Papers

The proposal is to probe Majorana modes in the system when its parameters are tuned to bring it into a disentangled ground state, which occur on the parametric curves known as disorder lines (DL). In such state certain correlation functions do not depend on separation. The exact results are presented for the XY spin chain in transverse field, also called the Kitaev chain in the Majorana representation. The single Majorana modes are shown to be localized near the ends of the chain, as in the states off the DL, while the disentangled $n$-particle Majorana modes ($n \geq 2$) penetrate into the bulk without attenuation. The predicted bulk-edge effects can be detected in the specially engineered optical chains and lattices.

We propose a method to realize stable, tunable two-component quantum mixtures of ultracold polar molecules. First, we show that a pair of polar molecules in two distinct rovibrational states exhibits a repulsive interaction, thereby leading to collisional shielding without requiring any external field. We refer to this as "vibrational shielding". This intercomponent interaction is tunable by an external static electric or a microwave field, with the latter stabilizing both inter- and intracomponent interactions in a two-component bulk mixture. Additionally, we show that two microwave fields can independently tune the interactions of the individual components. Our findings thus open the door to the experimental realization of tunable quantum mixtures using polar molecules, analogous to tunable magnetic Feshbach resonances in two-component atomic quantum gases.

A key enabling feature of future quantum networks is interoperability between platforms that operate at different wavelengths and with different qubit encodings. We demonstrate an interface that converts atom-photon entanglement from polarization encoding at an atomic wavelength to time-bin encoding in the telecom C-band. Atom-entangled photons at 854 nm are generated from a single $^{40}$Ca$^+$ ion. After quantum frequency conversion to 1550 nm, the photonic polarization qubit is converted into a time-bin qubit using a fiber-based Mach–Zehnder-like encoder. Full quantum tomography of the final state verifies that the process preserves entanglement with 96.3(4.2)% fidelity. Together with the independent work of Ferrari et al. [arXiv:2607.07805 (2026)], this is the first demonstration of polarization-to-time-bin conversion of photons entangled with a single atomic quantum memory. The telecom-compatible interface enables robust qubit transmission over optical fibers and provides a key building block for heterogeneous quantum networking architectures.

A recently derived nonlinear velocity theory of extreme type-II superconductors is shown to possess an exactly solvable one-dimensional sector. Its solutions include nonlinear Meissner states exhibiting universal tails, vortex sheets, and periodic laminar structures. The thermodynamic critical field emerges from a marginal Meissner profile equivalent to the normal-superconducting boundary and may be viewed as a half-soliton. The vortex sheet is a soliton characterized by a discontinuity of the velocity field, a continuous and localized magnetic field and vanishing superconducting density at its center, and may be interpreted as the coarse-grained limit of a dense row of Abrikosov vortices. Periodic solutions describe laminar states that may be interpreted as coarse-grained rectangular vortex lattices.

Qubit loss occurs when the physical carrier of a qubit leaves the computational system without directly revealing the event's location. Such errors are a major obstacle to fault-tolerant quantum computation on platforms including photonic, neutral-atom, and trapped-ion systems. Loss locations are commonly identified using additional hardware operations such as leakage-detection units (LDUs), which introduce space-time overhead and may themselves become a source of error. We investigate whether qubit loss on stabilizer codes can instead be inferred from syndrome data obtained through standard repeated stabilizer measurements. Under a non-entangling model for gates involving a lost qubit, we derive a sufficient condition for loss detectability in general stabilizer codes. The condition is based on the emergence of anticommutation between stabilizer checks after their support on the lost qubits is removed. By using that condition, we formulate the exact loss-inference problem using the observed set of non-deterministic checks together with its maximum-likelihood formulation. We then relax the problem to the minimum set cover problem with a greedy heuristic algorithm. We evaluate the resulting inference and loss-correction protocols on the rotated surface code via circuit-level noise simulations for trapped-ion and neutral-atom platforms. On both platforms, inference-based and adaptive protocols reduce the logical error rate relative to a noisy-LDU baseline in the low-to-moderate loss-rate regime relevant to near-term hardware, while requiring fewer space-time overheads.

Superselective multivalent binding enables sharp receptor-density discrimination in targeting and sensing, but what its logarithmic response measures microscopically remains unclear. Here, we derive an exact response decomposition of the selectivity into receptor-state reweighting and a direct occupation response. In the dilute quenched Poisson limit, the direct term vanishes and selectivity is exactly the mean receptor excess beneath bound particles, which can be measured at a single density from a sufficiently large co-registered receptor-particle image. Beyond Poisson statistics, the excess is normalized by the Fano factor for a linear count response, while changes in distribution shape require the full count-resolved response. Lattice simulations verify these relations across distinct receptor statistics, while off-lattice simulations show that particle crowding enters through the direct term. These results establish a fluctuation-response framework linking multivalent selectivity to the local receptor fluctuations preferentially sampled by adsorption.

A new self-sustaining process (SSP) is identified in an oscillating spatially-homogeneous shear flow using a nonlinear Kelvin mode model. This SSP consists of energetic spanwise-invariant 1D `sheets' and weaker spanwise-dependent 2D fluctuations. It is instantaneously 2D, with a time-dependent invariant direction in the flow-cross-shear plane, and has a varicose symmetry. The sheets oscillate in time and are linearly unstable generating fluctuations which then nonlinearly self-interact to reinforce the sheets. The linear instability of the sheet is shown to be due to a lift-up mechanism acting in tandem with `push-forward', which arises due to the `streamwise' shear of the sheets. As the Reynolds number $Re\rightarrow\infty$, both asymptotics and numerics show SSP lower branches with fluctuation velocity $|\boldsymbol{u}'|\sim Re^{-1/2}$. Implications are discussed for oscillatory wall-bounded flows.

We present the largest and most homogeneous catalog of radial velocity (RV) measurements for field RR Lyrae (RRL) variables, based on both proprietary and publicly available spectroscopic data. The sample includes 17,563 RRLs pulsating in the fundamental mode (12,353 RRab), in the first overtone (5,011 RRc), and in double-mode (199 RRd). The RV curve (RVC) templates for metallic and Balmer lines were used to derive RV amplitudes and $V_{\gamma}$ velocities, defined as the RV of the stellar barycenter with respect to the Sun. The typical accuracy across the catalog is on average 3.8 km s$^{-1}$ for well-sampled RVCs, 6.5 km s$^{-1}$ for RVCs with 3-7 phase points and 11.3 km s$^{-1}$ for RVCs with fewer than three phase points. The use of different spectroscopic diagnostics and RVC templates provides, within the errors, very similar $V_{\gamma}$ velocities. We found that the metallicity dependence of RV amplitudes is vanishing for metallic lines, but becomes increasingly significant for H$\gamma$ and H$\delta$. Moreover, the scaling relations between photometric (V, $G_{BP}$, G, $G_{RP}$) and RV amplitudes are linear for RRc and nonlinear for RRab variables, independently of the adopted diagnostic. This circumstantial evidence indicates that convection affects more luminosity than RV amplitudes when moving from the blue (hot) to the red (cool) edge of the instability strip. The spectroscopic Bailey diagram (RV amplitude versus period) shows a smooth transition and a reduced spread at a fixed period, when moving from metal-poor to metal-rich RRLs. Finally, we also found evidence that the metallicity distribution function of Blazhko RRLs is skewed toward the metal-intermediate and metal-rich regimes.

Restricted path integral Monte Carlo (RPIMC) sidesteps the fluctuating Fermion sign problem by confining paths within nodal regions of a trial density matrix, thereby recovering polynomial scaling. However, this nodal surface must be provided from elsewhere; unless it is exact, it introduces a fixed-node energy error. Here we introduce Spindrift, a Variational Density Matrix approach that learns the many-body Fermionic density matrix from a regularised Bloch residual, evaluated on samples drawn by a restricted Worm algorithm. Motivated by the `purity' of quantum statistical mechanics at high temperature (where kinetic energy dominates), we train the density matrix along an imaginary-time (descending temperature) curriculum from an exact infinite-temperature heat-kernel starting point, learning the condensation of quantum correlations as temperature drops, through successive corrections to the previous reference. We parametrise our model with a permutation-equivariant continuous normalising flow to generate quasi-particle backflow trajectories, modulated by a symmetric Jastrow factor. This architecture guarantees exact Fermionic antisymmetry and spatial symmetry throughout training. Simulating $N=3$ interacting Fermions in a two-dimensional harmonic trap, we demonstrate stable curriculum training. The learnt velocity field smoothly deforms the nodal structure away from the free-particle reference. Open-Worm G-sector trapping provides a natural diagnostic for nodal accuracy. Spindrift systematically lowers the restricted energy relative to the free-particle reference across all temperatures and successfully reproduces the benchmark energy at $\beta=1$, establishing a stable, physics-informed framework for finite-temperature quantum Monte Carlo where the nodal structure is learnt self-consistently.

The efficiency with which galaxies convert their available baryonic reservoir into stars sets a fundamental ceiling on stellar mass assembly in the early Universe and encodes the cumulative effect of stellar feedback. in this paper, we report the measurement of star-formation efficiency (SFE) of a photometrically and spectroscopically vetted reference sample at $z=9-10$, out of which 31 are spectroscopically confirmed. Among them, we highlight a spectroscopically confirmed galaxy, UNCOVER 3686 at $z = 9.31$, which has a stellar mass $M_\star = 10^{9.55}$ M$_\odot$ and physical properties comparable to the predictions of the feedback-free starburst (FFB) scenario. We use this galaxy as an anchor for the first direct observational test of whether galaxy at cosmic dawn with physical properties predicted in the FFB theory reach the maximum baryon conversion efficiencies predicted by the feedback-free starburst scenario. We find the SFE for this galaxy to lie between $\approx 20\%$ and $60\%$, a factor of 2 to 6 above empirical model predictions. The compact morphology ($R_e = 0.45$ kpc), young stellar age ($\sim 160$ Myr), low metallicity $(Z_\star/Z_\odot \approx 0.2)$, and inferred gas density $(n_{\rm gas} \sim 3\times 10^{3}$ cm$^{-3}$) of this galaxy are consistent with feedback-free (FFB) galaxy formation conditions. We conclude that UNCOVER 3686 is an excellent candidate for an FFB galaxy in which the global star formation efficiency approaches the theoretical limits due to weak stellar feedback.

HD 156424 is a hot magnetic star in the Sco OB4 association and has previously been identified as part of a binary system. Spectropolarimetric results show that the companion star is also strongly magnetic, and thus this is a rare example of a doubly magnetic hot binary. In this work, we aim to present a more detailed analysis of Transiting Exoplanet Survey Satellite data including phase variation. We find short-term phase variation consistent with an oblique magnetic rotator, as well as long-term phase variation consistent with the third element proposed previously. We performed asteroseismic modelling of the star and determined that the pulsations are most likely associated with the primary of the system. Our best-fit models are universally young, and we find that the star is well fitted by a model with $M$=7.5 M$_{\odot}$.

The proliferation of power electronics in multi-terminal transmission grids has increasingly led to harmonic distortions and dynamic instabilities. While Resonance Mode Analysis (RMA) provides deep insights into these system resonances, evaluating the critical modes of large-scale grids presents a severe computational bottleneck. Classical iterative techniques must continuously diagonalize massively high-dimensional, non-Hermitian admittance matrices across a wide frequency spectrum, a process that rapidly exhausts classical memory and processing limits. To overcome this scaling barrier, we propose a novel quantum-classical hybrid methodology that natively maps the transmission grid's admittance matrix onto a Quantum Processing Unit (QPU). Because the grid's matrix is non-Hermitian, standard quantum eigensolvers are insufficient; thus, we employ the Real Variance-based Variational Quantum Eigensolver (RVVQE) algorithm to accurately extract the complex eigenvalues that represent the system's modes. Validated against a standard 5-bus transmission system, the quantum-derived critical-resonance modal impedances demonstrate near-perfect alignment with the exact classical frequency responses. Crucially, by encoding the grid's state logarithmically into quantum memory, this methodology bypasses classical RAM limitations. The successful implementation of the RVVQE framework not only bridges the mathematical topologies of dissipative electrical grids and open quantum systems but also provides a profoundly scalable architecture capable of diagnosing resonance instabilities in massive, continental-scale networks that currently exceed classical computational boundaries.

This chapter gives an overview of the recent progress in extracting generalized parton distributions from lattice QCD. We briefly recall the theoretical principles of GPDs and explain the two most common lattice approaches, Ji's quasi-distributions and Radyushkin's pseudo-distributions. In the second part of the chapter, we review the lattice results obtained from these two frameworks. Finally, we offer a discussion of future prospects of lattice extractions of GPDs.

We use first-principles calculations and multipole analyses to demonstrate the relationship between ferroaxiality and chirality in the prototypical ferroaxial material K2Zr(PO4)2. Using the atomic-site electric toroidal monopole as a measure of electronic chirality in real space, we show that, while the paraxial phase of K2Zr(PO4)2 is non-chiral, the ferroaxial phase is antiferro-chiral. By applying an electric field, we induce a ferri-chiral state with net electronic chirality which is opposite for opposite underlying ferroaxial domains and can be tuned by the direction and strength of the electric field. Associated with the real-space induced chirality, we find a distinct response in momentum space, with induced non-zero components in the Berry curvature dipole tensor that switch sign between opposite ferri-chiral domains. Our findings therefore reveal hidden chirality in ferroaxial materials in both real and momentum space.

We introduce the data reduction pipeline for the Tartu Observatory Fiber-fed Echelle Spectrograph (TOFES). TOFES is installed in the Coudé room and will be connected to the 1.5 m Tartu Observatory AZT-12 telescope through a four-channel instrument adapter to be mounted at the Cassegrain focus of the telescope. The spectrograph has an average spectral resolution of 30,000 and covers the 390 to 900 nm wavelength band in a single exposure. The data reduction pipeline, based on the PyReduce package, was tested on spectra of the Sun. We also present the Spectroscopy-Toolbox package, which was developed to provide additional tools for diagnostics and spectral line identification for radial velocity measurements. The spectrograph will address a range of scientific questions, including the stellar characterisation of Herbig AeBe stars to measure accretion contamination from their protoplanetary disks, the stellar characterisation of exoplanet host-stars including the Ariel space mission targets, and radial velocity monitoring of large-scale atmospheric variability in massive stars.

The physical properties of a quantum system, whether pure or mixed, are described fully by its density matrix. Recovery of the density matrix through projective measurements – referred to as quantum state tomography – is a cornerstone of quantum optics and metrology. The implementation of this approach in transmission electron microscopy, in particular for the characterisation of an electron beam after inelastic scattering, has remained a longstanding challenge as a result of the complexity of scanning high-dimensional phase spaces, with the number of required measurements growing quadratically with space dimensionality. Here, we introduce a simplified approach by restricting tomography to the electron orbital angular momentum (OAM) subspace. By using an electron optical device known as an OAM sorter, we discretise the phase space into a finite set of measurable states, thus significantly reducing the experimental and computational burden. The resulting measurements suffice to probe essential features of inelastic scattering. We demonstrate the technique by studying the inelastic scattering of a structured electron probe exciting volume plasmons in a carbon film. The combined use of a structured beams and OAM-resolved quantum tomography reveals symmetry-breaking effects and offers insight into the coherence and evolution of the scattered quantum states. Analysis of the diagonalised density matrices further reveals the nature of the induced state transitions, demonstrating the power of the approach for quantum tomography of electron scattering.

We propose a new class of $CP$ sum rules in the $U$-spin limit, based on the observation that the weak phase in the Standard Model can be removed in the degenerate limit $m_d=m_s$. Unlike previous $U$-spin analyses formulated at the amplitude level, our sum rules are expressed directly in terms of decay widths. They apply to matched partial waves, spin observables, and angular moments and include nonpairwise cases beyond the usual single-insertion $d\leftrightarrow s$ relation.

The traditional distance ladder measures the standardized peak absolute magnitude M^B of Type Ia supernovae (SNIa). According to the SH0ES collaboration, the distance ladder value of M^B is highly discrepant with the value inferred from the cosmic microwave background (CMB) assuming the LCDM cosmology. This CMB-distance ladder tension is insensitive to the actual late time expansion history of the Universe. To derive a value of the Hubble constant H_0, from M^B requires a cosmological model. However, the magnitude-redshift relation of SNIa provides tight constrains the expansion history. As a consequence, uncertainties in the conversion of M^B into H_0 have no significant impact on the CMB-distance ladder tension. The tentative claim by the Dark Energy Spectroscopic Instrument collaboration for late time evolution of the dark energy equation of state does not alter this conclusion.

In this work, we show that warm sub-Saturns orbiting single stars are predominantly aligned, in contrast to hot sub-Saturns, which are frequently misaligned, with the two populations differing at the 3.2$\sigma$ level. Because both populations are observed around cool stars, they are free from the ambiguity introduced by the $T_{\rm eff}$-$\lambda$ dependence. Together with the established alignment of warm Jupiters, this demonstrates, among single-star systems, that spin-orbit misalignment arises specifically in the close-in “hot-Jupiter-analog” regime, where tidal circularization is efficient ($\tau_e<\tau_{\rm age}$) and high-eccentricity migration is expected to operate. We further find that the transition between aligned and misaligned sub-Saturns occurs at wider orbital separations ($a_{\rm final}/R_p = 338\pm27$) than for Jupiters ($a_{\rm final}/R_p = 117\pm9$), consistent with the expectation that the lower masses (smaller $M_p/M_*$) and stronger tidal dissipation (lower $Q_p$) of sub-Saturns allow them to be circularized into wider final orbits within their lifetimes. Taken together, these results provide the clearest direct evidence to date that, in single-star systems, spin-orbit misalignments are produced by high-eccentricity migration. If this framework is correct, spin-orbit misalignments may also emerge among hot-Jupiter analogs in other mass regimes, including hot brown dwarfs around hot stars at $a_{\rm final}/R_p\lesssim100$ and isolated hot super-Earths at $a_{\rm final}/R_p\lesssim1000$, with the corresponding transition locations shifted by the dependence of the orbital-circularization timescale on $M_p/M_*$ and $Q_p$.

We have studied the fidelity of spatial entanglement between dissociated atom and ion from two photon dissociation of hydrogen molecular ion H 2 + . Two processes for two photon dissociation of molecular ion have been considered (i) sequential two photon (STP) absorption and (ii) correlated two photon (CTP) absorption by the molecular ion. We compared the results for fidelity of spatial entanglement (FSE) between dissociated atom and ion for these two types of dissociation. In a previous study in our group [1] we have shown that when an atom interact with nonlocal mode of electromagnetic field (which has been derived field theoretically), simultaneous phase-correlated two pho1 ton absorption by the atom occurs within a very short time {\delta}t << {\omega} , where {\omega} is the laser frequency, and the rate of this correlated two photon absorption is linear in intensity. This will happen when the photon flux in the interaction region is high i.e. laser intensity is higher than 10 10 W/cm 2 . In this work we have extended this formalism to study the correlated two photon dissociation of molecular ion and to explore the effect of correlation between two simultaneous photo-absorption processes on the fidelity for spatial entanglement of dissociated atom and ion. Dependence of fidelity for spatial entanglement on the photon frequency has been studied for both the STP and CTP dissociation, to show that photon frequency can be used as control parameter to achieve maximum fidelity. Saturation of fidelity with the increase in time at which fidelity was calculated shows the robustness of the processes considered here. A scheme for detection of spatial entanglement between ion and atom has been suggested.

Exponential Hopfield networks store a number of patterns that grows exponentially with the number of neurons, and in their classical formulation they are auto-associative: they complete a corrupted copy of a memory into the memory itself. Many of the tasks one wants such a network to perform are instead hetero-associative, mapping a cue to a different target. We introduce and analyse an exponential neural network of $L$ layers of $N$ binary neurons, each layer carrying its own dataset, whose energy is an exponential of the product of the per-layer Mattis overlaps, so that it is minimised precisely when every layer retrieves the pattern of the same index; the stored association must be a surjective function of the cue, and we show why nothing else can be stored at all. A cavity/signal-to-noise analysis, made exact at leading order by a large-deviation evaluation of the noise, shows that the aligned hetero-associative state is a fixed point of the zero-temperature dynamics up to a number of stored patterns $P_c\sim e^{N\rho_L}$, exponential in the layer size, with an explicit rate $\rho_L$ that grows like $L\log 2$; enlarging the basins of attraction lowers the rate but never destroys its exponential character. Comparing the theory with structured data we find that the exponential capacity and the predicted basins survive correlated, many-to-one patterns: the network is a near-perfect content-addressable memory. The same closed forms describe, without refitting, a synthetic manifold, real T-cell-receptor/epitope triples and natural-language intent data, so the mechanism is domain-universal. Generalisation to unseen cues, though significantly above chance, stays below memorisation, and it is the geometry of the encoding, rather than the data domain, that sets how far above chance it reaches. In this family, exponential storage and strong generalisation are distinct capabilities.

We prove that the $\mathrm{iSWAP}$ gate maximises the spectral gap of the Hermitian second-moment operator on every connected graph with at least three vertices, among all two-local unitary circuit ensembles. We further prove that the polyhedral cone defined by asymmetric four-point inequalities is invariant under the transpose of the $\mathrm{iSWAP}$ semigroup, yielding a componentwise comparison certificate for its positive Perron–Frobenius eigenvector. These results resolve a conjecture of Kong, Li, and Liu.

The Retribution and Reciprocity Model (RRM) is a novel framework presented in evolutionary criminology to understand causes of crime through the lens of cooperation. We formalise RRM as an agent-based dynamical system in which criminal propensity evolves through pairwise interactions and through observations of others' interactions. The mathematical model extends bounded confidence opinion dynamics with two novel features: an agent-specific attractor representing the perception of the environment, and the participation of third-party witnesses. We prove that individual propensities remain bounded and establish sufficient conditions for convergence to an extreme value and to the agent's perception of the environment. Simulations show that the dominant system behaviour is not convergence but persistent oscillations, a rare phenomenon in bounded confidence models arising here without the adaptive confidence bounds through which it has previously been obtained. We derive a necessary condition for oscillations, and find that a population sharing a uniform but neutral perception of the environment tends to polarise to the extremes, while a uniform non-neutral perception tends to yield consensus. The polarising regime is confined to a narrow band of near-neutral perceptions, whose width decreases with population size and increases with the strength of reciprocal and retributive tendencies.

Photonic integrated circuits (PICs) are increasing in scale and routing complexity, driven by photonic computing, optical switching, programmable interferometer meshes, wavelength-routed optical networks-on-chip, and chip-to-chip optical interconnects. Manual waveguide planning becomes impractical as designs approach thousands of photonic components because routing must satisfy geometric, optical, electrical, and manufacturing constraints. This paper presents the Photonic Routing Optimization and Placement Engine (PROPEL), a memory-driven, native-accelerated adaptive vector-flow-field routing framework with process-aware waveguide generation for large-scale PIC design. PROPEL builds a routing kernel based on a bounded vector-flow-field algorithm and DRC validation. The same kernel supports passive optical routing, active optical-electrical routing, and topology-driven net assignment. C++ accelerates field and routing calculations, while Python performs detailed DRC replay, legality checking, route commitment, and GDSFactory-based geometry generation. Compared with state-of-the-art routing solutions, PROPEL is faster on 17 of 18 shared passive-routing cases, with a median speedup of 2.6x and a geometric-mean speedup of 2.5x, while maintaining zero design-rule violations. PROPEL also supports length, delay, and optical-path-length matching, process-map-aware waveguide generation, route-memory reuse, selective rip-up/reroute, and GDS-level legality replay. These capabilities address heterogeneous PIC layouts where optical, electrical, process, topology, matching, and manufacturability constraints must be handled together.

The brain supports computations through coordinated patterns of activity on an underlying network. These networks—from microscale navigational circuits in insects to macroscale brain areas in humans—are organized in structured ways that are thought to support their function. We seek a unifying quantitative framework to understand how network structure shapes the computations a network can readily support. To do so, we frame computation as a goal-directed transition of activity and quantify its cost on a given network using control theory. We then define the distribution of costs across all possible transitions as a $\textit{computational affordance landscape}$ that encodes which computations a network structure readily supports. We apply this framework to a circuit model for how insects maintain a sense of direction and show that updating orientation is the least costly computation, with predicted inputs consistent with known circuitry. In the human brain, we find that the affordance landscape varies systematically with the functional role of each network. Sensory networks display more heterogeneous landscapes (reflecting their role in specialized information processing), whereas association networks display more homogeneous landscapes (reflecting their role in generalized information processing). In recurrent neural networks trained on cognitive tasks, we show that learning progressively increases landscape heterogeneity, reshaping the distribution of affordable computations. Generally, we establish a quantitative framework for studying relationships between structure and computation in neural circuits, with future applications extending to other biological and physical networks.

We study a Nelson-type Hamiltonian describing a massive spinless non-relativistic particle moving in a planar soft quantum waveguide and linearly coupled to a massive scalar bosonic field. Our spectral analysis relies on comparing the curved waveguide with its straight counterpart. For the straight Hamiltonian, longitudinal translation invariance yields a fiber decomposition, and we prove that its spectrum is purely essential and gapless. For the curved Hamiltonian, we establish an HVZ-type formula for the bottom of the essential spectrum, involving that of the straight system and the one-boson threshold. We also derive a sufficient condition for the existence of non-empty discrete spectrum in the curved case, expressed in terms of an effective one-dimensional Schrödinger operator.

High-contrast imaging of exoplanets is limited by the presence of quasi-static speckles and existing post-processing methods remain above the theoretical noise limit. We investigate a novel framework that incorporates adaptive optics (AO) wavefront sensor telemetry into post-processing using a differentiable optical model of the ERIS vortex coronagraph. As a first proof of concept, we inject AO telemetry into an ERIS forward model and assess its ability to reproduce the on-sky point spread function (PSF). We find that jitter discrepancies between the science camera and the AO telemetry hinder accurate PSF reconstruction. We proposed a plan to characterise this jitter and find its mechanical origin.

Generation of relativistic runaway electrons has historically not been considered a possible problem in stellarators, but this may not hold in reactor-scale stellarators despite the lack of an externally driven plasma current. The magnitude of the plasma current governs the exponential generation of runaways, and even if there is no externally driven plasma current, the bootstrap current could be considerable in reactor-relevant stellarators. In this paper, we present a pilot study on the generation of runaway electrons in stellarator temperature collapse scenarios. To reliably study runaway electrons in stellarators, we implemented a stellarator plasma model in the runaway electron simulation tool DREAM. The model is used to explore when runaway electrons can be generated with regard to combinations of initial plasma current, temperature decay time scale, and post-decay temperature. Special consideration is given to runaway generation through avalanche multiplication in stellarators, and how it compares to tokamaks. We find that significant runaway electron generation is possible also in stellarators, and demonstrate under which conditions it could be a concern. However, our findings support the conception that runaway electrons will be less of a concern in reactor-scale stellarators compared to tokamaks.

The Poisson-bracket (PB) formalism is widely used to derive dynamics of coarse-grained (CG) fields to capture large-scale physics, extending the role of PBs in classical particle mechanics to macroscopic fields. It has been applied to fluctuations in critical phenomena, hydrodynamics of liquid crystals, liquid crystal elastomers, tissues, and the emergence of odd viscosity from spinning particles. The PB formalism can be formulated in either the Lagrangian framework, using reference space, or the Eulerian framework, using real space. Conventionally, the Lagrangian formulation is used for elastic solids, and the Eulerian one for fluids. However, growing interest in Eulerian descriptions of solids has emerged for phenomena naturally defined in real space, such as viscoelastic responses, moving interfaces, and field-induced structural changes in particles. Here we develop a systematic formulation for applying the Eulerian PB formalism to elastic systems with potentials typically written in Lagrangian space, and clarify its consistency with the Lagrangian counterpart. We show that the Eulerian formulation generates additional nonlinearities absent in the Lagrangian framework. Such nonlinearities originate from CG volume changes under coordinate transformation and from particle flow across neighboring CG volumes. They must be retained when nonlinear effects are important. To illustrate, we study chiral active solids of finite-sized particles, where active torques drive internal particle rotations and generate geometric nonlinearities. These nonlinearities give rise to the odd elastic modulus, which non-reciprocally couples two different shear modes in stress-strain response. By recovering this modulus directly from the Eulerian PB formalism, we demonstrate its ability to capture emergent nonlinear elastic behavior in driven active solids, whose stresses are naturally measured in real space.

Mapping Calabi-Yau geometry to early Universe cosmology remains a primary goal in string phenomenology. We present an inflationary mechanism where flux stationarity shifts the field dynamics, driving inflation along the volume-controlling saxion direction near a Hodge boundary. In this region, the internal geometry strictly dictates the scalar potential. This setup stabilizes the field against heavy moduli corrections without consuming extra flux tadpoles. As a result, the properties of the geometric boundary translate directly into primordial tensor perturbations, creating a clear physical link from string compactifications to measurable data. The resulting geometric predictions match current cosmic microwave background limits and provide specific, testable targets for upcoming LiteBIRD and CMB-S4 observations.