Miracle-dz/UniFAR-FTUs huggingface dataset:
Superlubricity - a new perspective on an established paradigm

: Superlubricity is a frictionless tribological state sometimes occurring in nanoscale material junctions. It is often associated with incommensurate surface lattice structures appearing at the interface. Here, by using the recently introduced registry index concept which quantifies the registry mismatch in layered materials, we prove the existence of a direct relation between interlayer commensurability and wearless friction in layered materials. We show that our simple and intuitive model is able to capture, down to fine details, the experimentally measured frictional behavior of a hexagonal graphene flake sliding on-top of the surface of graphite. We further predict that superlubricity is expected to occur in hexagonal boron nitride as well with tribological characteristics very similar to those observed for the graphitic system. The success of our method in predicting experimental results along with its exceptional computational efficiency opens the way for modeling large-scale material interfaces way beyond the reach of standard simulation techniques.
Trading Classical and Quantum Computational Resources

We propose examples of a hybrid quantum-classical simulation where a classical computer assisted by a small quantum processor can efficiently simulate a larger quantum system. First we consider sparse quantum circuits such that each qubit participates in O(1) two-qubit gates. It is shown that any sparse circuit on n+k qubits can be simulated by sparse circuits on n qubits and a classical processing that takes time $2^{O(k)} poly(n)$. Secondly, we study Pauli-based computation (PBC) where allowed operations are non-destructive eigenvalue measurements of n-qubit Pauli operators. The computation begins by initializing each qubit in the so-called magic state. This model is known to be equivalent to the universal quantum computer. We show that any PBC on n+k qubits can be simulated by PBCs on n qubits and a classical processing that takes time $2^{O(k)} poly(n)$. Finally, we propose a purely classical algorithm that can simulate a PBC on n qubits in a time $2^{c n} poly(n)$ where $c\approx 0.94$. This improves upon the brute-force simulation method which takes time $2^n poly(n)$. Our algorithm exploits the fact that n-fold tensor products of magic states admit a low-rank decomposition into n-qubit stabilizer states.
Reliability Ratio Weighted Bit Flipping– Sum Product Algorithm for Regular LDPC Codes

In this work, we introduce a novel decoding algorithm named “Reliability Ratio Weighted Bit Flipping–Sum Product” (RRWBFSP) is proposed for regular LDPC codes. “Sum Product” [4] and “Reliability Ratio Weighted Bit Flipping” [6] are two separate methods that are combined in the new algorithm. The simulations show novel algorithm to exceed Sum-Product decoding algorithms by 0.34 dB. In addition, when compared to the Sum-Product, the RRWBFSP approach has about the same computational complexity. Thus, LDPC codes, of which the “Double-Orthogonal Convolutional Recursive” (RCDO) subfamily is envisioned for use in electronic hard disks and mobile terminals, can be easily iteratively decoded. This would have the impact of prolonging the life of the batteries and consequently reducing the ecological footprint of the discarded batteries.
A Comparison of Machine Learning and Geostatistical Approaches for Mapping Forest Canopy Height over the Southeastern US Using ICESat-2

The availability of canopy height information in the Ice, Cloud, and Land Elevation Satellite-2’s (ICESat-2’s) land and vegetation product, or ATL08, presents opportunities for developing full-coverage products over broad spatial scales. The primary goal of this study was to develop a 30-meter canopy height map over the southeastern US, for the Southeastern Plains ecoregion and the Middle Atlantic Coastal Plains ecoregion. More specifically, this work served to compare well-known modeling approaches for upscaling canopy information from ATL08 to develop a wall-to-wall product. Focusing on only strong beams from nighttime acquisitions, the h_canopy parameter was extracted from ATL08 data. Landsat-8 bands and derived vegetation indices (normalized difference vegetation index, enhanced vegetation index, and modified soil-adjusted vegetation index) along with National Land Cover Database’s canopy cover and digital elevation models were used to extrapolate ICESat-2 canopy height from tracks to the regional level. Two different modeling techniques, random forest (RF) and regression kriging (RK), were applied for estimating canopy height. The RF model estimated canopy height with a coefficient of determination (R2) value of 0.48, root-mean-square error (RMSE) of 4.58 m, mean absolute error (MAE) of 3.47 and bias of 0.23 for independent validation, and an R2 value of 0.38, RMSE of 6.39 m, MAE of 5.04 and bias of −1.39 when compared with airborne lidar-derived canopy heights. The RK model estimated canopy heights with an R2 value of 0.69, RMSE of 3.49 m, MAE of 2.61 and bias of 0.03 for independent validation, and an R value of 0.68, R2 value of 0.47, RMSE of 5.96m, MAE of 4.52 and bias of −1.81 when compared with airborne lidar-derived canopy heights. The results suggest feasibility for the implementation of the RK method over a larger spatial extent and potential for combining other remote sensing and satellite data for future monitoring of canopy height dynamics.
Wash-Out in N(2)-dominated leptogenesis

We study the wash-out of a cosmological baryon asymmetry produced via leptogenesis by subsequent interactions. Therefore we focus on a scenario in which a lepton asymmetry is established in the out-of-equilibrium decays of the next-to-lightest right-handed neutrino. We apply the full classical Boltzmann equations without the assumption of kinetic equilibrium and including all quantum statistical factors to calculate the wash-out of the lepton asymmetry by interactions of the lightest right-handed state. We include scattering processes with top quarks in our analysis. This is of particular interest since the wash-out is enhanced by scatterings and the use of mode equations with quantum statistical distribution functions. In this way we provide a restriction on the parameter space for this scenario.
MAPPING DUST THROUGH EMISSION AND ABSORPTION IN NEARBY GALAXIES

Dust has long been identified as a barrier to measuring inherent galaxy properties. However, the link between dust and attenuation is not straightforward and depends on both the amount of dust and its distribution. Herschel imaging of nearby galaxies undertaken as part of the KINGFISH project allows us to map the dust as seen in emission with unprecedented sensitivity and ∼1 kpc resolution. We present here new optical integral field unit spectroscopy for eight of these galaxies that provides complementary 100–200 pc scale maps of the dust attenuation through observation of the reddening in both the Balmer decrement and the stellar continuum. The stellar continuum reddening, which is systematically less than that observed in the Balmer decrement, shows no clear correlation with the dust, suggesting that the distribution of stellar reddening acts as a poor tracer of the overall dust content. The brightest H ii regions are observed to be preferentially located in dusty regions, and we do find a correlation between the Balmer line reddening and the dust mass surface density for which we provide an empirical relation. Some of the high-inclination systems in our sample exhibit high extinction, but we also find evidence that unresolved variations in the dust distribution on scales smaller than 500 pc may contribute to the scatter in this relation. We caution against the use of integrated AV measures to infer global dust properties.
On the Dynamics of Glassy Systems

Glassy systems are disordered systems characterized by extremely slow dynamics. Examples are supercooled liquids, whose dynamics slow down under cooling. The specific pattern of slowing-down depends on the material considered. This dependence is poorly understood, in particular, it remains generally unclear which aspects of the microscopic structures control the dynamics and other macroscopic properties. Attacking this question is one of the two main aspects of this dissertation. We have introduced a new class of models of supercooled liquids, which captures the central aspects of the correspondence between structure and elasticity on the one hand, the correlation of structure and thermodynamic and dynamic properties on the other. Our results shed new light on the temperature-dependence of the topology of covalent networks, in particular, on the rigidity transition that occurs when the valence is increased. Other questions appear in glassy systems at zero temperature. In that situation, a glassy system can flow if an external driving force is imposed above some threshold. The first example we will consider is the erosion of a riverbed. Experiments support the existence of a threshold forcing, below which no erosion flux is observed. In this dissertation, we present a novel microscopic model to describe the erosion near threshold. This model makes new quantitative predictions for the spatial reparation of the flux. To study further the self-organization of driven glassy systems, we investigate the athermal dynamics of mean-field spin glasses. The spin glass self-organizes into the configurations that are stable, but barely so. Such marginal stability appears with the presence of a pseudogap in soft excitations. We show that the emergence of a pseudogap is deeply related to very strong anti-correlations emerging among soft excitations.
Study of the photon-induced formation and subsequent desorption of CH3OH and H2CO in interstellar ice analogs

Context. Methanol and formaldehyde are two simple organic molecules that are ubiquitously detected in the interstellar medium, in both the solid and gaseous phases. An origin in the solid phase and a subsequent nonthermal desorption into the gas phase is often invoked to explain their abundances in some of the environments where they are found. Experimental simulations under astrophysically relevant conditions have been carried out in the past four decades in order to find a suitable mechanism for that process. Aims. In particular, photodesorption from pure methanol ice (and presumably from pure formaldehyde ice) has been found to be negligible in previous works, probably because both molecules are very readily dissociated by vacuum-UV photons. Therefore, we explore the in situ formation and subsequent photon-induced desorption of these species, studying the UV photoprocessing of pure ethanol ice, and a more realistic binary H 2 O:CH 4 ice analog. Methods. Experimental simulations were performed in an ultra-high vacuum chamber. Pure ethanol and binary H 2 O:CH 4 ice samples deposited onto an infrared transparent window at 8 K were UV-irradiated using a microwave-discharged hydrogen flow lamp. Evidence of photochemical production of these two species and subsequent UV-photon-induced desorption into the gas phase were searched for by means of a Fourier transform infrared spectrometer and a quadrupole mass spectrometer, respectively. After irradiation, ice samples were warmed up to room temperature until complete sublimation was attained for detection of volatile products. Results. Formation of CH 3 OH was only observed during photoprocessing of the H 2 O:CH 4 ice analog, accounting for ~4% of the initial CH 4 ice column density, but no photon-induced desorption was detected. Photochemical production of H 2 CO was observed in both series of experiments. Formation of formaldehyde accounted for ≤45% conversion of the initial ethanol ice, but it could not be quantified during irradiation of the binary H 2 O:CH 4 ice analogs. Photochemidesorption of formaldehyde, i.e., photon-induced formation on the ice surface and inmediate desorption, was observed, with a yield of ~6 × 10 -5 (molecules/incident photon) in the case of the pure ethanol ice experiments, and ~4.4 × 10 -5 (molecules/incident photon) when the H 2 O:CH 4 ice analogs were photoprocessed. Photoprocessing of the ice analogs lead to formation of other species. Some of them were also found to desorb upon UV irradiation. Conclusions. While certain C-bearing species, in particular H 2 CO, were found to desorb upon irradiation, nonthermal desorption of CH 3 OH was not observed. So far, there is no experimental evidence of any efficient CH 3 OH desorption induced by UV photons. On the other hand, the observed photon-induced desorption of H 2 CO could account for the total formaldehyde abundance observed in the Horsehead photodissociation-dominated region.
Critical scaling of the mutual information in two-dimensional disordered Ising models

Rényi mutual information, computed from second Rényi entropies, can identify classical phase transitions from their finite-size scaling at critical points. We apply this technique to examine the presence or absence of finite temperature phase transitions in various two-dimensional models on a square lattice, which are extensions of the conventional Ising model by adding a quenched disorder. When the quenched disorder causes the nearest neighbor bonds to be both ferromagnetic and antiferromagnetic, (a) a spin glass phase exists only at zero temperature, and (b) a ferromagnetic phase exists at a finite temperature when the antiferromagnetic bond distributions are sufficiently dilute. Furthermore, finite temperature paramagnetic-ferromagnetic transitions can also occur when the disordered bonds involve only ferromagnetic couplings of random strengths. In our numerical simulations, the ‘zero temperature only’ phase transitions are identified when there is no consistent finite-size scaling of the Rényi mutual information curves, while for finite temperature critical points, the curves can identify the critical temperature Tc by their crossings at Tc and 2Tc.
Lattice dynamics of the cluster chain compounds 
M2Mo6Se6(M=K,Rb,Cs,In,and Tl)

The lattice dynamics of members of the M2Mo6Se6 family of materials with guest ions M = K, Rb, Cs, In, and Tl has been studied using inelastic x-ray scattering and Raman spectroscopy at room temperature, as well as by ab-initio calculations. We find a good match between calculations and experiment, both for structure factors (Eigenvectors) and for the calculated phonon frequencies. The observed lattice dynamics for Tl2Mo6Se6 show no signs of anharmonicity or absence of avoided dispersion crossings, thus ruling out previously hypothesised rattling phonon modes. The reduced mode energies for In2Mo6Se6 are identified as only partially responsible for the lower superconducting transition temperature Tc in this material when compared to Tl2Mo6Se6.
Stochastic resolution of the LHC inverse problem

We quantify the LHC inverse problem in the stochastic context by introducing a robust statistical discriminator mapping from the experimental signature space to the theory parameter space. Using this discriminator, after complementing LHC data by existing astrophysical, collider, and low energy measurements, we are able to significantly reduce the inverse problem. Our approach offers an essentially prior independent way to differentiate regions of the theory parameter space and uses LHC and other data on the same footing.
Gapped quantum criticality gains long-time quantum correlations

We show that gapped critical environment could remarkably prevent an enhanced decay of decoherence factor and quantum correlations at the critical point, which is non-trivially different from the ones in a gapless critical environment (Quan H. T. et al., Phys. Rev. Lett., 96 (2006) 140604). The quantum correlations display very fast decaying to their local minimum at the critical point while maximum decaying occurs away from this point. In particular, our results imply that the collapse of the decoherence factor is not an indicator of a quantum phase transition of the environment as opposed to what happens in a gapless criticality. In the weak-coupling regime, the relaxation time, at which the quantum correlations touch rapidly local minima, shows a power-law singularity as a function of the gap. Furthermore, quantum correlations decay exponentially with the second power of the relaxation time. Our results are important for a better understanding and characterisation of the gap critical environment and its ability as entangler in open quantum systems.
Weak localization and antilocalization in topological insulator thin films with coherent bulk-surface coupling

We evaluate quantum corrections to conductivity in an electrically gated thin film of a three-dimensional (3D) topological insulator (TI). We derive approximate analytical expressions for the low-field magnetoresistance as a function of bulk doping and bulk-surface tunneling rate. Our results reveal parameter regimes for both weak localization and weak antilocalization, and include diffusive Weyl semimetals as a special case.
Diagnosing aerosols in extrasolar giant planets with cross-correlation function of water bands

Transmission spectroscopy with ground-based, high-resolution instruments provides key insight into the composition of exoplanetary atmospheres. Molecules such as water and carbon monoxide have been unambiguously identified in hot gas giants through cross-correlation techniques. A maximum in the cross-correlation function (CCF) is found when the molecular absorption lines in a binary mask or model template match those contained in the planet. Here, we demonstrate how the CCF method can be used to diagnose broadband spectroscopic features such as scattering by aerosols in high-resolution transit spectra. The idea consists in exploiting the presence of multiple water bands from the optical to the near-infrared. We have produced a set of models of a typical hot Jupiter spanning various conditions of temperature and aerosol coverage. We demonstrate that comparing the CCFs of individual water bands for the models constrains the presence and the properties of the aerosol layers. The contrast difference between the CCFs of two bands can reach ~100 ppm, which could be readily detectable with current or upcoming high-resolution stabilized spectrographs spanning a wide spectral range, such as ESPRESSO, CARMENES, HARPS-N+GIANO, HARPS+NIRPS, SPIRou, or CRIRES+.
Review on the Energy Transformation Application of Black Phosphorus and Its Composites

Black phosphorus (BP) is a unique two-dimensional material with excellent conductivity, and a widely tunable bandgap. In recent years, its application in the field of energy has attracted extensive attention, in terms of energy storage, due to its high theoretical specific capacity and excellent conductivity, black phosphorus is widely used as electrode material in battery and supercapacitors, while for energy generating, it has been also used as photocatalyst and electrocatalysts to split water and produce hydrogen. Black phosphorus demonstrates even better stability and catalytic performance through further construction, doping, or heterojunction. This review briefly summarizes the latest research progress of black phosphorus and its composites in energy preparation and storage, as well as ammonia nitrogen fixation, and also looks into the possible development directions in the future.
Stimuli-responsive hybrid nanoconstructs for efficient theranostic applications in nanomedicine

The multidisciplinary ERC Starting Grant project “Hybrid immune-eluding nanocrystals as smart and active theranostic weapons against cancer” (TrojaNanoHorse) and the following ERC Proof-of-Concept Grant aim to develop a new generation of multifunctional theranostic nanosystems and apply them for improved cancer treatment, efficient cell imaging and for providing high safety for the hosting organism.
LOW-METALLICITY ABSORBERS ACCOUNT FOR HALF OF THE DENSE CIRCUMGALACTIC GAS AT z ≲ 1

We present an analysis of the metallicity distribution of the dense circumgalactic medium (CGM) of galaxies at 0.1 ≲ z ≲ 1.1 as probed by partial Lyman limit systems (pLLSs, 16.1 < log < 17.2) and LLSs (17.2 ≤ log < 17.7 in our sample). The new H i-selected sample, drawn from our Hubble Space Telescope COS G140L snapshot survey of 61 QSOs, has 20 pLLSs and 10 LLSs. Combined with our previous survey, we have a total of 44 pLLSs and 11 LLSs. We find that the metallicity distribution of the pLLSs is bimodal at z ≲ 1, with a minimum at [X/H] = −1. The low-metallicity peak comprises (57 ± 8)% of the pLLSs and is centered at [X/H] ≃ −1.87(1.3% solar metallicity), while the high-metallicity peak is centered at [X/H] ≃ −0.32 (48% solar metallicity). Although the sample of LLSs is still small, there is some evidence that the metallicity distributions of the LLSs and pLLSs are different, with a far lower fraction of very metal-poor ([X/H] < −1.4) LLSs than pLLSs. The fraction of LLSs with [X/H] < −1 is similar to that found in pLLSs (∼56%). However, higher H i column density absorbers (log > 19.0) show a much lower fraction of metal-poor gas; therefore, the metallicity distribution of gas in and around galaxies depends sensitively on NH i at z ≲ 1. We interpret the high-metallicity ([X/H] ≥ −1) pLLSs and LLSs as arising in outflows, recycling winds, and tidally stripped gas around galaxies. The low-metallicity pLLSs and LLSs imply that the CGM of z ≲ 1 galaxies hosts a substantial mass of cool, dense, low-metallicity gas that may ultimately accrete onto the galaxies.
Cosmological perturbations in the projectable version of Hořava-Lifshitz gravity

We consider linear perturbations about a homogeneous and isotropic cosmological background in the projectable version of Hořava-Lifshitz gravity. Starting from the action for cosmological perturbations, we identify the canonically normalized fluctuation variables. We find that - in contrast to what happens in the non-projectable version of the theory - the extra scalar cosmological perturbation mode is already dynamical at the level of linear perturbations and is either ghost-like or tachyonic depending on the value of a free parameter. This indicates a problem for the projectable version of Hořava-Lifshitz gravity.
A partial eclipse of the heart: the absorbed X-ray low state in Mrk 1048

We present two new XMM-Newton observations of an unprecedented low flux state in the Seyfert 1 Mrk 1048 (NGC 985), taken in 2013. The X-ray flux below 1 keV drops by a factor of 4-5, whereas the spectrum above 5 keV is essentially unchanged. This points towards an absorption origin for the low state, and we confirm this with spectral fitting, finding that the spectral differences can be well modelled by the addition of a partial covering neutral absorber, with a column density of $\sim3\times 10^{22}$~cm$^{-2}$ and a covering fraction of $\sim0.6$. The optical and UV fluxes are not affected, and indeed are marginally brighter in the more recent observations, suggesting that only the inner regions of the disk are affected by the absorption event. This indicates either that the absorption is due to a cloud passing over the inner disk, obscuring the X-ray source but leaving the outer disk untouched, or that the absorber is dust-free so the UV continuum is unaffected. We use arguments based on the duration of the event and the physical properties of the absorber to constrain its size and location, and conclude that it is most likely a small cloud at $\sim10^{18}$cm from the source.