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Irradiation by energetic ions, electrons, and UV photons induces sputtering and chemical processes (radiolysis) in the surfaces of icy moons, comets, and icy grains. Laboratory experiments, both of ideal surfaces and of more complex and realistic analog samples, are crucial to understand the interaction of surfaces of icy moons and comets with their space environment. This study shows the first results of mass spectrometry measurements from porous water ice regolith samples irradiated with electrons as a representative analogy to water-ice rich surfaces in the solar system. Previous studies have shown that most electron-induced H2O radiolysis products leave the ice as H2 and O2 and that O2 can be trapped under certain conditions in the irradiated ice. Our new laboratory experiments confirm these findings. Moreover, they quantify residence times and saturation levels of O2 in originally pure water ice. H2O may also be released from the water ice by irradiation, but the quantification of the released H2O is more difficult and the total amount is sensitive to the electron flux and energy.

Sputtering by solar wind ions is a key process driving the ejection of high-energy particles into the exospheres of airless bodies like asteroids, Mercury and the Moon. In view of upcoming missions which will deliver new in-situ data on these exospheres like the Artemis program at the Moon and BepiColombo at Mercury, a deeper understanding of sputtering effects is crucial. In this work, we combine sensitive quartz crystal microbalance measurements and numerical simulations to quantify sputter yields of Apollo soil 68501 under solar wind relevant conditions. We find that none of the commonly used simulation codes can reliably predict laboratory sputter yields without experimental benchmarks. All of the employed packages significantly overestimate the sputter yields of flat samples by at least a factor of 2 for the case of hydrogen. When accounting for surface roughness and regolith-like porosity, sputter yields are decreased even further to 7.3E-3 atoms\ion and 7.6E-2 atoms\ion for H and He at solar wind energies of 1 keV\amu, respectively. The reduced yields of porous regolith structures are largely independent of the ion incidence angle, making them applicable across a wide range of lunar latitudes. This study highlights the need for experimental validation of sputtering models to ensure accurate predictions for space weathering and lunar exosphere composition.

The IBEX-Lo instrument on the Interstellar Boundary Explorer (IBEX) mission observes primary and secondary interstellar helium in its 4 lowest energy steps. Observations of these helium populations have been systematically analyzed and compared to simulations using the analytic full integration of neutrals model (aFINM). A systematic difference is observed between the simulations and observations of secondary helium during solar cycle (SC) 24. We show that elastic scattering of primary helium by solar wind protons, which redistributes atoms from the core of the flux distribution, provides an explanation of the observed divergence from simulations. We verify that elastic scattering forms a halo in the wings of the primary He distribution in the spin-angle direction. Correcting the simulation for the effects of elastic scattering requires an increase of the estimated density of primary helium compared to previous estimates by Ulysses/GAS. Thus, based on our analysis of IBEX observations and $\chi ^2$ minimization of simulation data that include the effects of elastic scattering, any estimation of neutral interstellar helium density at 1 AU by direct detection of the peak flux of neutral helium needs to be adjusted by $~\sim$ 10%

Quantum computing has tremendous potential to overcome some of the fundamental limitations present in classical information processing. Yet, today's technological limitations in the quality and scaling prevent exploiting its full potential. Quantum computing based on superconducting quantum processing units (QPUs) is among the most promising approaches towards practical quantum advantage. In this article the basic technological approach of IQM Quantum Computers is described covering both the QPU and the rest of the full-stack quantum computer. In particular, the focus is on a 20-qubit quantum computer featuring the Garnet QPU and its architecture, which we will scale up to 150 qubits. We also present QPU and system-level benchmarks, including a median 2-qubit gate fidelity of 99.5% and genuinely entangling all 20 qubits in a Greenberger-Horne-Zeilinger (GHZ) state.

Jupiter's moon Io is a highly compelling target for future exploration that offers critical insight into tidal dissipation processes and the geology of high heat flux worlds, including primitive planetary bodies, such as the early Earth, that are shaped by enhanced rates of volcanism. Io is also important for understanding the development of volcanogenic atmospheres and mass-exchange within the Jupiter System. However, fundamental questions remain about the state of Io's interior, surface, and atmosphere, as well as its role in the evolution of the Galilean satellites. The Io Volcano Observer (IVO) would address these questions by achieving the following three key goals: (A) Determine how and where tidal heat is generated inside Io; (B) Understand how tidal heat is transported to the surface of Io; and (C) Understand how Io is evolving. IVO was selected for Phase A study through the NASA Discovery program in 2020 and, in anticipation of a New Frontiers 5 opportunity, an enhanced IVO-NF mission concept was advanced that would increase the Baseline mission from 10 flybys to 20, with an improved radiation design; employ a Ka-band communications to double IVO's total data downlink; add a wide angle camera for color and stereo mapping; add a dust mass spectrometer; and lower the altitude of later flybys to enable new science. This study compares and contrasts the mission architecture, instrument suite, and science objectives for Discovery (IVO) and New Frontiers (IVO-NF) missions to Io, and advocates for continued prioritization of Io as an exploration target for New Frontiers., Comment: Submitted to The Planetary Science Journal for peer-review on 14 August 2024

We measure the equation of state in a bilayer Hubbard system for different ratios of the two tunnelling amplitudes $t_\perp /t$. From the equation of state we deduce the compressibility and observe its dependency on $t_\perp /t$. Moreover, we infer thermodynamic number fluctuations from the equation of state by employing the fluctuation-dissipation theorem. By comparing the thermodynamic with local density fluctuations, we find that non-local density fluctuations in our bilayer Hubbard system become more prominent for higher $t_\perp /t$ in the low filling regime. To validate our measurements, we compare them to Determinant Quantum Monte Carlo simulations of a bilayer Hubbard system with 6$\times$6 lattice sites per layer.

Fermionic atoms in optical lattices have served as a compelling model system to study and emulate the physics of strongly-correlated matter. Driven by the advances of high-resolution microscopy, the recent focus of research has been on two-dimensional systems in which several quantum phases, such as anti-ferromagnetic Mott insulators for repulsive interactions and charge-density waves for attractive interactions have been observed. However, the aspired emulations of real materials, such as bilayer graphene, have to take into account that their lattice structure composes of coupled layers and therefore is not strictly two-dimensional. In this work, we realize a bilayer Fermi-Hubbard model using ultracold atoms in an optical lattice and demonstrate that the interlayer coupling controls a crossover between a planar anti-ferromagnetically ordered Mott insulator and a band insulator of spin-singlets along the bonds between the layers. Our work will enable the exploration of further fascinating properties of coupled-layer Hubbard models, such as theoretically predicted superconducting pairing mechanisms.

So far no designated mission to either of the two ice giants, Uranus and Neptune, exists. Almost all of our gathered information on these planets comes from remote sensing. In recent years, NASA and ESA have started planning for future mission to Uranus and Neptune, with both agencies focusing their attention on orbiters and atmospheric probes. Whereas information provided by remote sensing is undoubtedly highly valuable, remote sensing of planetary atmospheres also presents some shortcomings, most of which can be overcome by mass spectrometers. In most studies presented to date a mass spectrometer experiment is thus a favored science instrument for in situ composition measurements on an atmospheric probe. Mass spectrometric measurements can provide unique scientific data, i.e., sensitive and quantitative measurements of the chemical composition of the atmosphere, including isotopic, elemental, and molecular abundances. In this review paper we present the technical aspects of mass spectrometry relevant to atmospheric probes. This includes the individual components that make up mass spectrometers and possible implementation choices for each of these components. We then give an overview of mass spectrometers that were sent to space with the intent of probing planetary atmospheres, and discuss three instruments, the heritage of which is especially relevant to Uranus and Neptune probes, in detail. The main part of this paper presents the current state-of-art in mass spectrometry intended for atmospheric probe. Finally, we present a possible descent probe implementation in detail, including measurement phases and associated expected accuracies for selected species.

Rocky planets and moons experiencing solar wind sputtering are continuously supplying their enveloping exosphere with ejected neutral atoms. To understand the quantity and properties of the ejecta, well established Binary Collision Approximation Monte Carlo codes like TRIM with default settings are used predominantly. Improved models such as SDTrimSP have come forward and together with new experimental data the underlying assumptions have been challenged. We introduce a hybrid model, combining the previous surface binding approach with a new bulk binding model akin to Hofs\"ass & Stegmaier (2023). In addition, we expand the model implementation by distinguishing between free and bound components sourced from mineral compounds such as oxides or sulfides. The use of oxides and sulfides also enables the correct setting of the mass densities of minerals, which was previously limited to the manual setting of individual atomic densities of elements. All of the energies and densities used are thereby based on tabulated data, so that only minimal user input and no fitting of parameters are required. We found unprecedented agreement between the newly implemented hybrid model and previously published sputter yields for incidence angles up to 45{\deg} from surface normal. Good agreement is found for the angular distribution of mass sputtered from enstatite MgSiO$_3$ compared to latest experimental data. Energy distributions recreate trends of experimental data of oxidized metals. Similar trends are to be expected from future mineral experimental data. The model thus serves its purpose of widespread applicability and ease of use for modelers of rocky body exospheres., Comment: 23 pages, 6 figures, 3 tables

Enceladus, an icy moon of Saturn, possesses an internal water ocean and jets expelling ocean material into space. Cassini investigations indicated that the subsurface ocean could be a habitable environment having a complex interaction with the rocky core. Further investigation of the composition of the plume formed by the jets is necessary to fully understand the ocean, its potential habitability, and what it tells us about Enceladus' origin. Moonraker has been proposed as an ESA M-class mission designed to orbit Saturn and perform multiple flybys of Enceladus, focusing on traversals of the plume. The proposed Moonraker mission consists of an ESA-provided platform, with strong heritage from JUICE and Mars Sample Return, and carrying a suite of instruments dedicated to plume and surface analysis. The nominal Moonraker mission has a duration of 13.5 years. It includes a 23-flyby segment with 189 days allocated for the science phase, and can be expanded with additional segments if resources allow. The mission concept consists in investigating: i) the habitability conditions of present-day Enceladus and its internal ocean, ii) the mechanisms at play for the communication between the internal ocean and the surface of the South Polar Terrain, and iii) the formation conditions of the moon. Moonraker, thanks to state-of-the-art instruments representing a significant improvement over Cassini's payload, would quantify the abundance of key species in the plume, isotopic ratios, and physical parameters of the plume and the surface. Such a mission would pave the way for a possible future landed mission., Comment: Accepted for publication in The Planetary Science Journal

We numerically explore synthetic crystal diamond for realizing novel light sources in ranges which are up to now difficult to achieve with other materials, such as sub-10-fs pulse durations and challenging spectral ranges. We assess the performance of on-chip diamond waveguides for controlling light generation by means of nonlinear soliton dynamics. Tailoring the cross-section of such diamond waveguides allows to design dispersion profiles with custom zero-dispersion points and anomalous dispersion ranges exceeding an octave. Various propagation dynamics, including supercontinuum generation by soliton fission, can be realized in diamond photonics. In stark contrast to usual silica-based optical fibers, where such processes occur on the scale of meters, in diamond millimeter-scale propagation distances are sufficient. Unperturbed soliton-dynamics prior to soliton fission allow to identify a pulse self-compression scenario that promises record-breaking compression factors on chip-size propagation lengths.

We explore the parameter space for the contribution to Callisto's H corona observed by the Hubble Space Telescope (Roth et al. 2017a) from sublimated H2O and radiolytically produced H2 using the Direct Simulation Monte Carlo (DSMC) method. The spatial morphology of this corona produced via photo- and magnetospheric electron impact-induced dissociation is described by tracking the motion of and simulating collisions between the hot H atoms and thermal molecules including a near-surface O2 component. Our results indicate that sublimated H2O produced from the surface ice, whether assumed to be intimately mixed with or distinctly segregated from the dark non-ice or ice-poor regolith, cannot explain the observed structure of the H corona. On the other hand, a global H2 component can reproduced the observation, and is also capable of producing the enhanced electron densities observed at high altitudes by Galileo's plasma-wave instrument (Gurnett et al., 1997, 2000), providing the first evidence of H2 in Callisto's atmosphere. The range of H2 surface densities explored, under a variety of conditions, that are consistent with these observations is ~(0.4-1)x10^8 cm^-3. The simulated H2 escape rates and estimated lifetimes suggest that Callisto has a neutral H2 torus. We also place a rough upper limit on the peak H2O number density (<~10^8 cm^-3), column density (<~10^15 cm^-2), and sublimation flux (<~10^12 cm^-2 s^-1), all of which are 1-2 orders of magnitude less than that assumed in previous models. Finally, we discuss the implications of these results, as well as how they compare to Europa and Ganymede.

Recent laboratory efforts and telescopic observations of Europa have shown the relevance of a yellow colouration of sodium chloride (NaCl) caused by crystal defects generated by irradiation. We further investigate this process by irradiating (with energetic electrons) different types of analogues where NaCl is associated in different ways to water ice. We produce two types of icy analogues: compact slabs and granular particles where we investigate two particle sizes (5 and 70 $\mu$m). We perform electron irradiation at cryogenic temperatures (100 K) and under high vacuum (10-7 mbar) conditions, with energies of 1 and 5 keV. We observe the formation of two different types of colour centres. The so-called F-centres (460 nm) were formed in every sample, but the intensity of the absorption band within the compact slabs surpassed any other icy analogues and was comparable to the intensity of the absorption band within pure NaCl grains. M-centres (720 nm) have not been detected at the surface of Europa so far, and were close to the detection limit during our irradiation of compact slabs. The slabs could be good analogues for Europa_s surface as they produce mainly F-centres. Other notable differences have been observed between compact slabs and granular samples, such as the presence of an absorption band at 580 nm attributed to colloids of Na, exclusively within granular samples. Such absorptions have not been reported in previous studies., Comment: 57 pages, 13 figures

In this review we discuss all the relevant solar/stellar radiation and plasma parameters and processes that act together in the formation and modification of atmospheres and exospheres that consist of surface-related minerals. Magma ocean degassed silicate atmospheres or thin gaseous envelopes from planetary building blocks, airless bodies in the inner Solar System, and close-in magmatic rocky exoplanets such as CoRot-7b, HD219134b and 55 Cnc e are addressed. The depletion and fractionation of elements from planetary embryos, which act as the building blocks for protoplanets are also discussed. In this context the formation processes of the Moon and Mercury are briefly reviewed. The Lunar surface modification since its origin by micrometeoroids, plasma sputtering, plasma impingement as well as chemical surface alteration and the search of particles from the early Earth's atmosphere that were collected by the Moon on its surface are also discussed. Finally, we address important questions on what can be learned from the study of Mercury's environment and its solar wind interaction by MESSENGER and BepiColombo in comparison with the expected observations at exo-Mercurys by future space-observatories such as the JWST or ARIEL and ground-based telescopes and instruments like SPHERE and ESPRESSO on the VLT, and vice versa., Comment: 105 pages, 26 figures. This is a preprint of an article that is accepted for publication in Space Science Reviews

The ESA-JAXA BepiColombo mission will provide simultaneous measurements from two spacecraft, offering an unprecedented opportunity to investigate magnetospheric and exospheric dynamics at Mercury as well as their interactions with the solar wind, radiation, and interplanetary dust. Many scientific instruments onboard the two spacecraft will be completely, or partially devoted to study the near-space environment of Mercury as well as the complex processes that govern it. Many issues remain unsolved even after the MESSENGER mission that ended in 2015. The specific orbits of the two spacecraft, MPO and Mio, and the comprehensive scientific payload allow a wider range of scientific questions to be addressed than those that could be achieved by the individual instruments acting alone, or by previous missions. These joint observations are of key importance because many phenomena in Mercury's environment are highly temporally and spatially variable. Examples of possible coordinated observations are described in this article, analysing the required geometrical conditions, pointing, resolutions and operation timing of different BepiColombo instruments sensors., Comment: 78 pages, 14 figures, published

Results. We found that gas-phase silicon was present throughout the Rosetta mission. Furthermore, the presence of sodium and iron atoms near the comet's perihelion confirms that sputtering cannot be the sole release process for refractory elements into the gas phase. Nickel was found to be below the detection limit. The search for parent species of any of the identified gas phase refractories has not been successful. Upper limits for a suite of possible fragment species (SiH, SiC, NaH, etc.) of larger parent and daughter species have been obtained. Furthermore, Si did not exhibit the same drop in signal as do common cometary gases when the spacecraft is pointed away from the nucleus. The combined results suggest that a direct release of elemental species from small grains on the surface of the nucleus or from small grains in the surrounding coma is a more likely explanation than the previous assumption of release via the dissociation of gaseous parent molecules., Comment: Accepted for publication in A&A

MESSENGER observations suggest a magma ocean formed on proto-Mercury, during which evaporation of metals and outgassing of C- and H-bearing volatiles produced an early atmosphere. Atmospheric escape subsequently occurred by plasma heating, photoevaporation, Jeans escape, and photoionization. To quantify atmospheric loss, we combine constraints on the lifetime of surficial melt, melt composition, and atmospheric composition. Consideration of two initial Mercury sizes and four magma ocean compositions determine the atmospheric speciation at a given surface temperature. A coupled interior-atmosphere model determines the cooling rate and therefore the lifetime of surficial melt. Combining the melt lifetime and escape flux calculations provide estimates for the total mass loss from early Mercury. Loss rates by Jeans escape are negligible. Plasma heating and photoionization are limited by homopause diffusion rates of $\sim10^{6}$ kg/s. Loss by photoevaporation depends on the timing of Mercury formation and assumed heating efficiency and ranges from $\sim10^{6.6}$ to $\sim10^{9.6}$ kg/s. The material for photoevaporation is sourced from below the homopause and is therefore energy-limited rather than diffusion-limited. The timescale for efficient interior-atmosphere chemical exchange is less than ten thousand years. Therefore, escape processes only account for an equivalent loss of less than 2.3 km of crust ($0.3\%$ of Mercury's mass). Accordingly, $\leq0.02\%$ of the total mass of H$_2$O and Na is lost. Therefore, cumulative loss cannot significantly modify Mercury's bulk mantle composition during the magma ocean stage. Mercury's high core:mantle ratio and volatile-rich surface may instead reflect chemical variations in its building blocks resulting from its solar-proximal accretion environment., Comment: 25 pages, 8 figures, accepted to be published in The Planetary Science Journal

The identification of extraterrestrial life is one the most exciting and challenging endeavors in space research. The existence of extinct or extant life can be inferred from biogenic elements, isotopes, and molecules, but accurate and sensitive instruments are needed. In this whitepaper we show that Laser-based Mass Spectrometers are promising instrument for the in situ identification of atomic, isotopic, and molecular biosignatures. An overview of Laser ablation/Ionization Mass Spectrometry (LIMS) and Laser Desorption/Ionization Mass Spectrometry (LD-MS) instruments developed for space exploration is given. Their uses are discussed in the context of a Mars scenario and a Europa scenario. We show that Laser-based Mass Spectrometers are versatile and technologically mature instruments with many beneficial characteristics for the detection of life. Future planetary lander and rover missions should be encouraged to make use of Laser-based Mass Spectrometry instruments in their scientific payload., Comment: 10 pages, 1 figure. Submitted as a whitepaper for the Planetary Science and Astrobiology Decadal Survey 2023-2032

The mechanism of fermionic pairing is the key to understanding various phenomena such as high-temperature superconductivity and the pseudogap phase in cuprate materials. We study the pair correlations in the attractive Hubbard model using ultracold fermions in a two-dimensional optical lattice. By combining the fluctuation-dissipation theorem and the compressibility equation of state, we extract the interacting pair correlation functions and deduce a characteristic length scale of pairs as a function of interaction and density filling. At sufficiently low filling and weak on-site interaction, we observe that the pair correlations extend over a few lattice sites even at temperatures above the superfluid transition temperature.

The distant ice giants of the Solar System, Uranus and Neptune, have only been visited by one space mission, Voyager 2. The current knowledge on their composition remains very limited despite some recent advances. A better characterization of their composition is however essential to constrain their formation and evolution, as a significant fraction of their mass is made of heavy elements, contrary to the gas giants Jupiter and Saturn. An in situ probe like Galileo would provide us with invaluable direct ground-truth composition measurements. However, some of the condensibles will remain out of the grasp of a shallow probe. While additional constraints could be obtained from a complementary orbiter, thermochemistry and diffusion modeling can further help us to increase the science return of an in situ probe., Comment: Accepted for publication in Space Science Reviews