of 1310 nm is preferable to allocation at C-band due to lower nonlinear noise, despite fiber's larger attenuation at this wavelength.
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All authors Fedor Kiselev, Natalia Veselkova, Roman Goncharov, Vladimir Egorov
Quantum Physics
Dynamics of entanglement in non-Hermitian system of nonreciprocal coupling
Jiguo Wu, Shaojie Yang, Xiong Liu et al. (+3 more)
The exploration of the effect of non-Hermitian (NH) in
quantum systems is gaining renewed momentum as a result of the recent progress in experiments. It has been indicated that the ability to engineer the orders of exceptional points (EPs) can be fundamental to its applications in
quantum control, such as accelerating
entanglement generation; however, an initial survey of the interactions between different orders of EPs is still missing. In this work, we try to partially address this issue by employing a non-reciprocally coupled cavity system which can be experimentally realizable with a two-dimensional reconfigurable NH gauged
laser array. With deliberate design, our systems display both second and third orders of EPs. The sign of a novel, purely
quantum continuous
entanglement phase transition is observed, which reveals how multi-EP interactions alter
entanglement dynamics across different regimes while maintaining accelerated generation. Our findings reveil the genuinely
quantum NH physics of higher-order EPs, which has opened up a new avenue for future investigations of the higher-order degeneracy application and the dynamic phase transitions of
quantum systems.
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All authors Jiguo Wu, Shaojie Yang, Xiong Liu, Zhibo Jiang, Zhiyou Zhang, Rongchun Ge
Optics
BRAHMS: A cross-platform graphical toolkit for (3+1)D simulation of three-wave mixing in $\chi^{(2)}$ nonlinear media, with GPU and CPU backends
Alfredo Daniel Sanchez Rossi and Daniel Alejandro La Valle Huignard
We present BRAHMS, a cross-platform (Linux/Windows) graphical user interface, with GPU (CUDA) and CPU (OpenMP) backends, for the efficient and accurate simulation of three-wave mixing processes involving focused and pulsed Gaussian beams. The package solves the coupled $\chi^{(2)}$ nonlinear Schrödinger equations, including diffraction, dispersion, walk-off, and phase-mismatch effects simultaneously, in full (3+1)D. To our knowledge, this is the first open-source package that solves the complete second-order (three-wave-mixing) nonlinear-optics problem in (3+1)D while fully exploiting the parallel capabilities of modern GPUs, with an equivalent CPU backend available for users without GPU hardware. The GPU implementation is inherently scalable thanks to its Thrust-based design. The package provides a valuable tool for experimental design and for studying three-dimensional field propagation in nonlinear three-wave interactions, supporting applications such as second-harmonic generation (SHG), sum-frequency generation (SFG), and optical parametric generation (OPG). Its GUI requires no programming experience, so that users can readily set up simulations and interpret their results.
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Atmospheric and Oceanic Physics
GCMagicc v1: a fast generative emulator for multivariate climate-impact ensembles
Nicolai Meinshausen, Malte Meinshausen, Jared Lewis et al. (+6 more)
Projecting the impacts of
climate change requires large ensembles of
climate variables that match historical observations, align with the warming ranges assessed by the IPCC, and can efficiently run new future emissions scenarios, including the newest generation of
climate model scenarios (CMIP7) and pathways consistent with countries' Paris Agreement pledges. Generating such ensembles at the scale needed for impact studies is normally computationally prohibitive. We close this gap with GCMagicc, a hybrid model that pairs a simple physical
climate model with machine learning to generate ensembles of 10
climate variables at the resolution of full-scale Earth system models, without relying on GPU resources or retraining for new scenarios. Trained on 32 CMIP6 Earth system models and observational/reanalysis data, GCMagicc complements rather than replaces Earth system models. We apply it to a range of future pathways: the canonical SSP scenarios of the latest IPCC report (1.2-6.1{\deg}C warming, min-max across scenarios of 5-95 percentile ranges), current policies (2.3-4.0{\deg}C), national pledges under the Paris Agreement (1.5-3.3{\deg}C) and the CMIP7 range from the 'VL' to 'H' scenarios (1.2-4.2{\deg}C), releasing a large public
dataset. As an illustration, we perform an attribution analysis of the severe 2025 Iranian drought using GCMagicc ensembles, with three CMIP6 large ensembles for comparison, with and without anthropogenic forcings. The results suggest a strong anthropogenic signal: a median probability of drought at least as severe as observed of 29% with anthropogenic forcing, and zero under natural-forcing-only simulations. In the future, drought conditions are projected to materially worsen, amplifying the potential for agricultural and food security impacts and geopolitical conflicts that use water scarcity as a weapon. GCMagicc data is available at https://gcmagicc.org.
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All authors Nicolai Meinshausen, Malte Meinshausen, Jared Lewis, Zebedee Nicholls, Sarah Schöngart, Alister Self, Xinwei Shen, Karla Spiller, Elisabeth Vogel
Quantum Physics
Non-Markovian dynamics of a qubit on the zigzag edge of photonic graphene
Enrico Di Benedetto
We present an analytical study of the dynamics of a
qubit coupled to the zigzag edge of a photonic honeycomb
lattice. Leveraging a resolvent operator approach and exact
lattice Green's functions, we map the spectrum of
qubit-
photon bound states and complex poles to uncover the long-time scaling laws of the
qubit population. Unlike a
qubit coupled to the bulk of
graphene, the presence of a zero-energy flat band connecting the Dirac points suppresses long-time branch-cut-induced tails, instead driving damped Rabi oscillations. Potential experimental platforms are briefly discussed.
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High Energy Physics (Theory)
Scalar Casimir Effect on a Two-Dimensional Sphere with a Wu–Yang Magnetic Monopole
Jun-Cheng Zhang, Xiao-Yin Pan, Juhao Wu et al. (+1 more)
We investigate the Casimir effect of a complex scalar field on a two-dimensional sphere threaded by a fixed Wu–Yang
magnetic monopole at the center. In this background the charged scalar field is a section of a nontrivial complex line bundle over $S^2$, reflecting the monopole's nontrivial
topology. We solve the Klein–Gordon equation analytically and compute the Casimir energy using a generalized Abel–Plana formula for multivalued functions. We find that the monopole can reverse the sign of the Casimir pressure, turning an attractive force into a repulsive one when the monopole strength is sufficiently large. This behavior persists across a broad range of
curvature couplings and suggests that Wu–Yang monopoles may provide a source of repulsive
vacuum stress, with possible implications for gravitational and cosmological settings.
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All authors Jun-Cheng Zhang, Xiao-Yin Pan, Juhao Wu, Qing-hai Wang
Astrophysics of Galaxies
Series of core collapse numerical simulations (SOLANUM) I: Modelling the early and late infall in a sun-like protostar
D. Navarro-Almaida, B. Commerçon, U. Lebreuilly et al. (+5 more)
Magnetohydrodynamical simulations and interferometric observations toward young
stellar objects reveal the
accretion of gas that may alter the physical properties and chemical composition of protostellar disks. Our goal is to constrain the physical history and properties of late infalling gas, and assess its potential to change the physical and chemical properties of the disk. We carried out a core collapse simulation of 5 M$_{\odot}$ of gas endowed with tracer and sink particles during $\sim 3.6\times 10^{5}$ yr. We analyzed the properties of the rotationally supported disk, and the origin and physical history of the gas from which it is initially formed. We also selected the tracer particles that describe the late infall to analyze their origin and physical history, and compare them to the information obtained from the disk. The final mass of the sink reaches 1.02 M$_\odot$, while the mass of the disk stays fairly constant around 0.02 M$_\odot$. Throughout its
evolution, the disk radius increases up to $\sim 40$ au and its density is reduced by a factor of $\sim 8$. Filaments that channel gas from the envelope to the disk and sink appear as a result of the
magnetic interchange instability. Tracer particles can identify late infalling gas, whose physical properties resemble that of observed streamers and are only accreted in the final snapshots of the simulation. The origin and physical history of the late infalling gas are different from those of the gas that initially forms the disk. Core collapse simulations predict the appearance of filaments that connect the envelope to the disk. The late
accretion of gas through these channels has properties similar to those of streamers and brings gas to the disk with a different physical history that could translate into a different chemical composition.
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All authors D. Navarro-Almaida, B. Commerçon, U. Lebreuilly, P. Hennebelle, A. Ahmad, A. Fuente, P. Rivière-Marichalar, J. E. Pineda
Quantum Physics
Scaling-Enhanced Rapid Readout of a Qubit Ensemble Assisted by High-Frequency Detector Modes
Hiroki Nakabayashi and Yuichiro Matsuzaki
Quantum measurements of large
qubit ensembles are often performed indirectly by coupling the ensemble to a detector and subsequently measuring the detector. Despite the importance of rapid collective readout, it remains unclear what determines how the readout time scales with the number of
qubits $N$. Here, we first establish a
benchmark $N^{-1/2}$ for a broad class of detectors without ultraviolet high-frequency modes. We then show that the detector with unbounded high-frequency modes can surpass this
benchmark and yield a characteristic time scaling $N^{-1/(2-\nu)}$ for $0 < \nu < 2$, where $\nu$ characterizes the spectral structure of the detector. Our results establish high-frequency detector modes as a resource for achieving a scaling advantage in collective
quantum readout, with the detector spectrum directly controlling the scaling exponent of the readout time.
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General Relativity and Quantum Cosmology
Dynamical systems in quadratic teleparallel cosmology
Manuel Hohmann
We discuss the cosmological dynamics of general teleparallel quadratic
gravity. Using a suitable set of variables, we write the cosmological field equations as a homogeneous dynamical system. We find that this system generically features projective fixed points, where the dynamics can be solved analytically, and exhibits finite time singularities as well as an asymptotically vanishing cosmological expansion.
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Materials Science
A thermally grown SiO2 diffusion barrier enabling high-temperature investigation of Ag-Au-Pd-Pt thin films
Elaheh Akbarnejad, Aleksander Kostka, Advika Chesetti et al. (+6 more)
Combinatorial processing platforms (CPPs), integrating Si microtip arrays with combinatorial thin film synthesis and atom probe
tomography (APT), enable near-atomic-scale characterization of compositionally complex solid solutions (CCSSs) under diverse processing and reaction conditions, including oxidation, thermal phase stability and electrocatalytic reactions. Their application at elevated temperatures, however, can be limited when CCSS constituents such as Pd and Pt react with the Si support to form silicides. Although thermally grown SiO2 has proven effective as a
diffusion barrier between pure Pt and Si, its performance for multicomponent CCSS thin films is unclear. Here, using Ag-Au-Pd-Pt as a model system, we compare a 25 nm thermally grown SiO2 barrier with native Si
oxide during annealing using APT and transmission electron microscopy. Native Si
oxide prevents detectable interfacial reactions up to 300{\deg}C, but at 400{\deg}C Pd and Pt react with Si, causing silicide formation and substantial redistribution of the film constituents. At 600{\deg}C, extensive substrate reactions disrupt the CCSS film and produce a pronounced needle-shaped silicide morphology. In contrast, thermally grown SiO2 suppresses CCSS thin film-substrate reactions up to 600{\deg}C and retains the CCSS composition. The thermally grown SiO2 thus extends the applicable temperature range of Si-based CPPs to at least 600{\deg}C for near-atomic-scale characterization of CCSS thin films.
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All authors Elaheh Akbarnejad, Aleksander Kostka, Advika Chesetti, Alan Savan, Georg Fritz, Kamen Kozhuharov, Matthias Karl Klein, Yujiao Li, Alfred Ludwig
Atomic Physics
Nonlinear dynamics in an artificial feedback spin maser II: dependence on feedback configurations and time crystal effects
Lan Wu, Qingchang Li, Weiyu Wang et al. (+2 more)
Artificial feedback
spin masers exhibit rich nonlinear dynamics, yet a systematic framework for understanding and controlling their behaviors remains elusive. In this paper, we consider the polarity and
geometric configuration of the feedback field as important control parameters for studying the nonlinear dynamics of
spin masers. By cooperatively tuning the strength and phase delay of feedback field, we investigate the
spin dynamics at various configurations of the feedback field. Periodic, quasiperiodic and chaotic
spin oscillations are uncovered. Specifically, a unique
spin oscillation mode akin to the time
crystal effects emerges within a certain parameter regime. This work presents a different viewpoint understanding the nonlinear dynamics of
spin masers including the time
crystal.
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All authors Lan Wu, Qingchang Li, Weiyu Wang, Qianjin Ma, Guobin Liu
High Energy Astrophysical Phenomena
SN 2025fhm: A central-engine powered Ic-BL supernova associated with X-ray transient EP250304a
Cui-Ying Song, Nan Jiang, Xiaofeng Wang et al. (+32 more)
We present X-ray, optical, and
radio follow-up observations of EP250304a, an extragalactic fast X-ray transient (EFXT) discovered by the Einstein Probe. Its X-ray light curve exhibits two broad pulses with comparable peak fluxes within the first $\sim$1~ks, a feature rarely seen among low-luminosity gamma-ray bursts or EFXTs. Optical follow-up observations were carried out using the Korea Microlensing
Telescope Network, the Thai Robotic
Telescope, the Las Cumbres Observatory 1~m global network, the Gemini Multi-Object Spectrograph on Gemini south
telescope, and the Global
Supernova Network. The fast-cooling phase (within 3 days) of optical data can be well fitted by a shocked cocoon model. However, during the
supernova phase (SN 2025fhm, from 3 to 88 days), the late-time light curve cannot be explained solely by radioactive $^{56}$Ni decay, as demonstrated by a grid of simulations using the one-dimensional Lagrangian radiation hydrodynamics code SNEC, which reveals a significant energy excess at late epochs. To account for this excess, a central engine like a rapidly spinning, highly magnetized
neutron star is needed to provide additional energy injection. This model yields a best-fit
spin period of $\sim$12.60~ms and
magnetic field strength of $\sim 3.52\times10^{15} \rm G$, and it successfully explains both the late-time bolometric light curve and the early X-ray pulse structures. Our results indicate that EP250304a/SN 2025fhm is likely powered by a central magnetar rather than by radioactive decay alone, offering new insights into the energy budget and physical origin of EFXTs and their associated
supernovae.
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All authors Cui-Ying Song, Nan Jiang, Xiaofeng Wang, Yi-Han Iris Yin, Lingzhi Wang, Wenxiong Li, Shengyu Yan, Dae-Sik Moon, Tao An, Aleksandar Cikota, Samaporn Tinyanont, Liang-Duan Liu, Cui-Yuan Dai, Christopher D. Matzner, Bin-Bin Zhang, Lixin Yu, Qinyu Wu, Hong Soo Park, Sang Chul Kim, Youngdae Lee, Yu-Hao Zhang, Haowei Peng, Franz E. Bauer, Joseph R. Farah, Moira Andrews, Kathryn Wynn, Yuan Qi Ni, D. Andrew Howell, Curtis McCully, Ning-Chen Sun, Danfeng Xiang, Yuan Liu, Wenxin Wang, Yijia Zhang, Wei Chen