Papers

Using a finite-temperature two-center Thomas-Fermi-Dirac model, we investigate nonlinear plasma screening effects on the fusion reactions D-T, $^{12}$C-$^{12}$C, and p-$^{11}$B. The effective interaction between a reacting ion pair is obtained self-consistently at the mean-field level. Combining this potential with a complex Woods-Saxon nuclear potential, we solve the stationary Schrödinger equation to evaluate tunneling probabilities and reaction rates. Compared with Debye-Hückel theory, the two-center screening potential can be stronger or weaker, and the resulting fusion enhancement correspondingly amplified or suppressed, depending on the plasma conditions and the internuclear separation. We identify the underlying mechanisms: relative to the single-center prediction, the nonlinear evacuation of background ions suppresses screening, whereas nonlinear electron accumulation enhances it. The two channels respond to different plasma state parameters: the ionic suppression deepens with increasing coupling strength, whereas the electronic enhancement peaks at intermediate degeneracy. The two-center correction therefore follows a factorized scaling law in the nuclear charges of the reacting pair and the plasma state parameters. These findings highlight the importance of a self-consistent two-center treatment for determining effective interactions and evaluating static screening corrections to fusion reaction rates.

Hedin's formalism of functional derivatives is the best-known method for systematically constructing correlated electronic theories, largely due to the success of its lowest-order self-energy expansion, the $GW$ approximation. Beyond $GW$, diagrammatic resummation schemes attempt to mix correlations simultaneously across all particle-particle and particle-hole channels. Because such a comprehensive treatment is computationally prohibitive for realistic molecular systems, a highly effective alternative is to fully account for electronic correlations in one specific channel, typically the particle-hole channel. This idea was recently implemented for molecular systems [1], yielding a self-energy expressed in terms of excited-state energies and transition amplitudes from the solution of the Bethe-Salpeter equation, rather than the random phase approximation used in $GW$. While this approach is predictive and numerically efficient, it violates the fundamental positive-definiteness constraint of the electron spectral function in certain energy ranges. In this study, we resolve this physical flaw by deriving a positive semidefinite (PSD) extension of the theory using a rigorous framework based on the nonequilibrium Green's function formalism. The PSD constraint introduces new scattering channels and triplet intermediate states and restores the correct physical behavior. We demonstrate that it consistently improves quasiparticle energies across standard molecular benchmarks, with an accuracy comparable to coupled-cluster reference calculations.

We construct an explicit embedding of the rank two Racah algebra $\mathfrak{R}_2$ into the rank two Jacobi algebra $\mathfrak{J}_2$. Working in the differential model of $\mathfrak{J}_2$ on the triangle, we recall that the subalgebra structure of $\mathfrak{J}_2$ is organized by a pentagon whose four upper edges carry rank one Jacobi algebras and whose base carries a rank one Racah algebra. Promoting the two multiplication operators to Racah type generators by tridiagonalization turns every edge of the pentagon into a rank one Racah algebra and realizes $\mathfrak{R}_2$ inside $\mathfrak{J}_2$. We determine the common eigenfunctions of different commuting pairs explicitly as products of Gauss hypergeometric functions and Jacobi polynomials. Different overlap coefficients are computed involving univariate Wilson polynomials as well as, for one pair of bases, bivariate Racah polynomials of Tratnik type. We also recall how $\mathfrak{J}_2$ arises as a contraction of the rank two Racah algebra $\mathfrak{R}_2$.

Two-dimensional photonic crystals (2D PhCs) enable fine-grained control over a broad set of Bloch modes without the constraints of band occupancy and natural crystal structures, and, as intrinsically open systems, serve as versatile platforms for exploring diverse topological phenomena. Here, we develop a theoretical framework inspired by the irreducible-representation formalism in solid-state physics, while explicitly incorporating key characteristics of photonic Bloch systems, such as radiative coupling and transverse condition. Within this framework, we study the symmetry origins of local k-space topology, e.g., bound-states in the continuum and optical vortex beams, and Berry phase in two representative systems. We further analyze, from a group-theory perspective, how tailored structural designs and targeted symmetry perturbations can be exploited to manipulate these topological features. In particular, we showcase the application of the formalism to Bloch modes from distinct truncation approaches and specify the preferable regimes for each, both under a generic $n$-band configuration. The analysis can thereby be readily extended to a wide range of artificial wave crystals beyond scalar Schrödinger-like operators and two-level treatment.

Les Houches Event files are a standard format for Monte Carlo event generators in high-energy physics. pylhe is a lightweight pure-Python library for reading and writing LHE event data. It supports .lhe and compressed .lhe.gz files, implements the widely used LHE 3.0 features including multiple event weights and generator metadata, and also supports the recent HDF5-based LHEH5 format. By exposing events through a pythonic iterator and shared data structures, pylhe enables memory-efficient processing of large event samples without loading entire files into memory. The library also supports format conversion and integration with modern analysis workflows, including columnar analysis with Awkward Array and downstream machine-learning applications.

So far, the focus of state-of-the-art structure determination using x-ray free-electron laser (XFEL) pulses has been on macromolecular crystallography. This approach has achieved remarkable success in solving the structure of microcrystals smaller than a few micrometres, which are difficult to investigate using conventional synchrotron sources. However, successful applications of XFELs to inorganic and small-molecule crystallography have been limited due to rapid electron excitation in these samples. This same issue has also prevented the use of XFELs in charge-density studies of solids. In this study, we propose using hard x-ray pulses with an attosecond duration for x-ray imaging of charge density in organic and inorganic systems. Simulations of irradiated diamond and silicon showed that attosecond x-ray pulses consistently reduce the electronic excitation for a fixed photon energy and pulse fluence. Further reduction of transient electronic damage can be achieved by increasing the x-ray photon energy under these conditions. These theoretical predictions demonstrate a powerful and well-founded strategy for visualizing valence-electron distribution, opening up new prospects for diffraction imaging studies with XFELs.

We compare the deviations of circular orbits in the nonrelativistic and relativistic cases. General solutions of the deviation equations are obtained. We find the potentials for the nonrelativistic case and the metric components in general relativity for which trajectories close to circular ones are closed curves. Explicit expressions for the pericenter shift of an orbit close to a circular one in a static spherically symmetric spacetime are obtained. Estimates of the cosmological constant effect on the orbit pericenter shift are given. Finally, we find the spherically symmetric metric in which the Shirokov effect is absent.

The photothermal responsivity of a tensioned nanomechanical resonator, the fractional frequency shift per absorbed optical power, depends on which vibrational mode is tracked and where the heat is deposited. We derive a closed-form model of this dependence for square membranes by treating the membrane as a grid of independent tensile fibers, each responding to its mean temperature. The responsivity map splits into a mode-independent conduction envelope and a mode term that peaks on the antinodal rows and columns of the mode, not at the antinodes, because fibers rather than points carry the modal strain energy. Scanning photothermal measurements of the $(1,1)$, $(1,2)$, $(2,1)$, and $(2,2)$ modes of a square silicon nitride membrane confirm the predicted maps with a correlation $r \geq 0.998$, with the envelope amplitude as the only fitted parameter. On trampoline resonators, the tether-limited thermal conductance flattens the envelope, making the mode term directly visible in raw scans. The measured mode-resolved maps provide the design input for dual-mode photothermal sensing with common-mode drift suppression, identifying pairs, such as a membrane's $(1,1)$/$(2,2)$ or a trampoline's torsional modes, as candidates that combine large differential responsivity with a shared thermal and mechanical environment.

We present a study of the perovskite Ca0.4Sr0.6TiO3 using variable temperature transmission electron microscopy (TEM) and powder X-ray diffraction (PXRD). At room temperature and below, PXRD shows that the material adopts an orthorhombic Pbcm structure analogous to the P-phase of NaNbO3. Above 380 K the material transforms to a tetragonal I4/mcm phase. The structural distortions of these phases can be described as a combination of modes and order parameters associated with the M, T, ${\Delta}$ and R-points of the Brillouin zone, each of which can be associated with a different set of superstructure reflections visible in X-ray and electron diffraction patterns. For the I4/mcm phase only the expected R-point reflections are observed in PXRD while both M and R- reflections are observed in electron diffraction. Using ${\Delta}$ and R dark field TEM images we show that the phase transition proceeds by a loss of coherence of TiO6 octahedral tilting along the c-axis, leading to a microstructure of thin nanoscale platelets with a different local symmetry to the macroscopic structure. These persist well above the phase transition temperature and are probably responsible for the long-standing discrepancy between Raman spectroscopy and diffraction measurements in this materials system, as well as other secondary effects.

We study the Poisson operator on the interacting Fock space associated with a discrete-time quantum walk, which we call the QW-Poisson operator. First, we investigate the spectral properties of the QW-Poisson distribution. In particular, we establish a relation between the spectral distributions of the Poisson operator and the reversed Poisson operator on a general interacting Fock space via a size-biased transform. Next, we study the edge behavior of the density of the QW-Poisson distribution. We show that a phase transition occurs at the left endpoint of the support: depending on the parameter, the density either decays to $0$ or blows up to $+\infty$. Moreover, this phase transition coincides with the transition in the number of atoms of the QW-Poisson distribution, equivalently, in the point spectrum of the QW-Poisson operator, and with whether $0$ belongs to the spectrum of the QW-Poisson operator. Finally, we study a connection between the interacting Fock space associated with a discrete-time quantum walk and noncommutative probability theory. More precisely, we compute the moment-generating function and moments of the QW-Poisson operator, and obtain a limit theorem for the Konno distribution via a Poisson approximation. We also investigate the Boolean self-decomposability of the Konno distribution and the shifted reversed QW-Poisson distribution.

The photonic lantern is an all-photonic wavefront sensor native to single-mode-fibre-fed instruments, but its performance is almost always quoted through a specific reconstruction algorithm, obscuring how much wavefront information the device itself encodes. We develop, from first principles, the Fisher-information and Cramer-Rao theory of the photonic-lantern wavefront sensor, benchmark it against the quantum Cramer-Rao bound via an explicit multi-parameter quantum-Fisher-information calculation, and relate it to two established frameworks: the Fourier-filtering noise-propagation model of Chambouleyron et al (2023) and the classical/quantum sensitivity limit of Haffert et al (2023). Treating the lantern as a deterministic map from aberration coefficients to N output intensities, we derive the Poisson and read-noise Fisher information matrices (FIM), the per-mode CRLB, the per- photon Fisher-Rao geometry on the intensity simplex, and a flux- and estimator-independent sensitivity metric beta with quantum ceiling beta = 2. The lantern CRLB scales as N_ph^(-1/2) and is bounded, mode by mode, by the quantum limit of 1/2 rad rms per photon. That multi-parameter bound is jointly saturable: the phase generators are real and commuting, so the mean Uhlmann curvature vanishes and wavefront sensing carries no quantum incompatibility between simultaneously estimated modes, extending Haffert et al's single-mode ceiling to all low-order modes at once. We further show that the photon-noise sensitivity s_gamma of Chambouleyron et al is exactly the diagonal of our per- photon FIM, whereas the CRLB uses the diagonal of its inverse; the two coincide only for a diagonal FIM, so s_gamma is optimistic for a mode-mixing lantern. The framework is device-agnostic: it returns estimator-independent sensitivities comparable on a common beta <= 2 scale with pyramid, Zernike and PIAA-ZWFS sensors.

Recent advances in topological physics have revealed a counterintuitive class of antichiral edge and surface states that propagate in the same direction along spatially separated parallel boundaries. To date, however, experimental realizations of antichiral states have been restricted to first-order topological phases, while their higher-order counterparts–antichiral hinge states–have remained experimentally elusive. Here, we report the first experimental observation of antichiral hinge states in a gyromagnetic photonic crystal that realizes a three-dimensional (3D) modified Haldane model with dimerized interlayer coupling. Through microwave near-field mapping, we directly resolve their defining signatures: nonreciprocal, co-propagating transport along four parallel hinges and characteristically tilted hinge-state dispersions. These results extend antichiral topology into the higher-order regime and provide a new platform for 3D nonreciprocal topological photonic devices.

A Hubbard-Holstein dimer functions as a correlation-driven quantum battery, with ergotropy robustly stored, under some conditions, even in the presence of dissipation. We find that, although optimal work extraction can in principle recover all the stored energy, it requires unrealistically fine-tuned couplings. By contrast, a physically realizable protocol based on spectral matching between the battery and the load achieves substantial, albeit suboptimal, energy extraction. Our results identify a mechanism for quantum energy storage, provide a realistic route to work extraction that is amenable to machine-learning-based theoretical exploration, and suggest that quantum batteries may not be universally deployable: the microscopic mechanism responsible for storing energy can constrain the classes of systems able to efficiently extract it.

The Mid-infrared ELT Imager and Spectrograph (METIS) will be equipped with a SCAO system delivering Strehl ratios above 90% at L band (3.5 - 4.1 um) and close to 99% at N band (8 - 13 um) on bright stars. Yet, the actual wavefront quality seen by the METIS coronagraphic modules used for high-contrast imaging will be significantly affected by water vapour seeing, which add a strong chromatic component to dry air seeing in the mid-infrared. We analysed two years of VLTI/GRAVITY fringe tracker archives to assess the variability of differential water vapour column density at millisecond timescales on ELT scales. Our analysis suggests that water vapour seeing will add a median wavefront error of about 175 nm rms at N band, consisting mostly of low-order aberrations, with around 150 nm rms of tip-tilt errors. If not corrected, this effect would degrade the achievable sensitivity limits in terms of contrast by more than two magnitudes. To mitigate this effect, we plan to deploy a focal-plane wavefront sensing and control algorithm based on an asymmetric pupil using a deep learning approach. After briefly discussing the practical impacts of focal-plane wavefront control in METIS, we compare the expected high-contrast imaging performance with and without focal-plane wavefront control.

The Standard Model neither provides a dynamical explanation for the quark and lepton mass hierarchies, nor a rationale for why all of these masses save that of the top quark are suppressed compared to the electroweak scale. Motivated by this, we explore the alternative radiative mass generation hypothesis, specialising to the generation of the bottom, charm, and tau masses at one-loop level. A classification of all minimal models that use exotic scalars and exotic fermions only is presented, resulting in 25 possibilities featuring four exotic multiplets. As a bonus, some of the models produce a one-loop neutrino Dirac mass if a right-handed neutrino field is included, and some feature WIMP-like dark matter candidates. By way of example, we analyse the phenomenology of a benchmark model chosen from the set of 25 candidates and find that it is capable of exactly replicating the predicted Standard Model Yukawa couplings within the permitted parameter space.

We study large deviations of the maximum of the generalized TAP free energy introduced by Chen, Panchenko, and Subag for the Ising mixed $p$-spin model. The upper bound uses a new Guerra-type interpolation that may also be useful for other spin-glass models. The lower bound follows the strategy of Huang and Sellke. We show that supersymmetric critical points have no competitor at positive overlap on their own sphere. As such, they form a spherical code, which turns the annealed count into a lower bound on the probability of existence. This identifies the supersymmetric formula proposed by physicists with the large-deviation exponent for the existence of TAP maxima, rather than with the ordinary annealed complexity. The resulting rate function is the Legendre transform of a constrained Parisi value in the bottom-atom mass. The same argument, iterated in bands above TAP ancestors, would give a constructive proof of the Parisi formula for the Ising model under a technical strict stability assumption.

Dislocation loops govern the properties of crystalline materials, but extracting their detailed characteristics from atomistic simulations is difficult when loops are fragmented or embedded in compact defect debris. We present Savi-Bhransha, a graph-theoretic method that reconstructs interstitial and vacancy loops directly from local defect-displacement motifs, without constructing a global interface mesh. The method identifies Burgers-vector family, habit plane, loop size, segment-wise edge/screw character, and boundary and bulk defect populations for BCC, FCC, and HCP crystals. We apply it to single-cascade simulations over a range of energies in BCC W and HCP Zr, and to successive collision cascades in BCC W and FCC FeNiCr. We benchmark the method against the Dislocation Extraction Algorithm (DXA). Total dislocation lengths remain strongly correlated between the two methods, while Savi-Bhransha returns more stable loop-level objects in complex environments where DXA returns fragmented, overlapping open segments. Savi-Bhransha also better resolves mixed-morphology defects and dislocations near other defects, including vacancy clusters. Median runtime speedups are 6.34x for BCC W and 8.86x for HCP Zr, with peak-memory reductions up to 7.77x. In successive W cascades, the resolved boundary-defect concentration brackets transient-grating-spectroscopy measurements and the predicted Burgers-vector fraction agrees with room-temperature TEM. In FCC FeNiCr, the method resolves Heidenreich-Shockley dissociation, with a Shockley-pair signature in about 91% of surviving <110>-family interstitial clusters. Savi-Bhransha therefore enables efficient, topology-resolved analysis of large radiation-damage simulations and direct comparison with experimentally accessible observables.

Photometric space missions like Kepler and TESS have revealed unprecedented statistics of stellar flares, including the frequent detection of highly energetic superflares. Spectroscopic characterization of flares and especially superflares, however, is still not as commonly available. In contrast to broad-band photometry, spectroscopic data can give more insights into the physical parameters of flares, as well as allowing to identify possibly accompanying CMEs. In this context, we monitored the young planet-hosting flare star AU Mic for about 60 partial nights (>160 hours) between 2022 and 2023 spectroscopically with the ESO 1.52m telescope hosted by the PLATOSpec consortium. Here, we report on the search for signatures of flares and CMEs in these data, including the partial observation of a possible extreme superflare.

In the recent past investigations of stellar Coronal Mass Ejections (CMEs) and flares/superflares gained special attention because of their relevance for planetary habitability and stellar evolution. With respect to that, we present an observing campaign at the ESO152 telescope on LaSilla operated by the PLATOSpec consortium of the late-K/early-M dwarf binary CC Eri. The ESO152 telescope is currently equipped with an Echelle spectrograph which enables the investigation of a broad spectral range, allowing the investigation of CMEs and flares/superflares in various spectral lines. Within the observing campaign CC Eri was not observed by TESS, but we have coordinated g'-band photometry to cross-check for white light flares. Preliminary results of the observing campaign are presented.

We present a comparative analysis of acceleration data for gravitational systems drawn from multiple observational sources, including: (i) early-type galaxies (ETGs) (Lelli et al. 2017); (ii) Brightest Cluster Galaxies (BCGs) and galaxy clusters (Tian et al. 2020, 2024); and (iii) weak gravitational lensing of isolated galaxies (Brouwer et al. 2021; Mistele et al. 2024). These data are interpreted within a framework motivated by the Two-component Virial Theorem (2VT), which defines a global baryon-dark matter (DM) coupling and sets a characteristic acceleration scale. This baseline is complemented by two models that account for the main empirical features of the Radial Acceleration Relation (RAR) over a broad range of masses and accelerations. The Constant-Interaction Approximation Model (CIA) reproduces the observed RAR trends for ETGs, BCGs, and galaxy clusters. It extends earlier results (Dantas et al. 2000, 2018), and accounts for both the small intrinsic scatter and the emergence of a characteristic acceleration scale. At the very low accelerations probed by weak-lensing data (below accelerations of order $10^{-14}~\mathrm{m\,s^{-2}}$), however, this model breaks down. In this regime, the Virial-Motivated Interaction Model (VIM) incorporates the radial structure of the baryon-DM interaction through a local, radius-dependent contribution to the acceleration. Taken together, the 2VT (global scale), the CIA and the VIM provide a physically motivated framework that captures the main empirical features of the RAR.

Quantum nonlinear optics seeks to harness strong photon-photon interactions for scalable quantum technologies, although dissipative losses still pose a major barrier to near-unity conversion efficiency. Here, we bridge non-Hermitian physics with the quantum nonlinear domain by exploiting perfect absorption to identify and optimize few-photon nonlinear processes. We theoretically investigate two circuit QED systems, operating in the light-matter ultrastrong coupling regime. The first (i) enables simultaneous two-atom excitations by single photons, while the second (ii) realizes the strong coupling between a single-photon and a two-photon Fock states. We demonstrate that, since the strong optical nonlinearities cause quantum spectral features to emerge already at the level of linear response theory, the perfect absorption condition in $|S_{11}|$ enables near-deterministic single-photon down-conversion into (i) a qubit-qubit-correlated pair and (ii) a two-photon pair. We show that the conversion efficiency can be systematically optimized through experimentally accessible parameters, both linked to the emergence of Hermitian subspaces within the effective non-Hermitian Hamiltonians. These findings position non-Hermitian engineering as a broadly applicable route to optimizing quantum devices at the single-photon level, even beyond circuit-QED platforms.

Tunneling of ultracold bosons confined in a one-dimensional optical lattice results in a nontrivial gauge field depending on density-difference between the sites involved. The density dependent tunneling (DDT) causes a first-order quantum phase transition from the Bose-Einstein condensate to the localized soliton. Here, we examine the low-lying quasiparticle mode evolution across the transition in the weakly-interacting limit. To this end, we employ the discrete Bogoliubov theory and dispersion curves to reveal an increase in the quasiparticle energies of dipole (and higher) excitations with DDT in the soliton phase while preserving the zero-energy mode. This is due to the decrease in effective tunneling, resulting in a larger energy cost to move the soliton, and causes faster dipole oscillations. The repulsive on-site atomic interaction further shifts the critical gauge field of DDT to a larger value by stabilizing the lattice soliton. The latter is corroborated by a phase diagram in the complex gauge field plane and mode energy gap of quasiparticles. We further show that the soliton does not exhibit Bloch oscillations as the effective momentum becomes density-dependent and deforms its internal structure. The dynamical response of the trap quench does not excite the width of localized wave-packet, and the breathing oscillations are suppressed. The latter two dynamical properties of the condensate uniquely contrast the soliton state due to the density-dependent gauge field.

Phase contrast imaging (PCI) has been used for decades to study plasma density fluctuations, but its wavenumber response $k$ is constrained by the phase plate groove width and beam waist. Spiral phase contrast imaging (SPCI) with a spiral phase plate may offer broader sensitivity, even though its output signal is quadratic, because it has no constraint except at the central singularity, i.e., $k = 0$. In this work, we numerically compare the wavenumber response of both techniques using two distinct models: (i) static square phase objects with scale lengths $R$ ranging from 5 to 25 mm, and (ii) a time-evolving, anisotropic, multi-scale turbulence field with a Kolmogorov-like spectrum. For static square objects, PCI exhibits a lower cutoff at $k_{\text{min}} \approx 0.1$ mm$^{-1}$, while SPCI produces measurable signals down to $k_{\text{min}} \approx 0.007$ mm$^{-1}$ via the autocorrelation of the gradient spectrum. For the plasma-like turbulence model, PCI retains its lower cutoff at $k \approx 0.1$ mm$^{-1}$. In contrast, SPCI produces measurable signals down to $k \approx 0.007$ mm$^{-1}$. These results suggest that SPCI provides low-wavenumber information below the PCI cutoff, offering complementary diagnostic information for multi-scale plasma turbulence studies.

High-kinetic-inductance (HKI) transmission lines provide a promising platform for compact nonlinear superconducting microwave devices. Existing theoretical descriptions are typically based on the slowly varying envelope approximation, which becomes inadequate for strongly nonlinear resonant structures with pronounced spatial field variations. Here, we develop a theoretical framework for single-frequency nonlinear wave propagation in HKI transmission lines by formulating the problem as a boundary value problem that retains the full spatial dependence of the electromagnetic fields. Applying the method to resonant transmission-line geometries, we demonstrate power-dependent resonance shifts, bistable transmission solutions, and strongly direction-dependent transport arising from asymmetric impedance barriers, yielding transmission contrasts of up to $93\%$ without magnetic bias fields. The framework is further extended to a three-port stub geometry, where nonlinear interference produces shifted anti-resonances and Duffing-like spectral distortions. Our approach provides a versatile tool for the analysis and design of strongly nonlinear superconducting microwave devices.

Local-in-time well-posedness is established for a recently proposed diffuse interface model describing incompressible two-phase flows. The result constitutes the first analytical study of a model introduced by ten Eikelder et al. for the motion of a binary mixture of macroscopically immiscible, viscous, incompressible fluids with unmatched densities. In contrast to classic diffuse interface models based on a single mean velocity, this model is derived within the framework of mixture theory, assigning each phase its own momentum and mass balance, which results in a system of two coupled Navier–Stokes equations and two mass transport equations. The proof of the well-posedness result uses a fixed-point strategy, where the main difficulty lies in the analysis of the principal part of the associated linearized system.

We investigate the weak Bose-Einstein condensation (BEC) scenario of a noninteracting charged Bose gas simultaneously subjected to a strong magnetic field and rigid rotation. Using standard methods of finite-temperature quantum field theory and the generalized Fock-Schwinger formalism, we derive the corresponding thermodynamic potential in the nonrelativistic and lowest Landau level approximations. An appropriate modification of the effective chemical potential yields a consistent thermodynamic description and naturally introduces a magnetorotational fugacity. Within the high-temperature approximation, rigid rotation enters the thermodynamics solely through the Tolman-Ehrenfest local temperature. We demonstrate that rigid rotation does not qualitatively modify the weak BEC scenario induced by Landau quantization. The magnetorotational fugacity remains below unity throughout the phenomenologically relevant temperature range, while the continuous evolution of the ground state population and the absence of a singularity in the specific heat provide complementary signatures of the persistence of weak BEC. We further study the thermodynamic properties of the system under conditions relevant to quark-gluon plasma and neutron-star matter. We show that rotational effects are much more pronounced in the former. Our analysis reveals a new magnetic response to rigid rotation: while magnetic fields enhance diamagnetism, rotation drives it toward paramagnetism. This behavior reflects a competition between magnetic quantization and rotational orbital motion, emphasizing the role of rotation in shaping the magnetic response of bosonic matter.

We examine a one-dimensional binary mixture of ultradilute quantum droplets in the presence of a central potential defect. The properties of the potential strength and the number of atoms exhibit distinct polarization transitions and low-lying ollective excitation spectra. The balance of (attractive) Lee-Huang-Yang quantum fluctuations and repulsive mean-field interactions results in a self-bound quantum droplet in a potential well. However, the potential barrier causes the polarization transition with the number of atoms, which is reflected in the excitation spectrum as a discontinuity and softening of the quasiparticle modes. We reveal that the critical number of atoms for the transition decreases as the attractive intercomponent interaction increases. Finally, the quench time dynamics of the interaction in potential barrier and well show the localization and diffusive fragmented droplets of two-component systems.

Integrating few-layer materials into photonic circuits is a promising concept for novel on-chip photonic applications. We incorporate transition metal dichalcogenides (TMDs) with femtosecond-laser-written surface waveguides, which are embedded in fused silica chips. Our novel low-temperature optical spectroscopy setup enables coupling to the waveguide and simultaneous focus from the top to the TMD layer for a distinct excitation and collection of micro-photoluminescence ($\mu$PL) signals in several measurement geometries. Along these lines, we observe spectral changes of the A exciton for encapsulated TMD monolayers when capturing the $\mu$PL signal propagating through the waveguide. Depending on the thickness of the encapsulation with hexagonal boron nitride (hBN), these changes manifest as energetic redshifts of the A exciton, or even a splitting of the A exciton into two components. We attribute this behavior to strong coupling of the waveguide mode and the exciton in the sample, giving rise to the formation of propagating exciton-polaritons. Our interpretation is supported by calculations for a simplified model of a slab waveguide in the vicinity of an exciton by using the transfer matrix method. Having proven to be a highly adaptable framework for the study of propagating polaritons, our experimental platform likewise holds great promise for harnessing the unique properties of exciton-polaristons in integrated photonic circuits.

The stress analysis of a three-dimensional elastic hollow sphere subjected to uniaxial compression is revisited, employing an elastodynamic framework. Through the application of the Laplace transform, the scalar and vector potentials of displacement are expanded, facilitating a detailed exploration of the system's mechanical behavior. The static solutions for displacement and stress distributions are derived in the long-time limit, which reveal key insights into the response of the elastic hollow sphere. Notably, on the inner surface, certain quantities exhibit a peak at the point where the angle between the compressive force and the point on the surface becomes perpendicular, indicating localized stress concentration. These findings provide a robust analytical approach for understanding and predicting the behavior of elastic hollow spheres under uniaxial loading, with implications for material science and structural engineering.

Using liquid Nitrogen as the cryogenic fluid for pre-cooling purposes is almost ubiquitous across modern observatories. That method tends to be inefficient since it relies on the evaporation of the fluid afforded by the available surface area within the exchanger without capturing any of its latent heat. An additively manufactured heat exchanger could address that inefficiency by providing an increased evaporation area as well as internal structures that can interact with Nitrogen in its gaseous phase. A miniature pre-cooling system utilizing an existing cryostat was developed so the performance of conventionally and additively manufactured heat exchangers would be compared by recording the time required to cool an instrumented mass. Our findings indicate that there is a clear cost and performance advantage of additively manufactured heat exchangers when compared to conventional units, that could lead to reducing the operating costs of observatories hosting large size instruments such as HARMONI.