Astrophysics of Galaxies
The physical and chemical structure of TMC-1. The spatial distribution and excitation conditions of carbon, oxygen, and sulfur bearing species: Depletion of CO and CS
J. Cernicharo, B. Tercero, N. Marcelino et al. (+3 more)
We present a detailed study of the physical and chemical structure of TMC-1 from the observed spatial distribution of HC3N, NNH+, CN, and their isotopologues, the O-bearing species C18O, C17O, CH3OH, CH3CHO, and H2CO, and the S-bearing species CS, HCS+, H2CS, and H2CCS. The well known filamentary structure of TMC-1 can be interpreted as a single cloud with a velocity gradient perpendicular to the filament, or less likely as due to the
alignment of three independent clouds in the line sight with velocities of 5.3-5.7, 5.7-5.9, and 5.9-6.3 km/s. The main contribution to the emission of all studied C-bearing species is found at 5.83 kms/s. We conclude that the three velocity components are dynamically connected and that C-bearing molecules show a different behavior of their abundances compared to O-bearing species, which have emission peaks at 5.7 and 6.25 km/s, and appear at different spatial locations than cyanopolyynes and CnH and CnN radicals. The detection of 13C18O, with exactly the same line profile than that of C18O and C17O, excludes the possibility that the decrease of their emission at 5.83 km/s, could be due to self absorption or absorption by a foreground cloud component. Hence, as indicated by the spatial distribution of C18O and C17O, CO is significantly depleted at the velocities and positions where the emission of the carbon chains and radicals is found. This suggests that the emission of O-bearing species is coming from the external layers of the carbon-rich filaments. A comparison between S-bearing species and other molecules indicates that CS, CCS, HCS+, and H2CS are significantly depleted in the zone of CO depletion. A clear increase of the deuteration of several molecular species is found in the zones where CO and CS are depleted.
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All authors J. Cernicharo, B. Tercero, N. Marcelino, G. Esplugues, G. Molpeceres, M. Agúndez
General Relativity and Quantum Cosmology
Quantum noise and torque correlations in a torsion-bar Sagnac speed meter
Yuki Inoue, Mario Onglao, Daiki Tanabe et al. (+3 more)
Quantum fluctuations entering through weakly transmitting mirrors can limit a torsion-bar Sagnac speed meter for low-frequency gravitational-wave detection, even when its optical layout suppresses radiation-pressure back action. We show that, in the Cryogenic sub-Hz cROss torsion bar detector with
quantum NOn-demolition Speed meter (CHRONOS),
vacuum fields entering from behind the end and middle test masses can dominate the low-frequency
quantum noise despite cancellation of the torques on opposite ends of each bar. For a reference configuration with mirror power transmissions of only $10^{-7}$, these fields contribute $89.7\%$ of the total
quantum-noise power spectral density at 0.1 Hz. Omitting them would underestimate the amplitude spectral density by a factor of 3.11. Our input-output model connects the correlations produced by successive optical interactions to the forces on each bar and the measured signal. This connection shows why strong torque cancellation does not, by itself, ensure a corresponding improvement in detector sensitivity. Replacing mirror transmission with absorption at fixed reflectivity leaves the excess
quantum noise essentially unchanged for the two operating points studied. The predicted signal response and
quantum noise agree with independent FINESSE 3 calculations as recycling detuning and homodyne angle are varied. These results establish rear
vacuum fields as a limiting noise source in this torsion-bar speed meter and provide quantitative requirements for its mirror and readout design.
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All authors Yuki Inoue, Mario Onglao, Daiki Tanabe, Masashi Hazumi, Vivek Kumar, Apimook Watcharangkool
Astrophysics of Galaxies
The Role of Environment in Shaping the Assembly Timelines of Massive Quiescent Galaxies at Cosmic Noon
Tianmu Gao, J. Trevor Mendel, Letizia Bugiani et al. (+10 more)
JWST observations of massive quiescent
galaxies (MQGs) at $z\sim2$ have revealed diverse
star formation histories (SFHs). In this letter, we investigate whether these variations are linked to the environment in which MQGs reside, as quantified by the host dark matter
halo mass. We identify 12 MQGs from a representative sample of
galaxies at $1.6<z<3.5$ obtained by the Blue Jay survey, a JWST Cycle 1 program, and infer their SFHs via modelling of the deep NIRSpec medium-resolution spectra along with multi-band photometry. By correlating the formation and quenching epochs of individual MQGs with their respective host
halo masses from the 3D-HST survey, we find that after accounting for the
redshift range of the sample ($1.8<z<2.5$), MQGs in more massive
haloes formed at significantly earlier
cosmic epochs. Meanwhile, although these
galaxies also quenched earlier overall, the scatter in quenching epochs across similar
halo masses indicates that the quenching process likely involves other contributing factors and is not solely determined by
halo mass.
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All authors Tianmu Gao, J. Trevor Mendel, Letizia Bugiani, Minjung Park, Sirio Belli, Joel Leja, Claudia del P. Lagos, Amir H. Khoram, Rebecca L. Davies, Razieh Emami, Gabriel Maheson, Anita Zanella, Benjamin P. Collins
Quantum Physics
Zongxing Xiong, Chengshen Gao and Lvzhou Li
Entropy estimation of discrete probability distributions is a fundamental problem in statistical inference and
quantum property estimation. In this paper, we study the problem of estimating Rényi
entropy $H_\alpha(\mathbf{p})$ for any distribution $\mathbf{p} = (p_i)_{i=1}^n$ given its purified
quantum query-access. For non-integer $\alpha > 1$, our
algorithm estimates $H_\alpha(\mathbf{p})$ to within additive error $\epsilon$ using only $\widetilde{\mathcal{O}}\big(n^{\max\{1/2,1-1/\alpha\}}/\epsilon\big)$ queries, which improves the best known upper bound for dependence on both $n$ and $1/\epsilon$. For $0<\alpha<1$, our
algorithm has query complexity $\widetilde{\mathcal{O}}\big(n^{1/(2\alpha)}/\epsilon^{\max\{1,1/(2\alpha)\}}\big)$, which improves the dependence on $1/\epsilon$ of the current best upper bound without incresing its $n$ dependence. Our approach adapts the multi-level estimation framework to relative approximation of the power sums and leverage binary search to remove the requirement of prior knowledge of them. We also strengthen the precision-dependent lower bound to $\Omega\big(1/\epsilon^{\max\{1,1/(2\alpha)\}}\big)$ for $0<\alpha<1$, which identifies the optimal precision dependence of our
algorithm.
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Chaotic Dynamics
Stability of inverse cascade in NLS Wave turbulence
Guillaume Costa, Sergey Nazarenko and Giorgio Krstulovic
We study the stability of the inverse cascade in the 3D Nonlinear Schrodinger Wave Kinetic Equation (WKE) in the presence and absence of a condensate. Using theoretical arguments supported by numerical simulation, we show that, the Kolmogorov-Zakharov solution is stable with respect to small isotropic perturbations in the absence of a condensate. Conversely, introducing a condensate component leads to a growth of the condensate occupation and ultimately destabilizes the inverse cascade. The system then evolves towards a new steady-state whose properties depend on the condensate dissipation rate.
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Quantum Physics
Photon Demultiplexing Using Spatial Routing
Hashir Kuniyil, Asad Ali and Saif Al-Kuwari
Spatial sectioning of the far-field noncollinear field from spontaneous parametric down-conversion (SPDC) is a promising approach for multiparty
quantum communication. Although demonstrations with six pairs of users have been reported, the fundamental limits remain unknown. These include the maximum number of channels, the required degree of channel optimization, and the dependence on input parameters. In this paper, we provide a practical framework that answers these questions by connecting input parameters and invoking a design
theorem. For a representative configuration, we realize 12 user-pair channels with routing consistency exceeding $0.9999$ at a $12\%$ reduction in
photon flux. We further show that sectioning improves the accidental-coincidence budget linearly with the number of channels $N$, allowing the aggregate key rate to scale with the user count. These results provide a design strategy for spatial-division multiplexing of entangled
photons analogous to the channel-spacing standards used in wavelength-division networks.
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Space Physics
The Gannon Storm: Citizen science observations during the geomagnetic superstorm of 10 May 2024
Maxime Grandin, Emma Bruus, Vincent E. Ledvina et al. (+12 more)
The 10 May 2024 geomagnetic storm, referred to as the Gannon Storm in this paper, was one of the most extreme to have occurred in over 20 years. In the era of smartphones and social media, millions of people from all around the world were alerted to the possibility of exceptional auroral displays. Hence, many people not only witnessed but also photographed the aurora during this event. These citizen science observations, although not from scientific instruments operated by observatories or research groups, can prove invaluable in obtaining data to characterise this extraordinary event. In particular, many observers saw and photographed the aurora at mid-latitudes, where ground-based instruments targeting auroral studies are sparse or absent. We created an online survey and circulated it within networks of aurora photographers to collect observations of the aurora and disruptions in technological systems that were experienced during this superstorm. We obtained 696 citizen science reports from over 30 countries, containing information such as the time and location of aurora sightings, observed colours and auroral forms during the geomagnetic storm. We supplemented the obtained
dataset with 186 auroral observations logged in the Skywarden catalogue by citizen scientists. The main findings enabled by the data collected through these reports are that the aurora was widely seen from locations at geomagnetic latitudes ranging between 30{\deg} and 60{\deg}, with a few reports from even lower latitudes. This was significantly further equatorward than predicted by auroral oval models. The reported auroral emission colours, predominantly red and pink and intense enough to reach naked-eye visibility, suggest that the auroral electron precipitation contained large fluxes of low-energy (< 1 keV) particles. (...)
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All authors Maxime Grandin, Emma Bruus, Vincent E. Ledvina, Noora Partamies, Mathieu Barthelemy, Carlos Martinis, Rowan Dayton-Oxland, Bea Gallardo-Lacourt, Yukitoshi Nishimura, Katie Herlingshaw, Neethal Thomas, Eero Karvinen, Donna Lach, Marjan Spijkers, Calle Bergstrand
Quantum Physics
Deterministic and Programmable Fusion for Scalable Generation of Photonic Graph States
Yan Li, Yunfan Yang, Zenghui Bao et al. (+6 more)
Entanglement in multiphoton graph states is an important resource with various applications, such as measurement-based
quantum computing and
memory-less
quantum repeaters. While some primitive instances have been successfully prepared, scalable generation of large-scale graph states with programmable connections remains an outstanding challenge. Fusion provides a promising "divide-and-conquer" approach by linking smaller resource states into larger, more complex graphs. However, its practical scalability has been limited by the probabilistic nature of conventional fusion protocols, which necessitates extensive hardware overhead and feed-forward resources to achieve deterministic outcomes. Here, we introduce and experimentally demonstrate a deterministic fusion operation with built-in error mitigation, capable of connecting small time-bin-encoded cluster states–originally generated on-demand from a
quantum emitter–into larger, reconfigurable photonic graph states of increased sizes. The fusion operation is realized by nondestructively projecting pairs of flying microwave photonic
qubits into Bell states using superconducting
circuits with in-situ programmability. Crucially, the protocol features active reset and reuse of matter
qubits during graph state generation, thereby circumventing the coherence constraints of the
quantum emitter and enabling the generation of genuine multipartite
entanglement across 13 photonic
qubits. Our results establish a scalable framework for photonic graph-state synthesis, paving the way for fault-tolerant measurement-based
quantum computation and distributed
quantum networks.
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All authors Yan Li, Yunfan Yang, Zenghui Bao, Jize Yang, Luyan Sun, Yipu Song, Yukai Wu, Hongyi Zhang, Luming Duan
Astrophysics of Galaxies
Sleeping or Dead? Probing the Quenching Mechanism of JWST Dormant Galaxies at z > 3 with ALMA
Mengyuan Xiao, Songnan Qi, Pascal A. Oesch et al. (+16 more)
JWST has revealed a population of "dormant”
galaxies at z>3 with strong Balmer breaks and weak emission lines, whose
star formation appears to have declined only recently. Whether these
galaxies are undergoing a lasting transition toward quiescence or merely experiencing a temporary suppression of
star formation remains unclear. We investigate their molecular gas content using archival ALMA observations of [CII]158um and CO rotational transitions. Starting from all publicly available JWST/NIRSpec prism observations and using joint spectrophotometric fitting, we construct a parent sample at z>3 and log(Mstar/Msun)>9.5 in the ALMA-accessible COSMOS, UDS, and GOODS-South fields. Our final sample comprises 7 dormant
galaxies and 15 quiescent
galaxies with ALMA constraints on their molecular gas content (mostly 3 sigma upper limits). We find that dormant
galaxies exhibit systematically lower
star formation rates averaged over the past 10Myr (SFR10Myr) than over the past 100Myr (SFR100Myr), supporting a recent rapid decline in their
star formation. For the ~70% of the sample with sufficiently constraining ALMA observations, their molecular gas fractions lie at least ~0.3-2dex below those expected for main-sequence
galaxies. Moreover, the molecular gas fractions of dormant
galaxies show no systematic difference from those of quiescent
galaxies in our sample. This indicates that dormant
galaxies have already reached a gas-poor state shortly after quenching and favors a scenario in which the rapid shutdown of
star formation is associated with depletion or removal of the molecular gas reservoir, rather than primarily with suppressed
star formation efficiency while retaining a substantial molecular gas reservoir. Our results suggest that, if no substantial gas replenishment occurs in the future, dormant
galaxies are more consistent with becoming "dead” than with being temporarily "sleeping”.
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All authors Mengyuan Xiao, Songnan Qi, Pascal A. Oesch, Longji Bing, Miroslava Dessauges-Zavadsky, Andreas L. Faisst, Mahsa Sanati, Rashmi Gottumukkala, Gabriel Brammer, David Elbaz, Robert Feldmann, Yoshinobu Fudamoto, Lucas C. Kimmig, Benjamin Magnelli, Rui Marques-Chaves, Anurag Amol Sawarkar, Sune Toft, Francesco Valentino, Christina C. Williams
Quantum Physics
Majorana Edge Modes Reshape Kibble-Zurek Scaling in Kitaev Honeycomb Ribbons
Hyesung Choi, Antonio Mandarino and Mahn-Soo Choi
Recent progress in programmable
quantum simulators motivates exact
benchmarks for nonequilibrium dynamics in topological
quantum matter. We study the Kitaev honeycomb model driven through its critical regions by a linear ramp of the bond coupling $J_z$ over a ramp time $\tau$, comparing zigzag and armchair ribbons with fully periodic tubes. The production of excitations exhibits a geometry-dependent finite-size crossover controlled by $N_2/\sqrt{\tau}$, the ratio of the ribbon width to the Kibble–Zurek length. Periodic tubes obey the expected critical-line Kibble–Zurek scaling and serve as the boundary-free
benchmark. Zigzag ribbons follow the same scaling until defect production is exponentially suppressed by a finite-width algebraic gap floor associated with the formation of Majorana edge modes, whose occupation is pinned by inversion parity. Armchair ribbons instead support transient Majorana edge modes with exponentially small gaps, producing width-parity-dependent defect plateaus: exactly one defect per unit length for odd widths and an approximate, transient plateau near one half for even widths. The quench-generated
entanglement entropy and fermionic logarithmic negativity inherit the same geometry-dependent structure, and the negativity further distinguishes the coherence-borne
entanglement of the Kibble–Zurek regime from the population-borne
entanglement of the edge-mode plateaus. These results identify boundary Majorana modes as the mechanism controlling departures from ideal Kibble–Zurek dynamics and provide geometry-resolved
benchmarks for programmable simulations of topological matter.
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Quantum Physics
Quantum Folding in Chebyshev-Based Quantum Subspace Diagonalization
Seung Park, Dongni Chen, Stefano Chesi et al. (+2 more)
Quantum subspace diagonalization (QSD) with a Krylov space spanned by Chebyshev
polynomials of the
Hamiltonian is a natural ground-state method for fault-tolerant
quantum computers, but every guarantee it offers—convergence rate, noise floor, and the cost of turning its classical output back into a physical state—is controlled by the overlap of the reference state with the true ground state, which decays exponentially with system size for any product state and non-trivial
Hamiltonian. We propose
quantum folding: for a system governed by a local
Hamiltonian, seed the QSD with the product of the ground states of its subsystems, which differs from the target only through the interface terms. We prove a nonasymptotic error bound for the Chebyshev QSD that is linear in the measurement noise, by transplanting Kirby's effective-
Hamiltonian analysis to the Chebyshev–Krylov basis, and identify the block-encoding rescaling of the
Hamiltonian as a parameter of the guarantee. Exact simulations of antiferromagnetic Heisenberg chains show that the folded reference state reduces the Krylov dimension for a given accuracy severalfold and lowers the error under noise by two to five orders of magnitude relative to the Néel state. We show how the Ritz vector is prepared as a physical state and that the ground-state generation probability obeys a tight ceiling set by the overlap, so that recursive folding prepares ground states at
polynomial cost. Taken together, these results allow for a scalable QSD framework that avoids the exponentially small ground-state overlaps associated with conventional product-state initialization. Finally we compute the fold fidelity itself: a slow power law for the gapless
spin-1/2 chain, a size-independent constant for the gapped
spin-$1$ chain, and an exact closed form converging to 1/4 for the AKLT chain.
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All authors Seung Park, Dongni Chen, Stefano Chesi, Kyunghyun Baek, Mahn-Soo Choi
Materials Science · Cross-listed from cs.LG
Beyond DFT electronic band structures via dual-space orbital learning
Minhyuk Kang, Beom Seok Kang, Nikolai Argatoff et al. (+4 more)
Accurate electronic band structures are essential for predicting material properties, but high-fidelity calculations are computationally demanding. We introduce O-kRystal, a dual-space orbital-learning framework that uses a lower-cost Perdew-Burke-Ernzerhof (PBE) calculation as both an energy baseline and a source of structured orbital information. Combining PBE band energies with real- and reciprocal-space orbital
matrices, O-kRystal predicts higher-level corrections for individual electronic states as a function of
crystal momentum and
spin. For states within 5 eV of the band-edge midpoint, it predicts Heyd-Scuseria-Ernzerhof (HSE06) band energies with a mean absolute error of $0.171 \pm 0.009$ eV across nearly 6,000 three-dimensional materials spanning insulating, metallic,
magnetic, and nonmagnetic systems. On a separate
benchmark of six strongly correlated materials, it reduces the corresponding PBE band-energy MAE by 68.7% and resolves orbital-dependent changes in the relative placement of transition-metal d and ligand p states. Despite training only at high-
symmetry points, it maintains comparable accuracy at unseen points along band paths and reconstructs HSE06 densities of states from dense Brillouin-zone predictions. Finally, training O-kRystal on $G_0W_0$ quasiparticle energies for two-dimensional materials demonstrates its applicability across levels of theory and the potential of orbital learning for higher-fidelity, momentum-resolved electronic-structure prediction beyond density functional theory.
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All authors Minhyuk Kang, Beom Seok Kang, Nikolai Argatoff, Miguel Nouman, Danish Khan, William A. Goddard III, Anima Anandkumar
High Energy Physics (Phenomenology)
The Semileptonic B Frontier: LHC, B-factories, Lattice QCD & the Hunt for Precision
F. De Fazio, P. De Simone, M. Fedele et al. (+33 more)
This review document summarizes the main outcomes and key theoretical and experimental developments discussed at the workshop “The Semileptonic $B$ Frontier: LHC, $B$-Factories,
Lattice QCD & the Hunt for Precision”, held at Laboratori Nazionali di Frascati on 16–18 February, https://agenda.infn.it/event/49469/. Bringing together experimentalists and theorists, the meeting addressed recent advances and outstanding challenges in both charged-current ($b \to c/u\,\ell\nu$) and neutral-current ($b \to s\,\ell^+\ell^-$) semileptonic $b$-
hadron decays. We synthesize current experimental measurements from Belle, Belle~II, and LHCb with state-of-the-art theoretical inputs—including
Lattice QCD determinations, Heavy
Quark Expansion (HQE) frameworks, and QED radiative corrections. In addition to reviewing the status of CKM
matrix elements, hadronic form factor extractions, and Lepton Flavor Universality (LFU) tests, this report highlights novel observables and fitting techniques designed to maximize the sensitivity of future analyses and guide upcoming data-taking campaigns.
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All authors F. De Fazio, P. De Simone, M. Fedele, G. Finocchiaro, F. Mescia, M. Rotondo, A. Barone, B. Capdevila, M. De Cian, L. Dreyfus, M. Fael, G. Finauri, G. Gagliardi, G. Gaudino, D. Giusti, N. Gubernari, A-M. Heyn, F. Manganella, E. Minucci, B. Mitreska, E. Manoni, T. Martinov, L. Paolucci, Z. Polonsky, A. Poluektov, M. Palutan, F. Sanfilippo, S. Simula, A. Smecca, N. Tantalo, A. Tinari, A. Vaquero, R. Vazquez Gomez, M. Valli, L. Vittorio, V. Vobbilisetti
Instrumentation and Methods for Astrophysics
RPCA: a Resolved PSF reconstruction method for undersampled images
Lin Nie, Huanyuan Shan, Guoliang Li et al. (+11 more)
The Point-Spread Function (PSF) is a critical component in various astrophysical research areas, including
galaxy morphology, photometric
redshift determination, and weak
lensing studies. As the next generation of space
telescopes prepares for operations, including the China Space Station
Telescope (CSST), accurate PSF modeling has become increasingly important. However, accurately modeling the PSF remains challenging, particularly for poorly sampled images. To construct reliable PSF models based on
star images, we aim to develop a novel and robust method, which accounts for the pixel integration effect in modeling for reconstructing high-resolution PSFs from undersampled or poorly resolved images. In this paper, we present Resolved Principal Components Analysis (RPCA), a novel approach that accounts for pixel integration effects to enable the direct reconstruction of resolved PSFs from undersampled images via an Expectation-Maximization PCA (EMPCA) technique. Our method has been tested on a simulated PSF
dataset for the China Space Station
Telescope (CSST), where both observational and detector-induced effects were considered during simulation. The results demonstrate that RPCA achieves superior precision in PSF shape parameters compared to existing methods such as Multi-CCD (MCCD), Resolved Components Analysis (RCA), and PSFEx. Notably, RPCA {could reduce the bias of $\Delta R^2/R^2$ by approximately one order of magnitude with respect to MCCD, RCA and PSFEx. RPCA exhibits robust stability under realistic observational conditions, including varying signal-to-noise ratios (SNRs) and contamination from
cosmic rays and bad pixels. This suggests that RPCA could be a promising candidate for future CSST PSF modeling efforts.
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All authors Lin Nie, Huanyuan Shan, Guoliang Li, Tobías I. Liaudat, Chengliang Wei, Peng Wei, Tianmeng Zhang, Hekun Li, Lei Wang, Han Qu, Zhaojun Yan, Nan Li, You Wu, Peng Jia
Quantum Physics
On the structure of low-rank PPT entangled states violating Peres conjecture
Gurvir Singh and Manik Banik
Bound-entangled states with positive partial transpose (PPT) can exhibit
quantum steering and Bell nonlocality, disproving the long-standing Peres
conjecture and its stronger steering counterpart. These counterexamples, obtained through explicit constructions or numerical searches, raise the question of whether they share a common structural origin. We address this question in the low-rank regime by asking whether known counterexamples can be obtained, up to invertible local filtering, from the complement of an unextendible product basis (UPB). We find that the answer depends crucially on the local dimension. In $3\otimes3$, the rank-four structure of PPT entangled states implies that both the steerable PPT state of Moroder et al. and the Bell-nonlocal PPT state of Vértesi and Brunner can be obtained from UPB-complement states under invertible local filtering. For three
qubits, in contrast, rank-four states that are PPT across every bipartition are separable across each cut. Moreover, comparison of the product-vector structure of the relevant kernels shows that the known three-
qubit Bell-nonlocal PPT states cannot be obtained by invertible local filtering from the complement of any three-
qubit UPB. Going beyond rank four, we further show that a known rank-eight three-qutrit state, supported on the complement of a UPB and PPT across every bipartition, is genuinely multipartite entangled. These results show that UPBs provide a unifying structural origin for important low-rank PPT entangled states in $3\otimes3$, but that nonlocal bound
entanglement is not, in general, a UPB phenomenon.
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Quantum Physics
Single and coupled quantum van der Pol oscillators: Wigner-function dynamics, exact qutrit solutions, and synchronization
Rohitashwa Chattopadhyay, Vinayak Pendse and Shamik Gupta
We study
quantum van der Pol oscillator in which single-
photon pumping competes with a nonlinear two-
photon dissipative channel to produce a
quantum limit cycle, and the question of how two such oscillators with non-identical intrinsic frequencies synchronize in the sense of phase locking when coupled dissipatively to one another. For a single oscillator, starting from a Lindblad description of the dynamics, we derive the exact Wigner-function
evolution equation, and show that its Fokker–Planck approximation admits in the appropriate regime an equivalent classical Itô
stochastic description that reproduces remarkably well the full Lindblad dynamics. Notably, the
stochastic approach provides an efficient means of capturing system dynamics in the semiclassical regime, where a large number of energy eigenstates contribute and direct numerical simulations become computationally demanding. Restricting to the three lowest Fock states and using a parity
symmetry, we obtain in closed form the stationary-state density
matrix and its Wigner-function representation that displays pronounced nonclassical features. For two non-identical oscillators, we study the full Lindblad dynamics numerically and characterize synchronization through the stationary-state order parameter as a function of frequency mismatch and dissipative coupling. We find that increasing the effective nonlinear dissipative strength suppresses the synchronized region. Restricting the two oscillators to the three-level qutrit subspace, a parity
symmetry reduces the stationary-state problem to an exact $41$-dimensional linear system, allowing to compute the synchronization order parameter. In this reduced description, results in the limit of large dissipation agree closely with those from the full dynamics, while exhibiting in the limit of small dissipation a double-peak synchronization structure accompanied by a phase reversal.
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Earth and Planetary Astrophysics
On-sky performance and prospects of near-infrared CMOS detectors in exoplanet detection: first year of SPIRIT
Clàudia Janó-Muñoz, Matthew J. Hooton, Peter P. Pedersen et al. (+8 more)
Ultracool dwarfs are promising targets for detecting and characterising temperate terrestrial
exoplanets. Their flux peaks in the near-infrared, beyond the wavelength cut-off of the silicon-based CCDs used by ground-based surveys dedicated to observing them, such as SPECULOOS. We present the on-sky performance of SPIRIT (SPeculoos InfraRed Imager for Transits), an InGaAs CMOS detector on the Callisto
telescope at the SPECULOOS Southern Observatory, during its first year of operation, from mid-2022 to 2023. We use 328 visits of 73 targets to optimise our CMOS-specific reduction process, including our approach to glow effects and bad-pixel handling. We find the measured precision to be consistent with our theoretical noise model, achieving sub-part-per-thousand precision under good observing conditions across targets spanning $J$-band magnitudes of 10–13. We further illustrate SPIRIT's capabilities with two case studies: a simultaneous SPIRIT $zYJ$ and CCD $I + z$ observation of a TRAPPIST-1\,h transit, and monitoring observations of the fast-rotating dwarf LP~944-20. Our results confirm that InGaAs infrared CMOS detectors are a cost-effective and competitive technology for ground-based transit photometry of cool
stars, and that they show promising prospects to become a core part of the next generation of instruments.
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All authors Clàudia Janó-Muñoz, Matthew J. Hooton, Peter P. Pedersen, Didier Queloz, Khalid Barkaoui, Yasmin T. Davis, Michaël Gillon, Benjamin V. Rackham, Mathilde Timmermans, Amaury H. M. J. Triaud, Sebastián Zúñiga-Fernández
Quantum Physics
Trading energy for coherence in mode discrimination
Shuyang Meng and Valerio Scarani
Energy is arguably the main resource in classical physics; coherence is the prototypical
quantum resource. In this paper, we study the interplay between these two resources in the task of optimal mode discrimination. This task, motivated by cryptography and metrology, consists of finding in which mode a signal has been encoded, for a given finite set of possible modes. After recalling that the task can be cast as a semi-definite program, we solve completely the case of two-mode discrimination under a hard energy constraint $n\leq N$. Specifically, we identify the region of modes overlap, for which the maximal energy state (the Fock state with N excitations) is the best choice for discrimination. For other overlaps, having access to coherence leads to better discrimination.
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Cosmology and Nongalactic Astrophysics
Low-cost neural summaries for cosmological inference: an ensemble of convolutional neural networks trained on approximate simulations
Iñigo Sáez-Casares, Davide Bianchi, Matteo Calabrese et al. (+1 more)
Machine learning can build near-optimal summary statistics for extracting cosmological information from the large-scale structure of the Universe. Training them, however, requires large numbers of costly simulations. We aim to build a neural summary trained on fast, approximate low-resolution simulations that remains informative when applied to higher-resolution ones, reducing the cost of the training set. We train an ensemble of convolutional neural networks with different architectures to compress the matter overdensity fields of low-resolution particle-mesh simulations. The outputs of a subset of networks are concatenated into a summary statistic, which we use to constrain $\Omega_{\rm m}$ and $\sigma_8$ from high-resolution particle-mesh simulations, each about a thousand times more costly than their low-resolution counterparts. Theoretical predictions are provided by a Gaussian process emulator built from the high-resolution simulations. We test three strategies for selecting the smallest informative subset of networks. Constraints are compared with those from a reference power spectrum analysis. We also consider dark matter
halo catalogues from independent high-resolution $N$-body simulations. The neural summary extracts information beyond the binned power spectrum. Using multiple networks is essential: a single network can be less informative than the power spectrum. A greedy search based on posterior volume provides the tightest constraints with the fewest networks. The neural summary also outperforms the power spectrum for dark matter
haloes, at different number densities and
redshifts, despite being trained on low-resolution matter fields at $z=0$. This work demonstrates that an ensemble of networks trained on approximate simulations yields a summary statistic that remains informative on higher-fidelity data, including dark matter
haloes. (Abridged)
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All authors Iñigo Sáez-Casares, Davide Bianchi, Matteo Calabrese, Luigi Guzzo
Statistical Mechanics · Cross-listed from q-bio.QM
Maximum likelihood, neural networks and posterior mean for inferring fractional Brownian motion parameters
Daniel S. Han, Vaishnavi Ananthanarayanan and Matthew J. Simpson
Fractional Brownian motion (fBM) is a model of anomalous
diffusion parameterised by a Hurst exponent $H \in (0,1)$ and a generalised
diffusion coefficient $D_H > 0$. We jointly estimate $H$ and $D_H$ using maximum likelihood (MLE) from density measurements with Poisson counting noise and single-particle trajectory with Gaussian localisation error. We show that one density measurement in time cannot infer both $H$ and $D_H$ and that several time points are needed, which matters most for inference precision. For trajectories, we show that a neural network trained with a squared error loss approximates the posterior mean of $H$, which can be computed exactly at negligible cost. Paired with the profile-likelihood estimate of $D_H$, the posterior mean has the lowest root mean squared error in both $H$ and $D_H$, except near $H=0$ and $H=1$ where MLE estimates $H$ better. In vesicle trajectories from two
cell types, $H$ and $D_H$ form a continuum rather than distinct modes of motion. The posterior probability that each window within a track is subdiffusive or superdiffusive shows that $26\%$ of MRC5 fibroblast and $21\%$ of HeLa vesicle trajectories contain both subdiffusive and superdiffusive windows, against $2\%$ and $7\%$ expected from estimation uncertainty alone. Intracellular cargoes therefore switch between subdiffusion and superdiffusion over time rather than forming populations with fixed $H$.
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Atmospheric and Oceanic Physics
Generative modelling for multivariate spatio-temporal downscaling of monthly climate fields
Yu Huang, Shangshang Yang, Sebastian Bathiany et al. (+3 more)
Inferring
climate fields at higher spatio-temporal resolutions from coarse representations is essential for accessing socioeconomic and environmental impacts. The downscaling of modelled
climate fields faces a trade-off between data storage constraints, simulation efficiency, and resolution requirements. While many methods for spatial downscaling have been proposed, joint spatio-temporal downscaling has received comparable little
attention. When deriving, for example, daily fields from
climate datasets that are available only as monthly averages at coarser spatial resolution, it is highly challenging to faithfully reproduce extreme event statistics and spatiotemporal consistency. To address this task, we introduce a generative machine learning approach, using a
diffusion model to jointly downscale monthly temperature and precipitation fields into temporally consistent daily fields at higher spatial resolution. We demonstrate that our approach can generate high-dimensional multivariate
climate fields at daily temporal and 0.25{\deg} spatial resolution from monthly input fields at 1{\deg} spatial resolution, exhibiting coherent temporal dynamics and physically plausible spatial structures. In particular, by incorporating a conditional guidance technique, we show that a pre-trained
diffusion model can be directly leveraged to efficiently generate daily high-resolution fields conditioned on monthly inputs, without requiring additional fine-tuning or retraining. Our probabilistic approach thus provides an efficient and generalizable framework for spatio-temporal
climate downscaling, enabling flexible
climate fields generation for
climate impact assessments and digital Earth simulator constructions.
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All authors Yu Huang, Shangshang Yang, Sebastian Bathiany, Michael Aich, Philipp Hess, Niklas Boers
Astrophysics of Galaxies
PDRs4All XXIII. JWST-MIRI template spectra of PAHs in the Orion Bar obtained with blind signal separation
P. Amiot, O. Berné, J. Roux-Morin et al. (+12 more)
The aromatic infrared bands (AIBs) are observed in a wide variety of astrophysical sources, and now in unprecedented detail by the James Webb space
telescope (JWST). These bands are generally attributed to the emission from polycyclic aromatic hydrocarbon (PAHs). Our aim is to extract mid-infrared AIB template spectra from JWST observations of the Orion Bar photo-dissociation region that can be used to derive PAH properties from observations of other objects. We used the JWST MIRI-MRS observations from the PDRs4All program. We first isolated the AIBs from the data using a multi-component fitting approach. We then applied a non-negative
matrix factorization to the isolated AIB spectra and extracted two templates, named AIBirrad and AIBshield following previous work. The spatial distribution and spectral characteristics of these two spectra suggest that they originate from two chemical distinct populations. We interpret AIBirrad as emission originating from a PAH population strongly exposed to ultra-violet (UV) radiation and mainly composed of large, compact ionized PAHs. Conversely, AIBshield is interpreted as originating from a more shielded population of PAHs, which is less exposed to the UV by being more embedded in the cloud. This population consists of small, asymmetric and mainly neutral PAHs with bonded aliphatic side groups. These templates can serve to analyze PAH emission in a wide variety of objects observed with MIRI-MRS.
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All authors P. Amiot, O. Berné, J. Roux-Morin, I. Schroetter, C. Boersma, A. Fuente, J. R. Goicoechea, E. Habart, A. Maragkoudakis, T. Onaka, E. Peeters, M. Robberto, A.G.G.M Tielens, D. Van De Putte, S. Vicente
High Energy Astrophysical Phenomena
Black Hole Binary Mergers in Galactic Nuclei: Combined Effects of Secular Dynamics and Stellar Flybys
Hao Wang, Bin Liu and Johan Samsing
Galactic
nuclei, with the central supermassive black holes (SMBHs) and surrounding dense
star clusters, serve as natural laboratories for studying gravitational dynamics in extreme gravitational environments. In this work, we model the long term
evolution of black hole binaries (BHBs) in these environments by incorporating the tidal influence of the central SMBH, the potential of the nuclear
star cluster, SMBH induced relativistic precession, and
stochastic perturbations from stellar flybys. Our numerical simulations show that the long term
evolution of BHBs is predominantly governed by the SMBH-driven ZLK mechanism. However, once stellar flybys are included, they can modify both the binary angular momentum and energy. The cumulative effect of repeated flyby encounters substantially reshapes the long term dynamical
evolution, eventually leading systems toward either merger or disruption. Based on a population synthesis study, we find that this combined secular and non-secular channel produces a merger rate of approximately $\mathcal{R}\simeq16\mathrm{Gpc^{-3}yr^{-1}}$, which is significantly higher than the rates predicted by dynamical channels that neglect stellar flybys. Furthermore, we predict that a non-negligible fraction of merging systems would retain detectable eccentricities at low frequencies around 5 Hz, thus providing a distinctive observational signature for next generation ground based GW detectors. Our results demonstrate that the
stochastic perturbations from the surrounding environment are essential for modeling BHB
evolution in galactic
nuclei, and that this channel may contribute a major fraction of observed mergers.
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High Energy Astrophysical Phenomena
Linear Polarization of Synchrotron Radiation from Very-small-pitch-angle Electrons
Meng Nie and Jirong Mao
For synchrotron radiation with pitch angle $\alpha \ll 1/\gamma$ where $\gamma$ is the electron Lorentz factor, referred to as very-small-pitch-angle synchrotron radiation, the polarization properties differ significantly from those of conventional synchrotron radiation ($\alpha \gg 1/\gamma$). In this work, we investigate the linear polarization characteristics of very-small-pitch-angle synchrotron radiation from relativistic thermal and nonthermal electrons. We calculate the linear polarization by applying power-law and Maxwellian electron energy distributions. Moreover, some synchrotron sources exhibit a hybrid distribution of nonthermal and thermal electrons, and we also calculate the polarization degree for a hybrid electron energy distribution. The calculations are performed in the
radio, optical, X-ray, and $\gamma$-ray bands. Our results show that the linear polarization degree of very-small-pitch-angle synchrotron radiation is generally lower than that of conventional synchrotron radiation. Very-small-pitch-angle synchrotron radiation from both nonthermal and thermal electrons can produce significant linear polarization. However, the polarization exhibits diverse behaviors across different physical parameters. The general scenario provided in this work can be considered for the application to all kinds of synchrotron sources, as we suggest that the very-small-pitch-angle case is crucial for the study of synchrotron polarization.
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Quantum Physics
Acoustic scattering from quantum dynamics
Farhang Loran and Ali Mostafazadeh
Scattering of sound waves propagating in a compressible fluid is linked to the
quantum dynamics generated by a class of non-Hermitian
Hamiltonian operators. The scattering amplitude is expressed in terms of the corresponding
evolution operator. This is used to provide a new proof of the reciprocity
theorem in acoustic scattering, conduct analytic low-frequency acoustic scattering calculations, and study the scattering of sound waves by a finite planar array of delta-function point scatters embedded in an infinite acoustic slab. A detailed discussion of acoustic scattering properties of a homogeneous acoustic slab including a pair of delta-function point scatters on one of its faces is provided.
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Statistical Mechanics
Understanding the Mpemba Effect through a Rule of Thumb
Ran Yaacoby
In the Mpemba effect, a system prepared farther from
equilibrium relaxes faster than one prepared closer to it. Its persistence across diverse systems, and under different dynamics of the same system, suggests that it is largely rooted in
equilibrium properties, with the dynamics deciding only which mode relaxes slowest. Here we propose a simple rule of thumb for anticipating the Mpemba effect: the effect is expected when a single low-order
equilibrium moment is nonmonotonic in temperature. The bath singles out this moment as the slowest to relax, so that its displacement from its bath value sets the amplitude of the slowest relaxation mode. We establish this relation exactly for low-dimensional Ornstein–Uhlenbeck processes. We then extend the rule to mean-field models by approximating their relaxation near the final
equilibrium state by an Ornstein–Uhlenbeck process. For the mean-field Ising antiferromagnet, which we solve exactly in the thermodynamic limit, this approximation reproduces the main structure of the Mpemba phase diagram, including strong effects far from any phase transition. Finally, we give a general prescription for mean-field systems: identify the slowest
symmetry-allowed moment of the normal coordinates at the bath, and follow its
equilibrium value as a function of preparation temperature. This offers a practical route from
equilibrium observables to anomalous relaxation without diagonalizing the dynamics.
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Earth and Planetary Astrophysics
LiDO: The Large inclination Distant Objects Survey
Mike Alexandersen, Rosemary E. Pike, Ying-Tung Chen et al. (+20 more)
Previous trans-Neptunian objects (TNOs) discovery surveys targeted the ecliptic plane, where the overall highest density is seen. High-inclination objects spend little time near the plane, and are thus under-represented in previous TNO surveys. The Large inclination Distant Objects (LiDO) survey targets these high-inclination populations in 34 sq$.$deg., located in two blocks 14-21 degrees north and south of the ecliptic plane, finding 148 objects, all with i>14 degrees due to survey design. A careful characterization of detection efficiency and other survey parameters results in a "characterized sample" of 125 objects detected within the survey's magnitude and rate limits, thus suitable for model comparison via survey simulations. LiDO detected 62 TNOs classified as resonant, including 21 Plutinos, of which 12 are securely Kozai resonators (always coming to pericenter off-ecliptic), as well as 9 objects in the 5:2 resonance, and several mixed mode inclination-eccentricity resonators. No objects beyond 63 au were detected, despite sensitivity to objects as far as 150 au. We found that the i>14 degree orbital distribution of the previous model from OSSOS was rejectable with the inclusion of the 38 characterized hot classical TNOs from LiDO. We constructed a proof-of-concept orbital distribution model of hot classical TNOs based on long-term stability sculpting, which is statistically acceptable for the LiDO and OSSOS samples, while producing population estimates (21,000$^{+3000}_{-3000}$ hot classicals with H_r<8.3) consistent with OSSOS estimates. The discovery of 125 characterized mid-to-high inclination objects in a variety of orbital classifications provides useful constraints for population modeling and the migration history of the Solar System.
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All authors Mike Alexandersen, Rosemary E. Pike, Ying-Tung Chen, Samantha M. Lawler, Mark Comte, Lowell Peltier, J. J. Kavelaars, Kathryn Volk, Cameron Semenchuck, Cameron Collyer, Jaidyn Draper, Stephen Gwyn, Hermosillo Ruiz, Matthew J. Holman, Katrina Kianpoor, Cameron J. Morgan, Ruth Murray-Clay, Jonathan Pond, Benjamin Proudfoot, AbdulRahman Rabaa, Darin Ragozzine, Emily Rieger, Mriana Yadkoo
Cosmology and Nongalactic Astrophysics
specwizard: A Public Python Framework for Creating Synthetic Absorption Spectra from Hydrodynamical Simulations
Andrés Arámburo-García, Tom Theuns, Joop Schaye et al. (+1 more)
We present specwizard, a publicly available modular Python package for generating synthetic absorption spectra from hydrodynamical simulations. The code combines atomic data from the National Institute of Standards and Technology database with ionisation fractions computed using the cloudy spectral synthesis code for multiple ionising backgrounds, enabling consistent modelling of bound–bound and bound–free absorption for resonant transitions of all ions. specwizard employs a column-density–conserving projection scheme, includes natural line broadening for the Lyman series, and offers optional treatments of instrumental resolution and noise for direct comparison with high-resolution
quasar spectra. As example applications of the code, we shoot sightlines through the eagle cosmological simulation to generate a z = 3.2 synthetic
quasar spectrum containing H i Lyman-series transitions, including damping wings and Lyman-limit absorption. Additionally, we compute metal-absorption lines probing the circumgalactic medium of simulated
galaxies, and investigate the correlated absorption of H i and Si iii. We demonstrate that specwizard applied to outputs from eagle accurately reproduces key observational diagnostics of the Lyman-alpha forest, including the
redshift evolution of the mean transmission, the transmission PDF and the transmission power spectrum. We take advantage of the fact that the eagle simulation also reproduces the measured
evolution of the temperature-density relation to infer the
evolution of the amplitude of the ionizing background, finding excellent agreement with recent theoretical models and measurements.
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All authors Andrés Arámburo-García, Tom Theuns, Joop Schaye, Alexey Boyarsky
Superconductivity
Andreev-reflection spectroscopy of SrPt3P single crystals
Valeriy A. Stepanov, Nikolai D. Zhigadlo, Erik Piatti et al. (+1 more)
The interplay between inversion
symmetry breaking and superconducting pairing mechanisms is a long-standing puzzle of solid-state physics. Ternary platinum phosphide SrPt$_3$P is an excellent case study in this regard, since it shares the distorted anti-perovskite
crystal structure of non-centrosymmetric
superconductor CePt$_3$Si but preserves the inversion
symmetry center, enabling a direct comparison between the two compounds. Despite intense scrutiny, the superconducting pairing strength, gap
symmetry, and magnitude of SrPt$_3$P remain an open question. Here, we study the gap structure of high-quality SrPt$_3$P single
crystals with $T_c = 8.6$ K by using point-contact Andreev-reflection spectroscopy. The spectra systematically showed symmetric conductance maxima and a zero-bias minimum, as is typical of fully gapped
superconductors, and dips at finite voltage $V_\mathrm{dip}$ due to the local transition of the contact region to the resistive state. In contacts with high resistance, where the dips fall sufficiently far from the gap features, the conductance curves can be well fitted with a single isotropic $s$-wave gap. The temperature dependence $\Delta(T)$ of the gap amplitude extracted from the fit is in good agreement with the one predicted by the BCS theory, with a zero-temperature mean value $\Delta(0)=1.88\pm0.08$ meV, and a mean gap ratio $2\Delta/k_\mathrm{B}T_c = 5.2\pm0.2$.
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All authors Valeriy A. Stepanov, Nikolai D. Zhigadlo, Erik Piatti, Dario Daghero
Materials Science
A practical route to amorphous solid-state electrolyte structures by hybrid reverse Monte Carlo with foundation potentials
Xintian Wang, Xinyu Zhang, Denys Butenko et al. (+3 more)
Amorphous alkali oxychlorides are fast ion conductors, but their atomic structure remains unresolved. Total scattering sums all partial pair correlations into one curve that has no unique inversion, so the structure must be modeled. Melt-quench molecular dynamics builds a model from the interatomic potential alone, and reverse Monte Carlo (RMC) builds one from the measurement alone. The two have rarely been compared with all else held fixed. We
benchmark both routes and two hybrid schemes on amorphous \ce{Li_{0.9}NbO_{0.9}Cl_{4.1}} against one
neutron pair distribution function with one foundation potential. The hybrid schemes put the energy either in the acceptance rule (inline) or in short relaxations between blocks of refinement (alternating). Each refinement starts from a melt-quench glass or from a random packing of isolated units. The glass has the lowest energy and places the first-shell peaks correctly, but carries almost none of the oscillation beyond 6~Å (goodness of fit $R^{2} = 0.29$). Pure RMC fits the measurement to within its counting noise ($R^{2} = 0.99$), but at more than $1.3$~eV/atom above the glass, and niobium loses about half of its first-shell chlorine. Started from the glass, both hybrid schemes reach $R^{2} = 0.92$ within $0.1$~eV/atom of its energy and keep its coordination chemistry. Structures from the two inputs fit almost equally well and differ in energy by a tenth of the RMC penalty, yet they differ in whether their polyhedra are connected. The input is therefore part of the method. We recommend quenching a glass with a foundation potential and refining it against the measurement with a hybrid scheme. The resulting structure carries both the local chemistry and the medium-range order, and it is the starting point for modeling ion transport in these conductors.
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All authors Xintian Wang, Xinyu Zhang, Denys Butenko, Bolong Hong, Jinlong Zhu, Peichen Zhong