Search

In a previous work (Hern\'andez-Bernal et al. 2021) we performed an observational analysis of the Arsia Mons Elongated Cloud (AMEC), which stands out due to its impressive size and shape, quick dynamics, and the fact that it happens during the martian dusty season. Observations show that its morphology can be split in a head, on the western slope of the volcano of around 120 km in diameter; and a tail, that expands to the west reaching more than 1000 km in length, making the AMEC the longest orographic cloud observed so far in the solar system. In this work we run the LMD (Laboratoire de M\'et\'eorologie Dynamique) Mesoscale Model to gain insight into the physics of the AMEC. We note that it is coincident in terms of local time and seasonality with the fastest winds on the summit of Arsia Mons. A downslope windstorm on the western slope is followed by a hydraulic-like jump triggering a strong vertical updraft that propagates upwards in the atmosphere, causing a drop in temperatures of down to 30K at 40-50 km in altitude, spatially and temporarily coincident with the observed head of the AMEC. However the model does not reproduce the microphysics of this cloud: the optical depth is too low and the expansion of the tail does not happen in the model. The observed diurnal cycle is correctly captured by the model for the head of the cloud. This work raises new questions that will guide future observations of the AMEC.

Triton and Pluto are believed to share a common origin, both forming initially in the Kuiper Belt but Triton being later captured by Neptune. Both objects display similar sizes, densities, and atmospheric and surface ice composition, with the presence of volatile ices N2, CH4 and CO. Yet their appearance, including their surface albedo and ice distribution strongly differ. What can explain these different appearances? A first disparity is that Triton is experiencing significant tidal heating due to its orbit around Neptune, with subsequent resurfacing and a relatively flat surface, while Pluto is not tidally activated and displays a pronounced topography. Here we present long-term volatile transport simulations of Pluto and Triton, using the same initial conditions and volatile inventory, but with the known orbit and rotation of each object. The model reproduces, to first order, the observed volatile ice surface distribution on Pluto and Triton. Our results unambiguously demonstrate that obliquity is the main driver of the differences in surface appearance and in climate properties on Pluto and Triton, and give further support to the hypothesis that both objects had a common origin followed by a different dynamical history., Comment: 16 pages, 3 figures

Thermal tides are atmospheric planetary-scale waves with periods that are harmonics of the solar day. In the Martian atmosphere thermal tides are known to be especially significant compared to any other known planet. Based on the data set of pressure timeseries produced by the InSight lander, which is unprecedented in terms of accuracy and temporal coverage, we investigate thermal tides on Mars and we find harmonics even beyond the number 24, which exceeds significantly the number of harmonics previously reported by other works. We explore comparatively the characteristics and seasonal evolution of tidal harmonics and find that even and odd harmonics exhibit some clearly differentiated trends that evolve seasonally and respond to dust events. High-order tidal harmonics with small amplitudes could transiently interfere constructively to produce meteorologically relevant patterns.

Characterizing the exchange of water between the Martian atmosphere and the (sub)surface is a major challenge for understanding the mechanisms that regulate the water cycle. Here we present a new dataset of water ice detected on the Martian surface with the Thermal Emission Imaging System (THEMIS). The detection is based on the correlation between bright blue-white patterns in visible images and a temperature measured in the infrared that is too warm to beassociated with CO2 ice and interpreted instead as water ice. Using this method, we detect ice down to 21.4{\deg}S, 48.4{\deg}N, on the pole-facing slopes at mid-latitudes, and on any surface orientation poleward of 45{\deg} latitude. Water ice observed with THEMIS is most likely seasonal rather than diurnal. Our dataset is consistent with near-infrared spectroscopic data predictions by the Mars Planetary Climate Model. The water frost average temperature is 170 K, and the maximum temperature measured is 243 K, lower than the water ice melting point. We show that the melting of pure water ice on the surface is unlikely due to cooling by latent heat during its sublimation. However, 243 THEMIS images show frosts that are hot enough to form brines if salts are present on the surface. The water vapor pressure at the surface, calculated from the ice temperature, indicates a dry atmosphere in early spring, during the recession of the CO2 ice cap. When it sublimes, the frost acts as a vapor source that is wetter than the near-surface atmosphere, which stabilizes the subsurface ice., Comment: Accepted for publication in JGR: Planets

We present a comprehensive strategy and its practical implementation using the commercial ScanImage software platform to perform hyperspectral point scanning microscopy when a fast time dependent signal varies at each pixel level. In the proposed acquisition scheme the scan along the X axis is slowed down while the data acquisition is maintained at high pace to enable the rapid acquisition of the time dependent signal at each pixel level. The ScanImage generated raw 2D images have a very asymmetric aspect ratio between X and Y, the X axis encoding both for space and time acquisition. The results are X axis macro-pixel where the associated time depend signal is sampled therefore providing an hyperspectral information. We exemplified the proposed hyperspectral scheme in the context of time domain coherent Raman imaging where a pump pulse impulsively excites molecular vibrations that are subsequently probed by a time delayed probe pulse. In this case the time dependent signal is a fast acousto-optics delay line that can scan a delay of 4.5ps in 25$\mu$s, at each pixel level. We this acquisition scheme we demonstrate ultra-fast hyperspectral vibrational imaging in the low frequency range [10$cm^{-1}$, 150 $cm^{-1}$] over a 500 $\mu m$ field of view in 14ms (7 frames/s). The proposed acquisition scheme can be readily extended to other applications requiring to acquired a fast evolving signal at each pixel level.

We study the transport properties of underdoped trilayer cuprate HgBa$_2$Ca$_2$Cu$_3$O$_{8+ \delta}$ with doping level $p$ = 0.1 - 0.12 in magnetic field up to 88 T. We report for the first time in a cuprate superconductor a dramatic change of the quantum oscillation spectrum versus temperature, which is accompanied by a sign change of the Hall effect below $T \approx$ 10 K. Based on numerical simulations, we infer a Fermi surface reconstruction in the inner plane from an antiferromagnetic state (hole pockets) to a biaxial charge density wave state (electron pockets). We show that both orders compete and share the same hotspots of the Fermi surface and we discuss our result in the context of spin-fermion models., Comment: Main + Supplemental Information

Co$_3$Sn$_2$S$_2$ has been established as a prototype of magnetic Weyl semimetal, exhibiting a ''giant'' anomalous Hall effect in its ferromagnetic phase. An attractive feature of this material is that Weyl points lie close to Fermi level, so that one can expect a high reactivity of the topological properties to hole or electron doping. We present here a direct observation with Angle Resolved Photoemission Spectroscopy of the evolution of the electronic structure under different types of substitutions : In for Sn (hole doping outside the kagome Co plane), Fe for Co (hole doping inside the kagome Co plane) and Ni for Co (electron doping inside the kagome Co plane). We observe clear shifts of selected bands, which are due both to doping and to the reduction of the magnetic splitting by doping. We discriminate between the two by studying the temperature evolution from ferromagnetic to paramagnetic state. We discuss these shifts with the help of DFT calculations using the Virtual Crystal Approximation. We find that these calculations reproduce rather well the evolution with In, but largely fail to capture the effect of Fe and Ni, where local behavior at the impurity site plays an important role.

Understanding the set of conditions that allow rocky planets to have liquid water on their surface -- in the form of lakes, seas or oceans -- is a major scientific step to determine the fraction of planets potentially suitable for the emergence and development of life as we know it on Earth. This effort is also necessary to define and refine the so-called "Habitable Zone" (HZ) in order to guide the search for exoplanets likely to harbor remotely detectable life forms. Until now, most numerical climate studies on this topic have focused on the conditions necessary to maintain oceans, but not to form them in the first place. Here we use the three-dimensional Generic Planetary Climate Model (PCM), historically known as the LMD Generic Global Climate Model (GCM), to simulate water-dominated planetary atmospheres around different types of Main-Sequence stars. The simulations are designed to reproduce the conditions of early ocean formation on rocky planets due to the condensation of the primordial water reservoir at the end of the magma ocean phase. We show that the incoming stellar radiation (ISR) required to form oceans by condensation is always drastically lower than that required to vaporize oceans. We introduce a Water Condensation Limit, which lies at significantly lower ISR than the inner edge of the HZ calculated with three-dimensional numerical climate simulations. This difference is due to a behavior change of water clouds, from low-altitude dayside convective clouds to high-altitude nightside stratospheric clouds. Finally, we calculated transit spectra, emission spectra and thermal phase curves of TRAPPIST-1b, c and d with H2O-rich atmospheres, and compared them to CO2 atmospheres and bare rock simulations. We show using these observables that JWST has the capability to probe steam atmospheres on low-mass planets, and could possibly test the existence of nightside water clouds., Comment: Accepted for publication in Astronomy & Astrophysics

Ultrashort time-domain spectroscopy and field-resolved spectroscopy of molecular fingerprints are gold standards for detecting samples' constituents and internal dynamics. However, they are hindered by the Nyquist criterion, leading to prolonged data acquisition, processing times, and sizable data volumes. In this work, we present the first experimental demonstration of compressed sensing on field-resolved molecular fingerprinting by employing random scanning. Our measurements enable pinpointing the primary absorption peaks of atmospheric water vapor in response to terahertz light transients while sampling beyond the Nyquist limit. By drastically undersampling the electric field of the molecular response at a Nyquist frequency of 0.8 THz, we could successfully identify water absorption peaks up to 2.5 THz with a mean squared error of 12 * 10^-4. To our knowledge, this is the first experimental demonstration of time-domain compressed sensing, paving the path towards real-time field-resolved fingerprinting and acceleration of advanced spectroscopic techniques.

The spin dynamics in the block magnetic phase of the iron-based ladder compound \bfs\ has been studied by means of single crystal inelastic neutron scattering. Using linear spin wave theory and Monte-Carlo simulations, our analysis points to a magnetic Heisenberg model with effective frustrated antiferromagnetic couplings only, able to describe both the exotic block order and its dynamics. This new and purely antiferromagnetic picture offers a fruitful perspective to describe multiferroic properties but also understand the origin of the stripe-like magnetic instability observed under pressure as well as in other parent compounds with similar crystalline structure.

Two arguments have suggested the presence of subsurface water ice at latitudes lower than 30\textdegree~on Mars. First, the absence of CO2 frost on pole-facing slopes was explained by the presence of subsurface ice. Second, models suggested that subsurface ice could be stable underneath these slopes. We revisit these arguments with a new slope microclimate model. Our model shows that below 30{\deg} latitude, slopes are warmer than previously estimated as the air above is heated by warm surrounding plains. This additional heat prevents the formation of CO2 and subsurface water ice for most slopes. Higher than 30{\deg}S, our model suggests the presence of subsurface water ice. In sparse cases (steep dusty slopes), subsurface ice may exist down to 25{\deg}S. While hypothetical unstable ice deposits cannot be excluded by our model, our results suggest that water ice is rarer than previously thought in the +- 30{\deg} latitude range considered for human exploration., Comment: Accepted for publication in GRL

A large number of surface features (e.g., frost, gullies, slope streaks, recurring slope lineae) are observed on Martian slopes. Their activity is often associated with the specific microclimates on these slopes, which have been mostly studied with one-dimensional radiative balance models to date. We develop here a parameterization to simulate these microclimates in 3D Global Climate Models. We first demonstrate that any Martian slope can be thermally represented by a poleward or equatorward slope, i.e., the daily average, minimum, and maximum surface temperatures depend on the North-South component of the slope. Based on this observation, we implement here a subgrid-scale parameterization to represent slope microclimates (radiative fluxes, volatile condensation, ignoring slope winds for now) in the Mars Planetary Climate Model and validate it through comparisons with surface temperature measurements and frost detections on sloped terrains. With this new model, we show that slope microclimates do not have a significant impact on the seasonal CO$_2$ and H$_2$O cycles. Furthermore, short-scale slopes do not significantly impact the thermal state of the atmosphere. 91\% of the active gullies are found where our model predicts CO$_2$ frost, suggesting that their activity is related to processes involving CO$_2$ ice. However, the low thicknesses ($\leq$~tens of cm) predicted at mid-latitudes there rule out mechanisms involving large amounts ($\sim$ meters) of ice. This model opens the way to new studies on surface-atmosphere interactions in present and past climates., Comment: In revision for publication in JGR planets

We present a 40-MHz ultrafast optical parametric amplifier (OPA), tunable from 0.8 to 1 $\mu$m, with a relative intensity noise (RIN) matching the shot-noise floor (-160 dB/Hz) above 2 MHz. The OPA is pumped by a 20-W Kerr-lens mode-locked Ytterbium laser and seeded by a a supercontinuum generated in an all-normal-dispersion (ANDi) fiber. With an average output power >1.5 W, this compact and simple scheme is an attractive alternative to synchronously-pumped optical parametric oscillators, especially within the context of stimulated Raman scattering (SRS) imaging. To illustrate the latter, we perform chemical imaging of vinegar droplets in oil by SRS microscopy.

A new method for directly sampling the neutron resonance upscattering effect is presented. Alternatives have relied on inefficient rejection sampling techniques or large tabular storage of relative velocities. None of these approaches, which require pointwise energy data, are particularly well suited to the windowed multipole cross section representation. The new method called multipole analytic resonance scattering (MARS) overcomes these limitations by inverse transform sampling from the target relative velocity distribution where the cross section is expressed in the multipole formalism. The closed form relative speed distribution contains a novel special function we deem the incomplete Faddeeva function: $$ w(z, x) = \frac{i}{\pi} \int_{-\infty}^x \frac{e^{-t^2} dt}{z-t}. $$ We present the first results on its efficient numerical evaluation.

In recent years, radiation mapping has attracted widespread research attention and increased public concerns on environmental monitoring. In terms of both materials and their configurations, radiation detectors have been developed to locate the directions and positions of the radiation sources. In this process, algorithm is essential in converting detector signals to radiation source information. However, due to the complex mechanisms of radiation-matter interaction and the current limitation of data collection, high-performance, low-cost radiation mapping is still challenging. Here we present a computational framework using Tetris-inspired detector pixels and machine learning for radiation mapping. Using inter-pixel padding to increase the contrast between pixels and neural network to analyze the detector readings, a detector with as few as four pixels can achieve high-resolution directional mapping. By further imposing Maximum a Posteriori (MAP) with a moving detector, further radiation position localization is achieved. Non-square, Tetris-shaped detector can further improve performance beyond the conventional grid-shaped detector. Our framework offers a new avenue for high quality radiation mapping with least number of detector pixels possible, and is anticipated to be capable to deploy for real-world radiation detection with moderate validation., Comment: 29 pages, 20 figures. Ryotaro Okabe and Shangjie Xue contributed equally to this work

Sr2IrO4 and Sr3Ir2O7 form two families of spin-orbit Mott insulators with quite different charge gaps and an antiferromagnetic (AF) ground state. This offers a unique opportunity to study the impact of long-range magnetic order in Mott insulators. It appears to play a different role in the two families, as there is almost no change of the resistivity at the magnetic transition TN in Sr2IrO4 and a large one in Sr3Ir2O7. We use angle-resolved photoemission to study the evolution of the spectral lineshape through the magnetic transition. We use Ru and La substitutions to tune TN and discriminate changes due to temperature from those due to magnetic order. We evidence a shift and a transfer of spectral weight in the gap at TN in Sr3Ir2O7, which is absent in Sr2IrO4. We assign this behavior to a significantly larger coherent contribution to the spectral lineshape in Sr3Ir2O7, which evolves strongly at TN. On the contrary, the Sr2IrO4 lineshape is dominated by the incoherent part, which is insensitive to TN. We compare these findings to theoretical expections of the Slater vs Mott antiferromagnetism within Dynamical Mean Field Theory.

This chapter of the Planetary Exploration Horizon 2061 Report reviews the way the six key questions about planetary systems, from their origins to the way they work and their habitability, identified in chapter 1, can be addressed by means of solar system exploration, and how one can find partial answers to these six questions by flying to the different provinces to the solar system: terrestrial planets, giant planets, small bodies, and up to its interface with the local interstellar medium. It derives from this analysis a synthetic description of the most important space observations to be performed at the different solar system objects by future planetary exploration missions. These observation requirements illustrate the diversity of measurement techniques to be used as well as the diversity of destinations where these observations must be made. They constitute the base for the identification of the future planetary missions we need to fly by 2061, which are described in chapter 4. Q1- How well do we understand the diversity of planetary systems objects? Q2- How well do we understand the diversity of planetary system architectures? Q3- What are the origins and formation scenarios for planetary systems? Q4- How do planetary systems work? Q5- Do planetary systems host potential habitats? Q6- Where and how to search for life?, Comment: 107 pages, 37 figures, Horizon 2061 is a science-driven, foresight exercise, for future scientific investigations

In the bi-objective branch-and-bound literature, a key ingredient is objective branching, i.e. to create smaller and disjoint sub-problems in the objective space, obtained from the partial dominance of the lower bound set by the upper bound set. When considering three or more objective functions, however, applying objective branching becomes more complex, and its benefit has so far been unclear. In this paper, we investigate several ingredients which allow to better exploit objective branching in a multi-objective setting. We extend the idea of probing to multiple objectives, enhance it in several ways, and show that when coupled with objective branching, it results in significant speed-ups in terms of CPU times. We also investigate cut generation based on the objective branching constraints. Besides, we generalize the best-bound idea for node selection to multiple objectives and we show that the proposed rules outperform the, in the multi-objective literature, commonly employed depth-first and breadth-first strategies. We also analyze problem specific branching rules. We test the proposed ideas on available benchmark instances for three problem classes with three and four objectives, namely the capacitated facility location problem, the uncapacitated facility location problem, and the knapsack problem. Our enhanced multi-objective branch-and-bound algorithm outperforms the best existing branch-and-bound based approach and is the first to obtain competitive and even slightly better results than a state-of-the-art objective space search method on a subset of the problem classes.

Observations of the South Polar Residual Cap suggest a possible erosion of the cap, leading to an increase of the global mass of the atmosphere. We test this assumption by making the first comparison between Viking 1 and InSight surface pressure data, which were recorded 40 years apart. Such a comparison also allows us to determine changes in the dynamics of the seasonal ice caps between these two periods. To do so, we first had to recalibrate the InSight pressure data because of their unexpected sensitivity to the sensor temperature. Then, we had to design a procedure to compare distant pressure measurements. We propose two surface pressure interpolation methods at the local and global scale to do the comparison. The comparison of Viking and InSight seasonal surface pressure variations does not show changes larger than +-8 Pa in the CO2 cycle. Such conclusions are supported by an analysis of Mars Science Laboratory (MSL) pressure data. Further comparisons with images of the south seasonal cap taken by the Viking 2 orbiter and MARCI camera do not display significant changes in the dynamics of this cap over a 40 year period. Only a possible larger extension of the North Cap after the global storm of MY 34 is observed, but the physical mechanisms behind this anomaly are not well determined. Finally, the first comparison of MSL and InSight pressure data suggests a pressure deficit at Gale crater during southern summer, possibly resulting from a large presence of dust suspended within the crater.

Temperature profiles retrieved using the first set of data of the Emirates Mars InfraRed Spectrometer (EMIRS) obtained during the science phase of the Emirates Mars Mission (EMM) are used for the analysis of migrating thermal tides in the Martian atmosphere. The selected data cover a solar longitude (LS) range of 60{\deg}-90{\deg} of Martian Year (MY) 36. The novel orbit design of the Hope Probe leads to a good geographic and local time coverage that significantly improves the analysis. Wave mode decomposition suggests dominant diurnal tide and important semi-diurnal tide with maximal amplitudes of 6K and 2K, respectively, as well as the existence of ~0.5K ter-diurnal tide. The results agree well with predictions by the Mars Planetary Climate Model (PCM), but the observed diurnal tide has an earlier phase (3h), and the semi-diurnal tide has an unexpectedly large wavelength (~200km)., Comment: 11 pages, 5 figures, accepted by GRL special issue "The First Results from the Emirates Mars Mission (EMM)"

The Deep Atmosphere Venus Investigation of Noble gases, Chemistry, and Imaging (DAVINCI) mission described herein has been selected for flight to Venus as part of the NASA Discovery Program. DAVINCI will be the first mission to Venus to incorporate science-driven flybys and an instrumented descent sphere into a unified architecture. The anticipated scientific outcome will be a new understanding of the atmosphere, surface, and evolutionary path of Venus as a possibly once-habitable planet and analog to hot terrestrial exoplanets. The primary mission design for DAVINCI as selected features a preferred launch in summer/fall 2029, two flybys in 2030, and descent sphere atmospheric entry by the end of 2031. The in situ atmospheric descent phase subsequently delivers definitive chemical and isotopic composition of the Venus atmosphere during a cloud-top to surface transect above Alpha Regio. These in situ investigations of the atmosphere and near infrared descent imaging of the surface will complement remote flyby observations of the dynamic atmosphere, cloud deck, and surface near infrared emissivity. The overall mission yield will be at least 60 Gbits (compressed) new data about the atmosphere and near surface, as well as first unique characterization of the deep atmosphere environment and chemistry, including trace gases, key stable isotopes, oxygen fugacity, constraints on local rock compositions, and topography of a tessera., Comment: 41 pages, 14 figures, accepted for publication in the Planetary Science Journal

Anisotropic strain is an external field capable of selectively addressing the role of nematic fluctuations in promoting superconductivity. We demonstrate this using polarization-resolved elasto-Raman scattering to probe the evolution of nematic fluctuations under strain in the normal and superconducting states of the paradigmatic iron-based superconductor Ba(Fe$_{1-x}$Co$_x$)$_2$As$_2$. In the non-superconducting parent compound BaFe$_2$As$_2$ we observe a strain-induced suppression of the nematic susceptibility which follows the expected behavior of an Ising order parameter under a symmetry breaking field. For the superconducting compound, the suppression of the nematic susceptibility correlates with the decrease of the superconducting critical temperature $T_c$. Our results indicate a significant contribution of nematic fluctuations to electron pairing and validate theoretical scenarios of enhanced $T_c$ near a nematic quantum critical point., Comment: 5 pages, 3 figures + SM

Four-wave mixing processes are ubiquitous in ultrafast optics and the determination of the coefficients of the $\chi^{(3)}$ tensor is thus essential. We introduce a novel time-resolved ultrafast spectroscopic method to characterize the third-order nonlinearity on the femtosecond time-scale. This approach, coined as "nonlinear chirped Doppler interferometry", makes use of the variation of the optical group delay of a transmitted probe under the effect of an intense pump pulse in the nonlinear medium of interest. The observable is the spectral interference between the probe and a reference pulse sampled upstream. We show that the detected signal is enhanced when the pulses are chirped, and that, although interferometric, the method is immune to environmental phase fluctuations and drifts. By chirping adequately the reference pulse, the transient frequency shift of the probe pulses is also detected in the time domain and the detected nonlinear signal is enhanced. Nonlinear phase shifts as low as 10\,mrad, corresponding to a frequency shift of 30\,GHz, i.e. 0.01\% of the carrier frequency, are detected without heterodyne detection or active phase-stabilization. The diagonal and/or non-diagonal terms of reference glasses (SiO$_2$) and crystals (Al$_2$O$_3$, BaF$_2$, CaF$_2$) are characterized. The method is finally applied to measure the soft vibration mode of KTiOAsO$_4$ (KTA).

Liquid dye lasers have long been considered as ideal tunable laser sources in the visible range but are bulky, expensive, and require a complex system for dye circulation. Here, we present a system that relies on a low-cost blue laser diode as the pump source and a sealed dye cell with no flowing circuitry, resulting in a device that combines the convenience and size of a solid-state device with the stability of a liquid organic laser. A very high photo-stability is obtained (up to 1.2 x 10$^9$ pulses or 12 days at 1 kHz), which is five orders of magnitude higher than a solid-state dye laser operated in similar conditions. The number of pulses obtainable at low repetition rates is found to be limited by molecular self-diffusion and, hence, related to the total cuvette volume. In contrast, the repetition rate is limited to a few kHz, which suggests that thermal effects play a bigger role than triplet population effects. Thermal effects participate in the suppression of lasing through the buildup of a strong negative thermal lens; correcting the non-aberrant part of this thermal lens by resonator design enables the repetition rate to be pushed up to 14 kHz with possible further optimization. This work shows a route for building off-the-shelf, compact, low-cost, and convenient tunable pulsed lasers in the visible range that have superior stability over organic solid-state lasers.

A highly stable diode-pumped circulation-free liquid dye laser in a vertical external cavity is reported. The design is simple (no fabrication process step required, no fluid circuitry), compact (~ cm sized), and cost-effective. An optical efficiency of 18% with a M${}^2$ of 1 are reported, with an excellent photostability-no efficiency drop was seen after 1.4 million pulses at 50 Hz, a value comparable to flowing systems and much higher than values achievable with organic solid-state lasers. We show that thermal effects are central in the stability and also on the dynamics of this laser. The laser build-up and shutdown dynamics are studied in detail for different pump pulse durations/repetition rates; they reveal a pulse shortening with increasing pump pulse duration and repetition rate that are shown to be due to thermal lensing diffraction losses. This laser structure offers a very convenient and simple platform for testing or harvesting solution-processable gain materials.

Thermal tides in the Martian atmosphere are analyzed using temperature profiles retrieved from nadir observations obtained by the TIRVIM Fourier-spectrometer, part of the Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO). The data is selected near the northern summer solstice at solar longitude (LS) 75{\deg}-105{\deg} of Martian Year (MY) 35. The observations have a full local time coverage, which enables analyses of daily temperature anomalies. The observed zonal mean temperature is lower by 4-6K at ~100Pa, but higher towards the summer pole, compared to the LMD Mars General Circulation Model (GCM). Wave mode decomposition shows dominant diurnal tide and important semi-diurnal tide and diurnal Kelvin wave, with maximal amplitudes of 5K, 3K, and 2.5K, respectively, from tens to hundreds of Pa. The results generally agree well with the LMD Mars GCM, but with noticeable earlier phases of diurnal (~1h) and semi-diurnal (~3h) tides., Comment: 7 pages, 4 figures, accepted by GRL

Exposed scarps images and ice-penetrating radar measurements in the North Polar Layered Deposits (NPLD) of Mars show alternating layers that provide an archive of past climate oscillations, that are thought to be linked to orbital variations, akin to Milankovitch cycles on Earth. We use the Laboratoire de Meteorologie Dynamique (LMD) Martian Global Climate Model (GCM) to study paleoclimate states to enable a better interpretation of the NPLD physical and chemical stratigraphy. When a tropical ice reservoir is present, water vapor transport from the tropics to the poles at low obliquity is modulated by the intensity of summer. At times of low and relatively constant obliquity, the flux still varies due to other orbital elements, promoting polar layer formation. Ice migrates from the tropics towards the poles in two stages. First, when surface ice is present in the tropics, and second, when the equatorial deposit is exhausted, from ice that was previously deposited in mid-high latitudes. The polar accumulation rate is significantly higher when tropical ice is available, forming thicker layers per orbital cycle. However, the majority of the NPLD is sourced from ice that temporary resided in the mid-high latitudes and the layers become thinner as the source location moves poleward. The migration stages imprint different D/H ratios in different sections in the PLDs. The NPLD is isotopically depleted compared to the SPLD in all simulations. Thus we predict the D/H ratio of the atmosphere in contact with NPLD upper layers is biased relative to the average global ice reservoirs., Comment: 23 pages, 7 figures. JGR-planets (2022)

This paper presents a study of the structure dynamics in BaFe$_2$Se$_3$. We combined first-principle calculations, infrared measurements and a thorough symmetry analysis. Our study confirms that $Pnma$ cannot be the space group of BaFe$_2$Se$_3$, even at room temperature. The phonons assignment requires $Pm$ to be the BaFe$_2$Se$_3$ space group, not only in the magnetic phase, but also in the paramagnetic phase at room temperature. This is due to a strong coupling between a short range spin-order along the ladders, and the lattice degrees of freedom associated with the Fe-Fe bond length. This coupling induces a change in the bond-length pattern from an alternated trapezoidal one (as in $Pnma$) to an alternated small/large rectangular one. Out of the two patterns, only the latter is fully compatible with the observed block-type magnetic structure. Finally, we propose a complete symmetry analysis of the BaFe$_2$Se$_3$ phase diagram in the 0-600\,K range., Comment: 15 page, 5 fig

We report on the formation of topological defects emerging from the cycloidal antiferromagnetic order at the surface of bulk BiFeO$_3$ crystals. Combining reciprocal and real-space magnetic imaging techniques, we first observe, in a single ferroelectric domain, the coexistence of antiferromagnetic domains in which the antiferromagnetic cycloid propagates along different wavevectors. We then show that the direction of these wavevectors is not strictly locked to the preferred crystallographic axes as continuous rotations bridge different wavevectors. At the junctions between the magnetic domains, we observe topological line defects identical to those found in a broad variety of lamellar physical systems with rotational symmetries. Our work establishes the presence of these magnetic objects at room temperature in the multiferroic antiferromagnet BiFeO$_3$, offering new possibilities for their use in spintronics., Comment: 7 pages, 4 figures, supplemental material as ancillary file

The Atmospheric Chemistry Suite (ACS) onboard the ExoMars Trace Gas Orbiter (TGO) monitors the Martian atmosphere through different spectral intervals in the infrared light. We present a retrieval algorithm tailored to the analysis of spectra acquired in nadir geometry by TIRVIM, the thermal infrared channel of ACS. Our algorithm simultaneously retrieves vertical profile of atmospheric temperature up to 50 km, surface temperature, and integrated optical depth of dust and water ice clouds. The specificity of the TIRVIM dataset lies in its capacity to resolve the diurnal cycle over a 54 sol period. However, it is uncertain to what extent can the desired atmospheric quantities be accurately estimated at different times of day. Here we first present an Observing System Simulation Experiment (OSSE). We produce synthetic observations at various latitudes, seasons and local times and run our retrieval algorithm on these synthetic data, to evaluate its robustness. Different sources of biases are documented, in particular regarding aerosol retrievals. Atmospheric temperature retrievals are found robust even when dust and/or water ice cloud opacities are not well estimated in our OSSE. We then apply our algorithm to TIRVIM observations in April-May, 2018 and perform a cross-validation of retrieved atmospheric temperature and dust integrated opacity by comparisons with thousands of co-located Mars Climate Sounder (MCS) retrievals. Most differences between TIRVIM and MCS atmospheric temperatures can be attributed to differences in vertical sensitivity. Daytime dust opacities agree well with each other, while biases are found in nighttime dust opacity retrieved from TIRVIM at this season., Comment: 51 pages, 29 figures. Accepted in Juanuary 2022 for publication in Journal of Geophysical Research (Planets)

A stellar occultation by Neptune's main satellite, Triton, was observed on 5 October 2017 from Europe, North Africa, and the USA. We derived 90 light curves from this event, 42 of which yielded a central flash detection. We aimed at constraining Triton's atmospheric structure and the seasonal variations of its atmospheric pressure since the Voyager 2 epoch (1989). We also derived the shape of the lower atmosphere from central flash analysis. We used Abel inversions and direct ray-tracing code to provide the density, pressure, and temperature profiles in the altitude range $\sim$8 km to $\sim$190 km, corresponding to pressure levels from 9 {\mu}bar down to a few nanobars. Results. (i) A pressure of 1.18$\pm$0.03 {\mu}bar is found at a reference radius of 1400 km (47 km altitude). (ii) A new analysis of the Voyager 2 radio science occultation shows that this is consistent with an extrapolation of pressure down to the surface pressure obtained in 1989. (iii) A survey of occultations obtained between 1989 and 2017 suggests that an enhancement in surface pressure as reported during the 1990s might be real, but debatable, due to very few high S/N light curves and data accessible for reanalysis. The volatile transport model analysed supports a moderate increase in surface pressure, with a maximum value around 2005-2015 no higher than 23 {\mu}bar. The pressures observed in 1995-1997 and 2017 appear mutually inconsistent with the volatile transport model presented here. (iv) The central flash structure does not show evidence of an atmospheric distortion. We find an upper limit of 0.0011 for the apparent oblateness of the atmosphere near the 8 km altitude., Comment: 52 pages, 26 figures in the main paper, 2 figures in appendix B, 9 figures in appendix C, 1 long table over 5 pages

The stability of the phase difference between two white-light continua, generated from the same 180-fs pulses at 1035\,nm, is assessed by a modified Bellini-Hansch interferometer. Mutual spectral stability is studied as a function of several parameters: position of the nonlinear crystal with respect to the beam waist, interaction length, and pulse energy. Intensity-to-phase coupling coefficients are measured and stability regions are identified.

The detection of sulphur species in the Martian atmosphere would be a strong indicator of volcanic outgassing from the surface of Mars. We wish to establish the presence of SO2, H2S, or OCS in the Martian atmosphere or determine upper limits on their concentration in the absence of a detection. We perform a comprehensive analysis of solar occultation data from the mid-infrared channel of the Atmospheric Chemistry Suite instrument, on board the ExoMars Trace Gas Orbiter, obtained during Martian years 34 and 35. For the most optimal sensitivity conditions, we determine 1-sigma upper limits of SO2 at 20 ppbv, H2S at 15 ppbv, and OCS at 0.4 ppbv; the last value is lower than any previous upper limits imposed on OCS in the literature. We find no evidence of any of these species above a 3-sigma confidence threshold. We therefore infer that passive volcanic outgassing of SO2 must be below 2 ktons/day., Comment: 13 pages, 12 figures, received for production in A&A on the 19th of November 2021

Remote sensing observations from satellites and global biogeochemical models have combined to revolutionize the study of ocean biogeochemical cycling, but comparing the two data streams to each other and across time remains challenging due to the strong spatial-temporal structuring of the ocean. Here, we show that the Wasserstein distance provides a powerful metric for harnessing these structured datasets for better marine ecosystem and climate predictions. Wasserstein distance complements commonly used point-wise difference methods such as the root mean squared error, by quantifying differences in terms of spatial displacement in addition to magnitude. As a test case we consider Chlorophyll (a key indicator of phytoplankton biomass) in the North-East Pacific Ocean, obtained from model simulations, in situ measurements, and satellite observations. We focus on two main applications: 1) Comparing model predictions with satellite observations, and 2) temporal evolution of Chlorophyll both seasonally and over longer time frames. Wasserstein distance successfully isolates temporal and depth variability and quantifies shifts in biogeochemical province boundaries. It also exposes relevant temporal trends in satellite Chlorophyll consistent with climate change predictions. Our study shows that optimal transport vectors underlying Wasserstein distance provide a novel visualization tool for testing models and better understanding temporal dynamics in the ocean., Comment: 6 figures

Multilayered cuprates possess not only the highest superconducting temperature transition but also offer a unique platform to study disorder-free CuO$_2$ planes and the interplay between competing orders with superconductivity. Here, we study the underdoped trilayer cuprate HgBa$_2$Ca$_2$Cu$_3$O$_{8+ \delta}$ and we report the first quantum oscillation and Hall effect measurements in magnetic field up to 88 T. A careful analysis of the complex spectra of quantum oscillations strongly supports the coexistence of an antiferromagnetic order in the inner plane and a charge order in the outer planes. The presence of an ordered antiferromagnetic metallic state that extends deep in the superconducting phase is a key ingredient that supports magnetically mediated pairing interaction in cuprates., Comment: 6+5 pages, 4+6 figures

Neptune's moon Triton shares many similarities with Pluto, including volatile cycles of N2, CH4 and CO, and represents a benchmark case for the study of surface-atmosphere interactions on volatile-rich KBOs. Within the context of New Horizons observations of Pluto as well as recent Earth-based observations of Triton, we adapt a Plutonian VTM to Triton, and test its ability to simulate its volatile cycles, thereby aiding our understanding of its climate. We present VTM simulations exploring the volatile cycles on Triton over long-term and seasonal timescales for varying model parameters. We explore what scenarios and model parameters allow for a best match of the available observations. In particular, our set of observational constraints include Voyager 2 observations, ground-based NIR (0.8 to 2.4 {\mu}m) disk-integrated spectra and the evolution of surface pressure as retrieved from stellar occultations. Our results show that Triton's poles act as cold traps for volatile ices and favor the formation of polar caps extending to lower latitudes through glacial flow. As previously evidenced by other VTMs, North-South asymmetries in surface properties can favor the development of one cap over the other. Our best-case simulations are obtained for a global reservoir of N2 ice thicker than 200 m and a bedrock thermal inertia larger than 500 SI. The large N2 ice reservoir implies a permanent N2 southern cap extending to the equator. Our results also suggest that a small permanent polar cap exists in the northern (currently winter) hemisphere if the internal heat flux remains radiogenic (< 3 mW m-2). Finally, we provide predictions for the evolution of ice distribution, surface pressure, CO and CH4 atmospheric mixing ratios in the next decades. We also model the thermal lightcurves of Triton in 2022, which serve as predictions for future JWST observations., Comment: 69 pages, 29 figures, 3 tables. Accepted for publication in Icarus

We report a Raman scattering study of nematic degrees of freedom in the iron-based superconductor parent compound BaFe$_2$As$_2$ under tunable uniaxial strain. We demonstrate that the polarization resolved arsenic (As) phonon intensity can be used to monitor the nematic order parameter as a function of both temperature and strain. At low temperature in the nematic ordered phase we use it to track the continuous and reversible orientation of nematic domains under variable strain. At higher temperature, the evolution of the As phonon intensity under strain reflects an enhanced nematic susceptibility close to the nematic transition $T_S$. Its temperature dependence under strong strain follows qualitatively the expected behavior of an Ising order parameter under a symmetry breaking field. Our elasto-Raman study illustrates the interest of combining selective anisotropic strain with a symmetry resolved probe like Raman scattering. Elasto-Raman scattering can be applied to a wide variety of quantum materials where uniaxial strain tunes electronic orders., Comment: 14 pages (including appendix), 11 figures

The InSight mission, featuring continuous high-frequency high-sensitivity pressure measurements, is in ideal position to study the active atmospheric turbulence of Mars. Data acquired during 1.25 Martian year allows us to study the seasonal evolution of turbulence and its diurnal cycle. We investigate vortices (abrupt pressure drops), local turbulence (frequency range 0.01-2 Hz) and non-local turbulence often caused by convection cells and plumes (frequency range 0.002-0.01 Hz). Contrary to non-local turbulence, local turbulence is strongly sensitive at all local times and seasons to the ambient wind. We report many remarkable events with the arrival of northern autumn at the InSight landing site: a spectacular burst of daytime vortices, the appearance of nighttime vortices, and the development of nighttime local turbulence as intense as its daytime counterpart. Nighttime turbulence at this dusty season appears as a result of the combination of a stronger low-level jet, producing shear-driven turbulence, and a weaker stability., Comment: 15 pages, 5 figures, accepted version of the manuscript published in GRL

Time resolved pump and probe acoustics and first-principles calculations were employed to assess elastic properties of the TbMnO3 perovskite manganite having orthorhombic symmetry. Measuring sound velocities of bulk longitudinal and shear acoustic waves propagating along at least two different directions in the high symmetry planes (100), (010) and (001), provided a powerful mean to selectively determine the six diagonal elastic constants C11= 227 GPa, C22= 349 GPa, C33= 274 GPa, C44= 71 GPa, C55= 57 GPa, C66= 62 GPa. Among the three remaining off-diagonal ones, C23= 103 GPa was determined with a bissectrice direction. Density functional theory calculations with colinear spin-polarized provided complementary insights on their optical, elastic and magnetoelastic properties.

The TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI) is a community project that aims to quantify how dfferences in general circulation models (GCMs) could impact the climate prediction for TRAPPIST-1e and, subsequently its atmospheric characterization in transit. Four GCMs have participated in THAI so far: ExoCAM, LMD-Generic, ROCKE-3D and the UM. This paper, focused on the simulated observations, is the third part of a trilogy, following the analysis of two land planet scenarios (part I) and two aquaplanet scenarios (part II). Here, we show a robust agreement between the simulated spectra and the number of transits estimated to detect the land planet atmospheres. For the aquaplanet ones, using atmospheric data from any of the four GCMs would require at least 17 transits. This prediction corresponds to UM simulated data which produces the lowest and thinnest clouds. Between 35-40% more clouds are predicted by ExoCAM or LMD-G due to higher thick terminator clouds. For the first time this work provides "GCM uncertainty error bars" of 35-40% that need to be considered in future analyses of transmission spectra. We also analyzed the inter-transit variability induced by weather patterns and changes of terminator cloudiness between transits. Its magnitude differs significantly between the GCMs but its impact on the transmission spectra is within the measurement uncertainties. THAI has demonstrated the importance of model intercomparison for exoplanets and also paved the way for a larger project to develop an intercomparison meta-framework, namely the Climates Using Interactive Suites of Intercomparisons Nested for Exoplanet Studies (CUISINES)., Comment: Accepted in the Planetary Science Journal as Part III of a series of 3 THAI papers

To identify promising exoplanets for atmospheric characterization and to make the best use of observational data, a thorough understanding of their atmospheres is needed. 3D general circulation models (GCMs) are one of the most comprehensive tools available for this task and will be used to interpret observations of temperate rocky exoplanets. Due to parameterization choices made in GCMs, they can produce different results, even for the same planet. Employing four widely-used exoplanetary GCMs -- ExoCAM, LMD-G, ROCKE-3D and the UM -- we continue the TRAPPIST-1 Habitable Atmosphere Intercomparison by modeling aquaplanet climates of TRAPPIST-1e with a moist atmosphere dominated by either nitrogen or carbon dioxide. Although the GCMs disagree on the details of the simulated regimes, they all predict a temperate climate with neither of the two cases pushed out of the habitable state. Nevertheless, the inter-model spread in the global mean surface temperature is non-negligible: 14 K and 24 K in the nitrogen and carbon dioxide dominated case, respectively. We find substantial inter-model differences in moist variables, with the smallest amount of clouds in LMD-Generic and the largest in ROCKE-3D. ExoCAM predicts the warmest climate for both cases and thus has the highest water vapor content and the largest amount and variability of cloud condensate. The UM tends to produce colder conditions, especially in the nitrogen-dominated case due to a strong negative cloud radiative effect on the day side of TRAPPIST-1e. Our study highlights various biases of GCMs and emphasizes the importance of not relying solely on one model to understand exoplanet climates., Comment: 35 pages, 22 figures; Published in The Planetary Science Journal

With the commissioning of powerful, new-generation telescopes such as the James Webb Space Telescope (JWST) and the ground-based Extremely Large Telescopes, the first characterization of a high molecular weight atmosphere around a temperate rocky exoplanet is imminent. Atmospheric simulations and synthetic observables of target exoplanets are essential to prepare and interpret these observations. Here we report the results of the first part of the TRAPPIST-1 Habitable Atmosphere Intercomparison (THAI) project, which compares 3D numerical simulations performed with four state-of-the-art global climate models (ExoCAM, LMD-Generic, ROCKE-3D, Unified Model) for the potentially habitable target TRAPPIST-1e. In this first part, we present the results of dry atmospheric simulations. These simulations serve as a benchmark to test how radiative transfer, subgrid-scale mixing (dry turbulence and convection), and large-scale dynamics impact the climate of TRAPPIST-1e and consequently the transit spectroscopy signature as seen by JWST. To first order, the four models give results in good agreement. The intermodel spread in the global mean surface temperature amounts to 7K (6K) for the N2-dominated (CO2-dominated) atmosphere. The radiative fluxes are also remarkably similar (intermodel variations less than 5%), from the surface (1 bar) up to atmospheric pressures around 5 mbar. Moderate differences between the models appear in the atmospheric circulation pattern (winds) and the (stratospheric) thermal structure. These differences arise between the models from (1) large-scale dynamics, because TRAPPIST-1e lies at the tipping point between two different circulation regimes (fast and Rhines rotators) in which the models can be alternatively trapped, and (2) parameterizations used in the upper atmosphere such as numerical damping., Comment: Published in the Planetary Science Journal as Part I of a series of 3 THAI papers

Fully homomorphic encryption (FHE) is an encryption scheme which enables computation on encrypted data without revealing the underlying data. While there have been many advances in the field of FHE, developing programs using FHE still requires expertise in cryptography. In this white paper, we present a fully homomorphic encryption transpiler that allows developers to convert high-level code (e.g., C++) that works on unencrypted data into high-level code that operates on encrypted data. Thus, our transpiler makes transformations possible on encrypted data. Our transpiler builds on Google's open-source XLS SDK (https://github.com/google/xls) and uses an off-the-shelf FHE library, TFHE (https://tfhe.github.io/tfhe/), to perform low-level FHE operations. The transpiler design is modular, which means the underlying FHE library as well as the high-level input and output languages can vary. This modularity will help accelerate FHE research by providing an easy way to compare arbitrary programs in different FHE schemes side-by-side. We hope this lays the groundwork for eventual easy adoption of FHE by software developers. As a proof-of-concept, we are releasing an experimental transpiler (https://github.com/google/fully-homomorphic-encryption/tree/main/transpiler) as open-source software.

The development of next-generation autonomous control of fission systems, such as nuclear power plants, will require leveraging advancements in machine learning. For fission systems, accurate prediction of nuclear transport is important to quantify the safety margin and optimize performance. The state-of-the-art approach to this problem is costly Monte Carlo (MC) simulations to approximate solutions of the neutron transport equation. Such an approach is feasible for offline calculations e.g., for design or licensing, but is precluded from use as a model-based controller. In this work, we explore the use of Artificial Neural Networks (ANN), Gradient Boosting Regression (GBR), Gaussian Process Regression (GPR) and Support Vector Regression (SVR) to generate empirical models. The empirical model can then be deployed, e.g., in a model predictive controller. Two fission systems are explored: the subcritical MIT Graphite Exponential Pile (MGEP), and the critical MIT Research Reactor (MITR). Findings from this work establish guidelines for developing empirical models for multidimensional regression of neutron transport. An assessment of the accuracy and precision finds that the SVR, followed closely by ANN, performs the best. For both MGEP and MITR, the optimized SVR model exhibited a domain-averaged, test, mean absolute percentage error of 0.17 %. A spatial distribution of performance metrics indicates that physical regions of poor performance coincide with locations of largest neutron flux perturbation -- this outcome is mitigated by ANN and SVR. Even at local maxima, ANN and SVR bias is within experimental uncertainty bounds. A comparison of the performance vs. training dataset size found that SVR is more data-efficient than ANN. Both ANN and SVR achieve a greater than 7 order reduction in evaluation time vs. a MC simulation., Comment: 20 pages, 7 figures

The era of atmospheric characterization of terrestrial exoplanets is just around the corner. Modeling prior to observations is crucial in order to predict the observational challenges and to prepare for the data interpretation. This paper presents the report of the TRAPPIST Habitable Atmosphere Intercomparison (THAI) workshop (14-16 September 2020). A review of the climate models and parameterizations of the atmospheric processes on terrestrial exoplanets, model advancements and limitations, as well as direction for future model development was discussed. We hope that this report will be used as a roadmap for future numerical simulations of exoplanet atmospheres and maintaining strong connections to the astronomical community., Comment: Accepted in the AAS Planetary Science Journal (PSJ)

We report a polarization-resolved Raman spectroscopy study of the orbital dependence of the quasiparticles properties in the prototypical multi-band Fermi liquid Sr\textsubscript{2}RuO\textsubscript{4}. We show that the quasiparticle scattering rate displays $\omega^{2}$ dependence as expected for a Fermi liquid. Besides, we observe a clear polarization-dependence in the energy and temperature dependence of the quasiparticle scattering rate and mass, with the $d_{xz/yz}$ orbital derived quasiparticles showing significantly more robust Fermi liquid properties than the $d_{xy}$ orbital derived ones. The observed orbital dichotomy of the quasiparticles is consistent with the picture of Sr\textsubscript{2}RuO\textsubscript{4} as a Hund's metal. Our study establishes Raman scattering as a powerful probe of Fermi liquid properties in correlated metals., Comment: 9 pages, 4 figures, Supplementary Materials available at publisher site

CO2+H2 greenhouse warming has recently emerged as a promising scenario to sufficiently warm the early martian surface to allow the formation of valley networks and lakes. Here we present numerical 3-D global climate simulations of the early martian climate that we have performed assuming dense CO2+H2 atmospheres. Our climate model, derived from earlier works by Forget et al. (2013) and Wordsworth et al. (2013), is coupled to an asynchronous model of the long-term evolution of martian glaciers and lakes. Simulations were carried out at 40{\deg} obliquity to investigate how (i) water content and (ii) H2 content (added to 1 or 2 bars of CO2) can shape the climate and hydrologic cycle of early Mars. We show that the adiabatic cooling mechanism (Wordsworth et al. 2013) that leads to the accumulation of ice deposits in the southern highlands in cold climate (the so called 'icy highland scenario') also works in warm climates, with impact crater lakes acting as the main water reservoirs. This produces rainfall mainly localized in the southern highlands of Mars. If one adjust (i) the amount of CO2 and H2, (ii) the size and location of the water reservoirs, and (iii) the ancient topography (i.e. by removing Tharsis), the spatial patterns of surface runoff (from rainfall or snowmelt) in the simulations can match -- with a few exceptions -- the observed distribution of valley networks and impact crater lakes. Although our results are obtained for CO2-dominated atmospheres enriched with H2, they should also apply to assess the impact of any combination of powerful long-lived greenhouse gases on early Mars., Comment: Submitted for publication to Icarus. Comments and suggestions are welcome!

The superconducting phase of the $\mathrm{HgBa}_2\mathrm{CuO}_{4+\delta}$ (Hg-1201) and $\mathrm{HgBa}_2\mathrm{Ca}_2\mathrm{Cu}_3\mathrm{O}_{8+\delta}$ (Hg-1223) cuprates has been investigated by Raman spectroscopy under hydrostatic pressure. Our analysis reveals that the increase of $T_c$ with pressure is slower in Hg-1223 cuprate compared to the Hg-1201 due to a charge carrier concentration imbalance (accentuated by pressure) between the $\mathrm{CuO}_2$ layers of Hg-1223. We find that the energy variation under pressure of the apical oxygen mode from which the charge carriers are transferred to the $\mathrm{CuO}_2$ layers, is the same for both the Hg-1223 and Hg-1223 cuprates and it is controlled by the inter-layer compressibility. At last, we show that the binding energy of the Cooper pairs related to the maximum amplitude of the $d-$ wave superconducting gap at the anti-nodes, does not follow $T_c$ with pressure. It decreases while $T_c$ increases. In the particular case of Hg-1201, the binding energy collapses from 10 to 2 $K_B T_c$ as the pressure increases up to 10 GPa. These direct spectroscopic observations joined to the fact that the binding energy of the Cooper pairs at the anti-nodes does not follow $T_c$ either with doping, raises the question of its link with the pseudogap energy scale which follows the same trend with doping., Comment: 15 pages, 18 figures

We have performed elasticity measurements in the bulk multiferroic BiFeO3 (BFO) using acoustical pump and probe spectroscopy. The sound velocities of the (quasi)-longitudinal and of the two (quasi)-transverse acoustic waves along three independent directions of the (110) surface have been measured. Moreover, one surface wave and one longitudinal wave propagating perpendicular to the surface have been detected. Based on initial input values of the six independent Cij elastic constants determined by our density functional theory calculations and our eleven experimental velocities, the numerical resolution of the acoustic equations allows to determine all the Cij elastic constants of BFO. The propagation direction dependence of volume and surface waves phase velocities allows the unambiguously assignment of the waves, hence the polarization of phonons.

Pluto's atmospheric profiles (temperature and pressure) have been studied for decades from stellar occultation lightcurves. In this paper, we look at recent Pluto Global Climate Model (GCM) results (3D temperature, pressure, and density fields) from Bertrand et al. (2020) and use the results to generate model observer's plane intensity fields (OPIF) and lightcurves by using a Fourier optics scheme to model light passing through Pluto's atmosphere (Young, 2012). This approach can accommodate arbitrary atmospheric structures and 3D distributions of haze. We compared the GCM model lightcurves with the lightcurves observed during the 15-AUG-2018 Pluto stellar occultation. We find that the climate scenario which best reproduces the observed data includes an N2 ice mid-latitude band in the southern hemisphere. We have also studied different haze and P/T ratio profiles: the haze effectively reduces the central flash strength, and a lower P/T ratio both reduces the central flash strength and incurs anomalies in the shoulders of the central flash.