Geophysics
Flow-rate controls on trapped hydrogen redistribution in a heterogeneous sandstone: a synchrotron X-ray micro-CT study
Catherine Spurin, Sojwal Manoorkar, Sharon Ellman et al. (+7 more)
Subsurface hydrogen storage in porous geological formations is a promising strategy for balancing temporal mismatches between renewable energy generation and demand. The viability of large-scale hydrogen storage depends on predicting hydrogen distribution, trapping, and recovery during cyclic injection and withdrawal operations. However, these multiphase flow processes are influenced by rock heterogeneity, capillary hysteresis and trapping at the pore-scale. In this work, fast in-situ synchrotron X-ray
tomography was used to directly visualise hydrogen mobilisation during brine imbibition in a heterogeneous sandstone. By systematically varying the brine injection rate, the influence of flow conditions on hydrogen recovery, and the
evolution of trapped hydrogen were quantified. Significant mobilisation of disconnected hydrogen clusters was observed during imbibition, even at low capillary numbers ($< 10^{-6}$). Rock heterogeneity influenced trapping behaviour, particularly during the early stages of imbibition. Our results highlight the importance of incorporating pore-scale heterogeneity and transient trapping mechanisms into hydrogen storage predictions.
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All authors Catherine Spurin, Sojwal Manoorkar, Sharon Ellman, Ian B. Butler, Aliakbar Hassanpouryouzband, Damien Freitas, Fernando Alvarez-Borges, Robert Atwood, Katriona Edlmann, Eike Thaysen
Mesoscale and Nanoscale Physics
Symmetry considerations in chirality-induced spin selectivity
Dmitry Budker and Angela Wittmann
The chirality-induced
spin selectivity (CISS) effect, the coupling between structural chirality and electron
spin polarization, has been experimentally observed across many diverse systems. However, despite extensive theoretical effort, a unified mechanistic understanding remains elusive. In this perspective, we demonstrate how some of the basic properties of the fascinating effects of CISS can be understood based on straightforward
symmetry considerations commonly employed in fundamental particle physics. In particular, we show that CISS does not violate any fundamental
symmetries including parity and time-reversal. By anchoring CISS within the universal
language of
symmetry, we offer a robust conceptual foundation for interpreting experiments and guiding future theoretical and experimental designs.
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Quantum Physics
Floquet-Universal Hamiltonian Simulation
Emilio Onorati, Harriet Apel, Michael M. Wolf et al. (+1 more)
Analogue and digital
Hamiltonian simulation represent two distinct approaches to making one
quantum system replicate the physical properties of another, with consequences ranging from practical applications to complexity theory and
quantum gravity. They are rooted in two distinct regimes of
quantum dynamics: time-independent
Hamiltonians for the former; fully controllable time-dependent
quantum circuits in the latter. Time-periodic
Hamiltonians represent an intermediate regime. In this work, we establish a theory of Floquet simulation where we use periodically driven
Hamiltonians to synthesise time-independent ones. We show that a set of interactions $S$ can Floquet-simulate every
Hamiltonian in the Lie
algebra $\mathrm{Lie}(S)$, and consequently we give a complete and constructive characterisation of Floquet-universal
Hamiltonians that are able to produce any target
Hamiltonian. Notably, our construction uses only $O(1)$ local interaction strengths and ratios thereof, avoiding the impractical multi-scale local interaction strengths often required in analogue simulation via time-independent
Hamiltonians. Instead, the construction requires a range of driving frequencies which scales polynomially with system size for important classes such as $k$-local
lattice Hamiltonians. This has immediate complexity-theoretic implications, including numerous BQP-completeness and QMA-hardness results for natural physical properties and quantities studied in Floquet physics.
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All authors Emilio Onorati, Harriet Apel, Michael M. Wolf, Toby Cubitt
High Energy Astrophysical Phenomena
Recycling serendipitous observations of XRISM for dark matter searches
Lidiia Zadorozhna, Denys Malyshev and Oleg Ruchayskiy
Searches for radiative decays of keV-mass dark matter have been limited by energy resolution. We propose a strategy for the XRISM/Resolve low count rate observations, and search the 3.48-3.56 keV band for a decay line from the Milky Way
halo. Despite a lower exposure, our bounds are stronger than those from XRISM observations of
galaxy clusters. We also identify a residual at E = 3.5311 keV with ~3sigma local significance, coincident with the previously reported unidentified feature, and having no plausible atomic or instrumental counterpart. These bounds will continue to tighten as additional pointings become available.
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Pattern Formation and Solitons
Stability and instability analysis of resonance-induced nonlinear bound states
Jackson C. Turner and Michael I. Weinstein
We study the focusing one-dimensional cubic nonlinear Schrödinger / Gross–Pitaevskii equation (NLS-GP), where the potential of the underlying linear Schrödinger operator, $H_V=-\partial_x^2+V(x)$, is compactly supported. In \cite{turner2026resonance} the authors proved that purely imaginary zeros (transmission resonances) or purely imaginary poles in the lower half plane (scattering resonances) of a reflection coefficient of $H_V$ seed branches of resonance-induced nonlinear bound states, and that these states bifurcate at a strictly positive $L^2(\mathbb R)$ excitation threshold. This is in contrast to nonlinear bound states which bifurcate at zero $L^2$-norm from point spectra of $H_V$ (corresponding to poles in the upper half plane). In this paper we establish precise criteria for the nonlinear orbital stability and instability of the resonance-induced states near the bifurcation point. A corollary is that resonance-induced nonlinear states are orbitally stable if i) the underlying linear (scattering or transmission) resonance frequency is sufficiently small, and ii) the corresponding linear resonance eigenmode is strictly positive. Numerical simulations are presented to explore regimes not accessible to our theory, and to explore the large time dynamics for initial conditions near stable and unstable resonance-induced nonlinear bound states.
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Quantum Physics
Letao Wang, Abdel Lisser, Sreejith Sreekumar et al. (+1 more)
Geometric quantum machine learning incorporates
symmetry into
quantum models, but how
symmetry shapes their expressivity and guides effective model design remains insufficiently understood. We address this question through the
Fourier representation of
quantum Fourier models (QFMs).
Symmetry organizes the frequency spectrum into orbits and sums the
Fourier coefficients within each orbit into a symmetrized coefficient. When QFM trainable layers form independent exact 2-designs, the variance of each symmetrized coefficient equals the sum of the coefficient variances in its orbit. For single-layer QFMs with $\varepsilon$-approximate 2-design trainable layers, we bound the deviation from this identity. The resulting bound for individual
Fourier coefficients can be exponentially tighter than an existing bound. The hyperoctahedral group provides an example of orbit growth that can mitigate vanishing expressivity of the symmetrized coefficients. Symmetrization of QFMs over an elementary abelian 2-group also yields pure multivariate Chebyshev
polynomial basis functions. We introduce randomized encoding, which implements invariant models without ancilla
qubits or the additional
circuit depth for
quantum twirling. We evaluate the models as
quantum physics-informed neural networks (QPINNs) on two-dimensional screened Poisson and stationary viscous Hamilton-Jacobi equations. Under hard boundary constraints, QPINNs using exact symmetrization and randomized encoding achieve the lowest mean errors in the two
benchmarks, respectively.
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All authors Letao Wang, Abdel Lisser, Sreejith Sreekumar, Zeno Toffano
Mathematical Physics
Quadratic symmetry algebras and Sturm algebraization of superintegrable systems with magnetic fields
Shams Ara, Md Fazlul Hoque and Ian Marquette
We study two three-dimensional
quantum superintegrable systems in nonvanishing axially symmetric
magnetic fields. For each model the integrals generate a quadratic
algebra with a Casimir, and finite-dimensional deformed-oscillator representations yield algebraic spectra. The same spectra are recovered by separation of variables. In circular
parabolic coordinates the separated equations are sextic biconfluent-Heun equations with finite
polynomial sectors. We formulate them as Sturm
eigenvalue problems with the physical energy as a parameter and the separation constant diagonalized. After gauge transformation, each equation admits an $sl(2)$ algebraization and reduces to a finite tridiagonal
matrix. We also construct a pre-separation Sturm representation of each complete
Hamiltonian, taking the inverse-square coupling as the Sturm
eigenvalue. The transformed integrals remain commuting and, after fixing the axial integral, changing variables and gauge rotating, the two-variable Sturm
Hamiltonian and its non-central integrals belong to the universal enveloping
algebra $U(sl(3))$. We thus obtain three complementary algebraic descriptions: the quadratic-
algebra/deformed-oscillator representation of the original
Hamiltonian, the $sl(2)$ algebraization after
parabolic separation, and the $sl(3)$ algebraization of the complete Sturm problem before separation. Although the two
magnetic Hamiltonians are distinct in the original classification, fixing the axial integral reduces them to the same singular 2:1 oscillator normal form with different effective parameter
embeddings. This explains the common $sl(3)$ structure without implying equivalence of the original
magnetic systems. These results show how distinct hidden algebraic structures and exact or quasi-exact solvability can emerge at different stages of a multiseparable superintegrable system.
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Chaotic Dynamics
Multistability in the Duffing–Holmes oscillator: basins of antiperiodic, periodic, and chaotic attractors and their relative volumes
Arturo C. Marti and Edson D. Leonel
The periodically driven Duffing–Holmes oscillator is strongly multistable: for the same forcing amplitude and frequency, periodic, chaotic, and antiperiodic attractors coexist, each with its own basin of attraction. Antiperiodic orbits are periodic orbits invariant under a shift of half a driving period combined with a sign reversal of the coordinates, a
symmetry of the equations of motion. Guided by a continuation map of the parameter plane, which locates the regimes but is blind to their coexistence, we explore the space of initial conditions along two one-parameter cuts, at fixed forcing frequency and at fixed forcing amplitude.
Stochastic sampling of the full space yields an unbiased estimate of the relative volume of each basin as a function of the control parameter, on the same parameter grids on which single-trajectory bifurcation diagrams are computed by continuation. Basin maps on two-dimensional sections, complemented by maps of the order of the attractor reached from each initial condition, resolve the geometry of the coexisting basins where the competition between attractors is strongest. The relative volumes reveal windows of global antiperiodic dominance, in which the antiperiodic orbit attracts essentially every initial condition, separated by narrow intervals in which two or three qualitatively different attractors share the space in comparable proportions, as well as extended ranges of persistent coexistence; at large forcing amplitude, a single antiperiodic orbit of order one captures the whole space. Compared with the bifurcation diagrams, the abrupt changes of basin volume are the ensemble-level counterpart of the multistability-induced discontinuities of the sweeps, and the gradual shrinking of the antiperiodic basin explains why the branch followed by a sweep depends on the initial state and on the drive phase.
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Instrumentation and Methods for Astrophysics
hyprfine: simulating the 21-cm signal from the Dark Ages through to the Epoch of Reionization on a GPU
Harry T. J. Bevins
hyprfine is an analytic simulation of the sky-averaged 21-cm signal from $z=1100 - 6$ written using JAX and Python for native GPU capabilities. It models the average temperature of the 21-cm signal over
cosmic time as a function of the $\Lambda$-CDM cosmology parameters and the astrophysics of the first
stars and
galaxies. As far as we are aware, the code is the first analytic GPU native simulation of the 21-cm signal. It runs in a fraction of a second, parallelises efficiently across a GPU and is differentiable through the Dark Ages ($z \geq 35$). The code is publicly available at https://www.github.com/htjb/hyprfine.
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High Energy Physics (Theory)
Coherent Release Fronts in Krylov Chains and Thermal AdS$_2$ Response
Mohsen Alishahiha
We study coherent release from a finite serial Krylov sector into an exact conformal tail with asymptotically linear Lanczos coefficients. We derive the cumulative occupation up to a cut that moves to greater Krylov depth with time, tracking the probability accumulated behind the propagating front. This quantity separates the release dynamics of the finite sector from subsequent propagation through the tail. The tail sets the logarithmic transit scale, while the finite sector shapes the resulting distribution. The early edge records the number of serial steps before emission, while the late edge reflects slow resonances and interference and can also exhibit logarithmic enhancements. Thus, one- and two-site sectors can share the same leading resonance in their continued-fraction descriptions yet produce distinct cumulative occupation patterns. We illustrate this framework in thermal AdS$_2$, where a dressed oscillator yields, in the weak-coupling limit, a two-site shallow sector coupled to the conformal tail.
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Quantum Physics
Approximation theorems for fermionic Gaussian states
Amir-Reza Negari, Farzin Salek, Zoltán Zimborás et al. (+3 more)
A recurring principle in many-body physics is that sufficiently distributed interactions or correlations lead to an effectively mean-field description. For fermionic Gaussian states, we establish a quantitative version of this principle directly at the level of Majorana covariance
matrices. The main observation is that the admissibility condition for fermionic covariance
matrices imposes a quantitative monogamy constraint on two-point correlations: a fixed region has only a bounded covariance budget to distribute among many disjoint regions. We use this principle in three directions. First, for quadratic fermionic
Hamiltonians on finite simple graphs of high degree, we obtain product-state approximations to both the ground-state energy and the finite-temperature free energy, with error of order \(D^{-1/2}\) for \(D\)-regular graphs. Second, we prove a finite fermionic Gaussian de Finetti
theorem: a \(k\)-copy Gaussian state that is \(n\)-exchangeable under graded fermionic copy permutations is \(O(k/n)\)-close in trace norm to the product of its one-copy marginal. In particular, infinite exchangeability within the Gaussian class implies exact product structure. Third, for spatial fermionic Gaussian states with exponentially clustering mutual information, we prove that the conditional mutual information across a separating buffer decays as \(O(r^{-1})\), and hence, by recoverability, the state admits an \(O(r^{-1/2})\) trace-norm approximation by a recovered state. These results show that product and de Finetti approximations and recoverability estimates for fermionic Gaussian systems can all be derived directly from covariance-level structure.
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All authors Amir-Reza Negari, Farzin Salek, Zoltán Zimborás, Aram Harrow, Patrick Hayden, Jens Eisert
Fluid Dynamics
Rapid generation of relaxed centimeter-sized drops by capillary auto-ejection
Patric Mueller, Kai Ihrig, Achim Sack et al. (+2 more)
Many microgravity experiments require centimeter-sized spherical
liquid drops. In drop-tower experiments, only a few seconds of microgravity are available, so the drops must be generated and reach a nearly relaxed state within a very short time. We investigate capillary auto-ejection (puddle jumping) as a passive mechanism for producing free-floating drops and investigate how the supporting cavity can be shaped to minimize the relaxation time after ejection. For cavities with a
parabolic cross-section filled with a fixed
liquid volume, minimization of the initial
liquid surface area yields a unique shape, and smoothed particle hydrodynamics simulations show that this shape also gives the shortest relaxation time within the
parabolic family. Introducing a shallow central depression into the cavity reduces the relaxation time further, despite producing a larger initial
liquid surface area. These results provide design principles for capillary-driven drop generators that enable the rapid production of relaxed centimeter-sized drops during the short microgravity intervals available in drop towers.
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All authors Patric Mueller, Kai Ihrig, Achim Sack, Jonathan E. Kollmer, Thorsten Poeschel
Quantum Physics
Quantum Optimal Transport Barycenters: Existence, Duality, and Gaussian Rigidity
Augusto Gerolin and Zhiyi Lin
We develop a
Quantum Optimal Transport (QOT) barycenter framework for
quantum states, as an analog of Wasserstein barycenters~\cite{AguCar}, and establish existence and duality results for a broad class of possibly unbounded transport costs on separable
Hilbert spaces. Our framework provides, in particular, a unified treatment of $2$-
quantum Wasserstein (QW) barycenters in both the
quantum-state and
quantum-channel formulations by specializing to the canonical quadratic cost operators associated with the $2$-
quantum Wasserstein distances of Caglioti–Golse–Mouhot–Paul~\cite{caglioti2021towards,Golse-Mouhot-Paul:2016} and De Palma–Trevisan~\cite{DPaTre19}. The central results concern Gaussian input states and, in particular, Gaussian
rigidity: whether Gaussian input states force the 2-QW barycenter itself to be Gaussian and uniquely determined when the minimization is taken over all
quantum states. We first show that the barycenter problem admits a Gaussian minimizer and reduces to a finite-dimensional convex optimization problem over covariance
matrices. The main difficulty is that uniqueness of the optimal covariance does not, in general, imply uniqueness of the underlying
quantum state. We bridge this gap through a state-reconstruction principle under covariance complementary slackness that upgrades uniqueness of the optimal covariance to uniqueness of the full
quantum state, and thereby prove a global
rigidity theorem: if at least one Gaussian input is faithful, then the barycenter is unique among all
quantum states and is necessarily Gaussian. Faithfulness is sufficient but not necessary: families of pure inputs still determine a unique barycenter, whereas partially pure nonfaithful Gaussian inputs may admit multiple barycenters.
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Fluid Dynamics
Direct Modeling of Pore Size Evolution and Microcollapse in Lyophilization by Population Balance
Isaac Stonewall Wheeler, Vivek Narsimhan, Alina A. Alexeenko et al. (+1 more)
In the primary drying step of pharmaceutical freeze drying, it is well known that amorphous excipients are prone to "microcollapse" as they approach their glass transition temperature. Existing modeling approaches for this phenomenon generally entail either avoidance of this regime or an experimentally burdensome empirical assessment of the resulting drop in resistance to mass transfer. In this work, we approach the phenomenon head-on by developing a population balance model for the pore size distribution of a freeze-dried cake during microcollapse and relating the pore size to mass transfer resistance. By treating the population balance with the method of moments and an interpolative closure, we keep the model's computational burden on par with the literature-standard model for primary drying. For a literature example when mass transfer resistance clearly varies as a function of product temperature during drying, we fit the population balance model to cases with high and low product temperature and show that it can then simulate intermediate cases with equal accuracy. The validity of the expression for mass transfer resistance is demonstrated with another literature data set, where pore size distributions were measured after the fact for a formulation without microcollapse; only a single parameter from this model needs to be fit to those cases to yield predictive accuracy in product temperature on par with post-hoc empirical assessment. Finally, a sophisticated multi-experiment fit for one formulation across a range of conditions yields quantitative agreement in product temperatures, suggesting that the rate constant for microcollapse behavior may be a material parameter and independent of the precise porous geometry.
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All authors Isaac Stonewall Wheeler, Vivek Narsimhan, Alina A. Alexeenko, Davide Fissore
High Energy Astrophysical Phenomena
Slingshot on compact binaries in the nuclear region of galaxies as the origin of large offset gamma-ray bursts
Juan C. Rodríguez-Ramírez, Viviane Alfradique, Clécio R. Bom et al. (+1 more)
A growing number of gamma-ray bursts (GRBs) have been observed at large projected offsets from the centres of their putative host
galaxies, sometimes extending to several tens of kiloparsecs. When the GRB is associated with a kilonova, a compact binary with at least one
neutron star is expected to be involved, and the cause of the offset can be attributed to the
neutron star natal kick. In this work, we explore an alternative mechanism: the gravitational scattering of compact binaries populating the
nuclear region of the host
galaxy, by an intermediate-mass black hole or secondary supermassive black hole. We specifically consider populations of
neutron star-
neutron star (NS-NS),
neutron star-black hole (NS-BH), and
neutron star-white
dwarf (NS-WD) binaries, and analyse the ejection of bound systems from the
nuclear region through a gravitational-slingshot effect. We proceed analytically to derive the conditions for binary survival and to parametrise the post-encounter velocity. To quantify the associated merger offsets, we numerically integrate the post-slingshot trajectory of the binary centre-of-mass in host-
galaxy potentials that include the primary SMBH, the
stellar component, and the dark-matter
halo, considering both elliptical-like and spiral-like
galaxy profiles. Our parameter sampling shows that NS-NS and NS-WD binaries typically merge farther from the
galactic centre than NS-BH systems, with approximately 30-45% of successful ejections merging at three-dimensional distances exceeding 100 kpc; these extreme-offset mergers occur within $\sim$0.1-10 Gyr after ejection. These results motivate the analysed mechanism as a candidate channel for observed extreme-offset transients.
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All authors Juan C. Rodríguez-Ramírez, Viviane Alfradique, Clécio R. Bom, Davi C. Rodrigues
Quantum Physics
Trapdoored Clifford Operators and Applications
Minki Hhan and Hojune Lee
Random Clifford operators have numerous applications in
quantum computing, including randomized benchmarking, classical shadows, and
quantum authentication. However, sampling and implementing uniformly random $n$-
qubit Clifford incur near-quadratic complexity due to the size of Clifford group. We introduce a cryptographic way to overcome these barriers: trapdoored Clifford operator distributions whose samples are computationally indistinguishable from uniformly random Cliffords, yet implementing them can be much faster given the trapdoor. We construct a distribution of trapdoored Clifford operators whose elements can be sampled and implemented in near-linear time under a variant of the learning parity with noise assumption. Our constructions allow fast tableau action on Pauli labels for classical simulation, and also can be optimized to admit polylogarithmic-depth implementation. Along the way, we construct trapdoored
matrices over finite fields that support efficient multiplication by both a
matrix and its inverse, resolving an open question left by Vaikuntanathan and Zamir [SODA'26]. We use these constructions to obtain faster protocols based on random Cliffords. We also explore their applications to the worst-case to average-case reductions for
matrix and Clifford problems including the iterated
matrix multiplication and Clifford
circuit synthesis. In particular, we show the hardness of batching Clifford
circuits: synthesizing
circuits that apply the same Clifford to multiple registers is at least as hard as worst-case
matrix multiplication, even when synthesis succeeds on a small constant fraction of random Cliffords. This extends to approximate implementations by general
quantum circuits.
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Mathematical Physics · Cross-listed from math.FA
Ballistic Speed and Potential-Theoretic Recurrence for Homogeneous Open Quantum Random Walks
Ameur Dhahri, Chul Ki Ko, Farrukh Mukhamedov et al. (+1 more)
Our study connects root-mean-square ballistic transport to potential-theoretic recurrence for finite-range open
quantum random walks. In homogeneous walks with primitive local channels, finitely many simple periodic
Fourier peripheral
eigenvalues, no nonzero stationary
Fourier mode, and a nondegenerate quadratic spectral term, we prove a periodic uniform local limit
theorem and recover exponential finite-set return bounds for nonzero drift. The centered case yields strong Green-function asymptotics in at least three dimensions, as well as potential-kernel asymptotics in one and two dimensions. According to these assumptions, the RMS ballistic speed equals the drift norm, nonzero drift indicates transience, and centered walks are recurring in effective dimensions one and two but transitory in higher dimensions. The low-dimensional finding shows a recurrence of the origin projection in TOM. For reducible walks, an explicit harmonic \(h\)-transform converts each absorption component to an OQRW, providing a detailed breakdown of Green occupation potentials. The squared RMS speed is the absorption-weighted mean of squared component drifts, but the reduced drift-dimension classification also needs specific component return estimations. A centered noncommuting family validates the fundamental spectral assumptions in all dimensions and provides explicit potential constants. Exact finite traps and sparse reflecting barriers provide a complementary nonhomogeneous method for zero speed and TOM recurrence.
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All authors Ameur Dhahri, Chul Ki Ko, Farrukh Mukhamedov, Hyun Jae Yoo
Mathematical Physics
Quantum hierarchies of the ILW and BO equations and the DR cycles on the moduli spaces of curves
Alexandr Buryak and Abner Hernandez Rodriguez
In an earlier paper of P. Rossi and the first author, a construction of a wide class of
quantum hierarchies was presented, with the input data given by an arbitrary cohomological field theory. A crucial role in the construction is played by the double ramification (DR) cycles on the
moduli spaces of stable curves. As a special case, one gets a quantization of the hierarchy of the Intermediate Long Wave (ILW) equation. The ILW equation has two famous limits: the Korteweg–de Vries equation and the Benjamin–Ono (BO) equation, and for the latter one a
quantum hierarchy was constructed by Nazarov and Sklyanin. In our paper, we propose a
conjecture describing a relation between a limit of the
quantum ILW hierarchy and the Nazarov–Sklyanin hierarchy and present various checks to support it.
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Computational Physics
RFBniCS: An open-source simulation framework for redox flow batteries
Amirhossein Aghabarari, Jørgen S. Dokken, Martin T. Horsch et al. (+2 more)
We present RFBniCS, an open-source finite-element framework implemented in FEniCSx for simulating redox-flow-battery (RFB) half-
cells. RFBniCS solves an established macro-homogeneous porous-electrode model accounting for strongly coupled electrolyte flow, multicomponent species transport, ionic and electronic charge conservation, and interfacial Faradaic charge transfer. Different from other open-access tools, RFBniCS can perform transient RFB half-
cell simulations in one-, two-, and three-dimensional geometries while explicitly resolving the transport of both redox-active and supporting-electrolyte species. It also describes electrolyte flow through porous electrodes and, in the three-dimensional formulation, through adjacent flow channels. To verify the implementation, RFBniCS's predictions in parameter-limiting regimes are compared against other published implementations, with RFBniCS generally showing superior accuracy and speed. We further demonstrate RFBniCS's capabilities by a simulation of the transient response of the negative half-
cell of a vanadium redox flow battery, with a moderately concentrated supporting electrolyte. In the current implementation, RFBniCS provides the computational basis for studying redox-flow-battery half-
cells and can be extended to complex flow-field designs, alternative chemistries, full-
cell coupling, detailed membrane transport, and additional multiphysics effects.
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All authors Amirhossein Aghabarari, Jørgen S. Dokken, Martin T. Horsch, Eirik Valseth, Mathijs Janssen
Quantum Physics
Toward Optimal Circuit Depth for Geometrically Local Hamiltonian Simulation
Zheyu Shen, Yusen Wu, Penghui Yao et al. (+2 more)
Understanding the dynamics of interacting
quantum systems is a central goal of
quantum simulation. For geometrically local
Hamiltonians, locality suggests that digital simulation should retain much of the parallelism of the underlying dynamics. For a target accuracy $\epsilon$, we construct a nearest-neighbor
quantum circuit that simulates the dynamics of an $n$-
qubit, time-independent, finite-range
Hamiltonian with normalized local interaction strength on a fixed-dimensional
lattice for time $T\ge1$, with
circuit depth $O(T\log(nT/\epsilon))$ and gate count $O(nT\log(nT/\epsilon))$. This reduces the polylogarithmic overhead of Haah, Hastings, Kothari, and Low to a single logarithm. On logarithmic-scale blocks from the Lieb–Robinson decomposition, a shallow but highly accurate implementation is essential for reducing the
circuit depth. Our key observation is that spatial localization also controls the cost of high precision. In each block, the error of a constant-order product formula is compensated for by a correction, yielding exponential accuracy. The correction can be implemented with depth proportional to the block diameter, introducing no additional asymptotic depth scale beyond that required by spatial localization. Furthermore, we prove an unconditional
circuit-depth lower bound for uniform XXZ
Hamiltonians: at fixed
evolution time $T$ in the stated regime and sufficiently small fixed error $\epsilon$, any nearest-neighbor
quantum circuit simulating these dynamics requires depth $\Omega(\log n/\log\log n)$. This matches our $O(\log n)$ upper bound up to a doubly logarithmic factor, establishing near-optimal
circuit depth for
lattice Hamiltonian simulation in this regime. Together, these results clarify the role of locality and precision in determining the
circuit complexity of
quantum dynamics and suggest broader principles for spatially constrained
quantum computation.
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All authors Zheyu Shen, Yusen Wu, Penghui Yao, Xiao Yuan, Yukun Zhang
Cosmology and Nongalactic Astrophysics
Cosmological inference from a joint DESI DR1 full-shape power spectrum and bispectrum analysis
Caroline Guandalin, Prakhar Bansal, Pedro Carrilho et al. (+9 more)
The
galaxy bispectrum directly probes the non-linear gravitational
evolution of large-scale structure (LSS) and can break parameter degeneracies that remain in power-spectrum analyses. We present a joint full-shape cosmological analysis of three luminous red
galaxy (LRG)
redshift bins and the
quasar (QSO) sample from the first Data Release (DR1) of the Dark Energy Spectroscopic Instrument (DESI). We model the
redshift-space power spectrum at one loop and the tree-level bispectrum within the Effective Field Theory of LSS. The bispectrum is decomposed in the Tripolar Spherical Harmonics basis, for which the convolution with the survey window function can be formulated as a direct linear transformation of the theoretical multipoles. Our power-spectrum constraints are in good agreement with the official DESI DR1 full-modelling results. We investigate the impact of including the bispectrum in the inference, finding that the monopole substantially improves the constraints on the cold dark matter density and amplitude of matter fluctuations by 9-18% and 8-20%, respectively, in the individual-tracer analyses. The corresponding reductions are 15% and 10% for the combined LRG sample, and 6% and 4% when all tracers are combined. In a restricted test using the first LRG bin, the bispectrum quadrupole changes the marginalised uncertainties by only a few percent. Extending the analysis to $w_0w_a$CDM substantially broadens the cosmological posteriors, while the bispectrum produces only a mild change in the allowed dark-energy parameter region, which remains sensitive to the adopted prior ranges. Our results demonstrate the potential of higher-order clustering statistics to improve cosmological constraints, while providing a framework for incorporating the bispectrum into full-shape analyses of current and future spectroscopic
galaxy surveys.
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All authors Caroline Guandalin, Prakhar Bansal, Pedro Carrilho, Alejandro Aviles, Mike Shengbo Wang, Marcos Pellejero-Ibañez, Aaditya Sarma, Jaide Swanson, Marco Bonici, Florian Beutler, Arnaud de Mattia, Hee-Jong Seo
Atmospheric and Oceanic Physics
Varda-single-1.0: deterministic data-driven weather forecasting at 1 km resolution over Switzerland's complex topography
Alberto Pennino, Francesco Zanetta, Michele Cattaneo et al. (+28 more)
We present Varda-single-1.0, a medium-range data-driven weather prediction system built for the Alpine domain. It provides hourly deterministic regional forecasts on a mesh of 1 km resolution and global forecasts on a 31 km mesh. The system comprises two independently trained stretched-grid Graph
Transformer models with encoder-processor-decoder architecture, developed in the Anemoi framework: a 6-hourly autoregressive forecaster and a temporal downscaler reconstructing hourly forecasts between the forecaster's steps. Its training curriculum includes pre-training on ERA5 reanalysis data, followed by training on a 20-year kilometre-scale regional reanalysis, and finally fine-tuning on operational kilometre-scale analyses. Verified over one year against operational analyses and surface station observations, Varda-single is competitive with or improves on MeteoSwiss' operational numerical weather prediction baselines for most headline scores and variables. It broadly matches the skill of the high-resolution 1 km ICON-CH1-EPS control at lead times up to +33 h and generally outperforms the 2 km ICON-CH2-EPS control at lead times up to +120 h. Despite competitive aggregate scores, Varda-single underestimates some local wind maxima and produces overly smooth convective precipitation fields, consistent with the smoothing associated with squared-error training. To gain insight into the model's behaviour, we investigate three case studies beyond the aggregated headline scores, and find particular weaknesses in Varda-single's representation of local winds over complex terrain. Varda-single represents an important step in the development of high-resolution ML
forecasting over complex terrain, in complementing the operational regional numerical weather prediction models of MeteoSwiss with data-driven models and in providing a pretrained model for researchers and user-specific applications.
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All authors Alberto Pennino, Francesco Zanetta, Michele Cattaneo, Claire Merker, Radi Radev, Jonas Bhend, Louis Frey, Hugues de Laroussilhe, Ophélia Miralles, Carlos Osuna, Daniele Nerini, Andreas Pauling, Daniel Hupp, Ulrich Hamann, Mary McGlohon, Marti Bosch, Luca Lanzilao, Marco Arpagaus, Lukas Jansing, Daniel Leuenberger, Mark A. Liniger, Katrin Ehlert, Matthew Chantry, Håvard Homleid Haugen, Gert Mertes, Ana Prieto Nemesio, Mario Santa Cruz, Jasper Wijnands, Gabriel Moldovan, Harrison Cook, Oliver Fuhrer
Quantum Physics
Experimental realization of Wheeler's delayed-choice experiment with dual selections
Xiaowan Yang, Xinglei Yu, Liangsheng Li et al. (+5 more)
Wheeler's delayed-choice experiment demonstrates wave-particle duality of particles using different experimental configurations of a Mach-Zehnder interferometer. In a
quantum version of this experiment, the wave-particle behavior of
photons can be observed by controlling presence or absence of the second beam splitter. Here, we implement a delayed-choice experiment with dual selections based on entangled
photons, experimentally controlling both of two beam splitters in the Mach-Zehnder interferometer, where the presence and absence of the second beam splitter are simultaneously controlled through path encoding. Our experiment reveals the wave-particle behavior of single
photons under different configurations of two beam splitters. We further discuss the scenario when two beam splitters are in a
quantum superposition of being present and absent,
photons will be in a wave-particle
quantum superposition state.
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All authors Xiaowan Yang, Xinglei Yu, Liangsheng Li, Xinzhi Zhao, Tianle Zheng, Chengjie Zhang, Chuan-Feng Li, Guang-Can Guo
Mesoscale and Nanoscale Physics
Flux- and tunnel-parity-controlled Josephson nonreciprocity from singlet-triplet competition in a parallel double quantum dot
Debika Debnath, Fernando Dominguez and Patrik Recher
Nonreciprocal supercurrents in interacting nanostructures can arise when the positive and negative critical currents probe inequivalent portions of a phase-dependent many-body spectrum. We study this mechanism in a parallel double-
quantum-dot Josephson junction with strong intradot Coulomb repulsion, where local and non-local Cooper-pair transfer coexist. Using exact diagonalization of a zero-bandwidth
Hamiltonian with explicit superconducting orbitals, we show that orbital flux and the gauge-invariant tunnel-sign parity control the interference between local Josephson processes and non-local exchange. For detuned dots, this produces flux-tunable singlet, triplet, and doublet ground-state spectral branches and two rectification regimes. Near the boundaries of the charge sector with singly occupied dots [(1,1) sector], doublet branches compete with singlet or triplet branches, yielding diode efficiencies approaching 40%. Within the triplet-dominated (1,1) sector, nearby singlet crossings asymmetrically reshape the ground-state envelope even when both critical-current extrema lie on the triplet-like branch, producing a broader response of order 10-15%. Finite temperature generally suppresses charge-crossover rectification, however, for intermediate temperatures we find an enhancement of both the normalized efficiency and the absolute critical-current asymmetry in the triplet regime. These results establish phase-dependent many-body branch competition as a gate-, flux-, and tunnel-parity-sensitive source of Josephson nonreciprocity.
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High Energy Physics (Phenomenology)
Near Threshold Kaluza-Klein Graviton Decays and the Dark Dimension
Kevin Langhoff
Near threshold, intra-tower decays of Kaluza-Klein (KK) gravitons are pure $d$-wave, with rate $\Gamma \propto p^5$ in the decay products momentum $p$, rather than the $s$-wave $\Gamma \propto p$ assumed in the dark dimension literature. In a flat dark dimension this excludes KK gravitons as a dark matter candidate. Even if some other source of dark matter is assumed, the irreducible freeze-in abundance of KK gravitons produce MeV gamma rays which allows one to set upper limits on the reheating temperature; additionally using the lower bound on the reheating temperature from big-bang nucleosynthesis and the
cosmic microwave background requires the radius of the extra dimension to be almost three orders of magnitude smaller than the distance
conjecture would naively prefer, $R\sim \Lambda^{-1/4}$.
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Quantum Physics
QPI-DeepONet-MAC: A Scalable and Stable Hybrid Classical-Quantum Architecture for Physics-Informed Deep Operator Networks
Said Lantigua, José Valencia, Gilson Giraldi et al. (+2 more)
General operator learning for parametric partial differential equations (PDEs) is a fundamental challenge at the intersection of artificial intelligence and physics-based modeling. Physics-informed Deep Operator Networks (PI-DeepONets) incorporate governing equations into learning, but face optimization difficulties in high dimensions.
Quantum extensions offer additional representational capacity, yet their trainability can be hindered by barren plateaus. Here, we introduce QPI-DeepONet-MAC, a hybrid
quantum-classical architecture that integrates parameterized
quantum circuits into PI-DeepONets through a multiplicative-and-additive coupling (MAC) of classical representations and
quantum expectation values. We prove analytically that the proposed architecture retains universal operator approximation capabilities. Furthermore, we derive bounds on
quantum parameter gradients, establishing explicit conditions to avoid barren plateaus alongside a scaling criterion for trainability. Additionally, we derive a lower bound on the number of sensors required for a target accuracy, directly linking sampling requirements to input function regularity, domain dimension, and PDE dynamical growth. Finally, we propose an informational regularization scheme based on
quantum coherence and state fidelity dynamics to prevent coherence loss and preserve
quantum structure during training. Together, these results establish a theoretical foundation for
quantum-enhanced physics-informed operator learning and position QPI-DeepONet-MAC as a scalable, stable framework for solving parametric PDEs.
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All authors Said Lantigua, José Valencia, Gilson Giraldi, Renato Portugal, Jonas Maziero
Astrophysics of Galaxies
Diverse Protoclusters at $z\sim3$ Disclosed by Systematic Spectroscopy
Jun Toshikawa, Kentaro Koretomo, Nobunari Kashikawa et al. (+6 more)
We present the results from follow-up spectroscopy of three protocluster candidates at $z\sim3$, selected as overdense regions of $U$-dropout
galaxies in the wide-field imaging of the Hyper SuprimeCam Subaru Strategic Programme. All three targets exhibit tight clustering in three-dimensional space, i.e. on the sky ($>4\sigma$ overdensity) and in
redshift ($>98.4\%$ confidence), making for clear evidence of genuine protoclusters. Since these three protoclusters are identified by the same
dataset and technique, they represent a good sample to study the diversity of protocluster properties with minimal observational biases. Although the average population across the three protoclusters is consistent with field
galaxies, each protocluster individually exhibits distinguishing properties from each other or from field
galaxies. In one protocluster, member
galaxies stand out by a higher Ly$\alpha$ equivalent width ($EW_0$), and massive members that are still highly
star-forming. In contrast, relatively more suppressed
star formation appears in another protocluster where the Ly$\alpha$ $EW_0$ of member
galaxies is systematically lower. These variations can be attributed to differences in the developmental phase of protoclusters. If the presence of quenching
galaxies indicates a more mature system,
galaxies with stronger Ly$\alpha$ emissions may be more prevalent in the earlier stages of cluster formation. The uniform approach to searching protoclusters on which this study builds enables us to link observed variations at the onset of
cosmic noon to different pathways in the history of cluster formation.
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All authors Jun Toshikawa, Kentaro Koretomo, Nobunari Kashikawa, Stijn Wuyts, Marcin Sawicki, Malcolm N. Bremer, Yoshiaki Ono, Mariko Kubo, Tomoki Saito
Quantum Physics
Collision models: Markovian and Non-Markovian impurity models
Jacob Werner
Collision models provide a flexible framework for studying open
quantum systems and introducing non-Markovianity. We present a novel class of collision models, which we term Markovian
impurity models, motivated by physical scenarios in which information backflow is periodically blocked. Using the Breuer-Laine-Piilo (BLP) measure of non-Markovianity, we show that if a $p$-
impurity model is non-Markovian, then the corresponding $(p+1)$-
impurity model is also non-Markovian, implying the existence of a critical $p$ at which the process transitions from Markovian to non-Markovian. Numerical simulations are used to investigate how this critical parameter depends on the system-ancilla and ancilla-ancilla interaction strengths. We find that, altough exceptions exist, increasing either interaction strength generally lowers the critical $p$, while sufficiently weak ancilla-ancilla interactions lead to a regime in which the dynamics remain Markovian even in the absence of
impurities. Finally, we briefly introduce the complementary non-Markovian
impurity model.
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Astrophysics of Galaxies
Galaxy Protoclusters as Drivers of Cosmic Reionization: II. Te-Based Metallicities of Lyman-{\alpha} Emitters
C. Moya-Sierralta, C. L. Martin, L. F. Barrientos et al. (+15 more)
Context. Protoclusters at reionization are thought to host a significant fraction of the
cosmic star formation rate density, making them crucial for the timing and
topology of reionization. The gas-phase
metallicity, a key tracer of
galaxy evolutionary stage, can now be measured directly in the early Universe with JWST. Aims. We measure the gas-phase
metallicity of Lyman-$\alpha$ emitters (LAEs) in the LAGER-z7OD1 protocluster at $z\approx6.93$ via the direct ($T_e$-based) method using the [O III]$\lambda$4363 auroral line, and combine it with
stellar masses to constrain the mass-
metallicity relation (MZR) in dense environments. Methods. We use JWST/NIRSpec MSA G395H spectroscopy, derive
metallicities with self-consistent analytic prescriptions, and propagate the
dust-extinction uncertainty into an asymmetric error budget via Monte Carlo simulations based on the observed Balmer decrements.
Stellar masses come from BEAGLE SED fitting of JWST/NIRCam and UltraVISTA photometry. Results. We obtain five secure [O III]$\lambda$4363 detections and one upper limit, with 12+log(O/H) $\approx$ 7.2-8.0. The weighted spectral stack yields 12+log(O/H) = $7.76^{+0.06}_{-0.05}$, ~0.26 dex higher than stacks of LAEs at similar
redshifts from JWST surveys. However, the MZR fit gives a slope $\gamma$ = 0.232 +/- 0.214 and normalization $Z_0$ = 7.888 +/- 0.199, placing our sources below the established MZR of normal
galaxies and recent protocluster baselines at $z\sim5-7$. Conclusions. The higher
metallicity relative to general LAEs suggests accelerated assembly driven by the overdensity, while the offset below the MZR points to a complex interplay between mass build-up and gas
accretion. Since we target actively
star-forming LAEs, we are likely capturing a phase of pristine gas inflow from the intergalactic medium that fuels
star formation but dilutes the interstellar media of these protocluster members.
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All authors C. Moya-Sierralta, C. L. Martin, L. F. Barrientos, L. Infante, J. González-López, W. Hu, A. L. Faisst, Y. Harikane, A. M. Koekemoer, S. Malhotra, M. Ouchi, Z. Peng, J. Rhoads, J. Wang, J. R. Weaver, I. Wold, J. Yang, Z. Zheng
High Energy Physics (Phenomenology)
Probing the neutrino mass through semileptonic decays
Claire Chevallier
We argue that a detailed analysis of semileptonic decays can test the possibility of a massive
neutrino. The key observable, related to the forward-backward asymmetry, is exactly zero for a massless
neutrino but becomes non-zero if the neutral
lepton is heavy and interacts with Standard Model fields via left-handed operators. For right-handed interactions, this quantity differs significantly from zero even for a massless right-handed
neutrino. We demonstrate this explicitly using the example of a pseudoscalar
meson decaying into another pseudoscalar
meson.
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