Chemical Physics
Computing Reaction and Activation Energies of Pericyclic Reactions using a Symmetry-Adapted VQE Algorithm
Maitreyee Sarkar, Manikandan Paranjothy and Atul Kumar
Pericyclic reactions provide stringent tests for
quantum simulations because their mechanisms are governed by orbital
symmetry and involve correlated transition states. In this work, we employ the variational
quantum eigensolver (VQE) combined with a previously established
symmetry-guided active-space selection protocol based on
symmetry-matched fractions (SMF-VQE) to simulate Diel-Alder and Alder-ene reactions in complex systems involving extended pi-conjugation and multiple bonding. Although absolute electronic energies obtained from the current protocol exhibit significant deviations from the values computed using CCSD method, the
symmetry-guided active spaces yield substantial cancellation of deviations in the energy differences. As a result, reaction energies are predicted with error (relative to CCSD) less than one kcal per mol, while activation energies are reproduced within about five to six kcal per mol. The
symmetry-guided protocol also reduces the large combinatorial space of active-space choices to a single
symmetry-consistent selection for each reaction.
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Adaptation and Self-Organizing Systems · Cross-listed from math.DS
Stochastic Non-Linear Influence in Synchronisation Dynamics
Hannah Gallant, Dale Roberts and Alexander Kalloniatis
We propose a mathematical model that represents the influence of an external actor (influencer) on a network of actors (influenced). The model is an adaptation of control systems within the family of formulations inspired by the Kuramoto Model of synchronisation. Capturing influence as a capacity to affect the character or behaviour of another, we study an external node's ability to influence the synchronisation of the Kuramoto system while its global behaviour is pulled to the external node's frequency and away from its natural mean frequency. In our work, stochastically generated dynamical weights assigned to the links between the network and the external influencer whereby links from one system to the other are assigned via one-sided heavy tail noise, generated by the Gamma distribution. We perform numerical experiments to examine transition points in the ability of the external node to alter the behaviour of the influenced network; either to disrupt synchronisation or to drive it to collective frequencies determined by the external node. We examine the dependence of transition points on the external node's frequency, where too ambitious a driving frequency fails to influence the system while retaining a synchronised state, and reducing achieves a state of synchronisation at a frequency shifted from the mean natural frequency. We also look at the analytic approximation for the system close to synchronisation and fragmentation to understand its behaviour around this limit.
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Statistical Mechanics
Residual Saturation under Pressure-Controlled Drainage
Fernando Alonso-Marroquin and Hans J. Herrmann
Here, pressure-controlled drainage is formulated as bond percolation with trapping on the pore-network graph, establishing a direct connection between percolation theory and pressure–saturation relations. In two dimensions, the deviation of the residual saturation from its non-vanishing thermodynamic limit obeys a finite-size scaling law with exponent $\delta \approx 0.25$, independent of microscopic details of the
lattice. In three dimensions, finite-size corrections decay more rapidly ($\delta \approx 0.75$), while the asymptotic residual saturation remains finite and depends on coordination number. This extends the standard invasion-percolation picture beyond the breakthrough state, where the invading cluster is fractal and the invaded-phase saturation vanishes in the infinite-size limit.
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High Energy Physics (Theory)
Quantum gravity around ultracold black holes from DSSYK
Francesca Mariani, Thomas G. Mertens, Jacopo Papalini et al. (+1 more)
We propose a
quantum description of the ultracold Reissner-Nordström de Sitter black hole via a specific flat space limit of the double-scaled SYK model. Fluctuations in this regime reduce to flat JT
gravity, which is ill-behaved as a
quantum system. We show that including the first subleading correction to the dilaton potential breaks the leading order Hagedorn degeneracy but does not resolve the structural problem. Finally, we leverage the gauged description of the sine dilaton
gravity model to propose a novel quantization of the near-horizon dynamics of ultracold black holes. This leads to a new proposal for the partition function where states in the asymptotics of the spectrum are suppressed dynamically, and features of a discretized spacetime arise. We obtain a non-perturbative low temperature behavior of the partition function, which is quite different than the cold and Nariai physics. Our result can be interpreted as a dynamical way to enforce
cosmic censorship on the
quantum system.
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All authors Francesca Mariani, Thomas G. Mertens, Jacopo Papalini, Thomas Tappeiner
Materials Science
Atomic Scale Ordering of Sulfur Vacancies Enhances Charge Transport in Monolayer MoS$_2$
Alessandro Pecchia, Andrea Lorenzoni, Alexander Croy et al. (+2 more)
Defect engineering in two-dimensional
semiconductors has primarily focused on controlling the nature and concentration of atomic defects. Here, we show that the spatial arrangement of defects can be equally decisive in determining electronic transport. Using sulfur vacancies in monolayer MoS$_2$ as a model system, we investigate the impact of vacancy ordering through density functional theory, density functional tight-binding calculations, and
quantum transport simulations. We demonstrate that a periodic vacancy arrangement at a concentration of 11.1% transforms isolated defect states into a narrow dispersive in-gap miniband, whereas randomly distributed vacancies generate only localized electronic states. This electronic transition fundamentally alters charge transport, enabling band-like propagation through the defect network rather than transport limited by disconnected localized states. A systematic analysis of the complete
symmetry-reduced ensemble of 94 non-adjacent four-vacancy configurations shows that the ordered pattern lies within a broad low-energy
manifold and is not energetically anomalous, although it is not the thermodynamic ground state. Device-level simulations of Au/MoS$_2$/Au junctions reveal efficient
alignment of the metal
Fermi level with vacancy-derived states, promoting charge injection into the defect miniband. As a result, ordered vacancy arrays exhibit electrical currents up to five orders of magnitude higher than statistically equivalent random distributions and can approach, or locally exceed, the transport performance of pristine MoS$_2$. These findings establish atomic-scale defect ordering as a powerful design principle for two-dimensional materials, demonstrating that the organization of defects, beyond their concentration alone, provides a route to simultaneously preserve functionality and high electrical conductivity in highly defective
semiconductors.
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All authors Alessandro Pecchia, Andrea Lorenzoni, Alexander Croy, Francesco Mercuri, Massimiliano Cavallini
Instrumentation and Methods for Astrophysics
Swept-source heterodyne detection for interferometry in the H band
Félix Gudin and Nicolas Forget
It is well established that direct-detection interferometry outperforms heterodyne interferometry in terms of signal-to-noise ratio at optical wavelengths, not only because of the limited electronic bandwidth of photodetectors (typically <100 GHz), but also due to the shot-noise contribution of the optical local oscillator. The large-scale production of high-quality and cost-effective telecom components in the J+H band, and more recently in the K band, may open new schemes for the heterodyne signal detection and processing (e.g. correlation) as well as for the transport, distribution and control of the local oscillator. We describe how high-repetition-rate frequency-swept sources and telecom components could be exploited to parallelize, at reasonable cost, a large number of coherent detectors to expand the spectral coverage. We also present a first laboratory single-channel proof of concept that achieves a signal-to-noise ratio (SNR) probably sufficient for observing the brightest
stars in the H band with
telescopes of ~1 m2 at short integration time (<100 ms).
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Materials Science
Performance Analysis of Double Perovskite-Based Solar Cells Using SCAPS-1D Simulation: A brief review
H. Laltlanmawii, Lalrem Kima, Mahabur Rahman et al. (+7 more)
Lead-free double perovskites are among the rapidly developing next-generation
solar cell technologies, providing the required low toxicity, stability, as well as high optoelectronic potential. So far, experimentally prepared lead-free perovskite
solar cell devices are reported to have low power conversion efficiency (PCE) for practical application as compared to the lead-based perovskites. In recent years, numerical simulations have emerged as a cost-effective approach that plays a crucial role in expediting scientific research, can bridge the gap between experiment and theory, and provide predictive information regarding the preparation of
solar cells and their PCEs without undergoing real-time experiments. The tools, such as 1D numerical simulation software SCAPS-1D, are now needed to test newer architectures and determine what exactly is holding them back. So far in the field of
solar cell research, SCAPS-1D has been extensively used and looks like a powerful software due to its user-friendliness and simulation of results in a few seconds. The speed and ease of simulation make SCAPS-1D a very popular tool; as a result, it enables rapid optimization of a large number of photovoltaic devices and their performances without undergoing any experimental work, which can save time and money. However, one serious drawback is that the SCAPS-1D simulator works only for 1D configurations. It is ineffective in incorporating atomistic interactions and 3D effects. Hence, the efficacy of the SCAPS-1D simulator solely relies on the accuracy of the input parameters that the user provides, failing which may give wrong results and large deviations from accuracy.
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All authors H. Laltlanmawii, Lalrem Kima, Mahabur Rahman, Md. Ferdous Rahman, Dilshod Nematov, S. Bhattarai, C. V. M. Chaturvedi, Yazen M. Alawaideh, A. Laref, D. P. Rai
Instrumentation and Methods for Astrophysics
Demonstration of a Single-Laser-Diode-Pumped Ti:Sapphire Astrocomb on the Southern African Large Telescope
Ewan Allan, Yuk Shan Cheng, Kamalesh Dadi et al. (+13 more)
Astrocombs – broadband
lasers comprising thousands of narrow, uniformly spaced and atomically-referenced spectral lines – offer gold-standard wavelength calibration for ground-based optical
telescopes, with the potential for the cm/s precision needed for radial-velocity follow-ups of
exoplanet candidates from photometric space missions like Kepler, TESS and PLATO. Current astrocombs, particularly those operating in the visible spectrum, are complex and expensive, putting them beyond the reach of many observatories. Here, we present the first on-instrument demonstration of a new and simple astrocomb concept, providing calibration light across nearly the entire 550 nm to 890 nm red channel of the Southern African Large
Telescope's High Resolution Spectrograph (SALT-HRS). An octave-spanning supercontinuum generated in a silicon nitride waveguide by a GPS-referenced diode-pumped Ti:sapphire
laser is filtered to 21 GHz before fibre delivery to the spectrograph. Using the astrocomb, we obtain the wavelength solution for one order of SALT-HRS and the wavelength-dependent line-spread function of the instrument. With potential for further extension into the blue spectral region, this uniquely simple architecture brings visible-to-infrared astrocomb technology within the reach of a wider range of astronomical observatories.
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All authors Ewan Allan, Yuk Shan Cheng, Kamalesh Dadi, Pablo Castro-Marin, Jake M. Charsley, William Newman, Abdullah Alabbadi, Hanna Ostapenko, Richard A. McCracken, Pascal Del'Haye, Thomas Willemsen, Tobias Gross, Daniel L. Holdsworth, Malcolm C. Scarrott, Lisa A. Crause, Derryck T. Reid
Statistical Mechanics
An improved car-oriented mean-field theory for stochastic traffic flow models
Yasar Efe Dai, Andreas Schadschneider and Michael Schreckenberg
We propose an improved mean-field analysis of cellular automata models of single-lane vehicular traffic. By combining aspects of the Car-Oriented-Mean-Field (COMF) theory and the 2-site cluster method, which have been previously successfully applied to similar models, we aim to capture both short- and long-range correlations more accurately. In contrast to classical mean-field theories, the improved method is well suited for models with inhomogeneous stationary states and able to capture the essential properties of phase separation, e.g. in models with slow-to-start rules. The improved accuracy and new physical insights are illustrated through an application to the VDR model with $v_{\text{max}}=1$.
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Mathematical Physics · Cross-listed from math.PR
A new look at some aspects of one-dimensional random sequential adsorption and its continuum limit
Ross G. Pinsky
Fix a positive integer $k\ge2$, and for $n\ge k$, consider a row of $n$ molecules. From among the $n-k+1$ nearest-neighbor $k$-tuples of molecules, select one uniformly at random and bond the $k$ molecules. Now, from all the remaining nearest-neighbor $k$-tuples, again select one uniformly at random and bond the $k$ molecules. Continue like this until there are no nearest-neighbor $k$-tuples left. Let $M^{(n)}_k$ denote the expected value of the number of bonded molecules. An explicit integral formula for $m_k:=\lim_{n\to\infty}\frac{M^{(n)}_k}n$ is known, and an explicit formula for $m_\infty:=\lim_{k\to\infty}m_k$ is known. The constant $m_\infty$, known as the Rényi parking constant, arises as the limiting packing density for a continuous analog of the above discrete packing problems. These are all models of what is called random sequential adsorption (RSA). The first part of this paper studies the gaps of sizes $0,1,\cdots, k-1$ that arise between bonded $k$-tuples and shows that after scaling the $k$-grid, when $k\to\infty$ the empirical distribution of expected gaps in the discrete problem on the
lattice converges weakly to an appropriate gap distribution that is known to hold for the above noted continuous analog. The second part of the this paper considers two different models of the discrete bonding problem when both $k_1$-bonding and $k_2$-bonding occur, with $2\le k_1<k_2$. Explicit formulas are obtained for the analogs of $m_k$, and the asymptotic behavior of these analogs is studied both when $k_2\to\infty$ with $k_1$ fixed, and when $k_1,k_2\to\infty$ at certain ratios.
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Fluid Dynamics
A hybrid proper orthogonal decomposition and diffusion framework for reduced-order forecasting of turbulent flow dynamics
Rodrigo Abadia-Heredia, Xiangrui Zou, Manuel Lopez-Martin et al. (+2 more)
Forecasting turbulent flow dynamics requires a balance between predictive fidelity and computational efficiency.
Diffusion-based generative models can represent complex spatiotemporal dynamics, but their application to high-dimensional turbulent flows remains computationally expensive. In contrast, proper orthogonal decomposition (POD) provides compact, physically interpretable reduced-order representations, although aggressive modal truncation can remove relevant flow structures. This work introduces a hybrid reduced-order generative
forecasting framework that combines POD with Generative Learning of Effective Dynamics (G-LED). The method performs temporal prediction in a physics-based modal space and uses
diffusion-based reconstruction to recover physically meaningful flow-field representations. It is assessed using experimental measurements of the turbulent wake behind a circular cylinder. Three configurations are compared: full-field G-LED, global POD-G-LED, and localized POD-G-LED. Full-field G-LED provides the highest fidelity, preserving richer vorticity fluctuations and more consistent turbulent kinetic energy distributions, but requires approximately 17 h for
diffusion-model training, 7 h for
Transformer training, and 3 min to predict 100 future snapshots. By transferring prediction to a reduced POD space, global POD-G-LED reduces these costs to approximately 8 h, 2 h, and 50 s, respectively, while retaining dominant wake organization and coherent energetic structures. A localized POD-G-LED formulation assigns different modal resolutions to distinct wake regions and improves vorticity statistics and energetic distributions relative to the global reduced-order configuration. These results show that coupling physics-based modal representations with
diffusion-based generative reconstruction offers an effective route to efficient turbulent-flow
forecasting.
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All authors Rodrigo Abadia-Heredia, Xiangrui Zou, Manuel Lopez-Martin, Petros Koumoutsakos, Soledad Le Clainche
Materials Science
Nanomechanics of MXene flakes at gold interfaces
Pierluigi Bilotto, Sabine Schwarz, Marko Piljevic et al. (+3 more)
The demand for novel self-powering and sustainable electronics requires major efforts in identifying new advanced materials for nano-applications. MXene have gathered
attention due to their electronic and mechanical properties, however, their nanomechanical compliance against a metal-like interface is still not clearly identified. In this work, we employ atomic force microscopy to characterize the nanomechanical properties of a self-assembled thin flake of titanium carbide MXene (Ti3C2Tx) against a gold probe. The investigation returns an interfacial shear stress of 399 MPa, and the observation of nano-wear localized in the center of the MXene flake. Nevertheless, MXene flakes retained their crystallinity in the tribofilms as confirmed by transmission electron microscopy and electron energy loss spectroscopy. The outcomes of this work set the basis for the use of Ti3C2Tx in novel nano harvesting systems involving metal interfaces (e.g., tribovoltaic nanogenerators) with large scope in nanoelectronics, wearable sensing, electric vehicles, and robotics.
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All authors Pierluigi Bilotto, Sabine Schwarz, Marko Piljevic, Iago Peters, Michael Stöger-Pollach, Carsten Gachot
General Relativity and Quantum Cosmology · Cross-listed from math.DG
Ideal points, directed completion and the case of the maximally extended Schwarzschild spacetime
Nicola Gigli, Argam Ohanyan, Marco Picerni et al. (+2 more)
We study the directed completion of Lorentzian pre-length spaces, and we show that, under some natural assumptions which cover the case of smooth globally
hyperbolic spacetimes, it coincides with the future causal completion of Geroch–Kronheimer–Penrose. Moreover, we provide applications of our findings by characterizing the directed completion of the Kruskal–Szekeres spacetime in terms of its radial null geodesics.
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All authors Nicola Gigli, Argam Ohanyan, Marco Picerni, Zhe-Feng Xu, Matteo Zanardini
High Energy Physics (Theory)
Quantization of Algebraic Varieties Defined by Casimir Polynomials via Matrix Regularization: Fuzzy $S^7$ and Beyond
Akifumi Sako
We study the quantization of algebraic varieties defined by equations involving Casimir
polynomials of compact semisimple Lie
algebras. The Casimir
polynomials belong to the Poisson center of the corresponding Lie-Poisson
algebra. For this purpose, we employ a recently developed
matrix regularization of Lie-Poisson
algebras. In particular, using its formulation based on reducible representations, we construct quantizations of these algebraic varieties through their decomposition into coadjoint orbits, including singular orbits. As a concrete example, we present the construction of fuzzy $S^7$ in detail.
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Chemical Physics
Rotational-state-controlled dissociative ionization dynamics in $\mathrm{CF_2I_2}$
Nidin Vadassery, Ivo S. Vinklárek, Sebastian Trippel et al. (+1 more)
We investigated strong-field dissociative ionization of $\mathrm{CF_2I_2}$ ensembles prepared in different initial rotational-state distributions using an electrostatic deflector. Pronounced changes in ion-channel branching ratios revealed a strong dependence of the fragmentation dynamics on the initial rotational excitation. Analysis of fragment yields and their
laser-power dependences identifies resonance-enhanced multiphoton ionization through an intermediate excited state, $\mathrm{CF_2I_2^{\ast}}$. The measured branching behavior indicates competition between stabilization into bound ionic states and dissociative channels, driven by near-threshold non-adiabatic Coriolis-type coupling. Tuning the rotational energy by only a few $\mu$eV is sufficient to significantly alter the ionization dynamics and to redistribute the reaction products. These findings demonstrate the key role of rotational excitation in controlling non-adiabatic dynamics following strong-field ionization of $\mathrm{CF_2I_2}$.
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All authors Nidin Vadassery, Ivo S. Vinklárek, Sebastian Trippel, Jochen Küpper
Solar and Stellar Astrophysics
Characterization of the variability of the blue supergiant HD 14134
Suryani Guha, Michaela Kraus, Julieta P. Sanchez Arias et al. (+2 more)
The post-main sequence (MS)
evolution of massive
stars encompasses phases in which the
stars display high variability. One such class of objects are the blue supergiants which may be in either the pre- or post-red supergiant phase of their
evolution. Their variability patterns might provide constraints for a proper classification of the objects. We aim to characterise the observed variability of the B supergiant HD14134 and to investigate the imprint of a time-variable wind on the brightness variation of the
star and its impact on the detectability of pulsation signals. Spectroscopic data were collected over a 5-month period and combined with photometry from TESS.
Stellar parameters were derived from modelling of the time-averaged spectrum with CMFGEN and the SED and were confirmed with
stellar evolution models computed with MESA. The light curves and radial velocity curves of selected lines were analysed to determine pulsation signals. The wind variability and its imprint on the
stellar brightness were investigated from an analysis of the Halpha line. Predictions of mode excitations were computed with the GYRE pulsation code and compared to the frequencies determined from the observations. A g-mode with a period of ~19.2 d and its harmonics are consistently detected in all data sets. The spectra unveil strong, non-periodic wind variability and 3 frequency signals were identified as due to this wind variability. The
stellar parameters and age derived for HD14134 together with the absence of radial pulsations classify the
star as a post-MS object evolving towards the red-supergiant stage, questioning its classification as alpha Cyg variable. The results reinforce that simultaneous long-term spectroscopic and photometric monitoring is indispensable for reliable frequency detections and for disentangling of variabilities imprinted by a time-variable wind from those imposed by pulsations.
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All authors Suryani Guha, Michaela Kraus, Julieta P. Sanchez Arias, Peter Nemeth, Krzysztof Kaminski
Optics
Freeform super-oscillatory optics for CMOS-integrated THz super-resolution imaging
Jin Chen, Liang Gao, Hao Guo et al. (+5 more)
The diffraction limit fundamentally constrains the spatial resolution of far-field imaging systems. While near-field techniques can circumvent this limit, their inherently short working distances (WD) severely restrict practical applications. Super-oscillatory lenses (SOLs) offer a far-field alternative; however, conventional SOLs are plagued by discrete operating wavelengths, low efficiencies (below 5%), and formidable trade-offs among numerical aperture, chromatic aberration, and depth of focus (DOF). Here, we introduce a nonlocal, nonlinear-
curvature mechanism to design a freeform SOL that achieves ultrabroadband (0.3 to 1 THz), achromatic super-resolution focusing with an unprecedented efficiency of 44%. Operating at a 9 mm WD, the lens maintains a consistent sub-diffraction full-width at half-maximum (FWHM) of around 0.45 wavelength alongside an extended DOF of around 10 wavelengths. By integrating a compact 65-nm CMOS oscillator-radiator array, we establish an advanced imaging platform capable of resolving complex 2D and 3D sub-millimeter features (down to 0.15 mm). Readily scalable to the optical regime via two-
photon lithography, this freeform SOL paradigm paves the way for next-generation, high-performance integrated photonics.
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All authors Jin Chen, Liang Gao, Hao Guo, Zhi Chao Chen, Kang Jie Lin, Kam Man Shum, Ka Fai Chan, Chi Hou Chan
High Energy Physics (Theory)
Corrections to the Unruh Effect from Robin Boundary Conditions in Punctured Minkowski Spacetime
Nickolas P. Botta, João Paulo M. Pitelli and Ricardo A. Mosna
We consider a real massless scalar field in punctured Minkowski spacetime, endowed at the removed origin with the stable one-parameter family of Robin boundary conditions $G(0)-\beta G'(0)=0$, $\beta\geq0$. We obtain the boundary-induced part of the static ground-state Wightman function in closed form and study the response of a uniformly accelerated Unruh-DeWitt detector. The puncture breaks the boost
symmetry underlying the stationary Unruh response, so the boundary-induced pullback is nonstationary in proper time. The corresponding subtracted detector contribution can either enhance or suppress the ordinary Minkowski response and depends on the Robin parameter, the detector gap, and the portion of the trajectory sampled. For the unshifted, radially aligned trajectory studied in detail, we prove that the boundary-induced pullback is absolutely integrable in the two proper-time variables. Consequently, as the smooth interaction is extended over the full detector history, this contribution approaches a finite limit and remains $O(1)$, producing no additional term linear in the interaction duration. The formal Neumann limit is singular: the boundary-induced two-point function grows logarithmically because of an infrared singularity in the $s$-wave sector, and the numerical response exhibits growth consistent with this asymptotic behavior.
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Accelerator Physics
Laser-Plasma Accelerator Beams in Light Sources: Femtosecond High-Brightness Radiation through Chirped Pulse Injection
Sergey A. Antipov, Philipp Burghart, Ilya Agapov et al. (+2 more)
We propose a chirped-pulse injection scheme into a hard x-ray low-emittance synchrotron light source such as PETRA IV from a
laser-
plasma electron injector with active energy compression. The scheme enables delivering kA-scale short pulses with several tens of hertz repetition rate to any synchrotron beamline in the ring and allows producing femtosecond temporally coherent radiation pulses at target beamlines.
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All authors Sergey A. Antipov, Philipp Burghart, Ilya Agapov, Alberto Martinez de la Ossa, Wim Leemans
Quantum Physics
Single-eigenstate test of eigenstate thermalization hypothesis via perturbed eigenstate quench
Zhouhao Guo and Jiaju Zhang
We propose and numerically validate an efficient single-eigenstate diagnostic for the eigenstate thermalization hypothesis (ETH) based on a perturbed eigenstate quench protocol. By introducing a weak random perturbation to an energy eigenstate to break its stationarity, we characterize the time-averaged subsystem
evolution speed as a function of the subsystem-to-total system size ratio. The diagnostic relies on a robust qualitative distinction: eigenstates satisfying ETH exhibit an S-shaped curve with a clear inflection point near half the system size, while ETH-violating eigenstates display a convex J-shaped profile. We
benchmark the criterion across paradigmatic one-dimensional
spin chains covering chaotic, integrable, many-body localized, and
quantum many-body scar regimes, obtaining full agreement with established thermalization phenomenology. Our method circumvents the need for explicit thermal ensemble construction, providing a robust, experimentally feasible probe of eigenstate thermalization at the single-eigenstate level.
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Cosmology and Nongalactic Astrophysics
Fractal properties of the cosmic web
Jaan Einasto
The
cosmic web is one of the most complex systems in nature, consisting of
galaxies and clusters of
galaxies connected by filaments and walls, and separated by large empty regions known as
cosmic voids. The most common method for describing the web is the correlation function and its derivative, the structure function and fractal dimension function. In this paper I review the fractal properties of the
cosmic web within the concordance {\Lambda}CDM framework. I describe how the fractal function is derived from the angular and spatial distributions of
galaxies and discuss the relations between these approaches.
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High Energy Physics (Phenomenology)
Improved covariant analysis of $B_c^+ \to \chi_{c1}(nP)$ decays and implications for the nature of $\chi_{c1}(3872)$
Shi-Hang Zhang, Jia-Yi Zheng, Wei Li et al. (+5 more)
We study the weak decays $B_c^+\to\chi_{c1}(nP)\ell^+ \nu_{\ell}$ and $B_c^+\to\chi_{c1}(nP)X$ (n=1,2,3) within the Bethe-Salpeter formalism, treating $\chi_{c1}(3872)$ as the conventional $\chi_{c1}(2P)$ charmonium. We upgrade the covariant hadronic transition amplitude to consistently evaluate the final-state wave function in its rest frame, enabling a reliable description of large-
recoil processes and sizable relativistic corrections pertinent to highly excited charmonium. Our results provide a novel platform to probe the internal structure of $\chi_{c1}(3872)$ via $B_c$ decays. While the LHCb search for $B_c^+\to\chi_{c1}(3872)\pi^+$ yielded only an upper limit, we demonstrate that this is primarily due to insufficient luminosity, approximately 20 times the current $B_c$ data sample would be required for a definitive observation. In contrast, we identify the semileptonic mode $B_c^+\to\chi_{c1}(3872)\mu^+\nu_{\mu}$ as a far more promising channel, which could become accessible with merely twice the existing data set. Our predictions offer concrete guidance for upcoming LHCb analyses and complement ongoing efforts to resolve the nature of $\chi_{c1}(3872)$.
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All authors Shi-Hang Zhang, Jia-Yi Zheng, Wei Li, Su-Yan Pei, Tianhong Wang, Zhi-Hui Wang, Chao-Hsi Chang, Guo-Li Wang
Materials Science
Raman Signatures of Lithium Ion Dynamics in LLZO Garnet Electrolytes: Atomistic Insights from MD-Raman Calculations
Takeru Miyagawa, Willis O'Leary, Manuel Grumet et al. (+4 more)
Lithium lanthanum zirconate (LLZO) garnets are among the most promising solid electrolytes for next-generation batteries owing to their high ionic conductivity, chemical stability, and compatibility with lithium metal. Raman spectroscopy is commonly employed to distinguish the highly conductive cubic phase from the poorly conductive tetragonal phase of LLZO, yet the atomistic origin of these spectral differences and their direct connection to Li-ion transport remain unresolved. Here, we close this gap by comparing computed and experimental Raman spectra for the tetragonal, cubic, and Ta-doped variants of LLZO, with the computed spectra obtained from the MD-Raman approach that combines machine-learning molecular dynamics with first-principles polarizability calculations. We show that the contrasting ionic transport behavior across these LLZO variants is encoded in the vibrational dynamics of the lithium sublattice and gives rise to distinct features in their Raman spectra. A
symmetry-resolved analysis further reveals that experimentally observed Raman peaks do not correspond to individual normal modes, but instead arise from overlapping contributions of multiple
symmetry channels, challenging conventional peak-assignment approaches. By explicitly connecting experimentally accessible Raman signatures to the underlying atomic-scale dynamics, our results show how Raman spectroscopy can move beyond empirical phase identification toward a microscopic probe of Li-ion dynamics in lithium garnet electrolytes.
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All authors Takeru Miyagawa, Willis O'Leary, Manuel Grumet, Hyunwon Chu, Jennifer L.M. Rupp, Waldemar Kaiser, David A. Egger
Fluid Dynamics
Free-surface curvature and its relation to subsurface turbulence
Daniel J. Ruth and Filippo Coletti
The free surface atop a turbulent
liquid flow is deformed by the underlying fluid motion, with the
turbulence imprinting its geometry on the surface. Here we develop a theoretical framework to model such deformations based on the Euler equation with
gravity and surface tension, and evaluate it against simultaneous high-resolution measurements of surface topography and subsurface velocity fields in a zero-mean-flow turbulent water tank. We consider a range of Reynolds and Froude numbers, focusing on regimes in which the surface is unbroken. Over a range of spatial and temporal scales, we find close quantitative agreement between the measured surface
curvature and that which is modeled based on the velocity field a few millimeters beneath the surface, both from the statistical and the local/instantaneous standpoints. Importantly, we verify a strong correlation between the magnitudes of the surface
curvature and the divergence of the near-surface horizontal velocity, which in turn is directly related to gas and heat transfer at the air-water interface. We discuss how the sub-surface motion at increasing depths decorrelates from the surface shape, and does so more rapidly at smaller spatial scales. These findings demonstrate that measurements of surface deformations may be used to sense the state of the flow beneath the surface and provide a foundation to make optically-based inferences of processes controlled by near-surface
turbulence.
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Quantum Physics
Quantum SWITCH-induced non-Markovianity is not entirely quantum
Rajeev Gangwar and Ananda G. Maity
Indefinite causal order extends
quantum information processing beyond fixed causal structures, with the
quantum SWITCH serving as its canonical realization. By coherently superposing different orders of
quantum channels, the
quantum SWITCH has been shown to provide operational advantages in communication, computation, metrology, and related tasks. Despite these advances, the physical resources responsible for these advantages remains unclear. Recent studies have further revealed that the
quantum SWITCH can generate
memory effects, manifested as non-Markovian information backflow. In this work, we examine the origin of such
memory and determine whether they reflect genuine (
quantum) non-Markovianity or instead arises from classical origin. To this end, we analyze two representative scenarios: one based on discrete-time
evolution and another formulated through dynamical maps in open
quantum systems. We show that the
memory effects generated by the
quantum SWITCH are not genuinely
quantum non-Markovian, thereby prompting a re-examination of the source of
quantum advantage in indefinite causal order frameworks.
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Quantum Physics
Spectral evolution of two-photon emission in microresonators
Francesca Famà, Stefano Dello Russo, Stefano Giaccari et al. (+14 more)
High-Q silicon nitride microresonators are versatile sources for generating
photon pairs via four-wave mixing. We investigate the spectral coherence of this process, tracking the transition from the spontaneous
quantum regime to the onset of optical parametric oscillation. By combining time-correlation measurements with phase-sensitive measurements, we continuously monitor the emission linewidth as it evolves from a cavity-lifetime-limited linewidth toward the pump-linewidth scale. This characterization is essential for optimizing integrated sources for scalable
quantum networks.
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All authors Francesca Famà, Stefano Dello Russo, Stefano Giaccari, Salvatore Virzì, Lorenzo Lucia, Cecilia Clivati, Chiara Gionco, Mario Siciliani de Cumis, Stefano Condio, Erik Cerrato, Gianluca Bertaina, Alice Meda, Marco Gramegna, Marco Genovese, Filippo Levi, Ivo Pietro Degiovanni, Davide Calonico
Atomic Physics
Field Deviations in Dipole-Driven Linear Paul Traps: Effects of Endcap Boundaries and their Minimization
Vaibhav Mahendrakar, Nishant Joshi and S. A. Rangwala
Deviations from both the ideal linear Paul trap (LPT) geometry as well as the ideal quadrupole driving scheme introduce imperfections to ion trapping potentials. We investigate the effects of these imperfections in a LPT operated in a conventional dipole-drive configuration. We demonstrate the trapping of the Li$^+$ ions along the axial direction with zero and negative end-cap voltages. This occurs due to the modified axial $a-q$ space resulting from radial-to-axial coupling of the electric field. The dipole drive configuration lifts the degeneracy of the radial trapping potentials, resulting in unequal radial secular frequencies, and this is demonstrated experimentally. The combined effects of dipole drive and trap dimensions are summarized in a two-dimensional map that quantifies deviations from ideal behaviour. Based on this map, we propose a
geometric modification that significantly reduces radial-to-axial coupling of the potential.
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Instrumentation and Detectors
MOTION, a liquid xenon time projection chamber platform for high voltage technologies in dark matter detectors
Yanina Biondi, Alexander Jansen, Keyu Ding et al. (+3 more)
The XLZD observatory is a next-generation experiment designed to search for weakly interacting massive particles (WIMPs) and other rare events using a 60-80 tonne
liquid xenon time projection chamber (TPC). This detector aims to achieve sensitivity across the full WIMP parameter space down to the
neutrino fog, establishing the ultimate sensitivity for this dark matter search paradigm. This unprecedented scale introduces substantial engineering challenges and pushes operation into largely unexplored regimes: the interplay between high-voltage (HV) systems,
liquid xenon, and conducting materials in ultra-pure environments. To systematically investigate these challenges, we have built MOTION, a 70 kg LXe detector dedicated to understanding HV performance and electrostatic phenomena up to 200 kV (negative polarity). We describe the design and construction of the experimental infrastructure, including the cryogenic system, xenon purification and storage. MOTION enables controlled studies of dielectric breakdown in LXe, permitting systematic characterization of discharge mechanisms and their dependence on electrode geometry, surface condition, and applied voltage. The detector also facilitates investigations of field emission and photoemission from electrodes following various surface treatments, and provides a platform for validating the design of an HV feedthrough constructed from radiopure materials. The insights from these studies are essential for ensuring the operational stability, radiopurity, and scalability required for next-generation dark matter detectors.
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All authors Yanina Biondi, Alexander Jansen, Keyu Ding, Michael Schrank, Tom Sonius, Adrian Schwenck
Quantum Physics
Effect of Cross-Spectral Correlations on Qubit Dynamics: Coherence Revival and Relaxation Modulation
Siddhartha Dutta, Sujay Mondal and Abhijit Bandyopadhyay
We investigate the reduced dynamics of a
qubit subject to correlated longitudinal and transverse noise arising from its coupling to a shared bosonic bath. The environmental fluctuations are characterized by a positive-semidefinite
matrix-valued spectral density, whose complex off-diagonal elements encode correlations between dephasing and relaxation channels in the frequency domain. Within the second-order time-convolutionless framework, we derive closed time-local equations for the Bloch-vector components of the reduced density
matrix. The numerical implementation is validated against the exact pure-dephasing solution and the established behavior of the transverse-coupling
spin-
boson model. When both noise channels are present, the cross-spectral terms couple the otherwise distinct dephasing and relaxation sectors, producing dynamics that cannot be reproduced by adding independent noise contributions. In particular, the correlations generate non-monotonic population relaxation and a transient revival of coherence following its initial decay. The strength, bandwidth, delay, and phase of the cross spectrum provide control parameters for the magnitude and temporal structure of these effects. Our results demonstrate that correlated multi-axis noise can redistribute coherence loss and energy relaxation in time, thereby providing finite temporal windows of enhanced coherence or suppressed relaxation within the weak-coupling regime.
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High Energy Physics (Theory)
Wavefunctions of AdS$_3$ Universes and $T\bar{T}$-deformed Torus Partition Functions
Shinji Hirano
We study wavefunctions of
quantum gravity in asymptotically AdS$_3$ spacetimes and their relation to $T\bar{T}$-deformed
torus partition functions. We show that the deformed partition function is given by an invertible integral transform of bulk wavefunctions, which implements a change of representation from the York time to its conjugate, the spatial volume. The invertibility of the transform allows the bulk wavefunction to be reconstructed from the family of $T\bar{T}$-deformed partition functions. A $T\bar{T}$-deformed partition function at fixed coupling is the amplitude of the bulk state in a finite-width, fixed-volume wavepacket localized at the asymptotic boundary in York time. In the CFT limit, the wavepacket localizes at the boundary, recovering the standard
holographic relation. The
holographic screen of a given state is the support of the integrand of the transform: at large central charge, it separates from the wavepacket and reproduces finite-cutoff holography for the sign of the coupling with complex energies, and glue-on holography for the opposite sign. In Euclidean signature, the construction arises naturally from wavefunctions of Rindler AdS$_3$, while after a double Wick rotation it admits a Lorentzian interpretation in terms of closed AdS$_3$
torus universes without asymptotic boundaries. We also discuss de Sitter
torus universes and generalizations to other spatial
topologies and higher dimensions.
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