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We make absolute frequency measurements of Cs Rydberg transitions, $\vert 6S_{1/2}, F=3 \rangle \rightarrow \vert nS_{1/2}~(n=23\rm{-}90)\rangle$ and $\vert nD_{3/2,5/2}~(n=21\rm{-}90)\rangle$, with an accuracy of less than $ 72\,\rm kHz$. The quantum defect parameters for the measured Rydberg series are the most precise obtained to date. The quantum defect series is terminated at $\delta_4$, showing that prior fits requiring higher order quantum defects reflect uncertainties in the observations. The precision of the measured quantum defects allow for the calculation of Rydberg electric-dipole transitions and fine-structure intervals extrapolated from high principal quantum numbers, to rival that of sophisticated many-body relativistic calculations carried out at low Rydberg principal quantum numbers. We quantitatively predict the contributions to the quantum defect parameters from core polarization and core penetration of Cs inner shell electrons. A new value for the ionization energy, consistent across the $ nS_{1/2}$ and $ nD_{3/2,5/2}$ Rydberg series, is reported at $31406.467 751 48 (14)~\rm{cm}^{-1}$., Comment: 15 pages, 7 figures, 7 tables

Massive contact binaries are fundamental test-beds to study properties of close binaries en route to stellar mergers. Progress in their understanding has been largely impeded due to a dearth in their observed counterparts. We accumulate 61 over-contact binary candidates from the OGLE survey of the Magellanic Clouds and form the largest known sample of such systems. We mine the OGLE-IV catalogue for B-type and earlier systems which match our synthetic light curves, and thereafter examine their properties in comparison with our binary populations. Simultaneously, we also investigate the degeneracy in the light curves between over-contact and near-contact binaries and attempt to distinguish these populations. We construct new synthetic populations of such systems from detailed $\texttt{MESA}$ models with initial parameters of M$_\textrm{total,i}=14-80\,\textrm{M}_{\odot}$ and P$_\textrm{i}=0.6-23\,$days, and compute analogous $\texttt{PHOEBE}$ light curves. We then extract OGLE systems that match our synthetic light curves and compare their numbers, and distributions in periods, absolute V-band magnitudes and colours (V-I) with our population predictions. We expect massive over-contact binaries to have smooth equal-depth light curves due to their equal-mass ($q\approx1$) and consequently, equal-temperature components. We mine 47 and 14 predominantly B-type over-contact OGLE binaries from the Large and Small Magellanic Clouds respectively, with periods of $\approx0.6-1\,$d, along with a few wider O-type systems. This sample is consistent with our theoretically expected numbers and colour-magnitude and period distributions. Additionally, we find that binaries nearing contact have periods as large as $4.5\,$d and mass ratios of $q\approx0.4-0.95$, some of which may masquerade as over-contact binaries and thereby lead to potential observational misclassifications., Comment: 14 pages, 11 figures, submitted to A\&A

Many-body interactions in metal-organic frameworks are fundamental for emergent quantum physics. Unlike their solution counterpart, magnetization at surfaces in low-dimensional analogues is strongly influenced by magnetic anisotropy induced by the substrate and still not well understood. Here, we use on-surface coordination chemistry to synthesize on Ag(111) and superconducting Pb(111) an iron-based spin chain by using pyrene-4,5,9,10-tetraone precursors as ligands. Using low-temperature scanning probe microscopy, we compare their structures and low-energy spin excitations of coordinated Fe atoms with high S = 2 spin-state. Although the chain and coordination centers are identical on both substrates, the long-range spin-spin coupling due to a superexchange through the ligand observed on Ag is absent on Pb(111). We ascribe this reduction of spin-spin interactions on Pb to the depletion of electronic states around the Fermi level in the Pb(111) superconductor as compared to silver.

Magnetic impurities on superconductors present a viable platform for building advanced applications in quantum technologies. However, a controlled manipulation of their quantum states continues to pose a significant challenge, hindering the progress in the field. Here we show the manipulation of magnetic states in the radical molecule 4,5,9,10-tetrabromo-1,3,6,8-tetraazapyrene (TBTAP) on a Pb(111) superconducting surface using low-temperature scanning tunneling microscopy. Tunneling spectra reveal Yu-Shiba-Rusinov (YSR) states near the Fermi energy in isolated molecules. A quantum phase transition from singlet to doublet ground state is induced by changing the tip-molecule distance. Additionally, the presence of a second TBTAP molecule allows tuning of the YSR state position by altering the relative distance and can induce splitting of the YSR states for certain orientations. The construction of molecular chains up to pentamers shows periodic arrangements of charged and neutral molecules, with even-numbered chains forming a charged dimer structure at one end. Information can be encoded in these chains by switching the dimer position. These findings elucidate interactions between molecular assemblies and superconducting substrates, paving the way for advanced quantum-state engineering.

This study investigates the realm of liquid neural networks (LNNs) and their deployment on neuromorphic hardware platforms. It provides an in-depth analysis of Liquid State Machines (LSMs) and explores the adaptation of LNN architectures to neuromorphic systems, highlighting the theoretical foundations and practical applications. We introduce a pioneering approach to image classification on the CIFAR-10 dataset by implementing Liquid Neural Networks (LNNs) on state-of-the-art neuromorphic hardware platforms. Our Loihi-2 ASIC-based architecture demonstrates exceptional performance, achieving a remarkable accuracy of 91.3% while consuming only 213 microJoules per frame. These results underscore the substantial potential of LNNs for advancing neuromorphic computing and establish a new benchmark for the field in terms of both efficiency and accuracy., Comment: 8 pages, 3 figures, 3 tables

Surveys in the Milky Way and Large Magellanic Cloud revealed that the majority of massive stars will interact with companions during their lives. However, knowledge of the binary properties of massive stars at low metallicity, which approaches the conditions of the Early Universe, remains sparse. We present the Binarity at LOw Metallicity (BLOeM) campaign - an ESO large programme designed to obtain 25 epochs of spectroscopy for 929 massive stars in the SMC - the lowest metallicity conditions in which multiplicity is probed to date (Z = 0.2 Zsun). BLOeM will provide (i) the binary fraction, (ii) the orbital configurations of systems with periods P < 3 yr, (iii) dormant OB+BH binaries, and (iv) a legacy database of physical parameters of massive stars at low metallicity. The stars are observed with the LR02 setup of the giraffe instrument of the Very Large Telescope (3960-4570A, resolving power R=6200; typical signal-to-noise ratio S/N=70-100). This paper utilises the first 9 epochs obtained over a three-month time. We describe the survey and data reduction, perform a spectral classification of the stacked spectra, and construct a Hertzsprung-Russell diagram of the sample via spectral-type and photometric calibrations. The sample covers spectral types from O4 to F5, spanning the effective temperature and luminosity ranges 6.5

Time sharing between activities remains an indispensable part of everyday activity pattern. However, the issue has not yet been fully acknowledged within the existing time allocation models, potentially resulting in inaccuracies in valuing travel time savings. Therefore this study is aimed at addressing this gap by investigating the potential impact of introducing time sharing within such a framework, as well as factors determining it as represented by travel activities. In doing so, time constraint in the time allocation model of Small was modified to enable sharing the same time interval between different activities. The resulting expression indicated that such an augmentation could lead to lower estimates of value of time as a resource. On the other hand, empirical research based on the data from the National Passenger Survey 2004 used for calibrating cross-nested logit model indicated a number of factors affecting the choice of travel activities. It was discovered that significant include possession of equipment allowing particular activities, e.g. newspaper, paperwork or ICT devices, companionship, gender, length of the journey, frequency of using the service, possibility of working on the train, journey planning in advance, first class travel, termination of the trip in central London, peak-time travel and availability of seating., Comment: 15 pages, 2 Figures, Presented at European Transport Conference 2010

This study proposes a framework that extends existing time-coding time-to-first-spike spiking neural network (SNN) models to allow processing information changing over time. We explain spike propagation through a model with multiple input and output spikes at each neuron, as well as design training rules for end-to-end backpropagation. This strategy enables us to process information changing over time. The model is trained and evaluated on a Twitter bot detection task where the time of events (tweets and retweets) is the primary carrier of information. This task was chosen to evaluate how the proposed SNN deals with spike train data composed of hundreds of events occurring at timescales differing by almost five orders of magnitude. The impact of various parameters on model properties, performance and training-time stability is analyzed.

This first VELOCE data release comprises 18,225 high-precision RV measurements of 258 bona fide classical Cepheids on both hemispheres collected mainly between 2010 and 2022, alongside 1161 additional observations of 164 other stars. The median per-observation RV uncertainty is 0.037 km/s, and some reach 0.002 km/s. Non-variable standard stars characterize RV zero-point stability and provide a base for future cross-calibrations. We determined zero-point differences between VELOCE and 31 literature data sets using template fitting and measured linear period changes of 146 Cepheids. Seventy six spectroscopic binary Cepheids and 14 candidates are identified using VELOCE data alone and are investigated in detail in a companion paper (VELOCE II). Several new insights into Cepheid pulsations were obtained, including: a) the most detailed description of the Hertzsprung progression by RVs; b) the identification of double-peaked bumps in the RV curve; c) clear evidence that virtually all Cepheids feature spectroscopic variability signals that lead to modulated RV variability. We identified 36 such stars, of which 4 also exhibit orbital motion. Linear radius variations depend strongly on pulsation period and a steep increase in slope of the $\Delta$R/p versus logP-relation is found near 10d, challenging the existence of a tight relation between Baade-Wesselink projection factors and pulsation periods. We investigated the accuracy of RV time series measurements, v$_\gamma$, and RV amplitudes published in Gaia's DR3 and determined an average offset of 0.65 \pm 0.11 km/s relative to VELOCE. We recommend adopting a single set of template correlation parameters for distinct classes of large-amplitude variable stars to avoid systematic offsets in v$_\gamma$ among stars belonging to the same class. Peak-to-peak amplitudes of Gaia RVs exhibit significant (16%) dispersion compared to VELOCE. [abridged], Comment: A&A in press, 46 pages, 35 figures, 20 tables. Some data only available via the CDS at publication. VELOCE DR1 data will be made public in FITS format via zenodo.org at DOI: 10.5281/zenodo.10793507 upon publication of the paper in A&A

Gravitational waves from black-hole merging events have revealed a population of extra-galactic BHs residing in short-period binaries with masses that are higher than expected based on most stellar evolution models - and also higher than known stellar-origin black holes in our Galaxy. It has been proposed that those high-mass BHs are the remnants of massive metal-poor stars. Gaia astrometry is expected to uncover many Galactic wide-binary systems containing dormant BHs, which may not have been detected before. The study of this population will provide new information on the BH-mass distribution in binaries and shed light on their formation mechanisms and progenitors. As part of the validation efforts in preparation for the fourth Gaia data release (DR4), we analysed the preliminary astrometric binary solutions, obtained by the Gaia Non-Single Star pipeline, to verify their significance and to minimise false-detection rates in high-mass-function orbital solutions. The astrometric binary solution of one source, Gaia BH3, implies the presence of a 32.70 \pm 0.82 M\odot BH in a binary system with a period of 11.6 yr. Gaia radial velocities independently validate the astrometric orbit. Broad-band photometric and spectroscopic data show that the visible component is an old, very metal-poor giant of the Galactic halo, at a distance of 590 pc. The BH in the Gaia BH3 system is more massive than any other Galactic stellar-origin BH known thus far. The low metallicity of the star companion supports the scenario that metal-poor massive stars are progenitors of the high-mass BHs detected by gravitational-wave telescopes. The Galactic orbit of the system and its metallicity indicate that it might belong to the Sequoia halo substructure. Alternatively, and more plausibly, it could belong to the ED-2 stream, which likely originated from a globular cluster that had been disrupted by the Milky Way., Comment: 23 pages, accepted fro publication in A&A Letters. New version with small fixes

This paper introduces a groundbreaking digital neuromorphic architecture that innovatively integrates Brain Code Unit (BCU) and Fundamental Code Unit (FCU) using mixedsignal design methodologies. Leveraging open-source datasets and the latest advances in materials science, our research focuses on enhancing the computational efficiency, accuracy, and adaptability of neuromorphic systems. The core of our approach lies in harmonizing the precision and scalability of digital systems with the robustness and energy efficiency of analog processing. Through experimentation, we demonstrate the effectiveness of our system across various metrics. The BCU achieved an accuracy of 88.0% and a power efficiency of 20.0 GOP/s/W, while the FCU recorded an accuracy of 86.5% and a power efficiency of 18.5 GOP/s/W. Our mixed-signal design approach significantly improved latency and throughput, achieving a latency as low as 0.75 ms and throughput up to 213 TOP/s. These results firmly establish the potential of our architecture in neuromorphic computing, providing a solid foundation for future developments in this domain. Our study underscores the feasibility of mixedsignal neuromorphic systems and their promise in advancing the field, particularly in applications requiring high efficiency and adaptability, Comment: Accepted at 2024 International Joint Conference on Neural Networks

The Wide-field Spectroscopic Telescope (WST) is proposed as a new facility dedicated to the efficient delivery of spectroscopic surveys. This white paper summarises the initial concept as well as the corresponding science cases. WST will feature simultaneous operation of a large field-of-view (3 sq. degree), a high multiplex (20,000) multi-object spectrograph (MOS) and a giant 3x3 sq. arcmin integral field spectrograph (IFS). In scientific capability these requirements place WST far ahead of existing and planned facilities. Given the current investment in deep imaging surveys and noting the diagnostic power of spectroscopy, WST will fill a crucial gap in astronomical capability and work synergistically with future ground and space-based facilities. This white paper shows that WST can address outstanding scientific questions in the areas of cosmology; galaxy assembly, evolution, and enrichment, including our own Milky Way; origin of stars and planets; time domain and multi-messenger astrophysics. WST's uniquely rich dataset will deliver unforeseen discoveries in many of these areas. The WST Science Team (already including more than 500 scientists worldwide) is open to the all astronomical community. To register in the WST Science Team please visit https://www.wstelescope.com/for-scientists/participate, Comment: 194 pages, 66 figures. Comments are welcome (wstelescope@gmail.com)

Assembling and maintaining large arrays of individually addressable atoms is a key requirement for continued scaling of neutral-atom-based quantum computers and simulators. In this work, we demonstrate a new paradigm for assembly of atomic arrays, based on a synergistic combination of optical tweezers and cavity-enhanced optical lattices, and the incremental filling of a target array from a repetitively filled reservoir. In this protocol, the tweezers provide microscopic rearrangement of atoms, while the cavity-enhanced lattices enable the creation of large numbers of optical traps with sufficient depth for rapid low-loss imaging of atoms. We apply this protocol to demonstrate near-deterministic filling (99% per-site occupancy) of 1225-site arrays of optical traps. Because the reservoir is repeatedly filled with fresh atoms, the array can be maintained in a filled state indefinitely. We anticipate that this protocol will be compatible with mid-circuit reloading of atoms into a quantum processor, which will be a key capability for running large-scale error-corrected quantum computations whose durations exceed the lifetime of a single atom in the system., Comment: 8 pages, 6 figures

Parametric sound field synthesis methods, such as the Spatial Decomposition Method (SDM) and Higher-Order Spatial Impulse Response Rendering (HO-SIRR), are widely used for the analysis and auralization of sound fields. This paper studies the performances of various sound field synthesis methods in the context of the auralization of a critical listening room. The influence on the perceived spatial and timbral fidelity of the following factors is considered: the rendering framework, direction of arrival (DOA) estimation method, microphone array structure, and use of a dedicated center reference microphone with SDM. Listening tests compare the synthesized sound fields to a reference binaural rendering condition. Several acoustic parameters are measured to gain insights into objective differences between methods. A high-quality pressure microphone improves the SDM framework's timbral fidelity. Additionally, SDM and HO-SIRR show similarities in spatial fidelity. Performance variation between SDM configurations is influenced by the DOA estimation method and microphone array construction. The binaural SDM (BSDM) presentations display temporal artifacts impacting sound quality., Comment: 13 pages, 6 figures

We calculate, via variational techniques, single- and two-photon Rydberg microwave transitions, as well as scalar and tensor polarizabilities of sodium atom using the parametric one-electron valence potential, including the spin-orbit coupling. The trial function is expanded in a basis set of optimized Slater-type orbitals, resulting in highly accurate and converged eigen-energies up to $n=60$. We focus our studies on the microwave band 90-150 GHz, due to its relevance to laser excitation in the Earth's upper-atmospheric sodium layer for wavelength-dependent radiometry and polarimetry, as precise microwave polarimetry in this band is an important source of systematic uncertainty in searches for signatures of primordial gravitational waves within the anisotropic polarization pattern of photons from the cosmic microwave background. We present the most efficient transition coefficients in this range, as well as the scalar and tensor polarizabilities compared with available experimental and theoretical data.

Phosphorus pentamer (cyclo-P5-) ions are unstable in nature but can be synthesized at the Ag(111) surface. Unlike monolayer black phosphorous, little is known about their electronic properties when in contact with metal electrodes, although this is crucial for future applications. Here we characterize the atomic structure of cyclo-P5 assembled on Ag(111) using atomic force microscopy with functionalized tips and density functional theory. Combining force and tunneling spectroscopy, we find that a strong charge transfer induces an inward dipole moment at the cyclo-P5/Ag interface as well as the formation of an interface state. We probe the image potential states by field-effect resonant tunneling and quantify the increase of the local change of work function of 0.46 eV at the cyclo-P5 assembly. Our results suggest that the high-quality of the cyclo-P5/Ag interface might serve as a prototypical system for electric contacts in phosphorus-based semiconductor devices., Comment: 25 pages, 4 figures

The chirality of an object can be studied by measuring the circular dichroism, that is, the difference in absorption of light with different helicity. The chiral optical response of an object, however, can have two different origins. On the one hand, it can be linked to the chiral geometry of the object. On the other hand, it can be linked to the chiral material from which the object is made. Whereas previously, no distinction between the two contributions could be made, we report here a computational approach that allows us to separate these two contributions to the circular dichroism of an object. We consider separately the cases where geometry-related resonances affect the optical response and where they are absent. In both cases, we find the circular dichroism to be easily decomposable if a geometrically achiral object has a similar absorption spectrum to the chiral object under investigation. Furthermore, in the non-resonant case, the contribution attributed to the material can be obtained without taking any geometry into account. Besides being of fundamental importance, the possibility of disentangling both contributions will be important for guiding the future design of chiral objects and devices.

Effect of an external magnetic field on the critical sound attenuation and velocity of the longitudinal wave is studied in ferromagnets. We derive a parametric model that incorporates a crossover from the asymptotic critical behavior to the Landau-Ginzburg regular behavior far away from the critical point. The dynamics is based on the time dependent Ginzburg-Landau model with non conserved order parameter (model A). The variations of the sound attenuation coefficient and velocity have been obtained for arbitrary values of the magnetic field and reduced temperature. The scaling functions are given within the renormalization group formalism at one-loop order. Using MnP as an example, we show that such parametric crossover model yields an accurate description of ultrasonic data in a large region of temperatures and magnetic fields around the critical point., Comment: 19 pages,7 figures

The aim of this work is to create a complete list of sources exhibiting a long secondary period (LSP) in the ASAS-SN catalog of variable stars, and analyze the properties of this sample compared to other long period variables without LSP. We use the period-amplitude diagram to identify the 55572 stars showing an LSP, corresponding to 27% of the pulsating red giants in the catalog. We use the astrometric data from Gaia DR3 and the spectroscopic data provided by the APOGEE, GALAH, and RAVE surveys to investigate the statistical properties of the sample. We find that stars displaying an LSP have a spatial distribution that is more dispersed than the non-LSP giants, suggesting that they belong to an older population. Spectroscopically-derived ages seem to confirm this. The stars with an LSP also appear to be different in terms of C/O ratio from their non-LSP counterparts., Comment: Submitted to A&A

We demonstrate that it is possible to construct operators that stabilize the constraint-satisfying subspaces of computational problems in their Ising representations. We provide an explicit recipe to construct unitaries and associated measurements given a set of constraints. The stabilizer measurements allow the detection of constraint violations, and provide a route to recovery back into the constrained subspace. We call this technique ''quantum subspace correction". As an example, we explicitly investigate the stabilizers using the simplest local constraint subspace: Independent Set. We find an algorithm that is guaranteed to produce a perfect uniform or weighted distribution over all constraint-satisfying states when paired with a stopping condition: a quantum analogue of partial rejection sampling. The stopping condition can be modified for sub-graph approximations. We show that it can prepare exact Gibbs distributions on $d-$regular graphs below a critical hardness $\lambda_d^*$ in sub-linear time. Finally, we look at a potential use of quantum subspace correction for fault-tolerant depth-reduction. In particular we investigate how the technique detects and recovers errors induced by Trotterization in preparing maximum independent set using an adiabatic state preparation algorithm., Comment: 12 + 4 pages, 6 figures

Topological superconductivity emerges in chains or arrays of magnetic atoms coupled to a superconductor. However, the external controllability of such systems with gate voltages is detrimental for their future implementation in a topological quantum computer. Here we showcase the supramolecular assembly of radical molecules on Pb(111), whose discharge is controlled by the tip of a scanning tunneling microscope. Charged molecules carry a spin-1/2 state, as confirmed by observing Yu-Shiba-Rusinov in-gap states by tunneling spectroscopy at millikelvin temperature. Low energy modes are localized at island boundaries with a long decay towards the interior, whose spectral signature is consistent with Majorana zero modes protected by mirror symmetry. Our results open up a vast playground for the synthesis of gate-tunable organic topological superconductors., Comment: 21 pages 5 figures

Machine Learning as a Service (MLaaS) APIs provide ready-to-use and high-utility encoders that generate vector representations for given inputs. Since these encoders are very costly to train, they become lucrative targets for model stealing attacks during which an adversary leverages query access to the API to replicate the encoder locally at a fraction of the original training costs. We propose Bucks for Buckets (B4B), the first active defense that prevents stealing while the attack is happening without degrading representation quality for legitimate API users. Our defense relies on the observation that the representations returned to adversaries who try to steal the encoder's functionality cover a significantly larger fraction of the embedding space than representations of legitimate users who utilize the encoder to solve a particular downstream task.vB4B leverages this to adaptively adjust the utility of the returned representations according to a user's coverage of the embedding space. To prevent adaptive adversaries from eluding our defense by simply creating multiple user accounts (sybils), B4B also individually transforms each user's representations. This prevents the adversary from directly aggregating representations over multiple accounts to create their stolen encoder copy. Our active defense opens a new path towards securely sharing and democratizing encoders over public APIs., Comment: Accepted at NeurIPS2023

We investigate anomalous electrical transport properties of a Ni-TiO2 hybrid system displaying a unique nanostructured morphology. The system undergoes an insulator to metal transition below 150 K with a low temperature metallic phase that shows negative resistance in a four-probe configuration. Temperature dependent transport measurements and numerical modelling show that the anomalies originate from the dendritic architecture of the TiO2 backbone interspersed with Ni nanoparticles that paradoxically renders this polycrystalline, heterogeneous system highly anisotropic. The study critiques inferences that may be drawn from four-probe transport measurements and offers valuable insights into modelling conductivity of anisotropic hybrid materials.

Eutectic NiTiO$_3$-TiO$_2$ samples and their H$_2$ reduced Ni-TiO$_2$ samples, where high aspect ratio TiO$_2$ nanostructures are axially decorated with nodular Ni globules, are thoroughly explored to understand their effect in photo-response. We show that by employing this novel eutectic architecture, effectively exploiting the nano-structuring process along with the chosen material properties, the overall efficiency of the ensuing photoactive device is improved. We also show the competing photo-driven and photothermal-driven carrier mechanisms to define the total photo-response of the system. Additionally, the ability to function self-powered poses this approach as a potential strategy for achieving efficient photodetectors.